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Sample records for pulsed radar reflectometer

  1. First results from the small tight aspect ratio tokamak multifrequency pulse radar reflectometer

    NASA Astrophysics Data System (ADS)

    Shevchenko, V. F.; Walsh, M. J.

    1997-05-01

    A multifrequency pulse radar reflectometer (PRR) has been designed, commissioned, and is operating successfully on the small tight aspect ratio tokamak (START). The data obtained with this technique allow the study of the density profile evolution during the shot, revealing aspects of the plasma behavior during such events as the internal reconnection. A simple and effective profile-reconstruction algorithm using the stepwise profile approximation permits the monitoring of the plasma density profile immediately after each shot. Cross checks between the START hydrogen cyanide (HCN) interferometer and the line integral density determined by integrating the PRR generated data shows good agreement.

  2. Reflectometer

    NASA Astrophysics Data System (ADS)

    Malamed, E. R.; Putilov, I. E.; Tarasova, T. E.

    2006-03-01

    Our development concerns an optical instrument-making, particularly the reflectometers - the instruments intended for a measurement of a reflection coefficient of the smooth surfaces by an extra accuracy method using an interflection of the controllable sample. At the same time a problem of measurement of the light-transmission factor for transparent samples (with or without any optical antireflecting coating) is solved including a possibility of the multiple passing of the radiation through the investigated sample. The purpose of this research was a creation of a metrological test bench to measure reflection coefficients of mirrors with the high-reflective (close to 1) multi-layer interference surfaces with the help of the high-precision, noninvasive and nondestructive method and the measurement of the light-transmission factor for transparent samples. The detailed calculation of the optical scheme for several wave bands has been made. An analysis of the influence of different factors on a measurement error has been carried out. It has been demonstrated that the use of the offered reflectometer would allow to reduce the measurement errors.

  3. Downhole pulse radar

    DOEpatents

    Chang, Hsi-Tien

    1987-09-28

    A borehole logging tool generates a fast rise-time, short duration, high peak-power radar pulse having broad energy distribution between 30 MHz and 300 MHz through a directional transmitting and receiving antennas having barium titanate in the electromagnetically active region to reduce the wavelength to within an order of magnitude of the diameter of the antenna. Radar returns from geological discontinuities are sampled for transmission uphole. 7 figs.

  4. Downhole pulse radar

    DOEpatents

    Chang, Hsi-Tien

    1989-01-01

    A borehole logging tool generates a fast rise-time, short duration, high peak-power radar pulse having broad energy distribution between 30 MHz and 300 MHz through a directional transmitting and receiving antennas having barium titanate in the electromagnetically active region to reduce the wavelength to within an order of magnitude of the diameter of the antenna. Radar returns from geological discontinuities are sampled for transmission uphole.

  5. Phase-sensitive optical coherence reflectometer with differential phase-shift keying of probe pulses

    SciTech Connect

    Alekseev, A E; Vdovenko, V S; Sergachev, I A; Simikin, D E; Gorshkov, B G; Potapov, V T

    2014-10-31

    We report a new method for reconstructing the signal shape of the external dynamic perturbations along the entire length of the fibre of an optical coherence reflectometer. The method proposed is based on differential phase-shift keying of a probe pulse and demodulation of scattered light by the phase diversity technique. Possibilities of the method are demonstrated experimentally. (fibre-optic sensors)

  6. Performance of a reflectometer at continuous wave and pulsed neutron sources

    SciTech Connect

    Fitzsimmons, M.R.

    1995-12-31

    The Monte-Carlo simulations presented here involve simulations of reflectivity measurements of one sample using a reflectometer of traditional geometry at different neutron sources. The same reflectometer was used in all simulations. Only the characteristics of the neutron source, and the technique used to measure neutron wavelength were changed. In the case of the CW simulation, a monochromating crystal was used to select a nearly monochromatic beam (MB) from the neutron spectrum. In the simulations of the pulse sources, the time needed to traverse a fixed distance was measured, from which neutron wavelength is deduced.

  7. Microwave Imaging Radar Reflectometer System Utilizing Digital Beam Forming

    NASA Astrophysics Data System (ADS)

    Hu, Fengqi; Li, Meijiao; Domier, Calvin W.; Liu, Xiaoguang; Luhmann, Neville C., Jr.

    2016-10-01

    Microwave Imaging Reflectometry is a radar-like technique developed to measure the electron density fluctuations in fusion plasmas. Phased Antenna Arrays can serve as electronically controlled ``lenses'' that can generate the required wavefronts by phase shifting and amplitude scaling, which is being realized in the digital domain with higher flexibility and faster processing speed. In the transmitter, the resolution of the phase control is 1.4 degrees and the amplitude control is 0.5 dB/ step. A V-band double-sided, printed bow tie antenna which exhibits 49% bandwidth (46 - 76 GHz) is employed. The antenna is fed by a microstrip transmission line for easy impedance matching. The simple structure and the small antenna are suitable for low cost fabrication, easy circuit integration, and phased antenna array multi-frequency applications. In the receiver part, a sub-array of 32 channels with 200 mil spacing is used to collect the scattered reflected signal from one unit spot on the plasma cutoff surface. Pre-amplification is used to control the noise level of the system and wire bondable components are used to accommodate the small spacing between each channel. After down converting, base band signals are digitized and processed in an FPGA module. U.S. Department of Energy Grant No. DE-FG02-99ER54531.

  8. Fast pulsed radar reflectometry for the Textor Tokamak

    NASA Astrophysics Data System (ADS)

    Hugenholtz, C. A. J.; Donné, A. J. H.; Elzendoorn, B. S. Q.; van Gorkom, J. C.; Kooijman, W.; van der Laan, H. A.; van de Pol, M. J.; Putter, A. J.; van Ramele, H. J. F.; Smit, D.; de Vries, P. C.; Wijnoltz, F.; Pysik, W.; Waidmann, G.; Ermak, G. P.

    1999-01-01

    Progress in fusion research shows an increasing demand for diagnostics with high temporal and spatial resolution in order to study small and fast phenomena in fusion plasmas. Therefore, a new ten-channel pulsed radar reflectometer is under development for the TEXTOR Tokamak, to measure electron density profiles in the range of 0.4-4×1019m-3 at a high repetition rate of 2 MHz. An additional feature of this diagnostic is the possibility to perform correlation measurements at 10 MHz repetition rate to investigate density fluctuations. The reflectometer will scan the plasma with 1-ns-long radar pulses in the 18-57 GHz range. In spite of the long flight time of the pulses of about 100 ns, the above mentioned high repetition rates could be achieved by time multiplexing the generation and reception of the radar pulses. Temporal selection of the received pulses is performed by fast switching of the local oscillators inputs of the heterodyne receiver, to generate time windows in which the reception of the reflected pulses is expected. An embedded VME controller will manage the system and store the data with a speed of 20 Msamples/s, up to a maximum of 64 Mbyte data per plasma shot. In order to facilitate the handling of such a huge amount of data, an advanced data reduction scheme is being developed. Remote operation with a fast data link from FZ Jülich (Germany) to FOM Nieuwegein (The Netherlands) will be possible.

  9. Initial studies of reflectometer for ITER. Final report

    SciTech Connect

    Luhmann, N.C. Jr.

    1993-12-01

    ITER-related activities taking place over the last year were concentrated primarily on the area of advanced reflectometry systems. In particular, we have concentrated on reflectometer systems for density profile and density fluctuation studies on ITER. This interest has led us to spend much of our time investigating the pulsed radar time-of-flight reflectometer approaches (i.e. moderate pulse and ultrashort pulse). Pulsed radar systems offer the ability to make detailed profile measurements using fixed frequency sources, avoiding the need for highly stable sweepable sources as required by the more traditional FM radar systems.

  10. Measurement of edge density profiles of Large Helical Device plasmas using an ultrashort-pulse reflectometer

    NASA Astrophysics Data System (ADS)

    Yokota, Y.; Mase, A.; Kogi, Y.; Bruskin, L. G.; Tokuzawa, T.; Kawahata, K.

    2008-05-01

    We report here on the application of an ultrashort-pulse reflectometer (USPR) to Large Helical Device in National Institute for Fusion Science. An impulse with picosecond pulse width is used as a source in an USPR. Since the bandwidth of a source is inversely related to the pulse width, we can utilize the frequency range of microwave to millimeter-wave by using wide band transmission lines. The density profiles can be reconstructed by collecting time-of-flight signal of each frequency component of an impulse reflected from each cutoff layer. Remote control system using super science information network has been introduced to the present USPR system.

  11. VERITAS: a high-flux neutron reflectometer with vertical sample geometry for a long pulse spallation source

    NASA Astrophysics Data System (ADS)

    Mattauch, S.; Ioffe, A.; Lott, D.; Menelle, A.; Ott, F.; Medic, Z.

    2016-04-01

    An instrument concept of a reflectometer with a vertical sample geometry fitted to the long pulse structure of a spallation source, called “VERITAS” at the ESS, is presented. It focuses on designing a reflectometer with high intensity at the lowest possible background following the users' demand to investigate thin layers or interfacial areas in the sub-nanometer length scale. The high intensity approach of the vertical reflectometer fits very well to the long pulse structure of the ESS. Its main goal is to deliver as much usable intensity as possible at the sample position and be able to access a reflectivity range of 8 orders of magnitude and more. The concept assures that the reflectivity measurements can be performed in its best way to maximize the flux delivered to the sample. The reflectometer is optimized for studies of (magnetic) layers having thicknesses down to 5Å and a surface area of 1x1cm2. With reflectivity measurements the depth-resolved, laterally averaged chemical and magnetic profile can be investigated. By using polarised neutrons, additional vector information on the in-plane magnetic correlations (off-specular scattering at the pm length scale, GISANS at the nm length scale) can be studied. The full polarisation analysis could be used for soft matter samples to correct for incoherent scattering which is presently limiting neutron reflectivity studies to a reflectivity range on the order of 10-6.

  12. Micro pulse laser radar

    NASA Technical Reports Server (NTRS)

    Spinhirne, James D. (Inventor)

    1993-01-01

    An eye safe, compact, solid state lidar for profiling atmospheric cloud and aerosol scattering is disclosed. The transmitter of the micro pulse lidar is a diode pumped micro-J pulse energy, high repetition rate Nd:YLF laser. Eye safety is obtained through beam expansion. The receiver employs a photon counting solid state Geiger mode avalanche photodiode detector. Data acquisition is by a single card multichannel scaler. Daytime background induced quantum noise is controlled by a narrow receiver field-of-view and a narrow bandwidth temperature controlled interference filter. Dynamic range of the signal is limited to optical geometric signal compression. Signal simulations and initial atmospheric measurements indicate that micropulse lider systems are capable of detecting and profiling all significant cloud and aerosol scattering through the troposphere and into the stratosphere. The intended applications are scientific studies and environmental monitoring which require full time, unattended measurements of the cloud and aerosol height structure.

  13. A phase-sensitive optical time-domain reflectometer with dual-pulse phase modulated probe signal

    NASA Astrophysics Data System (ADS)

    Alekseev, A. E.; Vdovenko, V. S.; Gorshkov, B. G.; Potapov, V. T.; Simikin, D. E.

    2014-11-01

    A novel configuration of a phase-sensitive optical time-domain reflectometer (OTDR) utilizing dual-pulse phase modulations of the probe signal is presented and experimentally demonstrated. The proposed modulation method enables one to perform the demodulation and reconstruction of an external perturbation signal which impacts the fiber using the phase diversity technique. The proposed phase-sensitive OTDR has some advantages in comparison with conventional solutions, which are discussed. The feasibility of a double pulse OTDR with phase modulation is demonstrated and theoretically proved.

  14. Optimization of radar pulse compression processing

    NASA Astrophysics Data System (ADS)

    Song, Samuel M.; Kim, Woonkyung M.; Lee, Myung-Su

    1997-06-01

    We propose an optimal radar pulse compression technique and evaluate its performance in the presence of Doppler shift. The traditional pulse compression using Barker code increases the signal strength by transmitting a Barker coded long pulse. The received signal is then processed by an appropriate correlation processing. This Barker code radar pulse compression enhances the detection sensitivity while maintaining the range resolution of a single chip of the Barker coded long pulse. But unfortunately, the technique suffers from the addition of range sidelobes which sometimes will mask weak targets in the vicinity of larger targets. Our proposed optimal algorithm completely eliminates the sidelobes at the cost of additional processing.

  15. Intra-Pulse Radar-Embedded Communications

    DTIC Science & Technology

    2011-08-26

    Blunt, E. Mokole, R. Schneible, and M. Wicks, SciTech Publishing, 2010. 3. S.D. Blunt, T. Higgins, A.K. Shackelford , and K. Gerlach, “Multistatic... Shackelford , “Multi-dimensional Adaptive Processing for Angle-Dependent Radar Waveforms,” in preparation for IET Radar, Sonar & Navigation. 8. H... Shackelford , “Time-Range Adaptive Processing for Pulse Agile Radar,” 5 th International Waveform Diversity & Design Conference, Niagara Falls, Canada

  16. GSFC short pulse radar, JONSWAP-75

    NASA Technical Reports Server (NTRS)

    Levine, D. M.; Walton, W. T.; Eckerman, J.; Kutz, R. L.; Dombrowski, M.; Kalshoven, J. E., Jr.

    1977-01-01

    In September 1975, the Goddard Space Flight Center operated a short pulse radar during ocean wave measuring experiments off the coast of West Germany in the North Sea. The experiment was part of JONSWAP-75. The radar system and operations during the experiment are described along with examples of data.

  17. Removing interfering clutter associated with radar pulses that an airborne radar receives from a radar transponder

    DOEpatents

    Ormesher, Richard C.; Axline, Robert M.

    2008-12-02

    Interfering clutter in radar pulses received by an airborne radar system from a radar transponder can be suppressed by developing a representation of the incoming echo-voltage time-series that permits the clutter associated with predetermined parts of the time-series to be estimated. These estimates can be used to estimate and suppress the clutter associated with other parts of the time-series.

  18. Radiation hazard assessment of pulsed microwave radars.

    PubMed

    Puranen, L; Jokela, K

    1996-01-01

    Observed biological effects of pulsed microwave radiation are reviewed and the exposure standards for microwave radiation are summarized. The review indicates that the microwave auditory effect is the only well-established specific effect in realistic exposure situations. The threshold for the effect depends on the energy density per pulse and may be as low as 20 mJ/m2 for people with low hearing threshold. Energy density limits have been included in the most recent exposure standards. A new battery-operated, hand-held meter developed for measurements of pulse power densities around scanning radar antennas is described, and a simple new model for the calculation of power density in the main beam of radar antennas is presented. In the near field measured values differed from the calculated values by 2-3 dB.

  19. Photoconductive circuit element reflectometer

    DOEpatents

    Rauscher, C.

    1987-12-07

    A photoconductive reflectometer for characterizing semiconductor devices at millimeter wavelength frequencies where a first photoconductive circuit element (PCE) is biased by a direct current voltage source and produces short electrical pulses when excited into conductance by short first laser light pulses. The electrical pulses are electronically conditioned to improve the frequency related amplitude characteristics of the pulses which thereafter propagate along a transmission line to a device under test. Second PCEs are connected along the transmission line to sample the signals on the transmission line when excited into conductance by short second laser light pulses, spaced apart in time a determinable period from the first laser light pulses. Electronic filters connected to each of the second PCEs act as low-pass filters and remove parasitic interference from the sampled signals and output the sampled signals in the form of slowed-motion images of the signals on the transmission line. 4 figs.

  20. Photoconductive circuit element reflectometer

    DOEpatents

    Rauscher, Christen

    1990-01-01

    A photoconductive reflectometer for characterizing semiconductor devices at millimeter wavelength frequencies where a first photoconductive circuit element (PCE) is biased by a direct current voltage source and produces short electrical pulses when excited into conductance by short first laser light pulses. The electrical pulses are electronically conditioned to improve the frequency related amplitude characteristics of the pulses which thereafter propagate along a transmission line to a device under test. Second PCEs are connected along the transmission line to sample the signals on the transmission line when excited into conductance by short second laser light pulses, spaced apart in time a variable period from the first laser light pulses. Electronic filters connected to each of the second PCEs act as low-pass filters and remove parasitic interference from the sampled signals and output the sampled signals in the form of slowed-motion images of the signals on the transmission line.

  1. Radar Range Sidelobe Reduction Using Adaptive Pulse Compression Technique

    NASA Technical Reports Server (NTRS)

    Li, Lihua; Coon, Michael; McLinden, Matthew

    2013-01-01

    Pulse compression has been widely used in radars so that low-power, long RF pulses can be transmitted, rather than a highpower short pulse. Pulse compression radars offer a number of advantages over high-power short pulsed radars, such as no need of high-power RF circuitry, no need of high-voltage electronics, compact size and light weight, better range resolution, and better reliability. However, range sidelobe associated with pulse compression has prevented the use of this technique on spaceborne radars since surface returns detected by range sidelobes may mask the returns from a nearby weak cloud or precipitation particles. Research on adaptive pulse compression was carried out utilizing a field-programmable gate array (FPGA) waveform generation board and a radar transceiver simulator. The results have shown significant improvements in pulse compression sidelobe performance. Microwave and millimeter-wave radars present many technological challenges for Earth and planetary science applications. The traditional tube-based radars use high-voltage power supply/modulators and high-power RF transmitters; therefore, these radars usually have large size, heavy weight, and reliability issues for space and airborne platforms. Pulse compression technology has provided a path toward meeting many of these radar challenges. Recent advances in digital waveform generation, digital receivers, and solid-state power amplifiers have opened a new era for applying pulse compression to the development of compact and high-performance airborne and spaceborne remote sensing radars. The primary objective of this innovative effort is to develop and test a new pulse compression technique to achieve ultrarange sidelobes so that this technique can be applied to spaceborne, airborne, and ground-based remote sensing radars to meet future science requirements. By using digital waveform generation, digital receiver, and solid-state power amplifier technologies, this improved pulse compression

  2. A very wide frequency band pulsed/IF radar system

    NASA Technical Reports Server (NTRS)

    Jones, D. N.; Burnside, W. D.

    1988-01-01

    A pulsed/IF radar for compact range radar cross section measurements has been developed which converts RF returns to a fixed IF, so that amplification and grating may be performed at one frequency. This permits the use of components which have optimal performance at this frequency which results in a corresponding improvement in performance. Sensitivity and dynamic range are calculated for this system and compared with our old radar, and the effect of pulse width on clutter level is also studied. Sensitivity and accuracy tests are included to verify the performance of the radar.

  3. A bistatic pulse-Doppler intruder-detection radar

    NASA Astrophysics Data System (ADS)

    Walker, B. C.; Callahan, M. W.

    The U.S. Air Force's Aircraft Security Radar (ASR) is a small pulse-Doppler radar designed to detect intruders on the ground near parked aircraft, with a moving target detection effectiveness that encompasses high speed vehicles and intruders moving at as little as 2 cm/sec. The ASR is comparatively insensitive to weather, and will be affected only by severe wind and rain storms. Five ASRs are typically used around an aircraft, in order to reduce the area of coverage. Attention is given to the ASR's theory of operation, radar parameters, and both intruder and nuisance alarm test results.

  4. Study to investigate and evaluate means of optimizing the radar function for the space shuttle. [(pulse radar)

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Results are discussed of a study to define a radar and antenna system which best suits the space shuttle rendezvous requirements. Topics considered include antenna characteristics and antenna size tradeoffs, fundamental sources of measurement errors inherent in the target itself, backscattering crosssection models of the target and three basic candidate radar types. Antennas up to 1.5 meters in diameter are within specified installation constraints, however, a 1 meter diameter paraboloid and a folding, four slot backfeed on a two gimbal mount implemented for a spiral acquisition scan is recommended. The candidate radar types discussed are: (1) noncoherent pulse radar (2) coherent pulse radar and (3) pulse Doppler radar with linear FM ranging. The radar type recommended is a pulse Doppler with linear FM ranging. Block diagrams of each radar system are shown.

  5. Micromotion feature extraction of radar target using tracking pulses with adaptive pulse repetition frequency adjustment

    NASA Astrophysics Data System (ADS)

    Chen, Yijun; Zhang, Qun; Ma, Changzheng; Luo, Ying; Yeo, Tat Soon

    2014-01-01

    In multifunction phased array radar systems, different activities (e.g., tracking, searching, imaging, feature extraction, recognition, etc.) would need to be performed simultaneously. To relieve the conflict of the radar resource distribution, a micromotion feature extraction method using tracking pulses with adaptive pulse repetition frequencies (PRFs) is proposed in this paper. In this method, the idea of a varying PRF is utilized to solve the frequency-domain aliasing problem of the micro-Doppler signal. With appropriate atom set construction, the micromotion feature can be extracted and the image of the target can be obtained based on the Orthogonal Matching Pursuit algorithm. In our algorithm, the micromotion feature of a radar target is extracted from the tracking pulses and the quality of the constructed image is fed back into the radar system to adaptively adjust the PRF of the tracking pulses. Finally, simulation results illustrate the effectiveness of the proposed method.

  6. Covert situational awareness with handheld ultrawideband short-pulse radar

    NASA Astrophysics Data System (ADS)

    Barnes, Mark A.; Nag, Soumya; Payment, Tim

    2001-08-01

    Law enforcement and emergency services all face the difficult task of determining the locations of people within a building. A handheld radar able to detect motion through walls and other obstructions has been developed to fill this need. This paper describes the attributes and difficulties of the radar design and includes test results of the radar's performance. This discussion begins by summarizing key user requirements and the electromagnetic losses of typical building materials. Ultra-wideband (UWB) short pulse radars are well suited for a handheld sensor primarily because of their inherit time isolation in high clutter environments and their capability to achieve high resolution at low spectral center frequencies. There are also constraints that complicate the system design. Using a technique referred to as time-modulation allows the radars to reject range ambiguities and enhances electromagnetic compatibility with similar radars and ambient systems. An outline of the specifications of the radar developed and a process diagram on how it generates a motion map showing range and direction of the people moving within structures is included. Images are then presented to illustrate its performance. The images include adults, child, and a dog. The test results also include data showing the radar's performance through a variety of building materials.

  7. Study to investigate and evaluate means of optimizing the radar function. [systems engineering of pulse radar for the space shuttle

    NASA Technical Reports Server (NTRS)

    1975-01-01

    The investigations for a rendezvous radar system design and an integrated radar/communication system design are presented. Based on these investigations, system block diagrams are given and system parameters are optimized for the noncoherent pulse and coherent pulse Doppler radar modulation types. Both cooperative (transponder) and passive radar operation are examined including the optimization of the corresponding transponder design for the cooperative mode of operation.

  8. Pulse-to-pulse correlation in satellite radar altimeters. [for ocean wave height measurement

    NASA Technical Reports Server (NTRS)

    Walsh, E. J.

    1982-01-01

    Pulse-to-pulse correlation in satellite radar altimeters is examined to determine if range jitter in future altimeters could be reduced by increasing the pulse repetition frequency (PRF). Data from the Skylab radar altimeter is analyzed and compared with rules of thumb and the results of a Monte Carlo simulation. Altimeter range tracker configurations are reviewed and a simple curve is developed for the PRF below which decorrelation is assured. An adaptive PRF for future altimeters is recommended to conserve mission power while optimizing data collection during high-sea states.

  9. Clutter discrimination algorithm simulation in pulse laser radar imaging

    NASA Astrophysics Data System (ADS)

    Zhang, Yan-mei; Li, Huan; Guo, Hai-chao; Su, Xuan; Zhu, Fule

    2015-10-01

    Pulse laser radar imaging performance is greatly influenced by different kinds of clutter. Various algorithms are developed to mitigate clutter. However, estimating performance of a new algorithm is difficult. Here, a simulation model for estimating clutter discrimination algorithms is presented. This model consists of laser pulse emission, clutter jamming, laser pulse reception and target image producing. Additionally, a hardware platform is set up gathering clutter data reflected by ground and trees. The data logging is as clutter jamming input in the simulation model. The hardware platform includes a laser diode, a laser detector and a high sample rate data logging circuit. The laser diode transmits short laser pulses (40ns FWHM) at 12.5 kilohertz pulse rate and at 905nm wavelength. An analog-to-digital converter chip integrated in the sample circuit works at 250 mega samples per second. The simulation model and the hardware platform contribute to a clutter discrimination algorithm simulation system. Using this system, after analyzing clutter data logging, a new compound pulse detection algorithm is developed. This new algorithm combines matched filter algorithm and constant fraction discrimination (CFD) algorithm. Firstly, laser echo pulse signal is processed by matched filter algorithm. After the first step, CFD algorithm comes next. Finally, clutter jamming from ground and trees is discriminated and target image is produced. Laser radar images are simulated using CFD algorithm, matched filter algorithm and the new algorithm respectively. Simulation result demonstrates that the new algorithm achieves the best target imaging effect of mitigating clutter reflected by ground and trees.

  10. Ultra-wideband short-pulse radar with range accuracy for short range detection

    DOEpatents

    Rodenbeck, Christopher T; Pankonin, Jeffrey; Heintzleman, Richard E; Kinzie, Nicola Jean; Popovic, Zorana P

    2014-10-07

    An ultra-wideband (UWB) radar transmitter apparatus comprises a pulse generator configured to produce from a sinusoidal input signal a pulsed output signal having a series of baseband pulses with a first pulse repetition frequency (PRF). The pulse generator includes a plurality of components that each have a nonlinear electrical reactance. A signal converter is coupled to the pulse generator and configured to convert the pulsed output signal into a pulsed radar transmit signal having a series of radar transmit pulses with a second PRF that is less than the first PRF.

  11. Derivation of the radar range equation for a pulse-Doppler radar with range and velocity gating and coherent and noncoherent pulse integration

    NASA Astrophysics Data System (ADS)

    Masters, G.

    1986-06-01

    The radar range equation is employed in test planning to predict the probability of target detection for a given set of test conditions (target parameters, range, velocity, aspect angle, radar parameters, etc.). This technical memorandum documents the detailed development of the radar range equation including the effects of range gating, velocity gating, and both predetection and postdetection pulse integration.

  12. Range ambiguity resolution for high PRF pulse-Doppler radar

    NASA Astrophysics Data System (ADS)

    Postema, G. B.

    The range ambiguity resolution for high 'PRF pulse-Doppler radars can be resolved using a simple algorithm based on residue arithmetic. The unambiguous range is found from R = T + R(a), where T is the output of a look-up table and R(a) is one of the measured ambiguous ranges. This formula is easily extended to multiple PRF ranging systems, where three or more measurements are required for the ambiguity resolution. Target obscuration in clutter reduces the visibility and leads, especially in dense target environments, to ghost ranges. It is shown that long range coverage requires a small resolved pulse length and PRFs as low as practical in the intended clutter and target environment. Special attention is given to the generation of sparsely populated look-up tables that reduce the ghosting problem. A practical example for an S-band surveillance radar is presented.

  13. Range sidelobe elimination in phase-coded pulse radars

    NASA Astrophysics Data System (ADS)

    Dalle Mese, E.; Giuli, D.

    1982-08-01

    A method for reducing sidelobes in processing echoes received in phase-coded pulse radars is proposed. A recursive stable time-variant filter structure is derived which approximates an inverse code filter according to a least-squares optimality criterion. The application to the case of phase coding with binary Barker sequences is examined in detail. Performance of less complex but suboptimal filter structures are also evaluated.

  14. Autonomous radar pulse modulation classification using modulation components analysis

    NASA Astrophysics Data System (ADS)

    Wang, Pei; Qiu, Zhaoyang; Zhu, Jun; Tang, Bin

    2016-12-01

    An autonomous method for recognizing radar pulse modulations based on modulation components analysis is introduced in this paper. Unlike the conventional automatic modulation classification methods which extract modulation features based on a list of known patterns, this proposed method classifies modulations by the existence of basic modulation components including continuous frequency modulations, discrete frequency codes and discrete phase codes in an autonomous way. A feasible way to realize this method is using the features of abrupt changes in the instantaneous frequency rate curve which derived by the short-term general representation of phase derivative. This method is suitable not only for the basic radar modulations but also for complicated and hybrid modulations. The theoretical result and two experiments demonstrate the effectiveness of the proposed method.

  15. Forensic Application of FM-CW and Pulse Radar

    SciTech Connect

    S. K. Koppenjan; R. S. Freeland; M. L. Miller; R. E. Yoder

    2003-01-01

    Ground-penetrating radar (GPR) technology has supplied vital assistance in criminal investigations. However, law enforcement personnel desire further developments such that the technology is rapidly deployable, and that it provides both a simple user interface and sophisticated target identification. To assist in the development of target identification algorithms, our efforts involve gathering background GPR data for the various site conditions and circumstances that often typify clandestine burials. For this study, forensic anthropologists established shallow-grave plots at The University of Tennessee Anthropological Research Facility (ARF) that are specific to GPR research. These plots contain donated human cadavers lying in various configurations and depths, surrounded by assorted construction material and backfill debris. We scanned the plots using two GPR technologies: (1) a multi-frequency synthetic-aperture FM-CW radar (200-700 MHz) (GPR-X) developed by the U.S. Department of Energy's (DOE) Special Technologies Laboratory (STL), Bechtel Nevada (Koppenjan et al., 2000), and (2) a commercial pulse radar (SIR-20) manufactured by Geophysical Survey Systems, Inc. (400 and 900 MHz)(GSSI). The sweep-frequency data show the large biological mass decomposing within the torso as encircled ''hot spots.'' The 400-MHz pulse radar exhibit major horizontal reflectors above the body, with shadow reflectors (horizontal multiples) occurring beneath the body at 60 cm depth. The 400-MHz antenna was able to discern the grave walls and folded tarp covering the lower body. Under these moist, clay-rich conditions, the 900-MHz antenna was able to penetrate slightly beyond 30 cm beneath the concrete layer. However, neither system was able to penetrate beyond a one meter depth in the moist, clay-rich soil (fine, mixed, thermic Typic Paleudalf). Example scans from each system are provided, along with a discussion of the survey protocol and general performance.

  16. Advanced application flight experiment breadboard pulse compression radar altimeter program

    NASA Technical Reports Server (NTRS)

    1976-01-01

    Design, development and performance of the pulse compression radar altimeter is described. The high resolution breadboard system is designed to operate from an aircraft at 10 Kft above the ocean and to accurately measure altitude, sea wave height and sea reflectivity. The minicomputer controlled Ku band system provides six basic variables and an extensive digital recording capability for experimentation purposes. Signal bandwidths of 360 MHz are obtained using a reflective array compression line. Stretch processing is used to achieve 1000:1 pulse compression. The system range command LSB is 0.62 ns or 9.25 cm. A second order altitude tracker, aided by accelerometer inputs is implemented in the system software. During flight tests the system demonstrated an altitude resolution capability of 2.1 cm and sea wave height estimation accuracy of 10%. The altitude measurement performance exceeds that of the Skylab and GEOS-C predecessors by approximately an order of magnitude.

  17. Wake Vortex Tracking Using a 35 GHz Pulsed Doppler Radar

    NASA Technical Reports Server (NTRS)

    Neece, Robert T.; Britt, Charles L.; White, Joseph H.; Mudukutore, Ashok; Nguyen, Chi; Hooper, Bill

    2005-01-01

    A 35 GHz, pulsed-Doppler radar system has been designed and assembled for wake vortex detection and tracking in low visibility conditions. Aircraft wake vortices continue to be an important factor in determining safe following distances or spacings for aircraft in the terminal area. Currently, under instrument meteorological conditions (IMC), aircraft adhere to conservative, fixed following-distance guidelines based primarily on aircraft weight classifications. When ambient conditions are such that vortices will either drift or dissipate, leaving the flight corridor clear, the prescribed spacings are unnecessarily long and result in decreased airport throughput. There is a potential for significant airport efficiency improvement, if a system can be employed to aid regulators and pilots in setting safe and efficient following distances based on airport conditions. The National Aeronautics and Space Administration (NASA), the Federal Aviation Agency, and Volpe National Transportation Systems Center have promoted and worked to develop systems that would increase airport capacity and provide for safe reductions in aircraft separation. The NASA Aircraft Vortex Spacing System (AVOSS), a wake vortex spacing system that can provide dynamic adjustment of spacings based on real-time airport weather conditions, has demonstrated that Lidar systems can be successfully used to detect and track vortices in clear air conditions. To fill the need for detection capability in low-visibility conditions, a 35 GHz, pulsed-Doppler radar system is being investigated for use as a complimentary, low-visibility sensor for wake vortices. The radar sensor provides spatial and temporal information similar to that provided by Lidar, but under weather conditions that a Lidar cannot penetrate. Currently, we are analyzing the radar design based upon the data and experience gained during the wake vortex Lidar deployment with AVOSS at Dallas/Fort Worth International Airport. As part of this study

  18. Design of OFDM radar pulses using genetic algorithm based techniques

    NASA Astrophysics Data System (ADS)

    Lellouch, Gabriel; Mishra, Amit Kumar; Inggs, Michael

    2016-08-01

    The merit of evolutionary algorithms (EA) to solve convex optimization problems is widely acknowledged. In this paper, a genetic algorithm (GA) optimization based waveform design framework is used to improve the features of radar pulses relying on the orthogonal frequency division multiplexing (OFDM) structure. Our optimization techniques focus on finding optimal phase code sequences for the OFDM signal. Several optimality criteria are used since we consider two different radar processing solutions which call either for single or multiple-objective optimizations. When minimization of the so-called peak-to-mean envelope power ratio (PMEPR) single-objective is tackled, we compare our findings with existing methods and emphasize on the merit of our approach. In the scope of the two-objective optimization, we first address PMEPR and peak-to-sidelobe level ratio (PSLR) and show that our approach based on the non-dominated sorting genetic algorithm-II (NSGA-II) provides design solutions with noticeable improvements as opposed to random sets of phase codes. We then look at another case of interest where the objective functions are two measures of the sidelobe level, namely PSLR and the integrated-sidelobe level ratio (ISLR) and propose to modify the NSGA-II to include a constrain on the PMEPR instead. In the last part, we illustrate via a case study how our encoding solution makes it possible to minimize the single objective PMEPR while enabling a target detection enhancement strategy, when the SNR metric would be chosen for the detection framework.

  19. The pulse-pair algorithm as a robust estimator of turbulent weather spectral parameters using airborne pulse Doppler radar

    NASA Technical Reports Server (NTRS)

    Baxa, Ernest G., Jr.; Lee, Jonggil

    1991-01-01

    The pulse pair method for spectrum parameter estimation is commonly used in pulse Doppler weather radar signal processing since it is economical to implement and can be shown to be a maximum likelihood estimator. With the use of airborne weather radar for windshear detection, the turbulent weather and strong ground clutter return spectrum differs from that assumed in its derivation, so the performance robustness of the pulse pair technique must be understood. Here, the effect of radar system pulse to pulse phase jitter and signal spectrum skew on the pulse pair algorithm performance is discussed. Phase jitter effect may be significant when the weather return signal to clutter ratio is very low and clutter rejection filtering is attempted. The analysis can be used to develop design specifications for airborne radar system phase stability. It is also shown that the weather return spectrum skew can cause a significant bias in the pulse pair mean windspeed estimates, and that the poly pulse pair algorithm can reduce this bias. It is suggested that use of a spectrum mode estimator may be more appropriate in characterizing the windspeed within a radar range resolution cell for detection of hazardous windspeed gradients.

  20. Pulse compression with very low sidelobes in an airborne rain mapping radar

    NASA Astrophysics Data System (ADS)

    Tanner, A.; Durden, S. L.; Denning, R.; Im, E.; Li, F. K.; Ricketts, W.; Wilson, W.

    1994-01-01

    Pulse compression allows a substantial reduction in the peak transmitted power of a radar and is attractive for spaceborne remote sensing applications. In the case of a downward looking rain measuring radar, however, the range sidelobes associated with surface return can mask return from rain and must be kept to a minimum. Here, we describe the pulse compression system for the NASA/JPL Airborne Rain Mapping Radar. This system uses time-domain weighting of the transmitted pulse and is able to achieve a range sidelobe level of -55 dB or better in flight tests. This is significantly lower than other values reported in the open literature.

  1. Microwave reflectometer ionization sensor

    NASA Technical Reports Server (NTRS)

    Seals, Joseph; Fordham, Jeffrey A.; Pauley, Robert G.; Simonutti, Mario D.

    1993-01-01

    The development of the Microwave Reflectometer Ionization Sensor (MRIS) Instrument for use on the Aeroassist Flight Experiment (AFE) spacecraft is described. The instrument contract was terminated, due to cancellation of the AFE program, subsequent to testing of an engineering development model. The MRIS, a four-frequency reflectometer, was designed for the detection and location of critical electron density levels in spacecraft reentry plasmas. The instrument would sample the relative magnitude and phase of reflected signals at discrete frequency steps across 4 GHz bandwidths centered at four frequencies: 20, 44, 95, and 140 GHz. The sampled data would be stored for later processing to calculate the distance from the spacecraft surface to the critical electron densities versus time. Four stepped PM CW transmitter receivers were located behind the thermal protection system of the spacecraft with horn antennas radiating and receiving through an insulating tile. Techniques were developed to deal with interference, including multiple reflections and resonance effects, resulting from the antenna configuration and operating environment.

  2. Wrist Pulse Rate Monitor Using Self-Injection-Locked Radar Technology

    PubMed Central

    Wang, Fu-Kang; Tang, Mu-Cyun; Su, Sheng-Chao; Horng, Tzyy-Sheng

    2016-01-01

    To achieve sensitivity, comfort, and durability in vital sign monitoring, this study explores the use of radar technologies in wearable devices. The study first detected the respiratory rates and heart rates of a subject at a one-meter distance using a self-injection-locked (SIL) radar and a conventional continuous-wave (CW) radar to compare the sensitivity versus power consumption between the two radars. Then, a pulse rate monitor was constructed based on a bistatic SIL radar architecture. This monitor uses an active antenna that is composed of a SIL oscillator (SILO) and a patch antenna. When attached to a band worn on the subject’s wrist, the active antenna can monitor the pulse on the subject’s wrist by modulating the SILO with the associated Doppler signal. Subsequently, the SILO’s output signal is received and demodulated by a remote frequency discriminator to obtain the pulse rate information. PMID:27792176

  3. Wrist Pulse Rate Monitor Using Self-Injection-Locked Radar Technology.

    PubMed

    Wang, Fu-Kang; Tang, Mu-Cyun; Su, Sheng-Chao; Horng, Tzyy-Sheng

    2016-10-26

    To achieve sensitivity, comfort, and durability in vital sign monitoring, this study explores the use of radar technologies in wearable devices. The study first detected the respiratory rates and heart rates of a subject at a one-meter distance using a self-injection-locked (SIL) radar and a conventional continuous-wave (CW) radar to compare the sensitivity versus power consumption between the two radars. Then, a pulse rate monitor was constructed based on a bistatic SIL radar architecture. This monitor uses an active antenna that is composed of a SIL oscillator (SILO) and a patch antenna. When attached to a band worn on the subject's wrist, the active antenna can monitor the pulse on the subject's wrist by modulating the SILO with the associated Doppler signal. Subsequently, the SILO's output signal is received and demodulated by a remote frequency discriminator to obtain the pulse rate information.

  4. Application of Time Domain Reflectometers in Urban Settings

    EPA Science Inventory

    Time domain reflectometers (TDRs) are sensors that measure the volumetric water content of soils and porous media. The sensors consist of stainless steel rods connected to a circuit board in an epoxy housing. An electromagnetic pulse is propagated along the rods. The time, or per...

  5. Application of Time Domain Reflectometers in Urban Settings

    EPA Science Inventory

    Time domain reflectometers (TDRs) are sensors that measure the volumetric water content of soils and porous media. The sensors consist of stainless steel rods connected to a circuit board in an epoxy housing. An electromagnetic pulse is propagated along the rods. The time, or per...

  6. Preliminary tests of an airborne meteorological pulse Doppler radar

    NASA Astrophysics Data System (ADS)

    Trotter, B. L.; Strauch, R. G.; Frush, C. L.

    1980-05-01

    An X-band Doppler radar in the tail of a WP-3D research aircraft has been used to conduct tests which demonstrate that technology developed for ground-based Doppler radar can be applied to an airborne system. The Doppler spectra of meteorological targets and chaff have been measured with the airborne radar, and these measurements compared favorably with data obtained by wind sensors on the aircraft and with measurements made with a ground-based Doppler radar. This letter describes the airborne Doppler radar and the preliminary test results.

  7. Earth resources shuttle imaging radar. [systems analysis and design analysis of pulse radar for earth resources information system

    NASA Technical Reports Server (NTRS)

    1975-01-01

    A report is presented on a preliminary design of a Synthetic Array Radar (SAR) intended for experimental use with the space shuttle program. The radar is called Earth Resources Shuttle Imaging Radar (ERSIR). Its primary purpose is to determine the usefulness of SAR in monitoring and managing earth resources. The design of the ERSIR, along with tradeoffs made during its evolution is discussed. The ERSIR consists of a flight sensor for collecting the raw radar data and a ground sensor used both for reducing these radar data to images and for extracting earth resources information from the data. The flight sensor consists of two high powered coherent, pulse radars, one that operates at L and the other at X-band. Radar data, recorded on tape can be either transmitted via a digital data link to a ground terminal or the tape can be delivered to the ground station after the shuttle lands. A description of data processing equipment and display devices is given.

  8. Orthogonal on-off control of radar pulses for the suppression of mutual interference

    NASA Astrophysics Data System (ADS)

    Kim, Yong Cheol

    1998-10-01

    Intelligent vehicles of the future will be guided by radars and other sensors to avoid obstacles. When multiple vehicles move simultaneously in autonomous navigational mode, mutual interference among car radars becomes a serious problem. An obstacle is illuminated with electromagnetic pulses from several radars. The signal at a radar receiver is actually a mixture of the self-reflection and the reflection of interfering pulses emitted by others. When standardized pulse- type radars are employed on vehicles for obstacle avoidance and so self-pulse and interfering pulses have identical pulse repetition interval, this SI (synchronous Interference) is very difficult to separate from the true reflection. We present a method of suppressing such a synchronous interference. By controlling the pulse emission of a radar in a binary orthogonal ON, OFF pattern, the true self-reflection can be separated from the false one. Two range maps are generated, TRM (true-reflection map) and SIM (synchronous- interference map). TRM is updated for every ON interval and SIM is updated for every OFF interval of the self-radar. SIM represents the SI of interfering radars while TRM keeps a record of a mixture of the true self-reflection and SI. Hence the true obstacles can be identified by the set subtraction operation. The performance of the proposed method is compared with that of the conventional M of N method. Bayesian analysis shows that the probability of false alarm is improved by order of 103 to approximately 106 while the deterioration in the probability of detection is negligible.

  9. Measurement of lake ice thickness with a short-pulse radar system

    NASA Technical Reports Server (NTRS)

    Cooper, D. W.; Mueller, R. A.; Schertler, R. J.

    1976-01-01

    Measurements of lake ice thickness were made during March 1975 at the Straits of Mackinac by using a short-pulse radar system aboard an all-terrain vehicle. These measurements were compared with ice thicknesses determined with an auger. Over 25 sites were explored which had ice thicknesses in the range 29 to 60 cm. The maximum difference between radar and auger measurements was less than 9.8 percent. The magnitude of the error was less than + or - 3.5 cm. The NASA operating short-pulse radar system used in monitoring lake ice thickness from an aircraft is also described.

  10. Detection of personnel and small arms fire using pulse radar

    NASA Astrophysics Data System (ADS)

    Bonner, Joshua

    The scope is to fill in a gap of detecting targets using low power, small size radars. The main objective of this thesis is to show, through simulation, that a small, low power radar can be theoretically designed using standard radar principles to accomplish said task. The primary method used in this thesis is to ascertain the conclusion with two separate Matlab Simulations. First, the design of a radar to detect human sized targets moving along the ground and secondly, detection of small arms fire aimed towards helicopters were used as the primary examples. The results show that a human sized target can be detected up to a maximum of 4 km away using a radar with a power of 150 watts and a bullet up to several hundred meters using 1000 watts of power. The simulations show that such a radar is theoretical and mathematically plausible within the constraints.

  11. Fpga based L-band pulse doppler radar design and implementation

    NASA Astrophysics Data System (ADS)

    Savci, Kubilay

    As its name implies RADAR (Radio Detection and Ranging) is an electromagnetic sensor used for detection and locating targets from their return signals. Radar systems propagate electromagnetic energy, from the antenna which is in part intercepted by an object. Objects reradiate a portion of energy which is captured by the radar receiver. The received signal is then processed for information extraction. Radar systems are widely used for surveillance, air security, navigation, weather hazard detection, as well as remote sensing applications. In this work, an FPGA based L-band Pulse Doppler radar prototype, which is used for target detection, localization and velocity calculation has been built and a general-purpose Pulse Doppler radar processor has been developed. This radar is a ground based stationary monopulse radar, which transmits a short pulse with a certain pulse repetition frequency (PRF). Return signals from the target are processed and information about their location and velocity is extracted. Discrete components are used for the transmitter and receiver chain. The hardware solution is based on Xilinx Virtex-6 ML605 FPGA board, responsible for the control of the radar system and the digital signal processing of the received signal, which involves Constant False Alarm Rate (CFAR) detection and Pulse Doppler processing. The algorithm is implemented in MATLAB/SIMULINK using the Xilinx System Generator for DSP tool. The field programmable gate arrays (FPGA) implementation of the radar system provides the flexibility of changing parameters such as the PRF and pulse length therefore it can be used with different radar configurations as well. A VHDL design has been developed for 1Gbit Ethernet connection to transfer digitized return signal and detection results to PC. An A-Scope software has been developed with C# programming language to display time domain radar signals and detection results on PC. Data are processed both in FPGA chip and on PC. FPGA uses fixed

  12. Effects of pulse width and coding on radar returns from clear air

    NASA Technical Reports Server (NTRS)

    Cornish, C. R.

    1983-01-01

    In atmospheric radar studies it is desired to obtain maximum information about the atmosphere and to use efficiently the radar transmitter and processing hardware. Large pulse widths are used to increase the signal to noise ratio since clear air returns are generally weak and maximum height coverage is desired. Yet since good height resolution is equally important, pulse compression techniques such as phase coding are employed to optimize the average power of the transmitter. Considerations in implementing a coding scheme and subsequent effects of an impinging pulse on the atmosphere are investigated.

  13. Lidar-radar velocimetry using a pulse-to-pulse coherent rf-modulated Q-switched laser.

    PubMed

    Vallet, M; Barreaux, J; Romanelli, M; Pillet, G; Thévenin, J; Wang, L; Brunel, M

    2013-08-01

    An rf-modulated pulse train from a passively Q-switched Nd:YAG laser has been generated using an extra-cavity acousto-optic modulator. The rf modulation reproduces the spectral quality of the local oscillator. It leads to a high pulse-to-pulse phase coherence, i.e., phase memory, over thousands of pulses. The potentialities of this transmitter for lidar-radar are demonstrated by performing Doppler velocimetry on indoor moving targets. The experimental results are in good agreement with a model based on elementary signal processing theory. In particular, we show experimentally and theoretically that lidar-radar is a promising technique that allows discrimination between translation and rotation movements. Being independent of the laser internal dynamics, this scheme can be applied to any Q-switched laser.

  14. Hierarchical classification of dynamically varying radar pulse repetition interval modulation patterns.

    PubMed

    Kauppi, Jukka-Pekka; Martikainen, Kalle; Ruotsalainen, Ulla

    2010-12-01

    The central purpose of passive signal intercept receivers is to perform automatic categorization of unknown radar signals. Currently, there is an urgent need to develop intelligent classification algorithms for these devices due to emerging complexity of radar waveforms. Especially multifunction radars (MFRs) capable of performing several simultaneous tasks by utilizing complex, dynamically varying scheduled waveforms are a major challenge for automatic pattern classification systems. To assist recognition of complex radar emissions in modern intercept receivers, we have developed a novel method to recognize dynamically varying pulse repetition interval (PRI) modulation patterns emitted by MFRs. We use robust feature extraction and classifier design techniques to assist recognition in unpredictable real-world signal environments. We classify received pulse trains hierarchically which allows unambiguous detection of the subpatterns using a sliding window. Accuracy, robustness and reliability of the technique are demonstrated with extensive simulations using both static and dynamically varying PRI modulation patterns.

  15. Quantitative Gait Measurement With Pulse-Doppler Radar for Passive In-Home Gait Assessment

    PubMed Central

    Skubic, Marjorie; Rantz, Marilyn; Cuddihy, Paul E.

    2014-01-01

    In this paper, we propose a pulse-Doppler radar system for in-home gait assessment of older adults. A methodology has been developed to extract gait parameters including walking speed and step time using Doppler radar. The gait parameters have been validated with a Vicon motion capture system in the lab with 13 participants and 158 test runs. The study revealed that for an optimal step recognition and walking speed estimation, a dual radar set up with one radar placed at foot level and the other at torso level is necessary. An excellent absolute agreement with intraclass correlation coefficients of 0.97 was found for step time estimation with the foot level radar. For walking speed, although both radars show excellent consistency they all have a system offset compared to the ground truth due to walking direction with respect to the radar beam. The torso level radar has a better performance (9% offset on average) in the speed estimation compared to the foot level radar (13%–18% offset). Quantitative analysis has been performed to compute the angles causing the systematic error. These lab results demonstrate the capability of the system to be used as a daily gait assessment tool in home environments, useful for fall risk assessment and other health care applications. The system is currently being tested in an unstructured home environment. PMID:24771566

  16. Quantitative gait measurement with pulse-Doppler radar for passive in-home gait assessment.

    PubMed

    Wang, Fang; Skubic, Marjorie; Rantz, Marilyn; Cuddihy, Paul E

    2014-09-01

    In this paper, we propose a pulse-Doppler radar system for in-home gait assessment of older adults. A methodology has been developed to extract gait parameters including walking speed and step time using Doppler radar. The gait parameters have been validated with a Vicon motion capture system in the lab with 13 participants and 158 test runs. The study revealed that for an optimal step recognition and walking speed estimation, a dual radar set up with one radar placed at foot level and the other at torso level is necessary. An excellent absolute agreement with intraclass correlation coefficients of 0.97 was found for step time estimation with the foot level radar. For walking speed, although both radars show excellent consistency they all have a system offset compared to the ground truth due to walking direction with respect to the radar beam. The torso level radar has a better performance (9% offset on average) in the speed estimation compared to the foot level radar (13%-18% offset). Quantitative analysis has been performed to compute the angles causing the systematic error. These lab results demonstrate the capability of the system to be used as a daily gait assessment tool in home environments, useful for fall risk assessment and other health care applications. The system is currently being tested in an unstructured home environment.

  17. Review of pulsed CO2 laser radar technology

    NASA Astrophysics Data System (ADS)

    Hasson, V.

    The utility of CO2 laser radars is reviewed, and some relevant key transmitter technology issues are discussed. The utility aspect focuses on waveform and architectures and highlights the overall importance of the transmitter, from a weight/size/power consumption standpoint, in a laser radar system. The transmitter review covers major transmitter issues, namely, discharge techniques, frequency fidelity, and associated flow and acoustics control.

  18. Target Recognition Using Late-Time Returns from Ultra-Wideband, Short-Pulse Radar

    DTIC Science & Technology

    2004-06-01

    neglecting terms associated with surface resistance. The recognition sensor illuminates the target with a series of ultra-wideband, short radar pulses...the incident radar wave . Picture yourself looking into a mirror. If you can see your own face, you see the broadside of the mirror. Broadside is used...as an azimuth reference. Broadside illumination occurs when the incident wave approaches the object’s surface in a direction parallel to the surface

  19. FPGA based hardware optimized implementation of signal processing system for LFM pulsed radar

    NASA Astrophysics Data System (ADS)

    Azim, Noor ul; Jun, Wang

    2016-11-01

    Signal processing is one of the main parts of any radar system. Different signal processing algorithms are used to extract information about different parameters like range, speed, direction etc, of a target in the field of radar communication. This paper presents LFM (Linear Frequency Modulation) pulsed radar signal processing algorithms which are used to improve target detection, range resolution and to estimate the speed of a target. Firstly, these algorithms are simulated in MATLAB to verify the concept and theory. After the conceptual verification in MATLAB, the simulation is converted into implementation on hardware using Xilinx FPGA. Chosen FPGA is Xilinx Virtex-6 (XC6LVX75T). For hardware implementation pipeline optimization is adopted and also other factors are considered for resources optimization in the process of implementation. Focusing algorithms in this work for improving target detection, range resolution and speed estimation are hardware optimized fast convolution processing based pulse compression and pulse Doppler processing.

  20. Sub-nanosecond ranging possibilities of optical radar at various signal levels and transmitted pulse widths

    NASA Technical Reports Server (NTRS)

    Poultney, S. K.

    1971-01-01

    The behavior of the photomultiplier is considered, as well as the method of derivation of the photomultiplier output pulse and its relation to the reflected light pulse width and amplitude, and the calibration of range precision and accuracy. Pulsed laser radars with light pulse widths of 30, 3, and 0.1 nanosec a considered, with the 0.1 nanosec system capable of highest precision in several modes of operation, including a high repetition rate, single photoelectron reception mode. An alternate calibration scheme using a fast, triggerable light pulser is described in detail.

  1. Comparison of time of arrival vs. multiple parameter based radar pulse train deinterleavers

    NASA Astrophysics Data System (ADS)

    Lin, Samuel; Thompson, Michael; Davezac, Stephen; Sciortino, John C., Jr.

    2006-05-01

    This paper provides a comparison of the two main techniques currently in use to solve the problem of radar pulse train deinterleaving. Pulse train deinterleaving separates radar pulse trains into the tracks or bins associated with the detected emitters. The two techniques are simple time of arrival (TOA) histogramming and multi-parametric analysis. TOA analysis uses only the time of arrival (TOA) parameter of each pulse to deinterleave radar pulse trains. Such algorithms include Cumulative difference (CDIF) histogramming and Sequential difference (SDIF) histogramming. Multiparametric analysis utilizes any combination of the following parameters: TOA, radio frequency (RF), pulse width (PW), and angle of arrival (AOA). These techniques use a variety of algorithms, such as Fuzzy Adaptive Resonance Theory (Fuzzy-ART), Fuzzy Min-Max Clustering (FMMC), Integrated Adaptive Fuzzy Clustering (IAFC) and Fuzzy Adaptive Resonance Theory Map (Fuzzy-ARTMAP) to compare the pulses to determine if they are from the same emitter. Good deinterleaving is critical since inaccurate deinterleaving can lead to misidentification of emitters. The deinterleaving techniques evaluated in this paper are a sizeable and representative sample of both US and international efforts developed in the UK, Canada, Australia and Yugoslavia. Mardia [1989] and Milojevic and Popovich [1992] shows some of the early work in TOA-based deinterleaving. Ray [1997] demonstrates some of the more recent work in this area. Multi-parametric techniques are exemplified by Granger, et al [1998] and Thompson and Sciortino [2004]. This paper will provide an analysis of the algorithms and discuss the results obtained from the referenced articles. The algorithms will be evaluated for usefulness in deinterleaving pulse trains from agile radars.

  2. Real-time surveillance processor for synthetic pulse and antenna radar

    NASA Astrophysics Data System (ADS)

    Chassain, Thierry

    Consideration is given to a real-time surveillance computer which is characterized by the ability to digitally form antenna beams from a sparse phased array. This computer implements a large number of signal processing functions, from signal digitization to visualization (Doppler filtering and pulse compression). This computer is entirely digital, using only available standard components. Experimental results demonstrate the feasibility of signal processing based on synthetic pulse anad antenna radar principles.

  3. Study of coherent clutter model for airborne pulse-Doppler radar

    NASA Astrophysics Data System (ADS)

    Chen, Xingyu; Guan, Yifu

    2017-08-01

    This paper gives an efficient coherent clutter model for airborne pulse-Doppler radar in arbitrary posture. The ground is separated by range rings and angle units instead of range rings with Doppler units so as to reduce the computation cost. The MATLAB simulation gives the range-Doppler map of the clutter and the result proves the effectiveness of the clutter model.

  4. Non-MSE data compression for emitter location of radar pulse trains

    NASA Astrophysics Data System (ADS)

    Chen, Mo; Fowler, Mark L.

    2004-01-01

    This paper ties together and extends several recent results we have presented. We previously showed: (i) the usefulness of non-MSE distortion criteria in data compression for time-difference-of-arrival (TDOA) emitter location (SPIE 2001 & 2002), and (ii) the ability to exploit redundancy between radar pulses in a joint TDOA/FDOA (frequency-difference-of-arrival) location scheme (SPIE 2001 & 2002). In (ii) we showed how to compress radar signals by gating around the detected pulses and then putting the pulses into the rows of a matrix which is then compressed through use of the SVD; this approach employed a purely MSE distortion criterion. An open question in this approach was: Is it possible to eliminate some of the pulses from the pulse matrix to increase the compression ratio without significantly sacrificing location accuracy? We resolve this question by applying our proposed non-MSE to the FDOA accuracy and finding the optimal set of pulses to remove from the pulse matrix. The removal of pulses is shown to have negligible impact on the FDOA accuracy but does degrade the TDOA accuracy from that achievable using the SVD-based compression without pulse elimination. However, we demonstrate that the SVD method includes an inherent de-noising effect (common in SVD-based signal processing) that provides an improvement in TDOA accuracy over the case of no compression processing; thus, the overall impact on TDOA/FDOA accuracy is negligible while providing compression ratios on the order of 100:1 for typical radar signals.

  5. Study of radar pulse compression for high resolution satellite altimetry

    NASA Technical Reports Server (NTRS)

    Dooley, R. P.; Nathanson, F. E.; Brooks, L. W.

    1974-01-01

    Pulse compression techniques are studied which are applicable to a satellite altimeter having a topographic resolution of + 10 cm. A systematic design procedure is used to determine the system parameters. The performance of an optimum, maximum likelihood processor is analysed, which provides the basis for modifying the standard split-gate tracker to achieve improved performance. Bandwidth considerations lead to the recommendation of a full deramp STRETCH pulse compression technique followed by an analog filter bank to separate range returns. The implementation of the recommended technique is examined.

  6. Interpretation of measured data and the resolution analysis of the RTP 4-channel pulsed radar

    NASA Astrophysics Data System (ADS)

    Pavlo, Pavol

    1993-01-01

    An analysis is conducted of a four-channel pulsed radar for a tokamak; the radar's accuracies are dependent on time-of-flight measurements and number of sampling frequencies. Because the configuration is already established, emphasis is here placed on the interpretation of measured data and overall error minimization. The central density considered is above the critical density of all four frequencies, but not so high as to restrict measurements to the edge of the plasma. The overall error in estimating the reflection point position is obtained by balancing the inversion error and the time-measurement error.

  7. Monte Carlo simulation of wave sensing with a short pulse radar

    NASA Technical Reports Server (NTRS)

    Levine, D. M.; Davisson, L. D.; Kutz, R. L.

    1977-01-01

    A Monte Carlo simulation is used to study the ocean wave sensing potential of a radar which scatters short pulses at small off-nadir angles. In the simulation, realizations of a random surface are created commensurate with an assigned probability density and power spectrum. Then the signal scattered back to the radar is computed for each realization using a physical optics analysis which takes wavefront curvature and finite radar-to-surface distance into account. In the case of a Pierson-Moskowitz spectrum and a normally distributed surface, reasonable assumptions for a fully developed sea, it has been found that the cumulative distribution of time intervals between peaks in the scattered power provides a measure of surface roughness. This observation is supported by experiments.

  8. Fine range-motion simulation for hardware-in-the-loop testing of monostatic-pulsed LFM radars

    NASA Astrophysics Data System (ADS)

    Olson, Richard F., Jr.

    2011-06-01

    Frequency stepping is an established technique for increasing the range resolution of pulsed Linear Frequency Modulation (LFM, or chirp) radar waveforms [1]. When a monostatic radar system employs this waveform for increased range resolution measurements on an object with motion relative to the radar platform, simple changes in the received waveform arise, requiring fine motion compensation on a per-pulse basis. These motion effects include phase, frequency and frequency slope offsets which vary according to the transmitted pulse frequency and frequency rate, and the object range and range rate. All three offsets are easily compensated by complementary offsets in Direct Digital Synthesizer outputs used to form frequency conversion LO signals in the radar receiver. Radars employing stepped frequency LFM waveforms may be tested in a Hardware-in-the-Loop (HWIL) facility in simulations involving scenes or objects with radar-relative motion. Under these conditions, the motion effects on the radar receiver input signals must be accurately computed, synthesized and must modify the transmit signal prior to its return to the receiver. Engineers at the U.S. Army AMRDEC Advanced Simulation Center have developed signal processing techniques for accurate simulation of fine range motion effects to support HWIL testing of pulsed LFM radar systems. This paper provides an analysis of the signal processing involved for a simple model of an HWIL RF signal generation chain. Some results are presented from successful application of the motion simulation methods in an HWIL test setting.

  9. Ultra-Deep Bone Diagnostics with Fat-Skin Overlayers Using New Pulsed Photothermal Radar

    NASA Astrophysics Data System (ADS)

    Sreekumar, K.; Mandelis, A.

    2013-09-01

    The constraints imposed by the laser safety (maximum permissible exposure) ceiling on pump laser energy and the strong attenuation of thermal-wave signals in tissues significantly limit the photothermally active depth in most biological specimens to a level which is normally insufficient for practical applications (a few mm below the skin surface). A theoretical approach for improvement of the signal-to-noise ratio (SNR), minimizing the static (dc) component of the photothermal (PT) signal and making use of the PT radiometric nonlinearity has been introduced. At low frequencies fixed-pulse-width chirps of large peak power were found to be superior to all other equal energy modalities, with an SNR improvement by up to two orders of magnitude. Compared to radar peak delay and amplitude, the long-delayed radar output amplitude is found to be more sensitive to subsurface conditions. Two-dimensional spatial plots of this parameter depicting the back-surface conditions of bones with and without fat tissue overlayers are presented. Pulsed-chirp radar thermography has been demonstrated to monitor the degree of demineralization in goat rib bone with a substantial SNR and spatial resolution that is not practicable with harmonic radars of the same energy density.

  10. Short pulse radar used to measure sea surface wind speed and SWH. [Significant Wave Height

    NASA Technical Reports Server (NTRS)

    Hammond, D. L.; Mennella, R. A.; Walsh, E. J.

    1977-01-01

    A joint airborne measurement program is being pursued by NRL and NASA Wallops Flight Center to determine the extent to which wind speed and sea surface significant wave height (SWH) can be measured quantitatively and remotely with a short pulse (2 ns), wide-beam (60 deg), nadir-looking 3-cm radar. The concept involves relative power measurements only and does not need a scanning antenna, Doppler filters, or absolute power calibration. The slopes of the leading and trailing edges of the averaged received power for the pulse limited altimeter are used to infer SWH and surface wind speed. The interpretation is based on theoretical models of the effects of SWH on the leading edge shape and rms sea-surface slope on the trailing-edge shape. The models include the radar system parameters of antenna beam width and pulsewidth.

  11. Detection of Avalanche Victims Using Ultra-wideband Short-Pulse Radar

    NASA Astrophysics Data System (ADS)

    Chamma, Walid A.; Mende, Howard; Barrie, Greg; Robinson, Robert

    A short-pulse UWB radar system for search and rescue (SAR) operations of snow avalanche victims has been studied through numerical simulation and measurements. The FDTD method was used to model the radar system, the snow, and a realistic human phantom model buried in snow. A 0.5-ns UWB pulse with f0 = 2 GHz is used to illuminate the buried phantom from an array of nine transmitters. The reflected signals were received on a planer array and were processed using the time projection technique to generate ISAR images in the x-z and x-y planes. Farr impulse antennas were also used to measure reflected signals off buried targets, including a human phantom in snow. In both simulation and measurements, the removal of the background reflections (data with no buried targets) was a requirement to improve the dynamic range and toisolate the reflected signals due to buried targets.

  12. Micro-Doppler Ambiguity Resolution for Wideband Terahertz Radar Using Intra-Pulse Interference.

    PubMed

    Yang, Qi; Qin, Yuliang; Deng, Bin; Wang, Hongqiang; You, Peng

    2017-04-29

    Micro-Doppler, induced by micro-motion of targets, is an important characteristic of target recognition once extracted via parameter estimation methods. However, micro-Doppler is usually too significant to result in ambiguity in the terahertz band because of its relatively high carrier frequency. Thus, a micro-Doppler ambiguity resolution method for wideband terahertz radar using intra-pulse interference is proposed in this paper. The micro-Doppler can be reduced several dozen times its true value to avoid ambiguity through intra-pulse interference processing. The effectiveness of this method is proved by experiments based on a 0.22 THz wideband radar system, and its high estimation precision and excellent noise immunity are verified by Monte Carlo simulation.

  13. Micro-Doppler Ambiguity Resolution for Wideband Terahertz Radar Using Intra-Pulse Interference

    PubMed Central

    Yang, Qi; Qin, Yuliang; Deng, Bin; Wang, Hongqiang; You, Peng

    2017-01-01

    Micro-Doppler, induced by micro-motion of targets, is an important characteristic of target recognition once extracted via parameter estimation methods. However, micro-Doppler is usually too significant to result in ambiguity in the terahertz band because of its relatively high carrier frequency. Thus, a micro-Doppler ambiguity resolution method for wideband terahertz radar using intra-pulse interference is proposed in this paper. The micro-Doppler can be reduced several dozen times its true value to avoid ambiguity through intra-pulse interference processing. The effectiveness of this method is proved by experiments based on a 0.22 THz wideband radar system, and its high estimation precision and excellent noise immunity are verified by Monte Carlo simulation. PMID:28468257

  14. Note: A dual-chip stroboscopic pulsed RADAR for probing passive sensors

    NASA Astrophysics Data System (ADS)

    Minary, F.; Rabus, D.; Martin, G.; Friedt, J.-M.

    2016-09-01

    Stroboscopy provides an energy and computationally efficient means of sampling radiofrequency and microwave signals assumed to be reproducible under external excitation. While well known for impulse mode RADAR receivers, we here investigate its use for interrogating surface acoustic wave (SAW) transducers acting as passive cooperative targets. Amongst the originality of the implementation is the need to keep phase coherence between successive pulse generations which last up to tens of the radiofrequency periods to optimally transfer energy to the transducer. A two-chip receiver architecture is demonstrated, with a trigger signal compatible either with single-period avalanche transistor pulse excitation or frequency-agile direct digital synthesizer source.

  15. Monitoring the sea surface with a short pulse radar

    NASA Technical Reports Server (NTRS)

    Le Vine, D. M.

    1974-01-01

    A solution is presented for the scattering of short pulses from a stochastic, corrugated surface relative to the sea for the case of a narrow-beam transmitting antenna pointing near nadir. The spectrum of the received power and its time history are calculated and this solution is used to show that a measure of the variance of the surface ordinant can be obtained from the backscattered power. Included explicitly in the analysis is the finite nature of the source and the role of the small-scale wave structure (capillary wave range). It is shown that when sufficiently short pulses are transmitted, one can obtain a measure of the variance of the large scale surface ordinant from either the temporal spacing of the peaks in the returned power or from the envelope of the spectrum of the received power. Assuming an appropriate model for the statistics and spectrum of the surface ordinate, the variance can be used to compute the wind speed and the significant wave height of the surface.

  16. Pulse pressure monitoring through non-contact cardiac motion detection using 2.45 GHz microwave Doppler radar.

    PubMed

    Singh, Aditya; Lubecke, Victor; Boric-Lubecke, Olga

    2011-01-01

    The use of a Continuous Wave (CW) quadrature Doppler radar is proposed here for continuous non-invasive Pulse Pressure monitoring. A correspondence between the variation in systemic pulse and variation in the displacement of the chest due to heart is demonstrated, establishing feasibility for the approach. Arctangent demodulation technique was used to process baseband data from radar measurements on two test subjects, in order to determine the absolute cardiac motion. An Omron digital Blood pressure cuff was used to measure the systolic and diastolic blood pressures from which the pulse pressure was calculated. Correlation between pulse pressure and cardiac motion was observed through changes induced due to different postures of the body.

  17. Frequency hopping millimeter wave reflectometer

    NASA Astrophysics Data System (ADS)

    Cupido, L.; Sánchez, J.; Estrada, T.

    2004-10-01

    Reflectometry techniques are employed to study density fluctuations in fusion plasmas either using one channel or two channels with slightly different frequencies, to probe simultaneously closely spaced plasma layers (for radial correlation studies). The present article describes a novel system with increasing measuring capability utilizing only one single frequency that can be hopped during the discharge. This broadband fast hopping mm-wave reflectometer (BFHR) has been developed for both ASDEX upgrade (Max Plank Institute-Garching-Germany) and TJ-II stellarator (CIEMAT-Spain). The BFHR incorporates frequency synthesizers at microwave frequencies multiplied into the millimeter-wave range and uses heterodyne detection for sensitive phase and amplitude measurements.

  18. Highly depth-resolved chirped pulse photothermal radar for bone diagnostics.

    PubMed

    Kaiplavil, Sreekumar; Mandelis, Andreas

    2011-07-01

    A novel chirped pulse photothermal (PT) radiometric radar with improved sensitivity over the conventional harmonically modulated thermal-wave radar technique and alternative pulsed laser photothermal radiometry is introduced for the diagnosis of biological samples, especially bones with tissue and skin overlayers. The constraints imposed by the laser safety (maximum permissible exposure) ceiling on pump laser energy and the strong attenuation of thermal-wave signals in tissues significantly limit the photothermally active depth in most biological specimens to a level which is normally insufficient for practical applications (a few mm below the skin surface). A theoretical approach for improvement of signal-to-noise ratio (SNR), minimizing the static (dc) component of the photothermal signal and making use of the photothermal radiometric nonlinearity has been introduced and verified by comparing the SNR of four distinct excitation wave forms (sine-wave, square-wave, constant-width and constant duty-cycle pulses) for chirping the pump laser, under constant exposure energy. At low frequencies fixed-pulsewidth chirps of large peak power were found to be superior to all other equal-energy modalities, with an SNR improvement up to two orders of magnitude. Distinct thickness-dependent characteristic delay times in a goat bone were obtained, establishing an active depth resolution range of ~2.8 mm in a layered skin-fat-bone structure, a favorable result compared to the maximum reported pulsed photothermal radiometric depth resolution <1 mm in turbid biological media.

  19. Maximum detection range limitation of pulse laser radar with Geiger-mode avalanche photodiode array

    NASA Astrophysics Data System (ADS)

    Luo, Hanjun; Xu, Benlian; Xu, Huigang; Chen, Jingbo; Fu, Yadan

    2015-05-01

    When designing and evaluating the performance of laser radar system, maximum detection range achievable is an essential parameter. The purpose of this paper is to propose a theoretical model of maximum detection range for simulating the Geiger-mode laser radar's ranging performance. Based on the laser radar equation and the requirement of the minimum acceptable detection probability, and assuming the primary electrons triggered by the echo photons obey Poisson statistics, the maximum range theoretical model is established. By using the system design parameters, the influence of five main factors, namely emitted pulse energy, noise, echo position, atmospheric attenuation coefficient, and target reflectivity on the maximum detection range are investigated. The results show that stronger emitted pulse energy, lower noise level, more front echo position in the range gate, higher atmospheric attenuation coefficient, and higher target reflectivity can result in greater maximum detection range. It is also shown that it's important to select the minimum acceptable detection probability, which is equivalent to the system signal-to-noise ratio for producing greater maximum detection range and lower false-alarm probability.

  20. Sub-Nyquist sampling and detection in Costas coded pulse compression radars

    NASA Astrophysics Data System (ADS)

    Hanif, Adnan; Mansoor, Atif Bin; Imran, Ali Shariq

    2016-12-01

    Modern pulse compression radar involves digital signal processing of high bandwidth pulses modulated with different coding schemes. One of the limiting factors in the radar's design to achieve desired target range and resolution is the need of high rate analog-to-digital (A/D) conversion fulfilling the Nyquist sampling criteria. The high sampling rates necessitate huge storage capacity, more power consumption, and extra processing requirement. We introduce a new approach to sample wideband radar waveform modulated with Costas sequence at a sub-Nyquist rate based upon the concept of compressive sensing (CS). Sub-Nyquist measurements of Costas sequence waveform are performed in an analog-to-information (A/I) converter based upon random demodulation replacing traditional A/D converter. The novel work presents an 8-order Costas coded waveform with sub-Nyquist sampling and its reconstruction. The reconstructed waveform is compared with the conventionally sampled signal and depicts high-quality signal recovery from sub-Nyquist sampled signal. Furthermore, performance of CS-based detections after reconstruction are evaluated in terms of receiver operating characteristic (ROC) curves and compared with conventional Nyquist-rate matched filtering scheme.

  1. Microwave Imaging Reflectometer for TEXTOR

    SciTech Connect

    T. Munsat; E. Mazzucato; H. Park; B.H. Deng; C.W. Domier; N.C. Luhmann, Jr.; J. Wang; Z.G. Xia; A.J.H. Donne; and M. van de Pol

    2002-07-09

    Understanding the behavior of fluctuations in magnetically confined plasmas is essential to the advancement of turbulence-based transport physics. Though microwave reflectometry has proven to be an extremely useful and sensitive tool for measuring small density fluctuations in some circumstances, this technique has been shown to have limited viability for large amplitude, high kq fluctuations and/or core measurements. To this end, a new instrument based on 2-D imaging reflectometry has been developed to measure density fluctuations over an extended plasma region in the TEXTOR tokamak. This technique is made possible by collecting an extended spectrum of reflected waves with large-aperture imaging optics. Details of the imaging reflectometry concept, as well as technical details of the TEXTOR instrument will be presented. Data from roof-of-principle experiments on TEXTOR using a prototype system is presented, as well as results from a systematic off-line study of the advantages and limitations of the imaging reflectometer.

  2. Investigation of mixed ionospheric and fround scatter using high spectral content pulse sequences for SuperDARN radars

    NASA Astrophysics Data System (ADS)

    Spaleta, J.; Bristow, W. A.

    2013-12-01

    SuperDARN radars estimate plasma drift velocities from the Doppler shift observed on signals scattered from field-aligned density irregularities. These field-aligned density irregularities are embedded in the ionospheric plasma, and move at the same velocity as background plasma. As a result, the electromagnetic signals scattered from these irregularities are Doppler shifted. The SuperDARN radars routinely observe ionospheric scatter Doppler velocities ranging from zero to thousands of meters per second. The radars determine the Doppler shift of the ionospheric scatter by linear fitting the phase of an auto correlation function derived from the radar pulse sequence. The phase fitting technique employed assumes a single dominant velocity is present in the signal. In addition, the SuperDARN radars can also observe signals scattered from the ground. Once refracted by the ionospheric plasma and bent earthward, the radar pulses eventually reach the ground where they scatter, sending signal back to the radar. This ground-scatter signal is characterized as having a low Doppler shift and low spectral width. The SuperDARN radars are able to use these signal characteristics to discriminate the ground scatter signal from the ionospheric scatter, when regions of ground scatter are isolated from ionospheric scatter returns. The phase fitting assumption of a single dominate target can easily be violated at ranges where ground and ionospheric scatter mix together. Due to the wide elevation angle extent of the SuperDARN radar design, ground and ionospheric scatter from different propagation paths can mix together in the return signal. When this happens, the fitting algorithm attempts to fit to the dominant signal, and if ground scatter dominates, information about the ionospheric scatter at that range can be unresolved. One way to address the mix scatter situation is to use a high spectral content pulse sequence together with a spectral estimation technique. The high spectral

  3. A short-pulse K(a)-band instrumentation radar for foliage attenuation measurements.

    PubMed

    Puranen, Mikko; Eskelinen, Pekka

    2008-10-01

    A portable K(a)-band instrumentation radar for foliage attenuation measurements has been designed. It uses direct dielectric resonator oscillator multiplier pulse modulation giving a half power pulse width of 17 ns. The dual conversion scalar receiver utilizes either a digital storage oscilloscope in envelope detection format or a special gated comparator arrangement providing 1 m resolution and associated led seven segment display for data analysis. The calibrated dynamic range is better than 37 dB with an equivalent noise floor of 0.005 dBsm at 25 m test range distance. First experiments indicate an effective beamwidth close to 1 degree. The total weight is below 5 kg and the unit can be mounted on a conventional photographic tripod. Power is supplied from a 12 V/6 A h sealed lead acid battery giving an operating time in excess of 10 h.

  4. Radar Target Discrimination and Identification Using Extinction-Pulses and Single-Mode Extraction Pulses

    DTIC Science & Technology

    1991-01-31

    T-15 model ( home made and arbitrarily named) of length 30 cm, (3) a big B707 model of length 64.5 cm and (4) a big F-18 model of length 72 cm as shown...0018-926X/86/0700-0896501.00 © 1986 IEEE 87 CHEN et al. RADAR TARGET DISCRIMINATION 897 Fortunately, for most space vehicles , such as rockets and...and complex permittivities7 37 Jare defined as Eo=- 1’ 8 H. (6) E;=e2+ O/S (19) where 1h = S2 ;Z + M2S (20) V2H , -PH, = 0 (7) el = el + aIs (21) SUN ET

  5. High-power pulsed diode laser for automotive scanning radar sensor

    NASA Astrophysics Data System (ADS)

    Kimura, Yuji; Matsushita, Noriyuki; Kato, Hisaya; Abe, Katsunori; Atsumi, Kinya

    2000-02-01

    High performance pulsed AlGaAs/GaAs wide stripe diode laser has been developed for the automotive distance-measuring scanning radar sensor. The laser diode is required high output power of 15 W and a long time reliability in spite of being used in a harsh environment such as wide temperature range, mechanical vibrations at the front bumper and so on. The device is designed by employing a multiple quantum well structure as an active layer for high output power with low drive current and high temperature operations. Moreover we reduce catastrophic optical damage power level and control the beam divergence angle by introducing optimized optical waveguide layers. In the chips bonding part, we developed a new thin film Au-Sn-Ni solder system. The bonding temperature can be lowered by using this system, whereby the thermal damage to the laser diode can be reduced. Furthermore, highly stable bonding is carried out by improving wetting ability in this system. We have achieved more than 22 W light output power at 20A pulse current under room temperature and more than 16 W light output power under 90 degrees Celsius. High reliability over 10,000 hours is performed for automotive use under pulsed operation at 90 degrees Celsius, 50 ns pulse width, 8 kHz frequency and 15 W light output power.

  6. Pulse-to-pulse correlation in CryoSat SAR mode radar altimeter echoes from the sea surface

    NASA Astrophysics Data System (ADS)

    Smith, W. H.

    2012-12-01

    Serial correlation among successive radar echoes returned from the ocean surface is an important design constraint in satellite altimetry. Walsh [1974, 1982] established the conventional wisdom. Taking the radar footprint to be a uniformly radiating disk, he derived a theoretically expected echo decorrelation time of about 0.5 milliseconds. Following Walsh, ocean altimeters usually employ a pulse repetition frequency (PRF) around 2 kHz, in order to obtain statistically independent echoes at (so it is thought) the maximum possible rate. CryoSat, designed for ranging to ice surfaces, employs a PRF of 18.2 kHz in its SAR mode. CryoSat SAR echo sequences over ocean surfaces can be used to empirically determine the ocean echo decorrelation, and thus to test Walsh's model. Such a test is presented in this paper. The analysis begins by forming the ensemble average of complex cross products of pairs of echoes separated by a time lag L * PRI, where the pulse repetition interval (PRI) is 55 microseconds and the echo lag L runs from 0 to 32. The L = 0 case yields the conventional pulse-limited waveform, which is used to determine the sea state in each ensemble average. The averages of lagged echo cross products reveal the complex coherency, with sampling in both slow time (lag, L), and fast time (range, sampled in waveform gates). Data from many areas and sea states are analyzed, and the results are explained using a simple theory approximating the complex coherency expected from a Gaussian radar pulse. This theory generalizes the classical Brown [1977] waveform model to lagged echo cross products, and generalizes Walsh's work to the case of footprints with non-uniform illumination and diffuse edges. Phase is due to vertical motion of the antenna. Amplitude variations in fast time are due to horizontal motion of the antenna, and are independent of wave height; their functional form confirms Brown's assumption that scattering is independent of azimuth. In slow time, the

  7. Using a neural networks algorithm for high-resolution imaging in pulsed laser radar

    NASA Astrophysics Data System (ADS)

    Joodaki, Mojtaba; Kompa, Guenter; Golam Arshad, Seyed M.; Ahmadi, Vahid; Moravvej-Farshi, Mohammed K.

    2001-11-01

    A new imaging method which can obtain the gray levels directly from the output waveform of Pulsed Laser Radar (PLR) is developed. A simple digital signal processing technique and multi layer perceptrons (MLP) type neural network (NN) have been used to obtain the gray level information from the pulse shapes. The method has been implemented in a real PLR to improve contrast and speed of 2D imaging in PLR. To compare the method with the standard method, a picture consists of 16 gray levels (from 0 for black to 1 for white) with both method has been scanned. Because of the ability of NNs in extracting the information from nonlinear and noisy data and preprocessing of the noisy input pulse shapes to the NN, the average and maximum of errors in the gray levels in comparison with standard method more than 88.5% and 72.6% improved, respectively. Because in this method the effect of the noise is decreased, it is possible to make the imaging with the same resolution as in standard method but with a lower averaging in sampling unit and this dramatically increases speed of the measurements.

  8. Integrated multi-channel receiver for a pulsed time-of-flight laser radar

    NASA Astrophysics Data System (ADS)

    Jiang, Yan; Liu, Ruqing; Zhu, Jingguo

    2015-04-01

    An integrated multi-channel receiver for a pulsed time-of-flight (TOF) laser rangefinder has been designed in this paper. The receiver chip as an important component of the laser radar device has been implemented in a 0.18um CMOS process. It consists of sixteen channels and every channel includes preamplifier, amplifier stages, high-pass filter and a timing discriminator which contains a timing comparator and a noise comparator. Each signal paths is independent of other channels. Based on the simulations, the bandwidth and transimpedance of the amplifier channel are 652MHz, 99dBΩ. Under the simulation condition of TT corner and 27°C, the propagation delay of the discriminator is 2.15ns and the propagation delay dispersion is 223ps. The power consumption during continuous measurement is 810mW, and the operating temperature range of the device is -10~60°C.

  9. Fixed lag smoothing target tracking in clutter for a high pulse repetition frequency radar

    NASA Astrophysics Data System (ADS)

    Khan, Uzair; Shi, Yi Fang; Song, Taek Lyul

    2015-12-01

    A new method to smooth the target hybrid state with Gaussian mixture measurement likelihood-integrated track splitting (GMM-ITS) in the presence of clutter for a high pulse repetition frequency (HPRF) radar is proposed. This method smooths the target state at fixed lag N and considers all feasible multi-scan target existence sequences in the temporal window of scans in order to smooth the target hybrid state. The smoothing window can be of any length N. The proposed method to smooth the target hybrid state at fixed lag is also applied to the enhanced multiple model (EMM) tracking algorithm. Simulation results indicate that the performance of fixed lag smoothing GMM-ITS significantly improves false track discrimination and root mean square errors (RMSEs).

  10. 2-D Reflectometer Modeling for Optimizing the ITER Low-field Side Reflectometer System

    SciTech Connect

    Kramer, G.J.; Nazikian, R.; Valeo, E.J.; Budny, R.V.; Kessel, C.; Johnson, D.

    2005-09-02

    The response of a low-field side reflectometer system for ITER is simulated with a 2?D reflectometer code using a realistic plasma equilibrium. It is found that the reflected beam will often miss its launch point by as much as 40 cm and that a vertical array of receiving antennas is essential in order to observe a reflection on the low-field side of ITER.

  11. Reflectometer distance measurement between parallel conductive plates

    NASA Technical Reports Server (NTRS)

    Hearn, Chase P.; Neece, Robert T.

    1995-01-01

    This report presents an analytic and experimental investigation of the measurement problem in which a reflectometer is used to determine the distance to a target that is a highly conductive surface parallel to the reflectometer antenna ground plane. These parallel surfaces constitute a waveguide (WG) which can contribute parasitic perturbations that seriously degrade the accuracy of the measurements. Two distinct parallel-plate-waveguide (PPWG) phenomena are described, and their effects on both frequency and time-domain reflectometers are considered. The time-domain processing approach was found to be superior to a representative frequency-domain phase-measurement approach because of less susceptibility to perturbations produced by edge reflections and immunity to phase capture. Experimental results are presented which show that a simple radiating system modification can suppress parallel-plate (PP) propagation. The addition of a thin layer of lossy mu-metal 'magnetic absorber' to the antenna ground plane allowed a measurement accuracy of 0.025 cm (0.01 in.) when a vector network analyzer (VNA) is used as a time-domain reflectometer.

  12. Analysis and improved design considerations for airborne pulse Doppler radar signal processing in the detection of hazardous windshear

    NASA Technical Reports Server (NTRS)

    Lee, Jonggil

    1990-01-01

    High resolution windspeed profile measurements are needed to provide reliable detection of hazardous low altitude windshear with an airborne pulse Doppler radar. The system phase noise in a Doppler weather radar may degrade the spectrum moment estimation quality and the clutter cancellation capability which are important in windshear detection. Also the bias due to weather return Doppler spectrum skewness may cause large errors in pulse pair spectral parameter estimates. These effects are analyzed for the improvement of an airborne Doppler weather radar signal processing design. A method is presented for the direct measurement of windspeed gradient using low pulse repetition frequency (PRF) radar. This spatial gradient is essential in obtaining the windshear hazard index. As an alternative, the modified Prony method is suggested as a spectrum mode estimator for both the clutter and weather signal. Estimation of Doppler spectrum modes may provide the desired windshear hazard information without the need of any preliminary processing requirement such as clutter filtering. The results obtained by processing a NASA simulation model output support consideration of mode identification as one component of a windshear detection algorithm.

  13. Compact multichannel receiver using InGaAs APDs for single-pulse eye-safe laser radar imagery

    NASA Astrophysics Data System (ADS)

    Burns, Hoyt N.; Yun, Steven T.; Dinndorf, Kenneth M.; Hayden, David R.

    1997-08-01

    Active imaging laser radars form 3D images which can be processed to provide target identification and precision aimpoint definition in real time. Earlier raster-scanned and pushbroom-scanned 3D imaging laser radar receivers required multiple laser pulses to assemble a complete 3D image frame. Platform/target motion and atmospheric effects caused tearing and jitter in the assembled 3D images, which complicated the subsequent image processing and necessitated the use of stabilized scanning systems. This paper describes the current status of the parallel/multichannel imaging laser radar receiver (PMR) which is being developed under an SBIR Phaser II program by the USAF Wright Laboratories Armament Directorate. The PMR uses an array of multichannel laser radar receivers to form single-pulse, 3D laser radar images, thus eliminating the complex and costly scanning system, and enabling much higher frame rates than were ever before possible. The heart of the PMR is the multichannel optical receiver photonic hybrid (MORPH), a high performance 16-channel laser radar receiver module which uses an array of InGaAs avalanche photodiodes for eyesafe operation. The MORPH provides high downrange resolution, multihit range data for each detector on a compact circuit card. Optical flux is transferred from the receiver focal plane to each MORPH via a fiber optic ribbon cable. An array of MORPHs are plugged into a compact passive backplane, along with a single digital control card (DCC). The DCC, which is the same form factor as the MORPH, synchronizes the MORPHs and transfers the digital range information to the host processor over a standard parallel data interface cable. The system described here illustrates one approach to integrating and packaging high-density photonic arrays and their associated signal processing electronics to yield a compact, low power, scannerless, high performance imaging laser radar receiver, using existing technology.

  14. Blood Pressure Estimation Using Pulse Transit Time From Bioimpedance and Continuous Wave Radar.

    PubMed

    Buxi, Dilpreet; Redout, Jean-Michel; Yuce, Mehmet Rasit

    2017-04-01

    We have developed and tested a new architecture for pulse transit time (PTT) estimation at the central arteries using electrical bioimpedance, electrocardiogram, and continuous wave radar to estimate cuffless blood pressure. A transmitter and receiver antenna are placed at the sternum to acquire the arterial pulsation at the aortic arch. A four-electrode arrangement across the shoulders acquires arterial pulse across the carotid and subclavian arteries from bioimpedance as well as a bipolar lead I electrocardiogram. The PTT and pulse arrival times (PATs) are measured on six healthy male subjects during exercise on a bicycle ergometer. Using linear regression, the estimated PAT and PTT values are calibrated to the systolic and mean as well as diastolic blood pressure from an oscillometric device. For all subjects, the Pearson correlation coefficients for PAT-SBP and PTT-SBP are -0.66 (p = 0.001) and -0.48 (p = 0.0029), respectively. Correlation coefficients for individual subjects ranged from -0.54 to -0.9 and -0.37 to -0.95, respectively. The proposed system architecture is promising in estimating cuffless arterial blood pressure at the central, proximal arteries, which obey the Moens-Korteweg equation more closely when compared to peripheral arteries. An important advantage of PTT from the carotid and subclavian arteries is that the PTT over the central elastic arteries is measured instead of the peripheral arteries, which potentially reduces the changes in PTT due to vasomotion. Furthermore, the sensors can be completely hidden under a patients clothes, making them more acceptable by the patient for ambulatory monitoring.

  15. Breath Activity Monitoring With Wearable UWB Radars: Measurement and Analysis of the Pulses Reflected by the Human Body.

    PubMed

    Pittella, Erika; Pisa, Stefano; Cavagnaro, Marta

    2016-07-01

    Measurements of ultrawideband (UWB) pulses reflected by the human body are conducted to evidence the differences in the received signal time behaviors due to respiration phases, and to experimentally verify previously obtained numerical results on the body's organs responsible for pulse reflection. Two experimental setups are used. The first one is based on a commercially available impulse radar system integrated on a single chip, while the second one implements an indirect time-domain reflectometry technique using a vector network analyzer controlled by a LabVIEW virtual instrument running on a laptop. When the UWB source is placed close to the human body, a small reflection due to the lung boundaries is present in the received pulse well distanced in time from the reflection due to the air-skin interface; this reflection proved to be linked to the different respiration phases. The changes in the reflected pulse could be used to detect, through wearable radar systems, lung movements associated with the breath activity. The development of a wearable radar system is of great importance because it allows the breath activity sensing without interfering with the subject daily activities.

  16. Remote profiling of lake ice using an S-band short pulse radar aboard an all-terrain vehicle

    NASA Technical Reports Server (NTRS)

    Cooper, D. W.; Mueller, R. A.; Schertler, R. J.

    1975-01-01

    An airborne short-pulse radar system to measure ice thickness was designed. The system supported an effort to develop an all-weather Great Lakes Ice Information System to aid in extending the winter navigation season. Experimental studies into the accuracy and limitations of the system are described. A low power version was operated from an all-terrain vehicle on the Straits of Mackinac during March 1975. The vehicle allowed rapid surveying of large areas and eliminated the ambiguity in location between the radar system and the ground truth ice auger team. It was also possible to the effects of snow cover, surface melt water, pressure ridging, and ice type upon the accuracy of the system. Over 25 sites were explored which had ice thicknesses from 29 to 60 cm. The maximum radar overestimate was 9.8 percent, while the maximum underestimate was 6.6 percent. The average error of the 25 measurements was 0.1 percent.

  17. Detection capability of a pulsed Ground Penetrating Radar utilizing an oscilloscope and Radargram Fusion Approach for optimal signal quality

    NASA Astrophysics Data System (ADS)

    Seyfried, Daniel; Schoebel, Joerg

    2015-07-01

    In scientific research pulsed radars often employ a digital oscilloscope as sampling unit. The sensitivity of an oscilloscope is determined in general by means of the number of digits of its analog-to-digital converter and the selected full scale vertical setting, i.e., the maximal voltage range displayed. Furthermore oversampling or averaging of the input signal may increase the effective number of digits, hence the sensitivity. Especially for Ground Penetrating Radar applications high sensitivity of the radar system is demanded since reflection amplitudes of buried objects are strongly attenuated in ground. Hence, in order to achieve high detection capability this parameter is one of the most crucial ones. In this paper we analyze the detection capability of our pulsed radar system utilizing a Rohde & Schwarz RTO 1024 oscilloscope as sampling unit for Ground Penetrating Radar applications, such as detection of pipes and cables in the ground. Also effects of averaging and low-noise amplification of the received signal prior to sampling are investigated by means of an appropriate laboratory setup. To underline our findings we then present real-world radar measurements performed on our GPR test site, where we have buried pipes and cables of different types and materials in different depths. The results illustrate the requirement for proper choice of the settings of the oscilloscope for optimal data recording. However, as we show, displaying both strong signal contributions due to e.g., antenna cross-talk and direct ground bounce reflection as well as weak reflections from objects buried deeper in ground requires opposing trends for the oscilloscope's settings. We therefore present our Radargram Fusion Approach. By means of this approach multiple radargrams recorded in parallel, each with an individual optimized setting for a certain type of contribution, can be fused in an appropriate way in order to finally achieve a single radargram which displays all

  18. Radar principles

    NASA Technical Reports Server (NTRS)

    Sato, Toru

    1989-01-01

    Discussed here is a kind of radar called atmospheric radar, which has as its target clear air echoes from the earth's atmosphere produced by fluctuations of the atmospheric index of refraction. Topics reviewed include the vertical structure of the atmosphere, the radio refractive index and its fluctuations, the radar equation (a relation between transmitted and received power), radar equations for distributed targets and spectral echoes, near field correction, pulsed waveforms, the Doppler principle, and velocity field measurements.

  19. Feasibility Study and Design of a Wearable System-on-a-Chip Pulse Radar for Contactless Cardiopulmonary Monitoring

    PubMed Central

    Zito, Domenico; Pepe, Domenico; Neri, Bruno; Zito, Fabio; De Rossi, Danilo; Lanatà, Antonio

    2008-01-01

    A new system-on-a-chip radar sensor for next-generation wearable wireless interface applied to the human health care and safeguard is presented. The system overview is provided and the feasibility study of the radar sensor is presented. In detail, the overall system consists of a radar sensor for detecting the heart and breath rates and a low-power IEEE 802.15.4 ZigBee radio interface, which provides a wireless data link with remote data acquisition and control units. In particular, the pulse radar exploits 3.1–10.6 GHz ultra-wideband signals which allow a significant reduction of the transceiver complexity and then of its power consumption. The operating principle of the radar for the cardiopulmonary monitoring is highlighted and the results of the system analysis are reported. Moreover, the results obtained from the building-blocks design, the channel measurement, and the ultra-wideband antenna realization are reported. PMID:18389068

  20. Determination of mean surface position and sea state from the radar return of a short-pulse satellite altimeter

    NASA Technical Reports Server (NTRS)

    Barrick, D. E.

    1972-01-01

    Using the specular point theory of scatter from a very rough surface, the average backscatter cross section per unit area per radar cell width is derived for a cell located at a given height above the mean sea surface. This result is then applied to predict the average radar cross section observed by a short-pulse altimeter as a function of time for two modes of operation: pulse-limited and beam-limited configurations. For a pulse-limited satellite altimeter, a family of curves is calculated showing the distortion of the leading edge of the receiver output signal as a function of sea state (i.e., wind speed). A signal processing scheme is discussed that permits an accurate determination of the mean surface position--even in high seas--and, as a by-product, the estimation of the significant seawave height (or wind speed above the surface). Comparison of these analytical results with experimental data for both pulse-limited and beam-limited operation lends credence to the model. Such a model should aid in the design of short-pulse altimeters for accurate determination of the geoid over the oceans, as well as for the use of such altimeters for orbital sea-state monitoring.

  1. 2D microwave imaging reflectometer electronics

    SciTech Connect

    Spear, A. G.; Domier, C. W. Hu, X.; Muscatello, C. M.; Ren, X.; Luhmann, N. C.; Tobias, B. J.

    2014-11-15

    A 2D microwave imaging reflectometer system has been developed to visualize electron density fluctuations on the DIII-D tokamak. Simultaneously illuminated at four probe frequencies, large aperture optics image reflections from four density-dependent cutoff surfaces in the plasma over an extended region of the DIII-D plasma. Localized density fluctuations in the vicinity of the plasma cutoff surfaces modulate the plasma reflections, yielding a 2D image of electron density fluctuations. Details are presented of the receiver down conversion electronics that generate the in-phase (I) and quadrature (Q) reflectometer signals from which 2D density fluctuation data are obtained. Also presented are details on the control system and backplane used to manage the electronics as well as an introduction to the computer based control program.

  2. Design of a Doppler reflectometer for KSTAR

    SciTech Connect

    Lee, K. D. Nam, Y. U.; Seo, Seong-Heon; Kim, Y. S.

    2014-11-15

    A Doppler reflectometer has been designed to measure the poloidal propagation velocity on the Korea Superconducting Tokamak Advanced Research (KSTAR) tokamak. It has the operating frequency range of V-band (50-75 GHz) and the monostatic antenna configuration with extraordinary mode (X-mode). The single sideband modulation with an intermediate frequency of 50 MHz is used for the heterodyne measurement with the 200 MHz in-phase and quadrature (I/Q) phase detector. The corrugated conical horn antenna is used to approximate the Gaussian beam propagation and it is installed together with the oversized rectangular waveguides in the vacuum vessel. The first commissioning test of the Doppler reflectometer system on the KSTAR tokamak is planned in the 2014 KSTAR experimental campaign.

  3. 2D microwave imaging reflectometer electronics.

    PubMed

    Spear, A G; Domier, C W; Hu, X; Muscatello, C M; Ren, X; Tobias, B J; Luhmann, N C

    2014-11-01

    A 2D microwave imaging reflectometer system has been developed to visualize electron density fluctuations on the DIII-D tokamak. Simultaneously illuminated at four probe frequencies, large aperture optics image reflections from four density-dependent cutoff surfaces in the plasma over an extended region of the DIII-D plasma. Localized density fluctuations in the vicinity of the plasma cutoff surfaces modulate the plasma reflections, yielding a 2D image of electron density fluctuations. Details are presented of the receiver down conversion electronics that generate the in-phase (I) and quadrature (Q) reflectometer signals from which 2D density fluctuation data are obtained. Also presented are details on the control system and backplane used to manage the electronics as well as an introduction to the computer based control program.

  4. Designing clutter rejection filters with complex coefficients for airborne pulsed Doppler weather radar

    NASA Technical Reports Server (NTRS)

    Jamora, Dennis A.

    1993-01-01

    Ground clutter interference is a major problem for airborne pulse Doppler radar operating at low altitudes in a look-down mode. With Doppler zero set at the aircraft ground speed, ground clutter rejection filtering is typically accomplished using a high-pass filter with real valued coefficients and a stopband notch centered at zero Doppler. Clutter spectra from the NASA Wind Shear Flight Experiments of l991-1992 show that the dominant clutter mode can be located away from zero Doppler, particularly at short ranges dominated by sidelobe returns. Use of digital notch filters with complex valued coefficients so that the stopband notch can be located at any Doppler frequency is investigated. Several clutter mode tracking algorithms are considered to estimate the Doppler frequency location of the dominant clutter mode. From the examination of night data, when a dominant clutter mode away from zero Doppler is present, complex filtering is able to significantly increase clutter rejection over use of a notch filter centered at zero Doppler.

  5. Portable infrared reflectometer for evaluating emittance

    NASA Astrophysics Data System (ADS)

    Jaworske, Donald A.; Skowronski, Timothy J.

    2000-01-01

    Optical methods are frequently used to evaluate the emittance of candidate spacecraft thermal control materials. One new optical method utilizes a portable infrared reflectometer capable of obtaining spectral reflectance of an opaque surface in the range of 2 to 25 microns using a Michelson-Type FTIR interferometer. This miniature interferometer collects many infrared spectra over a short period of time. It also allows the size of the instrument to be small such that spectra can be collected in the laboratory or in the field. Infrared spectra are averaged and integrated with respect to the room temperature black body spectrum to yield emittance at 300 K. Integrating with respect to other black body spectra yields emittance values at other temperatures. Absorption bands in the spectra may also be used for chemical species identification. The emittance of several samples was evaluated using this portable infrared reflectometer, an old infrared reflectometer equipped with dual rotating black body cavities, and a bench top thermal vacuum chamber. Samples for evaluation were purposely selected such that a range of emittance values and thermal control material types would be represented, including polished aluminum, Kapton®, silvered Teflon®, and the inorganic paint Z-93-P. Results indicate an excellent linear relationship between the room temperature emittance calculated from infrared spectral data and the emittance obtained from the dual rotating black body cavities and thermal vacuum chamber. The prospect of using the infrared spectral data for chemical species identification will also be discussed. .

  6. Analytical Research by Computer Simulation of Developmental Polarimetric/Frequency Agile Pulsed Radars.

    DTIC Science & Technology

    1982-12-01

    one and one half meters radar length, made up of five reflectors randomly spaced, and having a radar cross section of five square meters each (Figures...1. Odd bounce scattering matrix (flat plate, trihedral corner reflector ) for linear polarization (see Figure 6) 2. Even bounce scattering matrix...is radar cross - section in meters squared R is range to target in meters Ls is system loss (unitless) Because this analysis is performed in the voltage

  7. Circuit Design to Stabilize the Reflectometer Local Oscillator Signals

    SciTech Connect

    Kung, C. C.; Kramer, G. J.; Johnson, E.; Solomon, W.; Nazikian, R.

    2005-10-04

    Reflectometry, which uses the microwave radar technique to probe the magnetically confined fusion plasmas, is a very powerful tool to observe the density fluctuations in the fusion plasmas. Typically, two or more microwave beams of different frequencies are used to study the plasma density fluctuations. The frequency separation between these two beams of the PPPL designed reflectometer system upgrade on the DIII-D tokamak can be varied over 18 GHz. Due to the performance of the associated electronics, the local oscillator (LO) power level at the LO port of the I/Q demodulator suffers more than 12 dB of power fluctuations when the frequency separation is varied. Thus, the I/Q demodulator performance is impaired. In order to correct this problem, a power leveling circuit is introduced in the PPPL upgrade. According to the test results, the LO power fluctuation was regulated to be within 1 dB for greater than 16 dB of input power variation over the full dynamic bandwidth of the receiver.

  8. An overview of avalanche photodiodes and pulsed lasers as they are used in 3D laser radar type applications

    NASA Astrophysics Data System (ADS)

    Dion, Bruno; Bertone, Nick

    2004-08-01

    This paper will examine how Avalanche Photodiodes (APD) and Infrared Pulsed lasers (PL) are used and optimized to provide the "intelligence" to smart weapons. The basics of APD's and PL will be covered and the principle "time of flight ranging" which is the underlining principle of 3D laser radar will be illustrated. The time of flight principle is used for range finding, lidar, 3D laser radar and speed measurements - this information can then be used to provide intelligence to the smart weapon. Examples of such systems are discussed and illustrated, for example: Cluster bombs, Proximity fuses, and how laser range finding systems can be incorporated with GPS to produce effective and lethal weapons. The APD's that are discussed include silicon APD's for cost effective weapons, and 1550nm APDs for eye-safe systems. An overview of the different PL's will be outlined, but the focus will be on 905nm laser pulsars for cost effective laser weapons.

  9. Bone-demineralization diagnosis in a bone-tissue-skin matrix using the pulsed-chirped photothermal radar

    NASA Astrophysics Data System (ADS)

    Kaiplavil, Sreekumar; Mandelis, Andreas

    2012-02-01

    A chirped pulsed photothermal radiometric radar is introduced for the diagnosis of biological samples, especially bones with tissue and skin overlayers. The constraints imposed by the laser safety (maximum permissible exposure, MPE) ceiling on pump laser energy and the strong attenuation of thermal-wave signals in tissues significantly limit the photothermally active depth in most biological specimens to a level which is normally insufficient for practical applications (approx. 1 mm below the skin surface). A theoretical approach for improvement of signal-to-noise ratio (SNR), minimizing the static (dc) component of the photothermal signal and making use of the photothermal radiometric nonlinearity has been introduced and verified by comparing the SNR of four distinct excitation wave forms (sine-wave, square-wave, constant- width and constant duty-cycle pulses) for chirping the pump laser, under constant exposure energy. At low frequencies fixed-pulsewidth chirps of large peak power were found to be superior to all other equal-energy modalities, with an SNR improvement up to two orders of magnitude. Distinct thickness-dependent characteristic delay times in a goat bone were obtained, establishing an active depth resolution range of ca. 2.8 mm in a layered skin-fat- bone structure, a favorable result compared to the maximum reported pulsed photothermal radiometric depth resolution < 1 mm in turbid biological media. Compared to radar peak delay and amplitude, the long-delayed radar output amplitude is found to be more sensitive to subsurface conditions. Two-dimensional spatial plots of this parameter depicting the back surface conditions of bones with and without fat-tissue overlayers are presented.

  10. High-depth-resolution 3-dimensional radar-imaging system based on a few-cycle W-band photonic millimeter-wave pulse generator.

    PubMed

    Tseng, Tzu-Fang; Wun, Jhih-Min; Chen, Wei; Peng, Sui-Wei; Shi, Jin-Wei; Sun, Chi-Kuang

    2013-06-17

    We demonstrate that a near-single-cycle photonic millimeter-wave short-pulse generator at W-band is capable to provide high spatial resolution three-dimensional (3-D) radar imaging. A preliminary study indicates that 3-D radar images with a state-of-the-art ranging resolution of around 1.2 cm at the W-band can be achieved.

  11. Brillouin optical reflectometer with a Brillouin active filter

    NASA Astrophysics Data System (ADS)

    Budylin, G. S.; Gorshkov, B. G.; Gorshkov, G. B.; Zhukov, K. M.; Paramonov, V. M.; Simikin, D. E.

    2017-07-01

    A new scheme of a fibre-optic Brillouin reflectometer is experimentally studied, in which the spectral line of spontaneous Brillouin scattering is selected by an active Brillouin filter represented by the tested fibre itself. To improve the reflectometer characteristics, a cyclic code and Raman amplification of the scattering signal are applied. With an averaging time of 5 min, scanning of 25 km of fibre with a spatial resolution of 4 m and a sampling resolution of 1 m are provided. The root-mean-square deviation in determining the Brillouin frequency is less than 1.1 MHz. The reflectometer sensitivity is evaluated with respect to the temperature changes and mechanical deformation.

  12. Assessment of cytogenetic damage and oxidative stress in personnel occupationally exposed to the pulsed microwave radiation of marine radar equipment.

    PubMed

    Garaj-Vrhovac, Vera; Gajski, Goran; Pažanin, Senijo; Sarolić, Antonio; Domijan, Ana-Marija; Flajs, Dubravka; Peraica, Maja

    2011-01-01

    Due to increased usage of microwave radiation, there are concerns of its adverse effect in today's society. Keeping this in view, study was aimed at workers occupationally exposed to pulsed microwave radiation, originating from marine radars. Electromagnetic field strength was measured at assigned marine radar frequencies (3 GHz, 5.5 GHz and 9.4 GHz) and corresponding specific absorption rate values were determined. Parameters of the comet assay and micronucleus test were studied both in the exposed workers and in corresponding unexposed subjects. Differences between mean tail intensity (0.67 vs. 1.22) and moment (0.08 vs. 0.16) as comet assay parameters and micronucleus test parameters (micronuclei, nucleoplasmic bridges and nuclear buds) were statistically significant between the two examined groups, suggesting that cytogenetic alterations occurred after microwave exposure. Concentrations of glutathione and malondialdehyde were measured spectrophotometrically and using high performance liquid chromatography. The glutathione concentration in exposed group was significantly lower than in controls (1.24 vs. 0.53) whereas the concentration of malondialdehyde was significantly higher (1.74 vs. 3.17), indicating oxidative stress. Results suggests that pulsed microwaves from working environment can be the cause of genetic and cell alterations and that oxidative stress can be one of the possible mechanisms of DNA and cell damage. Copyright © 2010 Elsevier GmbH. All rights reserved.

  13. Application of Time Domain Reflectometers in Urban Settings ...

    EPA Pesticide Factsheets

    Time domain reflectometers (TDRs) are sensors that measure the volumetric water content of soils and porous media. The sensors consist of stainless steel rods connected to a circuit board in an epoxy housing. An electromagnetic pulse is propagated along the rods. The time, or period, required for the signal to travel down the rods and back varies with the volumetric water content of the surrounding media and temperature. A calibration curve is needed for the specific media. TDRs were developed mostly for agricultural applications; however, the technology has also been applied to forestry and ecological research. This study demonstrates the use of TDRs for quantifying drainage properties in low impact development (LID) stormwater controls, specifically permeable pavement and rain garden systems. TDRs were successfully used to monitor the responses of urban fill, engineered bioretention media, and the aggregate storage layer under permeable pavement to multiple rain events of varying depth, intensity, and duration. The hydrologic performance of permeable pavement and rain garden systems has previously been quantified for underdrain systems, but there have been few studies of systems that drain to the underlying soils. We know of no published studies outlining the use of TDR technology to document drainage properties in media other than soil. In this study TDRs were installed at multiple locations and depths in underlying urban fill soils, engineered bior

  14. Laboratory Characterization of an Imaging Reflectometer System

    SciTech Connect

    T. Munsat; E. Mazzucato; H. Park; C.W. Domier; N.C. Luhmann Jr.; A.J.H. Donne; M. van de Pol

    2003-01-14

    While microwave reflectometry has proven to be a sensitive tool for measuring electron density fluctuations in many circumstances, it has also been shown to have limited viability for core measurements and/or conditions of strong turbulence. To this end, a new instrument based on 2-D imaging reflectometry has been developed to measure density fluctuations over an extended plasma region in the TEXTOR tokamak. Laboratory characterization of this instrument has been performed using corrugated reflecting targets as an approximation to plasma reflections including 2-D turbulent fluctuations of various magnitude and poloidal wavenumber. Within this approximation, the imaging reflectometer can recover the spectral and spatial characteristics of the reflection layer lost to or otherwise inaccessible to conventional techniques.

  15. A real-time receive method of wideband radar based on subband pulse compression

    NASA Astrophysics Data System (ADS)

    Li, Ming; Fu, Wei; Zhang, Peng; Wu, Yan

    2011-10-01

    The data rate with high capacity and speed of wideband signal makes its real-time processing limited by hardware and software. In this paper, wideband signal is made pulse compression based on subband pulse compression system. It is used uniform complex modulation to generate analysis filter bank and synthesis filter bank, then signals are processed in each subband. The processed results of simulated and measured datas indicate, that the parallel means of subband pulse compression raises the operation speed and improves real-time processing performance of the system, selecting proper subband number according to the data quantity when the result closed to that of directed pulse compression.

  16. Localized Optimization and Effectiveness Analysis of Medium PRF Airborne Pulse Doppler Radars in the Turkish Air Force

    DTIC Science & Technology

    2011-09-01

    Frequency SAM Surface-to-Air Missiles SAR Synthetic Aperture Radar SCR Signal-to-Clutter Ratio SLAR Side-Looking Airborne Radar SLC Sidelobe...functionality. Basically, radar propagates electromagnetic energy from an antenna to targets. The energy then reflects and scatters in various directions...DOPPLER RADAR A. RADAR FUNDAMENTALS Radars use EM energy in order to detect and locate objects such as aircraft, ships, etc. The operating principles

  17. A frequency-modulated continuous-wave reflectometer for the Lithium Tokamak Experiment

    NASA Astrophysics Data System (ADS)

    Kubota, S.; Majeski, R.; Peebles, W. A.; Bell, R. E.; Boyle, D. P.; Kaita, R.; Kozub, T.; Lucia, M.; Merino, E.; Nguyen, X. V.; Rhodes, T. L.; Schmitt, J. C.

    2017-05-01

    The frequency-modulated continuous-wave reflectometer on LTX (Lithium Tokamak Experiment) and the data analysis methods used for determining electron density profiles are described. The diagnostic uses a frequency range of 13.1-33.5 GHz, for covering a density range of 0.21-1.4 ×1013 cm-3 (in O-mode polarization) with a time resolution down to 8 μs. The design of the diagnostic incorporates the concept of an "optimized" source frequency sweep, which minimizes the large variation in the intermediate frequency signal due to a long dispersive transmission line. The quality of the raw data is dictated by the tuning characteristics of the microwave sources, as well as the group delay ripple in the transmission lines, which can generate higher-order nonlinearities in the frequency sweep. Both effects are evaluated for our diagnostic and best practices are presented for minimizing "artifacts" generated in the signals. The quality of the reconstructed profiles is also improved using two additional data analysis methods. First, the reflectometer data are processed as a radar image, where clutter due to echoes from the wall and backscattering from density fluctuations can be easily identified and removed. Second, a weighed least-squares lamination algorithm POLAN (POLynomial ANalysis) is used to reconstruct the electron density profile. Examples of density profiles in LTX are presented, along with comparisons to measurements from the Thomson scattering and the λ = 1 mm interferometer diagnostics.

  18. Automatic Modulation Classification of Common Communication and Pulse Compression Radar Waveforms using Cyclic Features

    DTIC Science & Technology

    2013-03-01

    from estimated duty cycle, cyclic spectral correlation, and cyclic cumulants. The modulations considered in this research are BPSK, QPSK, 16- QAM , 64- QAM ...spectral density PSK phase shift keying QAM quadrature amplitude modulation QPSK quadrature phase shift keying RADAR radio detection and ranging RF radio...spectrum sensing research, automatic modulation recognition has emerged as an important process in cognitive spectrum management and EW applications

  19. An analysis of short pulse and dual frequency radar techniques for measuring ocean wave spectra from satellites

    NASA Technical Reports Server (NTRS)

    Jackson, F. C.

    1980-01-01

    Scanning beam microwave radars were used to measure ocean wave directional spectra from satellites. In principle, surface wave spectral resolution in wave number can be obtained using either short pulse (SP) or dual frequency (DF) techniques; in either case, directional resolution obtains naturally as a consequence of a Bragg-like wave front matching. A four frequency moment characterization of backscatter from the near vertical using physical optics in the high frequency limit was applied to an analysis of the SP and DF measurement techniques. The intrinsic electromagnetic modulation spectrum was to the first order in wave steepness proportional to the large wave directional slope spectrum. Harmonic distortion was small and was a minimum near 10 deg incidence. NonGaussian wave statistics can have an effect comparable to that in the second order of scattering from a normally distributed sea surface. The SP technique is superior to the DF technique in terms of measurement signal to noise ratio and contrast ratio.

  20. The multipurpose time-of-flight neutron reflectometer “Platypus” at Australia's OPAL reactor

    NASA Astrophysics Data System (ADS)

    James, M.; Nelson, A.; Holt, S. A.; Saerbeck, T.; Hamilton, W. A.; Klose, F.

    2011-03-01

    In this manuscript we describe the major components of the Platypus time-of-flight neutron reflectometer at the 20 MW OPAL reactor in Sydney, Australia. Platypus is a multipurpose spectrometer for the characterisation of solid thin films, materials adsorbed at the solid-liquid interface and free-liquid surfaces. It also has the capacity to study magnetic thin films using spin-polarised neutrons. Platypus utilises a white neutron beam ( λ=2-20 Å) that is pulsed using boron-coated disc chopper pairs; thus providing the capacity to tailor the wavelength resolution of the pulses to suit the system under investigation. Supermirror optical components are used to focus, deflect or spin-polarise the broad bandwidth neutron beams, and typical incident spectra are presented for each configuration. A series of neutron reflectivity datasets are presented, indicating the quality and flexibility of this spectrometer. Minimum reflectivity values of <10 -7 are observed; while maximum thickness values of 325 nm have been measured for single-component films and 483 nm for a multilayer system. Off-specular measurements have also been made to investigate in-plane features as opposed to those normal to the sample surface. Finally, the first published studies conducted using the Platypus time-of-flight neutron reflectometer are presented.

  1. Green pulsed lidar-radar emitter based on a multipass frequency-shifting external cavity.

    PubMed

    Zhang, Haiyang; Brunel, Marc; Romanelli, Marco; Vallet, Marc

    2016-04-01

    This paper investigates the radio frequency (RF) up-conversion properties of a frequency-shifting external cavity on a laser beam. We consider an infrared passively Q-switched pulsed laser whose intensity modulation results from the multiple round-trips in the external cavity, which contains a frequency shifter. The output beam undergoes optical second-harmonic generation necessary to reach the green wavelength. We model the pulse train using a rate-equation model to simulate the laser pulses, together with a time-delayed interference calculation taking both the diffraction efficiency and the Gaussian beam propagation into account. The predictions are verified experimentally using a diode-pumped Nd:YAG laser passively Q-switched by Cr4+:YAG whose pulse train makes multiple round-trips in a mode-matched external cavity containing an acousto-optic frequency shifter driven at 85 MHz. Second-harmonic generation is realized in a KTP crystal, yielding RF-modulated pulses at 532 nm with a modulation contrast of almost 100%. RF harmonics up to the 6th order (1.020 GHz) are observed in the green output pulses. Such a RF-modulated green laser may find applications in underwater detection and ranging.

  2. Digital Beamforming and Pulse Compression in an Adaptive Array Radar System

    DTIC Science & Technology

    1991-02-25

    DC 20S03 1. AGENCY USE ONLY (Leave blank) I2. REPORT DATE I .REPORT TYPE AND DATES COVERED 1 1991 February 25 4. TITLE AND SUBTITLE 5 . FUNDING...down to a 5 M~z sample rate. The digitized signals are transmitted over a 160 bit wide data bus to a high speed bulk memory system. The Microram 3000N...magtape, displayed, or processed. TOD CLOCK PAS MEMORY RADAR INTERFACE UNIT t/D 1/0, L to NAV1 (ATION SYSTEM CONV FAST MEMORY NOVA WLM~l REO/WRITE IEEE

  3. AMOR - the versatile reflectometer at SINQ

    NASA Astrophysics Data System (ADS)

    Clemens, D.; Gross, P.; Keller, P.; Schlumpf, N.; Könnecke, M.

    2000-03-01

    We report on a new facility for neutron reflectometry situated at the end position of a cold neutron guide at the Swiss Spallation Neutron Source SINQ. The instrument is a flexible apparatus, adaptable to the needs of the user's individual experiment. Principally designed to operate in the time-of-flight mode it is also capable to exploit the fact that SINQ is a continuous source because PSI's developments in the field of thin film multilayers are fruitfully applied. By means of multilayer monochromators it can be converted into a constant wavelength reflectometer. Polarized neutron reflectometry on AMOR takes advantage of remanent FeCo/Ti:N supermirrors and multilayers which can be operated in a way that no spin flippers are needed. The time and angular contributions to the resolution in momentum transfer are separately determinable in TOF mode. The total length of the instrument is adjustable in order to optimize resolution together with the illumination of the sample's surface. Large sample environments can be placed on the sample table that is actively isolated against vibrations. Single detectors and an EMBL 3He area detector can be chosen, alternatively. The instrument concept as well as parameters of its components are presented.

  4. DIII-D divertor reflectometer system

    SciTech Connect

    Rhodes, T.L.; Doyle, E.J.; Nguyen, X.V.; Kim, K.W.; Peebles, W.A.; Doane, J.L.

    1997-01-01

    Divertor density profiles, asymmetries, turbulence, and MARFE diagnosis are extremely important and affect the divertor design process for ITER and other future devices. In addition, a functioning divertor density profile system will be essential for the operation of these machines. It is thus critical to prototype and demonstrate diagnostics capable of operating in a divertor environment. To meet these needs a divertor reflectometer system has been designed and installed on DIII-D. The design stresses flexibility, modularity, and simplicity. It consists of a circular, smoothwall, overmoded waveguide followed by a TE{sub 11}{R_arrow}HE{sub 11} mode converter (the HE{sub 11} mode is a low loss Gaussian mode with a very symmetric radiation pattern, optimal for this use) thus allowing use of an arbitrary polarization (f{sub pe},f{sub LH},f{sub RH}). The design provides for testing of a variety of antennas/probing directions including: upward to probe the X-point region, including MARFEs, sideways to probe outboard/inboard divertor legs, and oppositely directed to probe both divertor legs simultaneously. System design, operational considerations, and experimental data are presented. {copyright} {ital 1997 American Institute of Physics.}

  5. A RD-ESPRIT algorithm for coherent DOA estimation in monostatic MIMO radar using a single pulse

    NASA Astrophysics Data System (ADS)

    Chen, Chen; Zhang, Xiaofei

    2014-08-01

    This paper discusses the problem of coherent direction of arrival (DOA) estimation in a monostatic multi-input multi-output (MIMO) radar using a single pulse, and proposes a reduced dimension (RD)-estimation of signal parameters via rotational invariance techniques (ESPRIT) algorithm. We reconstruct the received data and then utilise it to construct a set of Toeplitz matrices. After that, we use RD-ESPRIT to obtain the DOAs of the sources. The proposed algorithm is effective for coherent angle estimation based on a single pulse, and it has much better angle estimation performance than the forward backward spatial smoothing (FBSS)-ESPRIT algorithm and the ESPRIT-like of Li, as well as very close angle estimation performance to the ESPRIT-like of Han. For complexity comparison, our algorithm has very close complexity to the FBSS-ESPRIT algorithm, and lower complexity than the ESPRIT-like of Han and the ESPRIT-like of Li. Simulation results present the effectiveness and improvement of our approach.

  6. Characteristics of ocean-reflected short radar pulses with application to altimetry and surface roughness determination

    NASA Technical Reports Server (NTRS)

    Miller, L. S.; Hayne, G. S.

    1972-01-01

    Current work related to geodetic altimetry is summarized. Special emphasis is placed on the effects of pulse length on both altimetry and sea-state estimation. Some discussion is also given of system tradeoff parameters and sea truth requirements to support scattering studies. The problem of analyzing signal characteristics and altimeter waveforms arising from rough surface backscattering is also considered.

  7. Doublet Pulse Coherent Laser Radar for Tracking of Resident Space Objects

    DTIC Science & Technology

    2014-09-01

    static targets, spinning cones returns for testing speckle decorrelation, and retro returns suitable for satellite tracking . With precision ranging and...coherent signals, models targets as collection of point scatterers and tracks each scatterer position and velocity. Speckle effects were faithfully...excellent performance since speckle is limiting the doublet pulse spacing. Furthermore, acceleration is also tracked very well. In this case

  8. Beam choppers for neutron reflectometers at steady flux reactors

    NASA Astrophysics Data System (ADS)

    Pleshanov, N. K.

    2017-09-01

    Realizations of the TOF technique for neutron reflectometers at steady flux reactors are compared. Beam choppers for neutron reflectometers divide into choppers of type 1 (Δλ = const) and 2 (Δλ / λ = const) . It follows from Monte-Carlo simulations that choppers of type 1 do not yield to more intricate choppers of type 2, widely used at neutron reflectometers. Because of a very fast drop of neutron reflectivities with the momentum transfer q, non-optimality of measurements with a chopper of type 1 is fully compensated by better statistics at large q, and is not so much essential at small q. To vary the TOF resolution with choppers of type 1, a phasing of two discs and a turning of the system of two discs are suggested. The fluxes of neutrons with wavelengths beyond the working range and the efficiencies of their elimination by means of a bandwidth limiting prechopper are evaluated.

  9. A reflectometer for at-wavelength characterisation of gratings

    NASA Astrophysics Data System (ADS)

    Eggenstein, F.; Schäfers, F.; Erko, A.; Follath, R.; Gaupp, A.; Löchel, B.; Senf, F.; Zeschke, T.

    2013-05-01

    The design for an UHV-reflectometer for XUV-radiation is presented, which is dedicated to at-wavelength characterisation on high precision gratings. At-Wavelength Metrology is a powerful and necessary characterisation tool for the development and characterisation of optical elements. Since the optical constants of the coating materials involved are dependent on wavelength, information on e.g. reflectivity can only be obtained at-wavelength and cannot be provided by ex-situ methods. In our institute a technology centre for production and characterisation of highly efficient precision gratings is established. Within this project a reflectometer for at-wavelength characterisation of the fabricated blazed gratings is developed and manufactured. This reflectometer complements the SXR-metrology instrumentation at BESSY-II: the existing reflectometer and the polarimeter/ellipsometer chamber for polarisation studies on magneto-optical samples or non-magnetic multilayers. The main feature of the reflectometer is the possibility to incorporate real gratings with a length up to 600 mm, adjustable in six degrees of freedom by a custom designed tripod system. The reflectivity is measured between -180° and +180° incidence angle for both s- and p-polarisation geometry. A variety of detectors with a high dynamic range is accessible. The reflectometer is coupled permanently to the new optics beamline on a BESSY-II bending magnet operating in the UV, EUV and soft x-ray range with the polarisation adjustable to either linear or elliptical. The station will be available by the end of 2013.

  10. Diting: A polarized time-of-flight neutron reflectometer at CMRR reactor in China

    NASA Astrophysics Data System (ADS)

    Li, Xinxi; Huang, Chaoqiang; Wang, Yan; Chen, Bo; Sun, Guang'ai; Liu, Yaoguang; Gong, Jian; Kang, Wu; Liu, Hangang

    2016-11-01

    A new time-of-flight neutron reflectometer with a polarization option is developed and tested at the Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang, China. Its scattering geometry is horizontal. The constructed neutron reflectometer is a multipurpose instrument that can be used for the characterization of a stratified microstructure and hidden interfaces of solid thin films. Diting is designed for both magnetic and nonmagnetic multi-layer thin films. Spin polarization and analysis are achieved by transmission magnetized supermirrors. The sample unit is equipped with an electromagnet, which can provide a vertical magnetic field range of 0-1.2 tesla. The available neutron beam is a white beam with wavelength range of 0.15-1.25 nm, which can be cut into different wavelength resolution neutron pulses by a four-disk chopper. A two-dimensional position-sensitive detector is employed to count the specular and off-specular reflected neutron beam. A minimum reflectivity of 10-6 is measured on this instrument.

  11. A PC based time domain reflectometer for space station cable fault isolation

    NASA Technical Reports Server (NTRS)

    Pham, Michael; McClean, Marty; Hossain, Sabbir; Vo, Peter; Kouns, Ken

    1994-01-01

    Significant problems are faced by astronauts on orbit in the Space Station when trying to locate electrical faults in multi-segment avionics and communication cables. These problems necessitate the development of an automated portable device that will detect and locate cable faults using the pulse-echo technique known as Time Domain Reflectometry. A breadboard time domain reflectometer (TDR) circuit board was designed and developed at the NASA-JSC. The TDR board works in conjunction with a GRiD lap-top computer to automate the fault detection and isolation process. A software program was written to automatically display the nature and location of any possible faults. The breadboard system can isolate open circuit and short circuit faults within two feet in a typical space station cable configuration. Follow-on efforts planned for 1994 will produce a compact, portable prototype Space Station TDR capable of automated switching in multi-conductor cables for high fidelity evaluation. This device has many possible commercial applications, including commercial and military aircraft avionics, cable TV, telephone, communication, information and computer network systems. This paper describes the principle of time domain reflectometry and the methodology for on-orbit avionics utility distribution system repair, utilizing the newly developed device called the Space Station Time Domain Reflectometer (SSTDR).

  12. A scaled down laboratory experiment of cross-borehole pulse radar signatures for detection of a terminated tunnel

    NASA Astrophysics Data System (ADS)

    Cho, Jae-Hyoung; Jung, Ji-Hyun; Kim, Se-Yun; Yook, Jong-Gwan

    2016-09-01

    In the cross-borehole pulse radar signatures measured near the front end of a terminated tunnel, the time-of-arrival (TOA) with fully penetrated tunnel is significantly shortened due to the relatively fast pulse propagation in an empty tunnel compared with the TOA obtained without a tunnel. To analyze the TOA variation with the protrusion length of the terminated tunnel from the line-of-sight between two antennas or boreholes, additional borehole pairs are required around the terminated tunnel in spite of their high construction costs. As an alternative, a laboratory scaled down experiment, which has a high ability to simulate different underground configurations, is designed for investigation into the TOA effects of tunnel termination. A round ceramic rod with a careful selection of its dielectric constant is immersed in pure water in a water tank and used to simulate the tunnel in the experiment. Coaxial fed dipole antennas with balanced wire and ferrite cores are used not only to suppress borehole-guided waves but also to generate a symmetric radiation pattern. The accuracy of the laboratory scaled down experiment is verified by the symmetricity of the measured diffraction pattern of the fully penetrated ceramic rod. Then, the TOA variation is measured for the protrusion length of the ceramic rod relative to the line-of-sight between two antennas from  +80 mm to  -80 mm with an equal step of 5 mm. Based on the scaled down experimental measurements of the TOA, it is found that a tunnel 1.2 m away from the measuring cross-borehole section closely approaches the scaled up variation curve under the same conditions of the protrusion length.

  13. Five years use of Pulse Doppler RADAR-utechnology in debris-flows monitoring - experience at three test sites so far

    NASA Astrophysics Data System (ADS)

    Koschuch, Richard; Brauner, Michael; Hu, Kaiheng; Hübl, Johannes

    2016-04-01

    Automatic monitoring of alpine mass movement is a major challenge in dealing with natural hazards. The presented research project shows a new approach in measurment and alarming technology for water level changes an debris flow by using a high-frequency Pulse Doppler RADAR. The detection system was implemented on 3 places (2 in Tirol/Austria within the monitoring systems of the IAN/BOKU; 1 in Dongchuan/China within the monitoring systems of the IMHE/Chinese Academy of Science) in order to prove the applicability of the RADAR in monitoring torrential activities (e.g. debris-flows, mudflows, flash floods, etc.). The main objective is to illustrate the principles and the potential of an innovative RADAR system and its versatility as an automatic detection system for fast (> 1 km/h - 300 km/h) alpine mass movements of any kind. The high frequency RADAR device was already successfully tested for snow avalanches in Sedrun/Switzerland (Lussi et al., 2012), in Ischgl/Austria (Kogelnig et al., 2012). The experience and the data of the five year showed the enormous potential of the presented RADAR technology in use as an independent warning and monitoring system in the field of natural hazard. We have been able to measure water level changes, surface velocities and several debris flows and can compare this data with the other installed systems.

  14. Prospects for high accuracy time dissemination and synchronization using coded radar pulses from a low-earth orbiting spacecraft

    NASA Technical Reports Server (NTRS)

    Detoma, Edoardo V.; Dionisio, C.

    1995-01-01

    The radar (an acronym for radio detection and ranging) is an instrument developed just before the WW-II to precisely measure the position of an object (target) in space. This is done by emitting a narrow pulse of electromagnetic energy in the RF spectrum, receiving the return echo and measuring the time of flight in the two-way path from the emitter to the target. The propagation delay provides a measure of the range to the target, which is not in itself sufficient to uniquely locate the position of the same in space. However, if a directional antenna is used, the direction of the echo can be assessed by the antenna pointing angles. In this way the position of the target can be uniquely determined in space. How well this can be done is a function of the resolution of the measurements performed (range and direction, i.e.: angles); in turn, the resolution will dictate the time and frequency requirements of the reference oscillator.

  15. Scrape-off layer reflectometer for Alcator C-Moda)

    NASA Astrophysics Data System (ADS)

    Hanson, G. R.; Wilgen, J. B.; Lau, C.; Lin, Y.; Wallace, G. M.; Wukitch, S. J.

    2008-10-01

    A two-frequency x-mode reflectometer operating from 100 to 146 GHz is deployed on Alcator C-Mod to measure the density profile and fluctuations in the scrape-off layer (SOL) immediately in front of the new J-port ICRF antenna and the new C-port lower hybrid launcher. The reflectometer covers densities from 1016 to 1020 m-3 at 5-5.4 T. To provide the greatest flexibility and capability to deal with density fluctuations approaching 100% peak-to-peak in the SOL, both full-phase and differential-phase measurement capabilities with sweep speeds of ˜10 μs to >1 ms are implemented. The differential-phase measurement uses a difference frequency of 500 MHz, corresponding to cutoff layer separations ranging from about 0.1 to 1 mm. The reflectometer has six sets of launchers: three on the ICRF antenna and three on the lower hybrid launcher. Both the ICRF antenna and the lower hybrid launcher incorporate reflectometer antennas at their top, bottom, and midplane locations.

  16. Application of Time Domain Reflectometers in Urban Settings

    EPA Science Inventory

    This is a poster for the Million Trees NYC research symposium in New York City, NY, March 5-6, 2010. The poster gives a summary of how time domain reflectometers can be installed in urban fill soil, engineered bioretention media, and recycled concrete aggregate to document the ...

  17. Application of Time Domain Reflectometers to Urban Settings

    EPA Science Inventory

    Time domain reflectometers (TDRs) are in-situ monitoring probes that produce a temperature-compensated signal proportional to soil moisture content of the surrounding material when calibrated to a particular media. Typically used in agricultural settings, TDRs may also be applied...

  18. Application of Time Domain Reflectometers to Urban Settings

    EPA Science Inventory

    Time domain reflectometers (TDRs) are in-situ monitoring probes that produce a temperature-compensated signal proportional to soil moisture content of the surrounding material when calibrated to a particular media. Typically used in agricultural settings, TDRs may also be applied...

  19. Ellipsoidal-mirror reflectometer accurately measures infrared reflectance of materials

    NASA Technical Reports Server (NTRS)

    Dunn, S. T.; Richmond, J. C.

    1967-01-01

    Reflectometer accurately measures the reflectance of specimens in the infrared beyond 2.5 microns and under geometric conditions approximating normal irradiation and hemispherical viewing. It includes an ellipsoidal mirror, a specially coated averaging sphere associated with a detector for minimizing spatial and angular sensitivity, and an incident flux chopper.

  20. Doublet Pulse Coherent Laser Radar for Tracking of Resident Space Objects

    NASA Technical Reports Server (NTRS)

    Prasad, Narasimha S.; Rudd, Van; Shald, Scott; Sandford, Stephen; Dimarcantonio, Albert

    2014-01-01

    In this paper, the development of a long range ladar system known as ExoSPEAR at NASA Langley Research Center for tracking rapidly moving resident space objects is discussed. Based on 100 W, nanosecond class, near-IR laser, this ladar system with coherent detection technique is currently being investigated for short dwell time measurements of resident space objects (RSOs) in LEO and beyond for space surveillance applications. This unique ladar architecture is configured using a continuously agile doublet-pulse waveform scheme coupled to a closed-loop tracking and control loop approach to simultaneously achieve mm class range precision and mm/s velocity precision and hence obtain unprecedented track accuracies. Salient features of the design architecture followed by performance modeling and engagement simulations illustrating the dependence of range and velocity precision in LEO orbits on ladar parameters are presented. Estimated limits on detectable optical cross sections of RSOs in LEO orbits are discussed.

  1. Radar Waveform Pulse Analysis Measurement System for High-Power GaN Amplifiers

    NASA Technical Reports Server (NTRS)

    Thrivikraman, Tushar; Perkovic-Martin, Dragana; Jenabi, Masud; Hoffman, James

    2012-01-01

    This work presents a measurement system to characterize the pulsed response of high-power GaN amplifiers for use in space-based SAR platforms that require very strict amplitude and phase stability. The measurement system is able to record and analyze data on three different time scales: fast, slow, and long, which allows for greater detail of the mechanisms that impact amplitude and phase stability. The system is fully automated through MATLAB, which offers both instrument control capability and in-situ data processing. To validate this system, a high-power GaN HEMT amplifier operated in saturation was characterized. The fast time results show that variations to the amplitude and phase are correlated to DC supply transients, while long time characteristics are correlated to temperature changes.

  2. Radar Waveform Pulse Analysis Measurement System for High-Power GaN Amplifiers

    NASA Technical Reports Server (NTRS)

    Thrivikraman, Tushar; Perkovic-Martin, Dragana; Jenabi, Masud; Hoffman, James

    2012-01-01

    This work presents a measurement system to characterize the pulsed response of high-power GaN amplifiers for use in space-based SAR platforms that require very strict amplitude and phase stability. The measurement system is able to record and analyze data on three different time scales: fast, slow, and long, which allows for greater detail of the mechanisms that impact amplitude and phase stability. The system is fully automated through MATLAB, which offers both instrument control capability and in-situ data processing. To validate this system, a high-power GaN HEMT amplifier operated in saturation was characterized. The fast time results show that variations to the amplitude and phase are correlated to DC supply transients, while long time characteristics are correlated to temperature changes.

  3. Impulse radar studfinder

    DOEpatents

    McEwan, T.E.

    1995-10-10

    An impulse radar studfinder propagates electromagnetic pulses and detects reflected pulses from a fixed range. Unmodulated pulses, about 200 ps wide, are emitted. A large number of reflected pulses are sampled and averaged. Background reflections are subtracted. Reflections from wall studs or other hidden objects are detected and displayed using light emitting diodes. 9 figs.

  4. Impulse radar studfinder

    DOEpatents

    McEwan, Thomas E.

    1995-01-01

    An impulse radar studfinder propagates electromagnetic pulses and detects reflected pulses from a fixed range. Unmodulated pulses, about 200 ps wide, are emitted. A large number of reflected pulses are sampled and averaged. Background reflections are subtracted. Reflections from wall studs or other hidden objects are detected and displayed using light emitting diodes.

  5. Doublet Pulse Coherent Laser Radar for Orbital Debris Tracking of Resident Space Objects

    NASA Astrophysics Data System (ADS)

    Prasad, N.; Rudd, V.,; DiMarcantonio, A.; Sandford, S.

    2014-09-01

    In this paper, the development of a long range ladar system known as ExoSPEAR at NASA Langley Research Center for tracking rapidly moving resident space objects is discussed. Based on 100 W, nanosecond class, near-IR laser, this ladar system with coherent detection technique is currently being investigated for short dwell time measurements of resident space objects (RSOs) in LEO and beyond for space surveillance applications. This unique ladar architecture is configured using a continuously agile doublet-pulse waveform scheme coupled to a closed-loop tracking and control loop approach to simultaneously achieve mm class range precision and mm/s velocity precision and hence obtain unprecedented track accuracies. Salient features of the design architecture followed by performance simulations illustrating the dependence of range and velocity precision in LEO orbits on ladar power aperture product will be presented. Estimated limits on detectable optical cross sections of RSOs in LEO orbits will be analyzed. The suitability of this ladar for precision orbit determination will be discussed.

  6. Optical time-domain reflectometer based multiplexed sensing scheme for environmental sensing

    NASA Astrophysics Data System (ADS)

    Carvalho, J. P.; Gouveia, C.; Santos, J. L.; Jorge, P. A. S.; Baptista, J. M.

    2012-04-01

    In our study, remote environmental sensing is presented using a standard optical time domain reflectometer (OTDR). The measurement of environmental parameters using optical sensors is an expanding area of research with growing importance. Fiber optic sensors are an interesting solution for that due to their high sensitivity, small size, and capability for on-site, real-time, remote, and distributed sensing capabilities. Our multiplexing sensing scheme approach uses transmissive filters (long period gratings - LPGs) interrogated by the OTDR return pulses. The loss induced at the resonance wavelengths varies with changes in the environment refractive index, temperature or other physical parameters. Experimental results show that the insertion of an erbium amplifier improves the measurement resolution in certain situations. Further analysis show that a remote multiplexed sensing scheme allows us to perform simple and low cost real time measurement of refractive index and temperature over long distances.

  7. ASIC-enabled High Resolution Optical Time Domain Reflectometer

    NASA Astrophysics Data System (ADS)

    Skendzic, Sandra

    Fiber optics has become the preferred technology in communication systems because of what it has to offer: high data transmission rates, immunity to electromagnetic interference, and lightweight, flexible cables. An optical time domain reflectometer (OTDR) provides a convenient method of locating and diagnosing faults (e.g. break in a fiber) along a fiber that can obstruct crucial optical pathways. Both the ability to resolve the precise location of the fault and distinguish between two discrete, closely spaced faults are figures of merit. This thesis presents an implementation of a high resolution OTDR through the use of a compact and programmable ASIC (application specific integrated circuit). The integration of many essential OTDR functions on a single chip is advantageous over existing commercial instruments because it enables small, lightweight packaging, and offers low power and cost efficiency. Furthermore, its compactness presents the option of placing multiple ASICs in parallel, which can conceivably ease the characterization of densely populated fiber optic networks. The OTDR ASIC consists of a tunable clock, pattern generator, precise timer, electrical receiver, and signal sampling circuit. During OTDR operation, the chip generates narrow electrical pulse, which can then be converted to optical format when coupled with an external laser diode driver. The ASIC also works with an external photodetector to measure the timing and amplitude of optical reflections in a fiber. It has a 1 cm sampling resolution, which allows for a 2 cm spatial resolution. While this OTDR ASIC has been previously demonstrated for multimode fiber fault diagnostics, this thesis focuses on extending its functionality to single mode fiber. To validate this novel approach to OTDR, this thesis is divided into five chapters: (1) introduction, (2) implementation, (3), performance of ASIC-based OTDR, (4) exploration in optical pre-amplification with a semiconductor optical amplifier, and

  8. A feasibility study of rain radar for the Tropical Rainfall Measuring Mission. IV - A discussion of pulse compression and adaptive scanning

    NASA Astrophysics Data System (ADS)

    Ihara, Toshio; Nakamura, Kenji

    1988-07-01

    The possible use of a pulse compression system on the Tropical Rainfall Measuring Mission to meet the requirement on the number of independent samples for the rain radar under the constraint on allowable power consumption. The applicability of a pulse compression system to the mission depends on the technological feasibility of reducing the range sidelobe levels of the strong surface echo down to at least -60 dB. It is found that applying the pulse compression technique to the mission is risky. The concept of adaptive scanning is examined, and its power saving efficiency is numerically evaluated for four kinds of rain searching schemes. It is shown that the power saving efficiency of adaptive scanning is considerably high for all the rain searching schemes evaluated.

  9. Development of five port reflectometer for reflection based sensing system

    NASA Astrophysics Data System (ADS)

    Baharuddin, S. A.; Cheng, E. M.; Lee, K. Y.; Zaaba, S. K.; Syahirah, K. N.; Abbas, Z.; Nasir, N. F. Mohd; Afendi, M.; Zakaria, Z.

    2017-03-01

    Five-Port Reflectometer is a microwave passivedevice where it implements the six-port algorithm to measure the complex reflection coefficient of material under test (MUT) through reflection on interface between MUT and microwave sensor. Initially, the Six-Port Reflectometer (SPR) was introduced by Engen in 1977 and major component used insix-port technique was designed in many types. When Riblet and Hanssonproposed ring junction with 5 ports only on 1981. Six ports ring junction has been reduced to five ports. In this paper, a dual frequency five ports ring junction circuit was designed, simulated and fabricated for reflection based sensing system. The fabricated five port ring junction is operating at frequencies of 0.64 GHz and 2.42 GHz. The measured result had good agreement with the simulated results for dual frequencies in terms of magnitude and phase.

  10. [Soft X-ray reflectometer with laser produced plasma source].

    PubMed

    Chen, Bo; Ni, Qi-liang; Cao, Ji-hong

    2005-03-01

    A soft X-ray reflectometor with laser-produced plasma source developed in the authorial lab is presented for the measurements of efficiencies of gratings, transmission of filter and reflectance of multilayer coatings. The reflectometer is composed of a soft X-ray laser-produced plasma source, a grazing incidence monochromator with a constant deviation angle, a vacuum chamber, a sample table, a photo-electronic unit and a computer controlling unit. The working wavelength is from 8 to 30 nm and the maximum sample size is 130 mm long by 120 mm wide by 120 mm high. In order to test the performances of the reflectometer, the reflectivity of multilayer coatings was obtained by using this device. The measured results agree well with the theoretical calculation. The reproducibility of measured reflectance is +/-0.6%.

  11. First results of NSTX-U SOL reflectometer

    NASA Astrophysics Data System (ADS)

    Lau, Cornwall; Caughman, John; Hosea, Joel; Perkins, Rory; Taylor, Gary; Wilgen, John

    2016-10-01

    The goal of the Oak Ridge National Laboratory (ORNL) scrape-off-layer (SOL) reflectometer is to measure the density profiles and fluctuations in front of the HHFW antenna on NSTX-U to help understand plasma-antenna coupling and RF-edge interactions, such as density profile modifications due to field-aligned power losses and/or parametric decay instabilities. Originally designed for NSTX parameters, the reflectometer has been upgraded to operate at the increased magnetic fields of NSTX-U by using a combination of O-mode cutoffs, and X-mode L and R cutoffs instead of only X-mode R-cutoff. The use of the X-mode L-cutoff, in particular, is necessary to achieve density profile measurements at the expected full magnetic field capability of NSTX-U. Reflectometer electronics and digitization systems were also upgraded to take measurements with a 20 μs time resolution, so as to reduce the effects of turbulence on the density profile measurement. The first results of these reflectometry measurements on NSTX-U will be shown for a range of plasma conditions. Demonstration that the reflectometer can measure the different cutoffs will also be shown. This work was supported at Oak Ridge National Laboratory, managed by UT-Battelle, LLC, for the U.S. Department of Energy under Contract No. DE-AC05-00OR22725, and at the Princeton Plasma Physics Laboratory under DOE Contract No. DE-AC02-09CH11466.

  12. Design of a horizontal neutron reflectometer for the European Spallation Source

    NASA Astrophysics Data System (ADS)

    Nekrassov, D.; Trapp, M.; Lieutenant, K.; Moulin, J.-F.; Strobl, M.; Steitz, R.

    2014-08-01

    A design study of a horizontal neutron reflectometer adapted to the general baseline of the long pulse European Spallation Source (ESS) is presented. The instrument layout comprises advanced solutions for the neutron guide, high-resolution pulse shaping and beam bending onto a sample surface being thoroughly adjusted to the properties of the ESS. The length of this instrument is roughly 55 m, enabling δλ/λ resolutions from 0.5% to 10%. The incident beam is focused in horizontal plane to boost measurements of sample sizes of 1×1 cm2 and smaller with potential beam deflection in both downward and upward directions. The primary range of neutron wavelengths utilized by the instrument is 2-7.1 Å. If the wavelength range needs to be extended, then this is possible by utilizing only every second (third, fourth) pulse by suppressing all other pulses by the chopper system and thus increase the longest usable wavelength to 12.2 (17.3, 22.4) Å. Angles of incidence can be set between 0° and 9° with a total accessible q-range from 4×10-3 Å-1 up to 1 Å-1, while the δθ/θ resolution can be freely set. The instrument operates in both θ/θ (free liquid surfaces) and θ/2θ (solid-liquid, air-solid interfaces) geometries. The experimental setup will in particular enable direct studies on ultrathin films (d ≈10 Å) and buried monolayers to multilayered structures of up to 3000 Å total thickness. The horizontal reflectometer will further foster investigations of hierarchical systems from nanometer to micrometer length scale (the latter by off-specular scattering), as well as their kinetics and dynamical properties, in particular under load (shear, pressure, external fields). Polarization and polarization analysis as well as the GISANS option are designed as potential modules to be implemented in the generic instrument layout. The instrument is highly flexible and offers a variety of different measurement modes. With respect to its mechanical components the instrument

  13. The effectiveness of adaptive PRF (Pulse Repetition Frequency) selection in minimizing range obscuration in the TDWR (Terminal Doppler Weather Radar) system

    NASA Astrophysics Data System (ADS)

    Crocker, S. C.

    1989-07-01

    An adaptive procedure for selecting radar pulse repetition frequency (PRF) has been developed as the primary means of minimizing the occurrence of range aliased echoes within operationally significant coverage areas (e.g., airport runways) of the Terminal Doppler Weather Radar (TDWR) system. This procedure underwent extensive testing at the S-Band TDWR testbed while located in Denver, CO, where it was judged to be highly successful at preserving the integrity of data collected within the vicinity of the Stapleton International Airport runways. The actual TDWR system will operate at a C-Band frequency, and an increase in potential range obscuration is expected over that experienced by the S-band testbed. This report discusses the anticipated performance of the PRF selection procedure in the C-Band environment by extrapolating results obtained using S-Band testbed data. The results conclusively demonstrates the efficacy of adaptive PRF selection as a method by which to reduce potential range obscuration. A worst-case scenario, for example, indicates that over 20 percent of the TDWR radar data collected about the airport runways has the potential for being contaminated with range aliased echoes at any given time during TDWR surveillance operations. With adaptive PRF selection, however, the expected obscuration is reduced to only 3 percent.

  14. Portable six-port reflectometer for determining moisture content of biomass material

    USDA-ARS?s Scientific Manuscript database

    A portable six-port reflectometer (SPR) for determining moisture content of biomass material is proposed for the first time in this paper. The proposed system consists of a 5.13 GHz reflectometer used with an open-ended half-mode substrateintegrated waveguide (HMSIW) sensor. The complex permittivity...

  15. Hemi-ellipsoidal mirror infrared reflectometer: development and operation.

    PubMed

    Wood, B E; Pipes, J G; Smith, A M; Roux, J A

    1976-04-01

    The development and testing of an ir hemi-ellipsoidal mirror reflectometer (HEMR), operational over a wavelength interval of 2-34 microm, are described. This optical system measures the hemispherical-directional reflectance of room temperature samples relative to a specular gold-coated surface. For a source and sample area commensurate with detectable energy requirements, it is shown experimentally that the HEMR is functional with very tolerable errors. Finally, the hemispherical-directional reflectance of test samples, e.g., black paints, gold diffuser, sulfur, cesium iodide, and others, is presented for wavelengths from 2 microm to 34 microm.

  16. HERITAGE: the concept of a giant flux neutron reflectometer for the exploration of 3-d structure of free-liquid and solid interfaces in thin films

    NASA Astrophysics Data System (ADS)

    Mattauch, S.; Ioffe, A.; Lott, D.; Bottyán, L.; Daillant, J.; Markó, M.; Menelle, A.; Sajti, S.; Veres, T.

    2017-01-01

    The instrumental concept of HERITAGE - a reflectometer with a horizontal sample geometry - well fitted to the long pulse structure of a neutron source is presented. It is constitutes a new class of reflectometers achieving the unprecedentedly high flux for classical specular reflectometry combined with off-specular reflectometry and grazing incidence small-angle scattering (GISANS), thus resulting in a complete 3-d exploration of lateral and in depth structures in thin films. This is achieved by specially designed neutron guides. In the horizontal direction (perpendicular to the scattering plane) the guide's elliptic shape focusses the neutrons onto the sample. In the vertical direction a multichannel geometry provides a smooth divergence distribution at the sample position while accepting the entire beam from a compact high-brilliance flat moderator. The modular collimation setup of HERITAGE provides extremely high flexibility in respect to sample geometries and environments, including the possibility to study virtually all types of solid and liquid interfaces, statically or kinetically. The use of multiple beam illumination allows for reflectivity and GISANS measurements at liquid interfaces both from above and below without a need to move the sample. This concept assures the delivery of the maximum possible and usable flux to the sample in both reflectivity and GISANS measurement regimes. The presented design outperforms the flux of all present-day and already for the ESS planned reflectometers and GISANS setups in flux and in measuring time for standard samples.

  17. Online clustering algorithms for radar emitter classification.

    PubMed

    Liu, Jun; Lee, Jim P Y; Senior; Li, Lingjie; Luo, Zhi-Quan; Wong, K Max

    2005-08-01

    Radar emitter classification is a special application of data clustering for classifying unknown radar emitters from received radar pulse samples. The main challenges of this task are the high dimensionality of radar pulse samples, small sample group size, and closely located radar pulse clusters. In this paper, two new online clustering algorithms are developed for radar emitter classification: One is model-based using the Minimum Description Length (MDL) criterion and the other is based on competitive learning. Computational complexity is analyzed for each algorithm and then compared. Simulation results show the superior performance of the model-based algorithm over competitive learning in terms of better classification accuracy, flexibility, and stability.

  18. Monte Carlo simulation of the spear reflectometer at LANSCE

    SciTech Connect

    Smith, G.S.

    1995-12-31

    The Monte Carlo instrument simulation code, MCLIB, contains elements to represent several components found in neutron spectrometers including slits, choppers, detectors, sources and various samples. Using these elements to represent the components of a neutron scattering instrument, one can simulate, for example, an inelastic spectrometer, a small angle scattering machine, or a reflectometer. In order to benchmark the code, we chose to compare simulated data from the MCLIB code with an actual experiment performed on the SPEAR reflectometer at LANSCE. This was done by first fitting an actual SPEAR data set to obtain the model scattering-length-density profile, {Beta}(z), for the sample and the substrate. Then these parameters were used as input values for the sample scattering function. A simplified model of SPEAR was chosen which contained all of the essential components of the instrument. A code containing the MCLIB subroutines was then written to simulate this simplified instrument. The resulting data was then fit and compared to the actual data set in terms of the statistics, resolution and accuracy.

  19. Real-time parallel implementation of Pulse-Doppler radar signal processing chain on a massively parallel machine based on multi-core DSP and Serial RapidIO interconnect

    NASA Astrophysics Data System (ADS)

    Klilou, Abdessamad; Belkouch, Said; Elleaume, Philippe; Le Gall, Philippe; Bourzeix, François; Hassani, Moha M'Rabet

    2014-12-01

    Pulse-Doppler radars require high-computing power. A massively parallel machine has been developed in this paper to implement a Pulse-Doppler radar signal processing chain in real-time fashion. The proposed machine consists of two C6678 digital signal processors (DSPs), each with eight DSP cores, interconnected with Serial RapidIO (SRIO) bus. In this study, each individual core is considered as the basic processing element; hence, the proposed parallel machine contains 16 processing elements. A straightforward model has been adopted to distribute the Pulse-Doppler radar signal processing chain. This model provides low latency, but communication inefficiency limits system performance. This paper proposes several optimizations that greatly reduce the inter-processor communication in a straightforward model and improves the parallel efficiency of the system. A use case of the Pulse-Doppler radar signal processing chain has been used to illustrate and validate the concept of the proposed mapping model. Experimental results show that the parallel efficiency of the proposed parallel machine is about 90%.

  20. Pulse

    MedlinePlus

    ... the underside of the opposite wrist, below the base of the thumb. Press with flat fingers until ... determine if the patient's heart is pumping. Pulse measurement has other uses as well. During or immediately ...

  1. Radar transponder operation with compensation for distortion due to amplitude modulation

    DOEpatents

    Ormesher, Richard C.; Tise, Bertice L.; Axline, Jr., Robert M.

    2011-01-04

    In radar transponder operation, a variably delayed gating signal is used to gate a received radar pulse and thereby produce a corresponding gated radar pulse for transmission back to the source of the received radar pulse. This compensates for signal distortion due to amplitude modulation on the retransmitted pulse.

  2. Characterization of a laser-produced plasma source for a laboratory EUV reflectometer

    NASA Astrophysics Data System (ADS)

    Scholze, Frank; Scholz, Frank; Tuemmler, Johannes; Ulm, Gerhard; Legall, Herbert; Nickles, Peter-Viktor; Sandner, Wolfgang; Stiel, Holger; van Loyen, Ludwig

    2003-06-01

    With the development of EUV lithography there is an increasing need for high-accuracy at-wavelength metrology. In particular, there is an urgent need for metrology at optical components like mirrors or masks close to the production line. Sources for metrology have to fit different demands on EUV power and spectral shape than sources for steppers systems. We present the results of the radiometric characterization of a laser produced plasma (LPP)-source, newly developed at Max-Born-Institute Berlin for use in an EUV reflectometer. It is operated with a high-power pointing-stabilized laser beam (energy per pulse up to 700 mJ, 10 ns pulse duration, < +/- 25 μrad pointing stability) at 532 nm which is focussed on a rotating Au target cylinder. The incident angle of the laser beam is set to 63°, the detecting angle 55° to the target normal. The source has been characterized regarding spectral photon flux, source size and source point stability. Two independently calibrated instruments, an imaging spectrometer and a double multilayer tool for in-band power measurements were used to obtain highly reliable quantitative values for the EUV emission of the Au-LPP source. Both instruments were calibrated by Physikalisch-Technische Bundesanstalt in its radiometry laboratory at the electron storage ring BESSY II. We obtained a source size of 30 μm by 50 μm (2s horizontal by vertical) and a stability of better than 2s=5 μm horizontally and 2s=9 μm vertically. A spectral photon flux of 1*10e14 /(s sr 0.1 nm) at 13.4 nm at a laser pulse energy of 630 mJ is obtained. The shot-to-shot stability of the source is about 5% (1s) for laser pulse energies above 200 mJ. For pulse energies between 200 mJ and 700 mJ, there is a linear relation between laser pulse energy and EUV output. The spectrum shows a flat continuos emission in the EUV spectral range, which is important for wavelength scanning reflectometry. High stability in total flux and spectral shape of the plasma emission as

  3. ALICE—An advanced reflectometer for static and dynamic experiments in magnetism at synchrotron radiation facilities

    SciTech Connect

    Abrudan, R.; Brüssing, F.; Salikhov, R.; Meermann, J.; Zabel, H.; Radu, I.; Ryll, H.; Radu, F.

    2015-06-15

    We report on significant developments of a high vacuum reflectometer (diffractometer) and spectrometer for soft x-ray synchrotron experiments which allows conducting a wide range of static and dynamic experiments. Although the chamber named ALICE was designed for the analysis of magnetic hetero- and nanostructures via resonant magnetic x-ray scattering, the instrument is not limited to this technique. The versatility of the instrument was testified by a series of pilot experiments. Static measurements involve the possibility to use scattering and spectroscopy synchrotron based techniques (photon-in photon-out, photon-in electron-out, and coherent scattering). Dynamic experiments require either laser or magnetic field pulses to excite the spin system followed by x-ray probe in the time domain from nano- to femtosecond delay times. In this temporal range, the demagnetization/remagnetization dynamics and magnetization precession in a number of magnetic materials (metals, alloys, and magnetic multilayers) can be probed in an element specific manner. We demonstrate here the capabilities of the system to host a variety of experiments, featuring ALICE as one of the most versatile and demanded instruments at the Helmholtz Center in Berlin-BESSY II synchrotron center in Berlin, Germany.

  4. Internal, nonperturbing, radio frequency wave monitor reflectometer system on the DIII-D tokamaka)

    NASA Astrophysics Data System (ADS)

    Lee, J. H.; Doyle, E. J.; Luhmann, N. C., Jr.; Peebles, W. A.; Petty, C. C.; Pinsker, R. I.; Rettig, C. L.; Rhodes, T. L.

    1995-02-01

    A new reflectometer system designed to monitor density fluctuations associated with rf waves has been successfully demonstrated on the DIII-D tokamak. It is a direct, internal, and nonperturbing diagnostic with access into the plasma core. This new diagnostic is motivated by a desire to improve understanding of rf wave physics issues, such as wave trajectory, heating mechanisms, rf wave deposition profile, and wave number, and is highly relevant to planned tokamaks such as ITER and TPX. This work is the first application of reflectometry to rf wave studies in a tokamak. Feedforward tracking receiver techniques are employed to remove frequency instabilities due to inherent drifts in the microwave sources and frequency pulling. In order to minimize spurious pickup of the rf pulse (˜60 MHz), heterodyne detection techniques are utilized, and all components are installed inside an rf shielding box. The system operates in the extraordinary mode (X-mode) at 70 GHz. In this paper, a detailed description of the system, and data illustrating its successful operation will be presented.

  5. AMOR - the time-of-flight neutron reflectometer at SINQ/PSI

    NASA Astrophysics Data System (ADS)

    Gupta, Mukul; Gutberlet, T.; Stahn, J.; Keller, P.; Clemens, D.

    2004-07-01

    The apparatus for multioptional reflectometry (AMOR) at SINQ/PSI is a versatile reflectometer operational in the time-of-flight (TOF) mode (in a wavelength range of 0.15 nm <λ < 1.3 nm) as well as in the monochromatic (theta-2theta) mode with both polarized and unpolarized neutrons. AMOR is designed to perform reflectometry measurements in horizontal sample-plane geometry which allows studying both solid-liquid and liquid-liquid interfaces. A pulsed cold neutron beam from the end position of the neutron guide is produced by a dual-chopper system (side-by-side) having two windows at 180^{circ} and rotatable with a maximum frequency of 200 Hz. In the TOF mode, the chopper frequency, width of the gating window and the chopper-detector distance can be selected independently providing a wide range of q-resolution (Delta q/q=1-10&%slash;). Remanent FeCoV/Ti : N supermirrors are used as polarizer/analyzer with a polarization efficiency of sim97&%slash;. For the monochromatic wavelength mode, a Ni/Ti multilayer is used as a monochromator, giving sim50&%slash; reflectivity at a wavelength of 0.47 nm. In the present work, a detailed description of the instrument and setting-up of the polarization option is described. Results from some of the recent studies with polarized neutrons and measurements on liquid surfaces are presented.

  6. Phase-sensitive optical time domain reflectometer for distributed fence-perimeter intrusion detection

    NASA Astrophysics Data System (ADS)

    Yu, Xuhui; Zhou, Deliang; Lu, Bin; Liu, Sufang; Pan, Ming

    2015-10-01

    In this paper, we demonstrate a distributed fence-perimeter intrusion detection system using a phase-sensitive optical time domain reflectometer (Φ-OTDR) with several advantages, such as high spatial resolution, large detection range, single-end measurement and immunity from electromagnetic interference. By the effort of generating a high-extinction-ratio optical pulse, optimizing the incident optical power and utilizing a differential algorithm, a home-made Φ-OTDR system, as a distributed vibration sensor, is implemented with a spatial resolution of 10 meter. Nowadays, a fence-perimeter intrusion detection system is desired for the security monitor. We set up a fence perimeter using a fiber cable containing only one fiber and a field experiment is carried out based on our Φ-OTDR system. Various vibration events are recorded and analyzed, including wind blowing, personal climbing and knocking. The experiment results reveal unique vibration characteristics of different events in the frequency domain and confirm the effectiveness of the homemade Φ-OTDR system in the application of the distributed fence-perimeter intrusion detection.

  7. Polarization discrimination in a phase-sensitive optical time-domain reflectometer intrusion-sensor system.

    PubMed

    Juarez, Juan C; Taylor, Henry F

    2005-12-15

    A distributed sensor system for detecting and locating intruders based on a phase-sensitive optical time-domain reflectometer (phi-OTDR) that utilizes polarization discrimination is described. The sensing element is a single-mode telecommunications fiber in a 3 mm diameter cable buried along a monitored perimeter in a 20-46 cm deep, 10 cm wide trench in clay soil. Light pulses from a continuous-wave Er fiber Fabry-Perot laser with a narrow (< 3 kHz) instantaneous linewidth and low (a few Kilohertz per second) frequency drift are injected into one end of the fiber, and the orthogonal polarizations of the backscattered light are monitored with separate receivers. Localized phase changes in the optical carrier are sensed by subtraction of a phi-OTDR trace from an earlier stored trace. In field tests with a monitored length of 12 km, detection of intruders on foot as far as 4.5 m from the cable line was consistently achieved.

  8. ALICE—An advanced reflectometer for static and dynamic experiments in magnetism at synchrotron radiation facilities

    NASA Astrophysics Data System (ADS)

    Abrudan, R.; Brüssing, F.; Salikhov, R.; Meermann, J.; Radu, I.; Ryll, H.; Radu, F.; Zabel, H.

    2015-06-01

    We report on significant developments of a high vacuum reflectometer (diffractometer) and spectrometer for soft x-ray synchrotron experiments which allows conducting a wide range of static and dynamic experiments. Although the chamber named ALICE was designed for the analysis of magnetic hetero- and nanostructures via resonant magnetic x-ray scattering, the instrument is not limited to this technique. The versatility of the instrument was testified by a series of pilot experiments. Static measurements involve the possibility to use scattering and spectroscopy synchrotron based techniques (photon-in photon-out, photon-in electron-out, and coherent scattering). Dynamic experiments require either laser or magnetic field pulses to excite the spin system followed by x-ray probe in the time domain from nano- to femtosecond delay times. In this temporal range, the demagnetization/remagnetization dynamics and magnetization precession in a number of magnetic materials (metals, alloys, and magnetic multilayers) can be probed in an element specific manner. We demonstrate here the capabilities of the system to host a variety of experiments, featuring ALICE as one of the most versatile and demanded instruments at the Helmholtz Center in Berlin-BESSY II synchrotron center in Berlin, Germany.

  9. A combined sea clutter and noise model appropriate to the operation of high-frequency pulsed Doppler radar in regions constrained by external noise

    NASA Astrophysics Data System (ADS)

    Gill, Eric W.; Walsh, John

    2008-08-01

    In recent years, bistatic pulsed high-frequency ground wave radar models of the ocean clutter have been developed. Several new features, distinct from earlier monostatic developments, appear as products of those analyses. One question that needs to be addressed is, "What characteristics of the theoretical clutter models are likely to be visible in experimental data collected from the ocean surface?" A major consideration in answering this question is the development of an appropriate noise model. Such a model along with an analogous clutter model is derived. This allows a simulation of time series data for both clutter and noise which may be treated using standard Fourier transform techniques to provide a periodogram for the typical combined noise/clutter spectrum of scattering from the ocean surface. The analysis proceeds on the assumption of an externally noise-limited system, with the noise being characterized as a white Gaussian zero-mean process. The aliasing due to noise undersampling is seen to be an integral part of the model. Statistical stationarity is assumed throughout. Both infinite and finite pulse trains are considered.

  10. Ion gyroscale fluctuation measurement with microwave imaging reflectometer on KSTAR

    NASA Astrophysics Data System (ADS)

    Lee, W.; Leem, J.; Yun, G. S.; Park, H. K.; Ko, S. H.; Wang, W. X.; Budny, R. V.; Luhmann, N. C.; Kim, K. W.

    2016-11-01

    Ion gyroscale turbulent fluctuations with the poloidal wavenumber kθ ˜ 3 cm-1 have been measured in the core region of the neutral beam (NB) injected low confinement (L-mode) plasmas on Korea superconducting tokamak advanced research. The turbulence poloidal wavenumbers are deduced from the frequencies and poloidal rotation velocities in the laboratory frame, measured by the multichannel microwave imaging reflectometer. Linear and nonlinear gyrokinetic simulations also predict the unstable modes with the normalized wavenumber kθρs ˜ 0.4, consistent with the measurement. Comparison of the measured frequencies with the intrinsic mode frequencies from the linear simulations indicates that the measured ones are primarily due to the E × B flow velocity in the NB-injected fast rotating plasmas.

  11. X-ray reflectometer for optical efficiency and scatter measurements

    NASA Technical Reports Server (NTRS)

    Reynolds, J. M.; Fields, S. A.; Holland, R. L.

    1978-01-01

    An instrument has been developed to determine the reflection efficiency and scatter characteristics of optical samples at X-ray wavelengths from 1.5 to 113 A. The reflectometer operates in an oil-free vacuum chamber and measures the reflection efficiency and scatter characteristics as a function of the angle of incidence. The reflection efficiency is given for 8.34-A radiation incident on a fused silica sample finished to a flatness of one-tenth of a wavelength. The experimental reflection efficiency is compared with the theoretical data. The scatter curves are given for the direct X-ray beam and for the beam reflected from the fused silica sample at an angle of incidence of 50 arcmin. The full-width-at-half-maximum (FWHM) resolution of the instrument is approximately 13 arcsec, as determined by a least-squares smoothing of the experimental data.

  12. Microwave Doppler reflectometer system in the Experimental Advanced Superconducting Tokamak.

    PubMed

    Zhou, C; Liu, A D; Zhang, X H; Hu, J Q; Wang, M Y; Li, H; Lan, T; Xie, J L; Sun, X; Ding, W X; Liu, W D; Yu, C X

    2013-10-01

    A Doppler reflectometer system has recently been installed in the Experimental Advanced Superconducting (EAST) Tokamak. It includes two separated systems, one for Q-band (33-50 GHz) and the other for V-band (50-75 GHz). The optical system consists of a flat mirror and a parabolic mirror which are optimized to improve the spectral resolution. A synthesizer is used as the source and a 20 MHz single band frequency modulator is used to get a differential frequency for heterodyne detection. Ray tracing simulations are used to calculate the scattering location and the perpendicular wave number. In EAST last experimental campaign, the Doppler shifted signals have been obtained and the radial profiles of the perpendicular propagation velocity during L-mode and H-mode are calculated.

  13. Techniques to Determine Maintenace Frequency of Permeable Pavement Systems with Time Domain Reflectometers (TDRs

    EPA Science Inventory

    As the surface clogs in permeable pavement systems, they lose effectiveness and require maintenance. There is limited direct guidance for determining when maintenance is needed to prevent surface runoff bypass. Research is being conducted using multiple time domain reflectomete...

  14. First results of the SOL reflectometer on Alcator C-Moda)

    NASA Astrophysics Data System (ADS)

    Lau, C.; Hanson, G.; Lin, Y.; Wilgen, J.; Wukitch, S.; Labombard, B.; Wallace, G.

    2012-10-01

    A swept-frequency X-mode reflectometer has been built on Alcator C-Mod to measure the scrape-off layer (SOL) density profiles adjacent to the lower hybrid launcher. The reflectometer system operates between 100 and 146 GHz at sweep rates from 10 μs to 1 ms and covers a density range of ˜1016-1020 m-3 at B0 = 5-5.4 T. This paper discusses the analysis of reflectometer density profiles and presents first experimental results of SOL density profile modifications due to the application of lower hybrid range-of-frequencies power to L-mode discharges. Comparison between density profiles measured by the X-mode reflectometer and scanning Langmuir probes is also shown.

  15. Assessment of Clogging Dynamics in Permeable Pavement Systems with Time Domain Reflectometers

    EPA Science Inventory

    Infiltration is a primary functional mechanism in green infrastructure stormwater controls. This study used time domain reflectometers (TDRs) to measure spatial infiltration and assess clogging dynamics of permeable pavement systems in Edison, NJ, and Louisville, KY. In 2009, t...

  16. Determination of moisture content in oil palm fruits using a five-port reflectometer.

    PubMed

    Yee, Lee Kim; Abbas, Zulkifly; Jusoh, Mohamad Ashry; Yeow, You Kok; Meng, Cheng Ee

    2011-01-01

    This paper presents the development of a PC-based microwave five-port reflectometer for the determination of moisture content in oil palm fruits. The reflectometer was designed to measure both the magnitude and phase of the reflection coefficient of any passive microwave device. The stand-alone reflectometer consists of a PC, a microwave source, diode detectors and an analog to digital converter. All the measurement and data acquisition were done using Agilent VEE graphical programming software. The relectometer can be used with any reflection based microwave sensor. In this work, the application of the reflectometer as a useful instrument to determine the moisture content in oil palm fruits using monopole and coaxial sensors was demonstrated. Calibration equations between reflection coefficients and moisture content have been established for both sensors. The equation based on phase measurement of monopole sensor was found to be accurate within 5% in predicting moisture content in the fruits when compared to the conventional oven drying method.

  17. Techniques to Determine Maintenace Frequency of Permeable Pavement Systems with Time Domain Reflectometers (TDRs

    EPA Science Inventory

    As the surface clogs in permeable pavement systems, they lose effectiveness and require maintenance. There is limited direct guidance for determining when maintenance is needed to prevent surface runoff bypass. Research is being conducted using multiple time domain reflectomete...

  18. Assessment of Clogging Dynamics in Permeable Pavement Systems with Time Domain Reflectometers

    EPA Science Inventory

    Infiltration is a primary functional mechanism in green infrastructure stormwater controls. This study used time domain reflectometers (TDRs) to measure spatial infiltration and assess clogging dynamics of permeable pavement systems in Edison, NJ, and Louisville, KY. In 2009, t...

  19. Radiometric Calibration Techniques for Signal-of-Opportunity Reflectometers

    NASA Technical Reports Server (NTRS)

    Piepmeier, Jeffrey R.; Shah, Rashmi; Deshpande, Manohar; Johnson, Carey

    2014-01-01

    Bi-static reflection measurements utilizing global navigation satellite service (GNSS) or other signals of opportunity (SoOp) can be used to sense ocean and terrestrial surface properties. End-to-end calibration of GNSS-R has been performed using well-characterized reflection surface (e.g., water), direct path antenna, and receiver gain characterization. We propose an augmented approach using on-board receiver electronics for radiometric calibration of SoOp reflectometers utilizing direct and reflected signal receiving antennas. The method calibrates receiver and correlator gains and offsets utilizing a reference switch and common noise source. On-board electronic calibration sources, such as reference switches, noise diodes and loop-back circuits, have shown great utility in stabilizing total power and correlation microwave radiometer and scatterometer receiver electronics in L-band spaceborne instruments. Application to SoOp instruments is likely to bring several benefits. For example, application to provide short and long time scale calibration stability of the direct path channel, especially in low signal-to-noise ratio configurations, is directly analogous to the microwave radiometer problem. The direct path channel is analogous to the loopback path in a scatterometer to provide a reference of the transmitted power, although the receiver is independent from the reflected path channel. Thus, a common noise source can be used to measure the gain ratio of the two paths. Using these techniques long-term (days to weeks) calibration stability of spaceborne L-band scatterometer and radiometer has been achieved better than 0.1. Similar long-term stability would likely be needed for a spaceborne reflectometer mission to measure terrestrial properties such as soil moisture.

  20. A novel reflectometer for relative reflectance measurements of CCDs

    NASA Astrophysics Data System (ADS)

    Hart, Murdock; Barkhouser, Robert H.; Gunn, James E.; Smee, Stephen A.

    2016-07-01

    The high quantum efficiencies (QE) of backside illuminated charge coupled devices (CCD) has ushered in the age of the large scale astronomical survey. The QE of these devices can be greater than 90%, and is dependent upon the operating temperature, device thickness, backside charging mechanisms, and anti-reflection (AR) coatings. But at optical wavelengths the QE is well approximated as one minus the reflectance, thus the measurement of the backside reflectivity of these devices provides a second independent measure of their QE. We have designed and constructed a novel instrument to measure the relative specular reflectance of CCD detectors, with a significant portion of this device being constructed using a 3D fused deposition model (FDM) printer. This device implements both a monitor and measurement photodiode to simultaneously collect in- cident and reflected measurements reducing errors introduced by the relative reflectance calibration process. While most relative reflectometers are highly dependent upon a precisely repeatable target distance for accurate measurements, we have implemented a method of measurement which minimizes these errors. Using the reflectometer we have measured the reflectance of two types of Hamamatsu CCD detectors. The first device is a Hamamatsu 2k x 4k backside illuminated high resistivity p-type silicon detector which has been optimized to operate in the blue from 380 nm - 650 nm. The second detector being a 2k x 4k backside illuminated high resistivity p-type silicon detector optimized for use in the red from 640 nm - 960 nm. We have not only been able to measure the reflectance of these devices as a function of wavelength we have also sampled the reflectance as a function of position on the device, and found a reflection gradient across these devices.

  1. Pulsed power

    NASA Astrophysics Data System (ADS)

    Stone, David H.

    Pulsed power systems are critical elements for such prospective weapons technologies as high-power microwaves, electrothermal and electromagnetic projectile launchers, neutral particle beams, space-based FELs, ground-based lasers, and charged particle beams. Pulsed power will also be essential for the development of nonweapon military systems such as lidars and ultrawideband radars, and could serve as the bases for nuclear weapon effect simulators. The pulsed power generation requirements for each of these systems is considered.

  2. Generation of High Resolution Radar Range Profiles and Range Profile Auto-Correlation Functions Using Stepped-Frequency Pulse Train

    DTIC Science & Technology

    1984-10-18

    resulting range resolution (of both the profile and itg auto- correlation function) is determined by the total bandwidth (i.e., the fre- quency spread...contrast provided by the resulting range profiles and range profile auto-correlation functions is determined. The target-to-clutter contrast provided by the...SIMULATION RESULTS FOR RANGE-PROFILES AND RANGE-PROFILE 86 AUTO -CORRELATION FIJNCTIONS OBTAINED BY PROCESSING RETURNS FROM FR9QUENCY-STEPPED PULSE

  3. Venus Radar Mapper (VRM): Multimode radar system design

    NASA Technical Reports Server (NTRS)

    Johnson, William T. K.; Edgerton, Alvin T.

    1986-01-01

    The surface of Venus has remained a relative mystery because of the very dense atmosphere that is opaque to visible radiation and, thus, normal photographic techniques used to explore the other terrestrial objects in the solar system are useless. The atmosphere is, however, almost transparent to radar waves and images of the surface have been produced via Earth-based and orbital radars. The technique of obtaining radar images of a surface is variously called side looking radar, imaging radar, or synthetic aperture radar (SAR). The radar requires a moving platform in which the antenna is side looking. High resolution is obtained in the cross-track or range direction by conventional radar pulse encoding. In the along-track or azimuth direction, the resolution would normally be the antenna beam width, but for the SAR case, a much longer antenna (or much sharper beam) is obtained by moving past a surface target as shown, and then combining the echoes from many pulses, by using the Doppler data, to obtain the images. The radar design of the Venus Radar Mapper (VRM) is discussed. It will acquire global radar imagery and altimetry data of the surface of Venus.

  4. Micropower impulse radar

    SciTech Connect

    Azevedo, S.; McEwan, T.E.

    1996-01-01

    Invented and developed at Lawrence Livermore National Laboratory is an inexpensive and highly sensitive, low-power radar system that produces and samples extremely short pulses of energy at the rate of 2 million per second. Called micropower impulse radar (MIR), it can detect objects at a greater variety of distances with greater sensitivity than conventional radar. Its origins in the Laboratory`s Laser Directorate stem from Nova`s transient digitizer. The MIR`s extraordinary range of applications include security, search and rescue, life support, nondestructive evaluation, and transportation.

  5. Using doppler radar images to estimate aircraft navigational heading error

    DOEpatents

    Doerry, Armin W [Albuquerque, NM; Jordan, Jay D [Albuquerque, NM; Kim, Theodore J [Albuquerque, NM

    2012-07-03

    A yaw angle error of a motion measurement system carried on an aircraft for navigation is estimated from Doppler radar images captured using the aircraft. At least two radar pulses aimed at respectively different physical locations in a targeted area are transmitted from a radar antenna carried on the aircraft. At least two Doppler radar images that respectively correspond to the at least two transmitted radar pulses are produced. These images are used to produce an estimate of the yaw angle error.

  6. Scrape-off layer reflectometer for Alcator C-Moda)

    NASA Astrophysics Data System (ADS)

    Lau, Cornwall; Hanson, Greg; Wilgen, John; Lin, Yijun; Wukitch, Steve

    2010-10-01

    A swept-frequency X-mode reflectometer is being built for Alcator C-Mod to measure the scrape-off layer density profiles at the top, middle, and bottom locations in front of both the new lower hybrid launcher and the new ion cyclotron range of frequencies antenna. The system is planned to operate between 100 and 146 GHz at sweep rates from 10 μs to 1 ms, and will cover a density range of approximately 1016-1020 m-3 at B0=5-5.4 T. To minimize the effects of density fluctuations, both differential phase and full phase reflectometry will be employed. Design, test data, and calibration results of this electronics system will be discussed. To reduce attenuation losses, tallguide (TE01) will be used for most of the transmission line system. Simulations of high mode conversion in tallguide components, such as e-plane hyperbolic secant radius of curvature bends, tapers, and horn antennas will be shown. Experimental measurements of the total attenuation losses of these components in the lower hybrid waveguide run will also be presented.

  7. Upgrades to the Polarized Neutron Reflectometer Asterix at LANSCE

    SciTech Connect

    Pynn, Roger

    2015-03-16

    We have upgraded the polarized neutron reflectometer, Asterix, at the Lujan Neutron Scattering Center at Los Alamos for the benefit of the research communities that study magnetic and complex-fluid films, both of which play important roles in support of the DOE’s energy mission. The upgrades to the instrument include: • A secondary spectrometer that was integrated with a Huber sample goniometer purchased with other funds just prior to the start of our project. The secondary spectrometer provides a flexible length for the scattered flight path, includes a mechanism to select among 3 alternative polarization analyzers as well as a support for new neutron detectors. Also included is an optic rail for reproducible positioning of components for Spin Echo Scattering Angle Measurement (SESAME). The entire secondary spectrometer is now non-magnetic, as required for neutron Larmor labeling. • A broad-band neutron polarizer for the incident neutron beam based on the V geometry. • A wide-angle neutron polarization analyzer • A 2d position-sensitive neutron detector • Electromagnetic coils (Wollaston prisms) for SESAME plus the associated power supplies, cooling, safety systems and integration into the data acquisition system. The upgrades allowed a nearly effortless transition between configurations required to serve the polarized neutron reflectometry community, users of the 11 T cryomagnet and users of SESAME.

  8. Laboratory reflectometer for the investigation of optical elements in a wavelength range of 5-50 nm: description and testing results

    NASA Astrophysics Data System (ADS)

    Garakhin, S. A.; Zabrodin, I. G.; Zuev, S. E.; Kas'kov, I. A.; Lopatin, A. Ya.; Nechay, A. N.; Polkovnikov, V. N.; Salashchenko, N. N.; Tsybin, N. N.; Chkhalo, N. I.; Svechnikov, M. V.

    2017-05-01

    We describe a laboratory reflectometer developed at the IPM RAS for precision measurements of spectral and angular dependences of the reflection and transmission coefficients of optical elements in a wavelength range of 5-50 nm. The radiation is monochromatised using a high-resolution Czerny-Turner spectrometer with a plane diffraction grating and two spherical collimating mirrors. A toroidal mirror focuses the probe monochromatic beam on a sample. The X-ray source is a highly ionised plasma produced in the interaction of a high-power laser beam with a solid target at an intensity of 1011-1012 W cm-2. To stabilise the emission characteristics, the target executes translatory and rotary motions in such a way that every pulse irradiates a new spot. The short-focus lens is protected from contamination by erosion products with the use of a specially designed electromagnetic system. The samples under study are mounted on a goniometer is accommodated in a dedicated chamber, which provides five degrees of freedom for samples up to 500 mm in diameter and two degrees of freedom for a detector. The sample mass may range up to 10 kg. The X-ray radiation is recorded with a detector composed of a CsI photocathode and two microchannel plates. A similar detector monitors the probe beam intensity. The spectral reflectometer resolution is equal to 0.030 nm with the use of ruled gratings with a density of 900 lines mm-1 (spectral range: 5-20 nm) and to 0.067 nm for holographic gratings with a density of 400 lines mm-1 (spectral range: 10-50 nm). We analyse the contribution of higher diffraction orders to the probe signal intensity and the ways of taking it into account in the measurements. Examples are given which serve to illustrate the reflectometer application to the study of multilayer mirrors and filters.

  9. Analysis of experimental NRL radar altimeter data

    NASA Technical Reports Server (NTRS)

    Walsh, E. J.

    1974-01-01

    An X-band radar capable of continuously variable transmitted pulse durations down to 1 nsec is being flown to investigate the interaction of radar altimeter signals with the sea surface. There is good agreement between the observed radar altimeter leading edge rise time for a 1-nsec transmitted pulse and the rise time predicted from the radar parameters and the sea state determined by a laser profilometer. Using a threshold tracker on 29-pulse averages for a transmitted pulse of 24 nsec, it was found that the range noise varied linearly with the power level of the threshold over a considerable range. The altimeter range quantization was 9.35 cm, and a minimum range noise of 3.9 cm was obtained. A comparison of pulse-to-pulse correlation observed in the radar data with that predicted by a Monte Carlo simulation is used to obtain a measure of sea surface scatterer motion.

  10. X-ray reflection from a water surface investigated by a new liquid interface reflectometer at SPring-8

    NASA Astrophysics Data System (ADS)

    Yano, Yohko F.; Uruga, Tomoya; Tanida, Hajime; Toyokawa, Hidenori; Terada, Yasuko; Takagaki, Masashi

    2007-10-01

    X-ray reflection measurement of a water surface was demonstrated using recently developed liquid interface reflectometer at SPring-8. The reflectometer equipped with two-dimensional hybrid pixel array detector, PILATUS, achieved x-ray reflectivity towards 10-9 with the integration time at each angle of only 1 sec, having enormous potential for quick measurements.

  11. Coded continuous wave meteor radar

    NASA Astrophysics Data System (ADS)

    Vierinen, Juha; Chau, Jorge L.; Pfeffer, Nico; Clahsen, Matthias; Stober, Gunter

    2016-03-01

    The concept of a coded continuous wave specular meteor radar (SMR) is described. The radar uses a continuously transmitted pseudorandom phase-modulated waveform, which has several advantages compared to conventional pulsed SMRs. The coding avoids range and Doppler aliasing, which are in some cases problematic with pulsed radars. Continuous transmissions maximize pulse compression gain, allowing operation at lower peak power than a pulsed system. With continuous coding, the temporal and spectral resolution are not dependent on the transmit waveform and they can be fairly flexibly changed after performing a measurement. The low signal-to-noise ratio before pulse compression, combined with independent pseudorandom transmit waveforms, allows multiple geographically separated transmitters to be used in the same frequency band simultaneously without significantly interfering with each other. Because the same frequency band can be used by multiple transmitters, the same interferometric receiver antennas can be used to receive multiple transmitters at the same time. The principles of the signal processing are discussed, in addition to discussion of several practical ways to increase computation speed, and how to optimally detect meteor echoes. Measurements from a campaign performed with a coded continuous wave SMR are shown and compared with two standard pulsed SMR measurements. The type of meteor radar described in this paper would be suited for use in a large-scale multi-static network of meteor radar transmitters and receivers. Such a system would be useful for increasing the number of meteor detections to obtain improved meteor radar data products.

  12. Direct detection of lower hybrid wave using a reflectometer on Alcator C-Moda)

    NASA Astrophysics Data System (ADS)

    Shiraiwa, S.; Baek, S.; Dominguez, A.; Marmar, E.; Parker, R.; Kramer, G. J.

    2010-10-01

    The possibility of directly detecting a density perturbation produced by lower hybrid (LH) waves using a reflectometer is presented. We investigate the microwave scattering of reflectometer probe beams by a model density fluctuation produced by short wavelength LH waves in an Alcator C-Mod experimental condition. In the O-mode case, the maximum response of phase measurement is found to occur when the density perturbation is approximately centimeters in front of the antenna, where Bragg scattering condition is satisfied. In the X-mode case, the phase measurement is predicted to be more sensitive to the density fluctuation close to the cut-off layer. A feasibility test was carried out using a 50 GHz O-mode reflectometer on the Alcator C-Mod tokamak, and positive results including the detection of 4.6 GHz pump wave and parametric decay instabilities were obtained.

  13. Density fluctuation measurements on the ATF (Advanced Toroidal Facility) using a two-frequency reflectometer

    SciTech Connect

    Anabitarte, E. . Inst. de Energias Renovables); Hanson, G.R.; Harris, J.H.; Wilgen, J.B.; Bell, J.D.; Dunlap, J.L.; Hidalgo, C.; Thomas, C.E.; Uckan, T. )

    1990-01-01

    A microwave reflectometer system has been installed and operated on the Advanced Toroidal Facility (ATF) to measure density fluctuations. This system consists of two individual reflectometers that use the same antenna system and operate in the 30- to 40-GHz band. This arrangement allows operation at two frequencies along the same radial chord so that radial coherence measurements are possible. During the initial operating period of the reflectometer, a correlation was observed between a change in the edge density fluctuation spectrum and a transition to improved confinement. Recently, local measurements of the density fluctuation spectra in electron-cyclotron-heated (ECH) plasmas has been shown to agree with Langmuir probe measurements at the edge. Furthermore, structure in the spectra has been observed in some ECH plasmas. 4 refs., 3 figs.

  14. Ultra-wideband radar motion sensor

    DOEpatents

    McEwan, T.E.

    1994-11-01

    A motion sensor is based on ultra-wideband (UWB) radar. UWB radar range is determined by a pulse-echo interval. For motion detection, the sensors operate by staring at a fixed range and then sensing any change in the averaged radar reflectivity at that range. A sampling gate is opened at a fixed delay after the emission of a transmit pulse. The resultant sampling gate output is averaged over repeated pulses. Changes in the averaged sampling gate output represent changes in the radar reflectivity at a particular range, and thus motion. 15 figs.

  15. Ultra-wideband radar motion sensor

    DOEpatents

    McEwan, Thomas E.

    1994-01-01

    A motion sensor is based on ultra-wideband (UWB) radar. UWB radar range is determined by a pulse-echo interval. For motion detection, the sensors operate by staring at a fixed range and then sensing any change in the averaged radar reflectivity at that range. A sampling gate is opened at a fixed delay after the emission of a transmit pulse. The resultant sampling gate output is averaged over repeated pulses. Changes in the averaged sampling gate output represent changes in the radar reflectivity at a particular range, and thus motion.

  16. Detrimental Effect Elimination of Laser Frequency Instability in Brillouin Optical Time Domain Reflectometer by Using Self-Heterodyne Detection

    PubMed Central

    Li, Yongqian; Li, Xiaojuan; An, Qi; Zhang, Lixin

    2017-01-01

    A useful method for eliminating the detrimental effect of laser frequency instability on Brillouin signals by employing the self-heterodyne detection of Rayleigh and Brillouin scattering is presented. From the analysis of Brillouin scattering spectra from fibers with different lengths measured by heterodyne detection, the maximum usable pulse width immune to laser frequency instability is obtained to be about 4 µs in a self-heterodyne detection Brillouin optical time domain reflectometer (BOTDR) system using a broad-band laser with low frequency stability. Applying the self-heterodyne detection of Rayleigh and Brillouin scattering in BOTDR system, we successfully demonstrate that the detrimental effect of laser frequency instability on Brillouin signals can be eliminated effectively. Employing the broad-band laser modulated by a 130-ns wide pulse driven electro-optic modulator, the observed maximum errors in temperatures measured by the local heterodyne and self-heterodyne detection BOTDR systems are 7.9 °C and 1.2 °C, respectively. PMID:28335508

  17. Detrimental Effect Elimination of Laser Frequency Instability in Brillouin Optical Time Domain Reflectometer by Using Self-Heterodyne Detection.

    PubMed

    Li, Yongqian; Li, Xiaojuan; An, Qi; Zhang, Lixin

    2017-03-20

    A useful method for eliminating the detrimental effect of laser frequency instability on Brillouin signals by employing the self-heterodyne detection of Rayleigh and Brillouin scattering is presented. From the analysis of Brillouin scattering spectra from fibers with different lengths measured by heterodyne detection, the maximum usable pulse width immune to laser frequency instability is obtained to be about 4 µs in a self-heterodyne detection Brillouin optical time domain reflectometer (BOTDR) system using a broad-band laser with low frequency stability. Applying the self-heterodyne detection of Rayleigh and Brillouin scattering in BOTDR system, we successfully demonstrate that the detrimental effect of laser frequency instability on Brillouin signals can be eliminated effectively. Employing the broad-band laser modulated by a 130-ns wide pulse driven electro-optic modulator, the observed maximum errors in temperatures measured by the local heterodyne and self-heterodyne detection BOTDR systems are 7.9 °C and 1.2 °C, respectively.

  18. High speed reflectometer for EUV mask-blanks

    NASA Astrophysics Data System (ADS)

    Wies, Christian; Lebert, Rainer; Jagle, Bernhard; Juschkin, L.; Sobel, F.; Seitz, H.; Walter, Ronny; Laubis, C.; Scholze, F.; Biel, W.; Steffens, O.

    2005-06-01

    AIXUV GmbH and partners have developed a high speed Reflectometer for EUV mask-blanks which is fully compliant with the SEMI-standard P38 for EUV-mask-blank metrology. The system has been installed in June 2004 at SCHOTT Lithotec AG. It features high throughput, high lateral and spectral resolution, high reproducibility and low absolute uncertainty. Using AIXUV's EUV-LAMP and debris mitigation, low cost-of-ownership and high availability is expected. The spectral reflectance of up to 3 mask-blanks per hour can be measured with at least 20 spots each. The system is push button-controlled. Results are stored in CSV file format. For a spot size of 0.1x1 mm2, 2000 spectral channels of 1.6 pm bandwidth are recorded from 11.6 nm to 14.8 nm. The reflectance measurement is based on the comparison of the sample under test to two reference mirrors calibrated at the PTB radiometry laboratory at BESSY II. The three reflection spectra are recorded simultaneously. For each spot more than 107 photons are accumulated in about 20 s, providing statistical reproducibility below 0.2% RMS. The total uncertainty is below 0.5% absolute. Wavelength calibration better than 1 pm RMS over the whole spectral range is achieved by reference to NIST published wavelengths of about 100 xenon emission lines. It is consistent with the wavelength of the krypton 3d-5p absorption resonance at 13.5947 nm to better than 2 pm.

  19. High speed reflectometer for EUV mask-blanks

    NASA Astrophysics Data System (ADS)

    Wies, C.; Lebert, R.; Jaegle, B.; Juschkin, L.; Sobel, F.; Seitz, H.; Walter, R.; Laubis, C.; Scholze, F.; Biel, W.; Steffens, O.

    2005-05-01

    AIXUV GmbH and partners have developed a high speed Reflectometer for EUV mask-blanks which is fully compliant with the SEMI-standard P38 for EUV-mask-blank metrology. The system has been installed in June 2004 at SCHOTT Lithotec AG. It features high throughput, high lateral and spectral resolution, high reproduci-bility and low absolute uncertainty. Using AIXUV's EUV-LAMP and debris mitigation, low cost-of-ownership and high availability is expected. The spectral reflectance of up to 3 mask-blanks per hour can be measured with at least 20 spots each. The system is push button-controlled. Results are stored in CSV file format. For a spot size of 0.1×1 mm2, 2000 spectral chan-nels of 1.6 pm bandwidth are recorded from 11.6 nm to 14.8 nm. The reflectance measurement is based on the comparison of the sample under test to two reference mirrors calibrated at the PTB radiometry laboratory at BESSY II. The three reflection spectra are recorded simultaneously. For each spot more than 107 photons are ac-cumulated in about 20 s, providing statistical reproducibility below 0.2 % RMS. The total uncertainty is below 0.5 % absolute. Wavelength calibration better than 1 pm RMS over the whole spectral range is achieved by refe-rence to NIST published wavelengths of about 100 xenon emission lines. It is consistent with the wavelength of the krypton 3d-5p absorption resonance at 13.5947 nm to better than 2 pm.

  20. Rapid X-ray reflectivity measurement using a new liquid interface reflectometer at SPring-8

    NASA Astrophysics Data System (ADS)

    Yano, Y. F.; Uruga, T.; Tanida, H.; Toyokawa, H.; Terada, Y.; Takagaki, M.; Yamada, H.

    2009-02-01

    X-ray reflectivity measurements of liquid surfaces were demonstrated using a recently developed liquid interface reflectometer at SPring-8. The reflectometer, equipped with a two-dimensional hybrid pixel array detector (PILATUS), achieved x-ray reflectivity towards 10-9 with an integration time at each angle of only 1 sec, offering enormous potential for rapid measurements. Time-resolved measurements at a time resolution of 1 min were performed on the adsorption process of a globular protein lysozyme on a water/air interface.

  1. A multichannel reflectometer for edge density profile measurements at the ICRF antenna in ASDEX Upgrade

    NASA Astrophysics Data System (ADS)

    Tudisco, O.; Silva, A.; Ceccuzzi, S.; D'Arcangelo, O.; Rocchi, G.; Fuenfgelder, H.; Bobkov, V.; Cavazzana, R.; Conway, G. D.; Friesen, J.; Gonçalves, B.; Mancini, A.; Meneses, L.; Noterdaeme, J. M.; Siegl, G.; Simonetto, A.; Tsujii, N.; Tuccillo, A. A.; Vierle, T.; Zammuto, I.; ASDEX Upgrade Team, Ftu Team

    2014-02-01

    A multichannel reflectometer will be built for the new three-straps ICRF antenna of ASDEX Upgrade (AUG), to study the density behavior in front of it. Ten different accesses to the plasma are available for the three reflectometer channels that can be interchanged without breaking the machine vacuum. Frequency is scanned from 40 GHz to 68 GHz, in 10μs, which corresponds to a cut-off density ranging from 1018÷1019m-3 in the Right cut-off of the X-mode propagation, for standard toroidal magnetic field values of AUG.

  2. Low noise Kα-band hopping reflectometer based on yttrium iron garnet sources at TEXTOR

    NASA Astrophysics Data System (ADS)

    Soldatov, S.; Krämer-Flecken, A.; Zorenko, O.

    2011-03-01

    The heterodyne hopping reflectometer system based on wide-tuned low noise yttrium iron garnet sources was developed for TEXTOR experiment. Being installed in 1998 it successfully operates more than 10 years providing the measurements of plasma density fluctuations. Owing to the advance multihorn antennae systems installed at three different positions around the tokamak, the correlation properties as well as the propagation measurements of plasma density fluctuations are realized. The reflectometer operates in ordinary polarization mode providing the access mostly to plasma gradient and pedestal region. The capabilities of the diagnostic are illustrated with the examples of measured fluctuation characteristics in the variety of TEXTOR plasmas.

  3. Measurement of electromagnetic fields generated by air traffic control radar systems with spectrum analysers.

    PubMed

    Barellini, A; Bogi, L; Licitra, G; Silvi, A M; Zari, A

    2009-12-01

    Air traffic control (ATC) primary radars are 'classical' radars that use echoes of radiofrequency (RF) pulses from aircraft to determine their position. High-power RF pulses radiated from radar antennas may produce high electromagnetic field levels in the surrounding area. Measurement of electromagnetic fields produced by RF-pulsed radar by means of a swept-tuned spectrum analyser are investigated here. Measurements have been carried out both in the laboratory and in situ on signals generated by an ATC primary radar.

  4. A new hand-held optical reflectometer to measure enamel erosion: correlation with surface hardness and calcium release

    PubMed Central

    Carvalho, Thiago Saads; Baumann, Tommy; Lussi, Adrian

    2016-01-01

    In the present study, the surface reflection intensity (SRI) was measured from enamel with different induced erosion degrees using a hand-held pen-size reflectometer (Hand-Held) and a Table-Top reflectometer. To validate the Hand-Held reflectometer, we correlated its optical signals with the change of surface microhardness (SMH), and amount of calcium released from the enamel samples during erosion. We used 124 tooth enamel specimens that were exposed to an erosive challenge of either 1, 2, 4, 6, 8, or 10 minutes. SRI and SMH were measured before and after the erosive challenge and we also measured the amount of calcium released to the citric acid. Relative SRI loss (rSRIloss) and relative SMH loss (rSMHloss) were calculated. rSRIloss from the Hand-Held and the Table-Top reflectometers were similar and significantly correlated to rSMHloss and calcium release. The regression analyses showed a significant association between rSRIloss from both reflectometers and rSMHloss and calcium, showing that both reflectometers can be used to measure erosive demineralization of enamel. The Hand-Held reflectometer is capable of assessing in vitro erosion, correlating to other commonly used methods. It is small, easy to handle and provides fast measurement, being a possible candidate to measure erosion in clinical studies. PMID:27121129

  5. A new hand-held optical reflectometer to measure enamel erosion: correlation with surface hardness and calcium release.

    PubMed

    Carvalho, Thiago Saads; Baumann, Tommy; Lussi, Adrian

    2016-04-28

    In the present study, the surface reflection intensity (SRI) was measured from enamel with different induced erosion degrees using a hand-held pen-size reflectometer (Hand-Held) and a Table-Top reflectometer. To validate the Hand-Held reflectometer, we correlated its optical signals with the change of surface microhardness (SMH), and amount of calcium released from the enamel samples during erosion. We used 124 tooth enamel specimens that were exposed to an erosive challenge of either 1, 2, 4, 6, 8, or 10 minutes. SRI and SMH were measured before and after the erosive challenge and we also measured the amount of calcium released to the citric acid. Relative SRI loss (rSRIloss) and relative SMH loss (rSMHloss) were calculated. rSRIloss from the Hand-Held and the Table-Top reflectometers were similar and significantly correlated to rSMHloss and calcium release. The regression analyses showed a significant association between rSRIloss from both reflectometers and rSMHloss and calcium, showing that both reflectometers can be used to measure erosive demineralization of enamel. The Hand-Held reflectometer is capable of assessing in vitro erosion, correlating to other commonly used methods. It is small, easy to handle and provides fast measurement, being a possible candidate to measure erosion in clinical studies.

  6. An analysis of the effects of secondary reflections on dual-frequency reflectometers

    NASA Technical Reports Server (NTRS)

    Hearn, C. P.; Cockrell, C. R.; Harrah, S. D.

    1990-01-01

    The error-producing mechanism involving secondary reflections in a dual-frequency, distance measuring reflectometer is examined analytically. Equations defining the phase, and hence distance, error are derived. The error-reducing potential of frequency-sweeping is demonstrated. It is shown that a single spurious return can be completely nullified by optimizing the sweep width.

  7. Determination of Moisture Content in Oil Palm Fruits Using a Five-Port Reflectometer

    PubMed Central

    Yee, Lee Kim; Abbas, Zulkifly; Jusoh, Mohamad Ashry; Yeow, You Kok; Meng, Cheng Ee

    2011-01-01

    This paper presents the development of a PC-based microwave five-port reflectometer for the determination of moisture content in oil palm fruits. The reflectometer was designed to measure both the magnitude and phase of the reflection coefficient of any passive microwave device. The stand-alone reflectometer consists of a PC, a microwave source, diode detectors and an analog to digital converter. All the measurement and data acquisition were done using Agilent VEE graphical programming software. The relectometer can be used with any reflection based microwave sensor. In this work, the application of the reflectometer as a useful instrument to determine the moisture content in oil palm fruits using monopole and coaxial sensors was demonstrated. Calibration equations between reflection coefficients and moisture content have been established for both sensors. The equation based on phase measurement of monopole sensor was found to be accurate within 5% in predicting moisture content in the fruits when compared to the conventional oven drying method. PMID:22163837

  8. Development and Operation of a Hemi-Ellipsoidal Mirror Infrared Reflectometer from 2 to 34 micrometers

    DTIC Science & Technology

    1975-07-01

    operation of a hemi-ellipsoidal mirror reflectometer (HEMR) which presently has a reflectance measurement capability for wave- lengths in the 2- to 34-Mm...the two types of surfaces. 7.0 PROCEDURE Before a reflectance measurement was made, the hemi-ellipsoidal mirror alignment was established•. _The hemi

  9. Radar Performance Improvement. Angle Tracking Modification to Fire Control Radar System for Space Shuttle Rendezvous

    NASA Technical Reports Server (NTRS)

    Little, G. R.

    1976-01-01

    The AN/APQ-153 fire control radar modified to provide angle tracking was evaluated for improved performance. The frequency agile modifications are discussed along with the range-rate improvement modifications, and the radar to computer interface. A parametric design and comparison of noncoherent and coherent radar systems are presented. It is shown that the shuttle rendezvous range and range-rate requirements can be made by a Ku-Band noncoherent pulse radar.

  10. Pulse Circuits of Radar Stations

    DTIC Science & Technology

    1982-08-06

    SUPERVISION (Recommendation for the Teacher ) Effective use of the book in an auditorium under the supervision of a teacher and the latter’s participation...work independently, students voluntari. y outline the material in . their notebooks and can approach the teacher with an,, questions (for example, on...cirves, circuits) and provide them to the teacher for a critique. The teacher examines the answer and, depending on the degree of its correctness and

  11. A Time Domain Reflectometer with 100 ps precision implemented in a cost-effective FPGA for the test of the KLOE-2 Inner Tracker readout anodes

    NASA Astrophysics Data System (ADS)

    Bencivenni, G.; Czerwinski, E.; De Lucia, E.; De Robertis, G.; Domenici, D.; Erriquez, O.; Fanizzi, G.; Felici, G.; Liuzzi, R.; Loddo, F.; Mongelli, M.; Morello, G.; Ranieri, A.; Valentino, V.

    2013-01-01

    A Time Domain Reflectometer implemented in a single cost-effective Field Programmable Gate Array device is shown to achieve a precision around 100 ps. The Time to Digital Converter section of the device is based on a tapped delay line followed by an encoder and shows both Differential and Integral Non-Linearity below one least significant bit. The same Field Programmable Gate Array houses an 8051 8-bits microprocessor, for the control of the pulse signals generation, the acquisition and the first treatment of raw data. Principles of operation, architecture, performance and preliminary trials on the prototype are presented in this paper. As an example of possible application, the proposed circuit has been usefully used to perform the quality control of the micro-strip anodic planes of the Gas Electron Multiplier Inner Tracker of the KLOE-2 experiment.

  12. Internal, nonperturbing, radio frequency wave monitor reflectometer system on the DIII-D tokamak (abstract)a)

    NASA Astrophysics Data System (ADS)

    Lee, J. H.; Doyle, E. J.; Luhmann, N. C., Jr.; Peebles, W. A.; Petty, C. C.; Pinsker, R. I.; Rettig, C. L.; Rhodes, T. L.

    1995-01-01

    A new reflectometer system designed to monitor density fluctuations associated with rf waves has been successfully demonstrated on the DIII-D tokamak. It is a direct, internal, and nonperturbing diagnostic with access into the plasma core. This new diagnostic is motivated by a desire to improve understanding of rf wave physics issues, such as wave trajectory, heating mechanisms, rf wave deposition profile, and wave number, and is highly relevant to planned tokamaks such as ITER and TPX. This work is the first application of reflectometry to rf wave studies in a tokamak. Feedforward tracking receiver techniques are employed to remove frequency instabilities due to inherent drifts in the microwave sources and frequency pulling. In order to minimize spurious pickup of the rf pulse (˜60 MHz), heterodyne detection techniques are utilized, and all components are installed inside an rf shielding box. The system operates in the extraordinary mode (X mode) at 70 GHz. In this paper, a detailed description of the system, and data illustrating its successful operation will be presented.

  13. Modern radar: Theory, operation and maintenance /2nd edition/

    NASA Astrophysics Data System (ADS)

    Safford, E. L., Jr.

    1981-02-01

    A compendium on radar systems and theory is presented. The development of the magnetron and the klystron is reviewed along with the methods used to solve the original radar problems. The early display devices are surveyed with a view to their ongoing evolution. The pulse, Doppler, CW, and pulse-Doppler radar systems are detailed. Target reflectivity, pulse calculations, Doppler clutter, signal processing, and bandwidth are discussed. The uses and basic components are examined of the radar systems utilized in military, intruder detection, avionics, aerospace, police, satellite, and guided missile applications. A coverage of radar frequency components, tracking systems, aircraft signatures, and receivers is provided.

  14. Whither radar?

    NASA Astrophysics Data System (ADS)

    Radford, M. F.

    The evolution of radar technology in the future is examined with respect to both civilian and military applications. Consideration is given to four broad categories of radar technology where improvements in the state of the art are expected. The categories include: antenna design; transmitter design; receiver/signal processor design; and data handling/radar management technology. The influence of CAD/CAM techniques and very high performance ICs on radar system design is evaluated. A formula is presented for calculating the performance requirements of a radar system with respect to sensitivity, resolution, and optimum data rate.

  15. Characteristics of Sunset radar

    NASA Technical Reports Server (NTRS)

    Green, J. L.

    1983-01-01

    Located in a narrow canyon 15 km west of Boulder, Colorado, the Sunset pulsed Doppler radar was the first radar designed and constructed specifically as a VHF ST radar. The antenna system is a phased array of coaxial-colinear dopoles with computer-controlled phase shifters for each line of dipoles. It operates at a frequency of 40.475 MHz and a wavelength of 7.41M. Peak transmitter power is 100 kW. Aperture efficiency is 0.58 and resistive loss is 0.30 for its 3600 sq m area. The practical steering rate is 1 record/minute/position to any arbitrary antenna beam position. The first clear-air turbulence echoes and wind velocity measurements were obtained in 1974. Significant accomplishments are listed.

  16. Coherent IR radar technology

    NASA Astrophysics Data System (ADS)

    Gschwendtner, A. B.; Harney, R. C.; Hull, R. J.

    Recent progress in the development of coherent IR radar equipment is reviewed, focusing on the Firepond laser radar installation and the more compact systems derived for it. The design and capabilities of Firepond as a long-range satellite-tracking device are outlined. The technological improvements necessary to make laser radar mobile are discussed: a lightweight, stable 5-10-W transmitter laser for both CW and pulsed operation, a 12-element HgCdTe detector array, an eccentric-pupil Ritchey-Chretien telescope, and a combination of near-field phase modification and anamorphic expansion to produce a fan beam of relatively uniform intensity. Sample images obtained with a prototype system are shown, and the applicability of the mobile system to range-resolved coherent DIAL measurement is found to be similar to that of a baseline DIAL system.

  17. Moving target detection for frequency agility radar by sparse reconstruction

    NASA Astrophysics Data System (ADS)

    Quan, Yinghui; Li, YaChao; Wu, Yaojun; Ran, Lei; Xing, Mengdao; Liu, Mengqi

    2016-09-01

    Frequency agility radar, with randomly varied carrier frequency from pulse to pulse, exhibits superior performance compared to the conventional fixed carrier frequency pulse-Doppler radar against the electromagnetic interference. A novel moving target detection (MTD) method is proposed for the estimation of the target's velocity of frequency agility radar based on pulses within a coherent processing interval by using sparse reconstruction. Hardware implementation of orthogonal matching pursuit algorithm is executed on Xilinx Virtex-7 Field Programmable Gata Array (FPGA) to perform sparse optimization. Finally, a series of experiments are performed to evaluate the performance of proposed MTD method for frequency agility radar systems.

  18. Moving target detection for frequency agility radar by sparse reconstruction.

    PubMed

    Quan, Yinghui; Li, YaChao; Wu, Yaojun; Ran, Lei; Xing, Mengdao; Liu, Mengqi

    2016-09-01

    Frequency agility radar, with randomly varied carrier frequency from pulse to pulse, exhibits superior performance compared to the conventional fixed carrier frequency pulse-Doppler radar against the electromagnetic interference. A novel moving target detection (MTD) method is proposed for the estimation of the target's velocity of frequency agility radar based on pulses within a coherent processing interval by using sparse reconstruction. Hardware implementation of orthogonal matching pursuit algorithm is executed on Xilinx Virtex-7 Field Programmable Gata Array (FPGA) to perform sparse optimization. Finally, a series of experiments are performed to evaluate the performance of proposed MTD method for frequency agility radar systems.

  19. Rain radar instrument definition

    NASA Astrophysics Data System (ADS)

    Vincent, Nicolas; Chenebault, J.; Suinot, Noel; Mancini, Paolo L.

    1996-12-01

    As a result of a pre-phase a study, founded by ESA, this paper presents the definition of a spaceborne Rain Radar, candidate instrument for earth explorer precipitation mission. Based upon the description of user requirements for such a dedicated mission, a mission analysis defines the most suitable space segment. At system level, a parametric analysis compares pros and cons of instrument concepts associated with rain rate retrieval algorithms in order to select the most performing one. Several trade-off analysis at subsystem level leads then to the definition of the proposed design. In particular, as pulse compression is implemented in order to increase the radar sensitivity, the selected method to achieve a pulse response with a side-lobe level below--60 dB is presented. Antenna is another critical rain radar subsystem and several designs are com pared: direct radiating array, single or dual reflector illuminated by single or dual feed arrays. At least, feasibility of centralized amplification using TWTA is compared with criticality of Tx/Rx modules for distributed amplification. Mass and power budgets of the designed instrument are summarized as well as standard deviations and bias of simulated rain rate retrieval profiles. The feasibility of a compliant rain radar instrument is therefore demonstrated.

  20. The Radar Roadmap

    DTIC Science & Technology

    2013-01-01

    LIMITATION OF ABSTRACT Same as Report ( SAR ) 18. NUMBER OF PAGES 25 19a. NAME OF RESPONSIBLE PERSON a. REPORT unclassified b. ABSTRACT unclassified c...ABSTRACT Same as Report ( SAR ) 18. NUMBER OF PAGES 25 19a. NAME OF RESPONSIBLE PERSON a. REPORT unclassified b. ABSTRACT unclassified c. THIS PAGE...object bistatic radars. The former allows high resolution without the use of pulse compression techniques and the latter promises cheaper systems by

  1. [Correction method for infrared spectral emissivity measurement system based on integrating sphere reflectometer].

    PubMed

    Zhang, Yu-Feng; Dai, Jing-Min; Zhang, Yu; Pan, Wei-Dong; Zhang, Lei

    2013-08-01

    In view of the influence of non-ideal reference standard on spectral emissivity measurement, by analyzing the principle of infrared emissivity measurement system based on integrating sphere reflectometer, a calibration method suitable for measuring spectral emissivity system using the reflection measurement was proposed. By fitting a spectral reflectance curve of the reference standard sample to the given reflectance data, the correction coefficient of measurement system was computed. Then the output voltage curve of reference standard sample was corrected by this coefficient. The system error caused by the imperfection of reference standard was eliminated. The correction method was applied to the spectral emissivity measurement system based on integrating sphere reflectometer. The results measured by the corrected system and the results measured by energy comparison measurement were compared to verify the feasibility and effectivity of this correction method in improving the accuracy of spectral emissivity measurement.

  2. High-aperture monochromator-reflectometer and its usefulness for CCD calibration

    NASA Astrophysics Data System (ADS)

    Vishnyakov, Eugene A.; Shcherbakov, Alexander V.; Pertsov, Andrei A.; Polkovnikov, Vladimir N.; Pestov, Alexey E.; Pariev, Dmitry E.; Chkhalo, Nikolai I.

    2017-05-01

    We present a laboratory high-aperture monochromator-reflectometer employing laser-plasma radiation source and three replaceable Schwarzschild objectives for a certain range of applications in the soft X-ray spectral waveband. Three sets of X-ray multilayer mirrors for the Schwarzschild objectives enable operation of the reflectometer at the wavelengths of 135, 171 and 304 Å, while a goniometer with three degrees of freedom allows different measurement modes. We have used the facility for a laboratory CCD calibration at the wavelengths specified. Combined with the results of the CCD sensitivity measurements conducted in the VUV spectral waveband, the total outcome provides a more comprehensive understanding of the CCD effectivity in a wide spectral range.

  3. Radar Polarimetry

    DTIC Science & Technology

    2004-12-01

    RADAR CROSS SECTION (RCS) σ.................................................. 15 D. THE RADAR SYSTEM...spherical surface, as [13]: rV V s iV rH H s iH E D E E D E ρ ρ = Γ = Γ (2.27) 15 C. RADAR CROSS SECTION (RCS) σ The radar cross section is...Interpretation ⎥ ⎦ ⎤ ⎢ ⎣ ⎡ 10 01 Odd- bounce Surface, sphere, corner reflectors ⎥ ⎦ ⎤ ⎢ ⎣ ⎡ −10 01 Even-bounce Dihedral ⎥

  4. Planetary Radar

    NASA Technical Reports Server (NTRS)

    Neish, Catherine D.; Carter, Lynn M.

    2015-01-01

    This chapter describes the principles of planetary radar, and the primary scientific discoveries that have been made using this technique. The chapter starts by describing the different types of radar systems and how they are used to acquire images and accurate topography of planetary surfaces and probe their subsurface structure. It then explains how these products can be used to understand the properties of the target being investigated. Several examples of discoveries made with planetary radar are then summarized, covering solar system objects from Mercury to Saturn. Finally, opportunities for future discoveries in planetary radar are outlined and discussed.

  5. Planetary Radar

    NASA Technical Reports Server (NTRS)

    Neish, Catherine D.; Carter, Lynn M.

    2015-01-01

    This chapter describes the principles of planetary radar, and the primary scientific discoveries that have been made using this technique. The chapter starts by describing the different types of radar systems and how they are used to acquire images and accurate topography of planetary surfaces and probe their subsurface structure. It then explains how these products can be used to understand the properties of the target being investigated. Several examples of discoveries made with planetary radar are then summarized, covering solar system objects from Mercury to Saturn. Finally, opportunities for future discoveries in planetary radar are outlined and discussed.

  6. Natural Fiber Span Reflectometer Providing a Virtual Phase Signal Sensing Array Capability

    DTIC Science & Technology

    2005-08-13

    simultaneously transmitted as a composite optical signal to a 24 receiver where these are collected and photodetected . By 7 I correlating the photodetected ...fiber span time- 4 domain reflectometer system in accordance with the present 5 invention; 6 FIG. 4 is an electrical schematic of a balanced ... photodetected in optical receiver, 15, by optically 4 interfering the composite back propagating lightwave on the 5 local oscillator signal. As one of the

  7. Three dimensional measurements of Geodesic Acoustic Mode with correlation Doppler reflectometers

    NASA Astrophysics Data System (ADS)

    Zhong, W. L.; Shi, Z. B.; Xu, Y.; Zou, X. L.; Duan, X. R.; Chen, W.; Jiang, M.; Yang, Z. C.; Zhang, B. Y.; Shi, P. W.; Liu, Z. T.; Xu, M.; Song, X. M.; Cheng, J.; Ke, R.; Nie, L.; Cui, Z. Y.; Fu, B. Z.; Ding, X. T.; Dong, J. Q.; Liu, Yi.; Yan, L. W.; Yang, Q. W.; Liu, Yong; the HL-2A Team

    2015-10-01

    Correlation Doppler reflectometers have been newly developed in the HL-2A Tokamak. Owing to the flexibility of the diagnostic arrangements, the multi-channel systems allow us to study, simultaneously, the radial properties of edge turbulence and its long-range correlation in both the poloidal and toroidal direction. With these reflectometers, three-dimensional spatial structure of Geodesic Acoustic Mode (GAM) is surveyed, including the symmetric feature of Er fluctuations in both poloidal and toroidal directions, and the radial propagation of GAMs. The bi-coherence analysis for the Er fluctuations suggests that the three-wave nonlinear interaction could be the mechanism for the generation of GAM. The temporal evolution of GAM during the plasma density modulation experiments has been studied. The results show that the collisional damping plays a role in suppressing the GAM magnitudes, and hence, weakening the regulating effects of GAM on ambient turbulence. Three dimensional correlation Doppler measurements of GAM activity demonstrate that the newly developed correlation Doppler reflectometers in HL-2A are powerful tools for edge turbulence studies with high reliability. A shorter version of this contribution is due to be published in PoS at: ``1st EPS conference on Plasma Diagnostics''.

  8. Pulse Compression Made Easy With VSIPL++

    DTIC Science & Technology

    2007-11-02

    Engine VSI/Pro C/ASM Kernel Object Oriented Strategies - Deferred Evaluation Synthetic Aperature Radar Pulse CompressionCritical Benchmarks... Synthetic Aperature Radar Pulse Compression VSIPL++ (C++)API VSIPL C API VSI/Pro Internal C++ Engine VSI/Pro C / ASM Kernels • What are the benefits of a...state of the art radar systems. Pulse Compression: The VSIPL way The pseudocode: Create Vectors Create Forward FFT object Create Inverse FFT object

  9. Advanced architectures for real-time Delay-Doppler Map GNSS-reflectometers: The GPS reflectometer instrument for PAU (griPAU)

    NASA Astrophysics Data System (ADS)

    Valencia, E.; Camps, A.; Marchan-Hernandez, J. F.; Bosch-Lluis, X.; Rodriguez-Alvarez, N.; Ramos-Perez, I.

    2010-07-01

    In recent years Global Navigation Satellite System's signals Reflectometry (GNSS-R) has stood as a potential powerful remote sensing technique to derive scientifically relevant geophysical parameters such as ocean altimetry, sea state or soil moisture. This has brought out the need of designing and implementing appropriate receivers in order to track and process this kind of signals in real-time to avoid the storage of huge volumes of raw data. This paper presents the architecture and performance of the Global Positioning System (GPS) Reflectometer Instrument for PAU (griPAU), a real-time high resolution Delay-Doppler Map reflectometer, operating at the GPS L1 frequency with the C/A codes. The griPAU instrument computes 24 × 32 complex points DDMs with configurable resolution (Δ fDmin = 20 Hz, Δ τmin = 0.05 chips) and selectable coherent (minimum = 1 ms, maximum = 100 ms for correlation loss Δ ρ < 90%) and incoherent integration times (minimum of one coherent integration period and maximum not limited but typically <1 s). A high sensitivity (DDM peak relative error = 0.9% and DDM volume relative error = 0.03% @ Ti = 1 s) and stability (Δ ρ/Δ t = -1 s -1) have been achieved by means of advanced digital design techniques.

  10. Helicopter discrimination apparatus for the murine radar

    DOEpatents

    Webb, Jr., John G.; Gray, Roger M.

    1977-01-01

    A helicopter discrimination apparatus for a radar utilizing doppler filtering to discriminate between a missile and ground clutter. The short duration of the doppler filter pulses which are emitted by helicopter rotor blades are processed to prevent false alarms, thus allowing the radar-protected helicopter to operate in formation with other helicopters while maintaining protection against infra-red-seeking missiles.

  11. Radar research at the University of Kansas

    NASA Astrophysics Data System (ADS)

    Blunt, Shannon D.; Allen, Christopher; Arnold, Emily; Hale, Richard; Hui, Rongqing; Keshmiri, Shahriar; Leuschen, Carlton; Li, Jilu; Paden, John; Rodriguez-Morales, Fernando; Salandrino, Alessandro; Stiles, James

    2017-05-01

    Radar research has been synonymous with the University of Kansas (KU) for over half a century. As part of this special session organized to highlight significant radar programs in academia, this paper surveys recent and ongoing work at KU. This work encompasses a wide breadth of sensing applications including the remote sensing of ice sheets, autonomous navigation methods for unmanned aerial vehicles (UAVs), novel laser radar capabilities, detection of highenergy cosmic rays using bistatic radar, different forms of waveform diversity such as MIMO radar and pulse agility, and various radar-embedded communication methods. The results of these efforts impact our understanding of the changing nature of the environment, address the proliferation of unmanned systems in the US airspace, realize new sensing modalities enabled by the joint consideration of electromagnetics and signal processing, and greater facilitate radar operation in an increasingly congested and contested spectrum.

  12. Spaceborne radar

    NASA Technical Reports Server (NTRS)

    Moore, R. K.; Eckerman, J.; Meneghini, R.; Atlas, D.; Boerner, W. M.; Cherry, S.; Clark, J. F.; Doviak, R. J.; Goldhirsh, J.; Lhermitte, R. M.

    1981-01-01

    The spaceborne radar panel considered how radar could be used to measure precipitation from satellites. The emphasis was on how radar could be used with radiometry (at microwave, visible (VIS), and infrared (IR) wavelengths) to reduce the uncertainties of measuring precipitation with radiometry alone. In addition, the fundamental electromagnetic interactions involved in the measurements were discussed to determine the key work areas for research and development to produce effective instruments. Various approaches to implementing radar systems on satellites were considered for both shared and dedicated instruments. Finally, a research and development strategy was proposed for establishing the parametric relations and retrieval algorithms required for extracting precipitation information from the radar and associated radiometric data.

  13. Imaging synthetic aperture radar

    DOEpatents

    Burns, Bryan L.; Cordaro, J. Thomas

    1997-01-01

    A linear-FM SAR imaging radar method and apparatus to produce a real-time image by first arranging the returned signals into a plurality of subaperture arrays, the columns of each subaperture array having samples of dechirped baseband pulses, and further including a processing of each subaperture array to obtain coarse-resolution in azimuth, then fine-resolution in range, and lastly, to combine the processed subapertures to obtain the final fine-resolution in azimuth. Greater efficiency is achieved because both the transmitted signal and a local oscillator signal mixed with the returned signal can be varied on a pulse-to-pulse basis as a function of radar motion. Moreover, a novel circuit can adjust the sampling location and the A/D sample rate of the combined dechirped baseband signal which greatly reduces processing time and hardware. The processing steps include implementing a window function, stabilizing either a central reference point and/or all other points of a subaperture with respect to doppler frequency and/or range as a function of radar motion, sorting and compressing the signals using a standard fourier transforms. The stabilization of each processing part is accomplished with vector multiplication using waveforms generated as a function of radar motion wherein these waveforms may be synthesized in integrated circuits. Stabilization of range migration as a function of doppler frequency by simple vector multiplication is a particularly useful feature of the invention; as is stabilization of azimuth migration by correcting for spatially varying phase errors prior to the application of an autofocus process.

  14. MAS Bulletin. PILOT - A Radar for Covert Operations

    DTIC Science & Technology

    1989-04-28

    pulsed radar and ......... aTIC QUALITY flT’SPECTED 2 quiet frequency modulated continuous waves ( FMCW ) radar . Display: The transceiver box is equipped...Box 39, FPO Now York 09510-0700 Phone (AV)235-4131 (Comm) 409-4131 MASB 28-89 0"I PILOT- A Radar For Covert Operations " , L CO TE Background. Radar ...is an idispensable sensor for naval oper- Antenna: .,., ations at night and under conditions of poor visibility. However, conventional pulsed radar

  15. The instrumental principles of MST radars and incoherent scatter radars and the configuration of radar system hardware

    NASA Technical Reports Server (NTRS)

    Roettger, Juergen

    1989-01-01

    The principle of pulse modulation used in the case of coherent scatter radars (MST radars) is discussed. Coherent detection and the corresponding system configuration is delineated. Antenna requirements and design are outlined and the phase-coherent transmitter/receiver system is described. Transmit/receive duplexers, transmitters, receivers, and quadrature detectors are explained. The radar controller, integrator, decoder and correlator design as well as the data transfer and the control and monitoring by the host computer are delineated. Typical operation parameters of some well-known radars are summarized.

  16. Multibeam synthetic aperture radar for global oceanography

    NASA Technical Reports Server (NTRS)

    Jain, A.

    1979-01-01

    A single-frequency multibeam synthetic aperture radar concept for large swath imaging desired for global oceanography is evaluated. Each beam iilluminates a separate range and azimuth interval, and images for different beams may be separated on the basis of the Doppler spectrum of the beams or their spatial azimuth separation in the image plane of the radar processor. The azimuth resolution of the radar system is selected so that the Doppler spectrum of each beam does not interfere with the Doppler foldover due to the finite pulse repetition frequency of the radar system.

  17. Ultra-wideband Radar for Building Interior Imaging

    DTIC Science & Technology

    2008-12-01

    simulations, we assume that the radar operates as an UWB pulse radar. The radar transmitter and receiver are assumed to be in the far- field (we use plane...system during field experiments and compare those with the results of our Xpatch computer models. We also demonstrate a computational approach...the low-frequency, ultra-wideband ( UWB ) microwave radar demonstrated great potential for building mapping, as well as for detecting targets behind

  18. Tangential velocity measurement using interferometric MTI radar

    SciTech Connect

    Doerry, Armin W.; Mileshosky, Brian P.; Bickel, Douglas L.

    2006-01-03

    Radar systems use time delay measurements between a transmitted signal and its echo to calculate range to a target. Ranges that change with time cause a Doppler offset in phase and frequency of the echo. Consequently, the closing velocity between target and radar can be measured by measuring the Doppler offset of the echo. The closing velocity is also known as radial velocity, or line-of-sight velocity. Doppler frequency is measured in a pulse-Doppler radar as a linear phase shift over a set of radar pulses during some Coherent Processing Interval (CPI). An Interferometric Moving Target Indicator (MTI) radar can be used to measure the tangential velocity component of a moving target. Multiple baselines, along with the conventional radial velocity measurement, allow estimating the true 3-D velocity of a target.

  19. RADAR WARNING SYSTEM,

    DTIC Science & Technology

    RADAR TRACKING, *AIRCRAFT DEFENSE SYSTEMS, RADAR EQUIPMENT, AIR TO AIR, SEARCH RADAR, GUIDED MISSILES, HIGH SPEED BOMBING, EARLY WARNING SYSTEMS, FIRE CONTROL SYSTEM COMPONENTS, AIRCRAFT, TIME, CHINA.

  20. Registration of Alfvén resonances in TCABR tokamak by the scanning reflectometer at sideband frequencies

    NASA Astrophysics Data System (ADS)

    Ruchko, L. F.; Elfimov, A. G.; Teixeira, C. M.; Elizondo, J. I.; Sanada, E.; Galvão, R. M. O.; Manso, M. E.; Silva, A.

    2011-02-01

    A frequency scanning O-mode reflectometer was used for studies of plasma density oscillations during local Alfvén wave (LAW) excitation in the Tokamak Chauffage Alfvén Brésilien (TCABR) at the frequency fA = 5 MHz. It was found that the spectrum of the reflectometer output signal, which consists mainly of the "beat" frequency fB, is modified by the LAW excitation, and two additional frequency peaks appear, which are symmetrical in relation to the LAW excitation frequency f = fA ± fB. This result opens the possibility to improve the efficiency of studying the LAW induced density oscillations. The symmetry of these frequency peaks yields the possibility of finding the microwave frequency at which the reflectometer cutoff layer coincides with radial position of the LAW resonance zone in the TCABR tokamak.

  1. Development of frequency modulated continuous wave reflectometer for electron density profile measurement on the HL-2A tokamak

    SciTech Connect

    Zhong, W. L. Shi, Z. B.; Liu, Z. T.; Chen, W.; Jiang, M.; Li, J.; Cui, Z. Y.; Song, X. M.; Chen, L. Y.; Ding, X. T.; Liu, Yi; Yan, L. W.; Yang, Q. W.; Duan, X. R.; Huang, X. L.; Zou, X. L.

    2014-01-15

    The frequency modulated continuous wave reflectometer was developed for the first time on the HL-2A tokamak. The system utilizes a voltage controlled oscillator and an active multiplier for broadband coverage and detects as heterodyne mode. Three reflectometers have been installed and operated in extraordinary mode polarization on HL-2A to measure density profiles at low field side, covering the Q-band (33–50 GHz), V-band (50–75 GHz), and W-band (75–110 GHz). For density profile reconstruction from the phase shift of the probing wave, a corrected phase unwrapping method is introduced in this article. The effectiveness of the method is demonstrated. The density profile behavior of a fast plasma event is presented and it demonstrates the capability of the reflectometer. These diagnostics will be contributed to the routine density profile measurements and the plasma physics study on HL-2A.

  2. The evaluation of satellite-borne weather radar system designs using real ground-based radar data

    NASA Technical Reports Server (NTRS)

    Dobson, E. B.; Kalshoven, J. E., Jr.

    1977-01-01

    The paper presents method of evaluating proposed satellite radar systems using real radar data, and discusses methods of displaying the results which will hopefully facilitate easy comparison of systems. A single pencil beam pulsed radar system is considered while the precipitation data base comes from six rain days observed by SPANDAR. The many additional factors that must be considered in the radar equation such as attenuation and scattering (Mie and Rayleigh) are discussed along with some indication where possible errors lie.

  3. Topical report on subsurface fracture mapping from geothermal wellbores. Phase I. Pulsed radar techniques. Phase II. Conventional logging methods. Phase III. Magnetic borehole ranging

    SciTech Connect

    Hartenbaum, B.A.; Rawson, G.

    1980-09-01

    To advance the state-of-the-art in Hot Dry Rock technology, an evaluation is made of (i) the use of radar to map far-field fractures, (ii) the use of more than twenty different conventional well logging tools to map borehole-fracture intercepts, and (iii) the use of magnetic dipole ranging to determine the relative positions of the injection well and the production well within the fractured zone. It is found that according to calculations, VHF backscatter radar has the potential for mapping fractures within a distance of 50 +- 20 meters from the wellbore. A new technique for improving fracture identification is presented. Analyses of extant data indicate that when used synergistically the (1) caliper, (2) resistivity dipmeter, (3) televiewer, (4) television, (5) impression packer, and (6) acoustic transmission are useful for mapping borehole-fracture intercepts. Improvements in both data interpretation techniques and high temperature operation are required. The surveying of one borehole from another appears feasible at ranges of up to 200 to 500 meters by using a low frequency magnetic field generated by a moderately strong dipole source (a solenoid) located in one borehole, a sensitive B field detector that traverses part of the second borehole, narrow band filtering, and special data inversion techniques.

  4. Refractive and Relativistic Effects on ITER Low Field Side Reflectometer Design

    SciTech Connect

    Wang, G.; Rhodes, T. L.; Peebles, W. A.; Harvey, R. W.; Budny, R. V.

    2010-06-01

    The ITER low field side reflectometer faces some unique design challenges, among which are included the effect of relativistic electron temperatures and refraction of probing waves. This paper utilizes GENRAY, a 3- D ray tracing code, to investigate these effects. Using a simulated ITER operating scenario, characteristics of the reflected RF waves returning to the launch plane are quantified as a function of a range of design parameters, including antenna height, antenna size, and antenna radial position. Results for edge/SOL measurement with both O- and X-modes using proposed antennas are reported.

  5. Handheld directional reflectometer: an angular imaging device to measure BRDF and HDR in real time

    NASA Astrophysics Data System (ADS)

    Mattison, Phillip R.; Dombrowski, Mark S.; Lorenz, James M.; Davis, Keith J.; Mann, Harley C.; Johnson, Philip; Foos, Bryan

    1998-10-01

    Many applications require quantitative measurements of surface light scattering, including quality control on production lines, inspection of painted surfaces, inspection of field repairs, etc. Instruments for measuring surface scattering typically fall into two main categories, namely bidirectional reflectometers, which measure the angular distribution of scattering, and hemispherical directional reflectometers, which measure the total scattering into the hemisphere above the surface. Measurement of the bi-directional reflectance distribution function (BRDF) gives the greatest insight into how light is scattered from a surface. Measurements of BRDF, however, are typically very lengthy measurements taken by moving a source and detector to map the scattering. Since BRDF has four angular degrees of freedom, such measurements can require hours to days to complete. Instruments for measuring BRDF are also typically laboratory devices, although a field- portable bi-directional reflectometer does exist. Hemispherical directional reflectance (HDR) is a much easier measurement to make, although care must be taken to use the proper methodology when measuring at wavelengths beyond 10 micrometer, since integrating spheres (typically used to make such measurements) are very energy inefficient and lose their integrating properties at very long wavelengths. A few field- portable hemispherical directional reflectometers do exist, but typically measure HDR only at near-normal angles. Boeing Defense and Space Group and Surface Optics Corporation, under a contract from the Air Force Research Laboratory, have developed a new hand-held instrument capable of measuring both BRDF and HDR using a unique, patented angular imaging technique. A combination of an hemi-ellipsoidal mirror and an additional lens translate the angular scatter from a surface into a two-dimensional spatial distribution, which is recorded by an imaging array. This configuration fully maps the scattering from a half

  6. An MSK Radar Waveform

    NASA Technical Reports Server (NTRS)

    Quirk, Kevin J.; Srinivasan, Meera

    2012-01-01

    The minimum-shift-keying (MSK) radar waveform is formed by periodically extending a waveform that separately modulates the in-phase and quadrature- phase components of the carrier with offset pulse-shaped pseudo noise (PN) sequences. To generate this waveform, a pair of periodic PN sequences is each passed through a pulse-shaping filter with a half sinusoid impulse response. These shaped PN waveforms are then offset by half a chip time and are separately modulated on the in-phase and quadrature phase components of an RF carrier. This new radar waveform allows an increase in radar resolution without the need for additional spectrum. In addition, it provides self-interference suppression and configurable peak sidelobes. Compared strictly on the basis of the expressions for delay resolution, main-lobe bandwidth, effective Doppler bandwidth, and peak ambiguity sidelobe, it appears that bi-phase coded (BPC) outperforms the new MSK waveform. However, a radar waveform must meet certain constraints imposed by the transmission and reception of the modulation, as well as criteria dictated by the observation. In particular, the phase discontinuity of the BPC waveform presents a significant impediment to the achievement of finer resolutions in radar measurements a limitation that is overcome by using the continuous phase MSK waveform. The phase continuity, and the lower fractional out-of-band power of MSK, increases the allowable bandwidth compared with BPC, resulting in a factor of two increase in the range resolution of the radar. The MSK waveform also has been demonstrated to have an ambiguity sidelobe structure very similar to BPC, where the sidelobe levels can be decreased by increasing the length of the m-sequence used in its generation. This ability to set the peak sidelobe level is advantageous as it allows the system to be configured to a variety of targets, including those with a larger dynamic range. Other conventionally used waveforms that possess an even greater

  7. Spaceborne Imaging Radar-C instrument

    NASA Technical Reports Server (NTRS)

    Huneycutt, Bryan L.

    1993-01-01

    The Spaceborne Imaging Radar-C is the next radar in the series of spaceborne radar experiments, which began with Seasat and continued with SIR-A and SIR-B. The SIR-C instrument has been designed to obtain simultaneous multifrequency and simultaneous multipolarization radar images from a low earth orbit. It is a multiparameter imaging radar that will be flown during at least two different seasons. The instrument operates in the squint alignment mode, the extended aperture mode, the scansar mode, and the interferometry mode. The instrument uses engineering techniques such as beam nulling for echo tracking, pulse repetition frequency hopping for Doppler centroid tracking, generating the frequency step chirp for radar parameter flexibility, block floating-point quantizing for data rate compression, and elevation beamwidth broadening for increasing the swath illumination.

  8. Fly eye radar or micro-radar sensor technology

    NASA Astrophysics Data System (ADS)

    Molchanov, Pavlo; Asmolova, Olga

    2014-05-01

    To compensate for its eye's inability to point its eye at a target, the fly's eye consists of multiple angularly spaced sensors giving the fly the wide-area visual coverage it needs to detect and avoid the threats around him. Based on a similar concept a revolutionary new micro-radar sensor technology is proposed for detecting and tracking ground and/or airborne low profile low altitude targets in harsh urban environments. Distributed along a border or around a protected object (military facility and buildings, camp, stadium) small size, low power unattended radar sensors can be used for target detection and tracking, threat warning, pre-shot sniper protection and provides effective support for homeland security. In addition it can provide 3D recognition and targets classification due to its use of five orders more pulses than any scanning radar to each space point, by using few points of view, diversity signals and intelligent processing. The application of an array of directional antennas eliminates the need for a mechanical scanning antenna or phase processor. It radically decreases radar size and increases bearing accuracy several folds. The proposed micro-radar sensors can be easy connected to one or several operators by point-to-point invisible protected communication. The directional antennas have higher gain, can be multi-frequency and connected to a multi-functional network. Fly eye micro-radars are inexpensive, can be expendable and will reduce cost of defense.

  9. Performance and data analysis aspects of the new DIII-D monostatic profile reflectometer system

    SciTech Connect

    Zeng, Lei; Peebles, William A.; Doyle, Edward J.; Rhodes, Terry L.; Crocker, Neal; Nguyen, X.; Wannberg, Craig W.; Wang, Guiding

    2014-08-07

    A new frequency-modulated (FMCW) profile reflectometer system, featuring a monostatic antenna geometry (using one microwave antenna for both launch and receive), has been installed on the DIII-D tokamak, providing a first experimental test of this measurement approach for profile reflectometry. Significant features of the new system are briefly described in this paper, including the new monostatic arrangement, use of overmoded, broadband transmission waveguide, and dual-polarization combination/demultiplexing. Updated data processing and analysis, and in-service performance aspects of the new monostatic profile reflectometer system are also presented. By using a raytracing code (GENRAY) to determine the approximate trajectory of the probe beam, the electron density (ne) profile can be successfully reconstructed with L-mode plasmas vertically shifted by more than 10 cm off the vessel midplane. Specifically, it is demonstrated that the new system has a capability to measure ne profiles with plasma vertical offsets of up to ±17 cm. Furthermore, examples are also presented of accurate, high time and spatial resolution density profile measurements made over a wide range of DIII-D conditions, e.g. the measured temporal evolution of the density profile across an L-H transition.

  10. GINA-A polarized neutron reflectometer at the Budapest Neutron Centre

    SciTech Connect

    Bottyan, L.; Merkel, D. G.; Nagy, B.; Sajti, Sz.; Deak, L.; Endroczi, G.; Fuezi, J.; Petrenko, A. V.; Major, J.

    2013-01-15

    The setup, capabilities, and operation parameters of the neutron reflectometer GINA, the recently installed 'Grazing Incidence Neutron Apparatus' at the Budapest Neutron Centre, are introduced. GINA, a dance-floor-type, constant-energy, angle-dispersive reflectometer is equipped with a 2D position-sensitive detector to study specular and off-specular scattering. Wavelength options between 3.2 and 5.7 A are available for unpolarized and polarized neutrons. Spin polarization and analysis are achieved by magnetized transmission supermirrors and radio-frequency adiabatic spin flippers. As a result of vertical focusing by a five-element pyrolytic graphite monochromator, the reflected intensity from a 20 Multiplication-Sign 20 mm{sup 2} sample has been doubled. GINA is dedicated to studies of magnetic films and heterostructures, but unpolarized options for non-magnetic films, membranes, and other surfaces are also provided. Shortly after its startup, reflectivity values as low as 3 Multiplication-Sign 10{sup -5} have been measured by the instrument. The instrument capabilities are demonstrated by a non-polarized and a polarized reflectivity experiment on a Si wafer and on a magnetic film of [{sup 62}Ni/{sup nat}Ni]{sub 5} isotope-periodic layer composition. The facility is now open for the international user community. Its further development is underway establishing new sample environment options and spin analysis of off-specularly scattered radiation as well as further decreasing the background.

  11. Performance and data analysis aspects of the new DIII-D monostatic profile reflectometer system

    DOE PAGES

    Zeng, Lei; Peebles, William A.; Doyle, Edward J.; ...

    2014-08-07

    A new frequency-modulated (FMCW) profile reflectometer system, featuring a monostatic antenna geometry (using one microwave antenna for both launch and receive), has been installed on the DIII-D tokamak, providing a first experimental test of this measurement approach for profile reflectometry. Significant features of the new system are briefly described in this paper, including the new monostatic arrangement, use of overmoded, broadband transmission waveguide, and dual-polarization combination/demultiplexing. Updated data processing and analysis, and in-service performance aspects of the new monostatic profile reflectometer system are also presented. By using a raytracing code (GENRAY) to determine the approximate trajectory of the probe beam,more » the electron density (ne) profile can be successfully reconstructed with L-mode plasmas vertically shifted by more than 10 cm off the vessel midplane. Specifically, it is demonstrated that the new system has a capability to measure ne profiles with plasma vertical offsets of up to ±17 cm. Furthermore, examples are also presented of accurate, high time and spatial resolution density profile measurements made over a wide range of DIII-D conditions, e.g. the measured temporal evolution of the density profile across an L-H transition.« less

  12. Survey and adjustment methods applied on an 11 axes high performance reflectometer for synchrotron radiation

    SciTech Connect

    Eggenstein, F. Bischoff, P.; Schäfers, F.; Schroeter, T.; Senf, F.; Sokolov, A.; Zeschke, T.; Erko, A.

    2016-07-27

    At BESSY-II a new UV-and XUV optics beamline [1] has recently been setup with an in-house developed versatile reflectometer [2], [3], [4] for at-wavelength metrology on reflective and diffractive optical elements up to 4 kg mass. High precision measurements of the reflection and polarization properties are feasible by a 360° azimuthal rotation of the sample around the beam of light, where samples can be adjusted reproducibly with a novel UHV-Tripod within arc sec and μm precision. The azimuthal rotation requires an extremely high precision adjustment of the goniometer axis with respect to the incident light beam. Here we describe sophisticated methods with which we achieve nearly perfect agreement of the azimuthal rotation axis and the synchrotron beam in the 30 arc sec range. By using geodetic instruments (lasertracker, theodolite, autocollimator) the quality of the reflectometer UHV-mechanics has been characterized with respect to stiffness and radial run out with highest precision [5].

  13. A Soft X-Ray/EUV Reflectometer Based on a Laser Produced Plasma Source.

    PubMed

    Gullikson, E M; Underwood, J H; Batson, P C; Nikitin, V

    1992-01-01

    A soft x-ray reflectometer is described which is based on a laser-produced plasma source and is continuously tunable over the range 40 Å < λ < 400 Å. The source is produced by focusing 0.532-μm light from a Q-switched Nd:YAG laser on a solid target. The x-ray wavelength is defined using a high throughput spherical grating monochromator with moderate resolving power (λ/Δλ ≈ 100 to 500). A time-averaged monochromatized flux of more than 109 photons/s in a 1% bandwidth at 100 eV is obtained. Photon "shot noise" limited measurements are obtained by the use of an I0 detector to normalize out the shot-to-shot variations in source intensity. Measurements with submillimeter spot sizes are readily obtainable. Various detectors have been used and the advantages and disadvantages of each are discussed. The higher order contamination of the monochromator output has been analyzed using a second grating for the purpose of making measurement corrections. The reflectometer thus provides the capability for precision absolute measurements of the reflectance of gratings and multilayer mirrors, the transmittance of thin film filters, or other properties of x-ray optical elements.

  14. Development of frequency modulation reflectometer for Korea Superconducting Tokamak Advanced Research tokamak

    NASA Astrophysics Data System (ADS)

    Seo, Seong-Heon; Park, Jinhyung; Wi, H. M.; Lee, W. R.; Kim, H. S.; Lee, T. G.; Kim, Y. S.; Kang, Jin-Seob; Bog, M. G.; Yokota, Y.; Mase, A.

    2013-08-01

    Frequency modulation reflectometer has been developed to measure the plasma density profile of the Korea Superconducting Tokamak Advanced Research tokamak. Three reflectometers are operating in extraordinary polarization mode in the frequency range of Q band (33.6-54 GHz), V band (48-72 GHz), and W band (72-108 GHz) to measure the density up to 7 × 1019 m-3 when the toroidal magnetic field is 2 T on axis. The antenna is installed inside of the vacuum vessel. A new vacuum window is developed by using 50 μm thick mica film and 0.1 mm thick gold gasket. The filter bank of low pass filter, notch filter, and Faraday isolator is used to reject the electron cyclotron heating high power at attenuation of 60 dB. The full frequency band is swept in 20 μs. The mixer output is directly digitized with sampling rate of 100 MSamples/s. The phase is obtained by using wavelet transform. The whole hardware and software system is described in detail and the measured density profile is presented as a result.

  15. A novel multi-channel quadrature Doppler backward scattering reflectometer on the HL-2A tokamak

    NASA Astrophysics Data System (ADS)

    Shi, Zhongbing; Zhong, Wulu; Jiang, Min; Yang, Zengchen; Zhang, Boyu; Shi, Peiwan; Chen, Wei; Wen, Jie; Chen, Chengyuan; Fu, Bingzhong; Liu, Zetian; Ding, Xuantong; Yang, Qingwei; Duan, Xuru

    2016-11-01

    A novel 16-channel fixed frequency Doppler backward scattering (DBS) reflectometer system has been developed on the HL-2A tokamak. This system is based on the filter-based feedback loop microwave source (FFLMS) technique, which has lower phase noise and lower power variation compared with present tunable frequency generation and comb frequency array generation techniques [J. C. Hillesheim et al. Rev. Sci. Instrum. 80, 083507 (2009) and W. A. Peebles et al. Rev. Sci. Instrum. 81, 10D902 (2010)]. The 16-channel DBS system is comprised of four × four-frequency microwave transmitters and direct quadrature demodulation receivers. The working frequencies are 17-24 GHz and 31-38 GHz with the frequency interval of 1 GHz. They are designed to measure the localized intermediate wave-number (k⊥ρ ˜ 1-2, k⊥ ˜ 2-9 cm-1) density fluctuations and the poloidal rotation velocity profile of turbulence. The details of the system design and laboratory tests are presented. Preliminary results of Doppler spectra measured by the multi-channel DBS reflectometer systems are obtained. The plasma rotation and turbulence distribution during supersonic molecular beam injection are analyzed.

  16. FSR: a field portable spectral reflectometer to measure ground from NIR to LWIR

    NASA Astrophysics Data System (ADS)

    Moreau, Louis; Bourque, Hugo; Ouellet, Réal; Prel, Florent; Roy, Claude; Vallieres, Christian; Thériault, Guillaume

    2011-11-01

    ABB Bomem has recently designed a field-deployable reflectometer. The Full Spectrum Reflectometer (FSR) measures the diffuse reflectance of surfaces in the 0.7 μm to 13.5 μm spectral range. The spectral resolution is adjustable from 32 to 4 cm-1. The instrument is portable, battery-operated and designed for field usage in a single, lightweight and ruggedized package. In its simplest mode, the instrument is automated and can be operated by non-specialist personnel with minimal training. The FSR has a laboratory mode to measure targets brought to the instrument in a sampling cup and a field mode with automated measurement sequence. To facilitate the measurement of various ground surfaces, the instrument is packaged in a three-point mount for easy target access and stability. One of the mount is the sampling port. The instrument has its own built-in NIR and LWIR infrared sources to illuminate the ground area to be measured. The instrument includes two built-in references for calibration: a Spectralon diffuser and an Infragold diffuser. The first units were commissioned to build a spectral database of surfaces in various conditions (humidity, temperature, texture, mixing, etc.) and in the presence of interfering chemicals (oils, solvents, etc.) but the instrument can also serve other purposes such as the identification of unknown materials.

  17. SuperADAM: Upgraded polarized neutron reflectometer at the Institut Laue-Langevin

    SciTech Connect

    Devishvili, A.; Zhernenkov, K.; Dennison, A. J. C.; Toperverg, B. P.; Wolff, M.; Hjoervarsson, B.; Zabel, H.

    2013-02-15

    A new neutron reflectometer SuperADAM has recently been built and commissioned at the Institut Laue-Langevin, Grenoble, France. It replaces the previous neutron reflectometer ADAM. The new instrument uses a solid state polarizer/wavelength filter providing a highly polarized (up to 98.6%) monochromatic neutron flux of 8 Multiplication-Sign 10{sup 4} n cm{sup -2} s{sup -1} with monochromatization {Delta}{lambda}/{lambda}= 0.7% and angular divergence {Delta}{alpha}= 0.2 mrad. The instrument includes both single and position sensitive detectors. The position sensitive detector allows simultaneous measurement of specular reflection and off-specular scattering. Polarization analysis for both specular reflection and off-specular scattering is achieved using either mirror analyzers or a {sup 3}He spin filter cell. High efficiency detectors, low background, and high flux provides a dynamic range of up to seven decades in reflectivity. Detailed specifications and the instrument capabilities are illustrated with examples of recently collected data in the fields of thin film magnetism and thin polymer films.

  18. GINA--A polarized neutron reflectometer at the Budapest Neutron Centre

    NASA Astrophysics Data System (ADS)

    Bottyán, L.; Merkel, D. G.; Nagy, B.; Füzi, J.; Sajti, Sz.; Deák, L.; Endrőczi, G.; Petrenko, A. V.; Major, J.

    2013-01-01

    The setup, capabilities, and operation parameters of the neutron reflectometer GINA, the recently installed "Grazing Incidence Neutron Apparatus" at the Budapest Neutron Centre, are introduced. GINA, a dance-floor-type, constant-energy, angle-dispersive reflectometer is equipped with a 2D position-sensitive detector to study specular and off-specular scattering. Wavelength options between 3.2 and 5.7 Å are available for unpolarized and polarized neutrons. Spin polarization and analysis are achieved by magnetized transmission supermirrors and radio-frequency adiabatic spin flippers. As a result of vertical focusing by a five-element pyrolytic graphite monochromator, the reflected intensity from a 20 × 20 mm2 sample has been doubled. GINA is dedicated to studies of magnetic films and heterostructures, but unpolarized options for non-magnetic films, membranes, and other surfaces are also provided. Shortly after its startup, reflectivity values as low as 3 × 10-5 have been measured by the instrument. The instrument capabilities are demonstrated by a non-polarized and a polarized reflectivity experiment on a Si wafer and on a magnetic film of [62Ni/natNi]5 isotope-periodic layer composition. The facility is now open for the international user community. Its further development is underway establishing new sample environment options and spin analysis of off-specularly scattered radiation as well as further decreasing the background.

  19. Development of frequency modulation reflectometer for Korea Superconducting Tokamak Advanced Research tokamak

    SciTech Connect

    Seo, Seong-Heon; Wi, H. M.; Lee, W. R.; Kim, H. S.; Lee, T. G.; Kim, Y. S.; Park, Jinhyung; Kang, Jin-Seob; Bog, M. G.; Yokota, Y.; Mase, A.

    2013-08-15

    Frequency modulation reflectometer has been developed to measure the plasma density profile of the Korea Superconducting Tokamak Advanced Research tokamak. Three reflectometers are operating in extraordinary polarization mode in the frequency range of Q band (33.6–54 GHz), V band (48–72 GHz), and W band (72–108 GHz) to measure the density up to 7 × 10{sup 19} m{sup −3} when the toroidal magnetic field is 2 T on axis. The antenna is installed inside of the vacuum vessel. A new vacuum window is developed by using 50 μm thick mica film and 0.1 mm thick gold gasket. The filter bank of low pass filter, notch filter, and Faraday isolator is used to reject the electron cyclotron heating high power at attenuation of 60 dB. The full frequency band is swept in 20 μs. The mixer output is directly digitized with sampling rate of 100 MSamples/s. The phase is obtained by using wavelet transform. The whole hardware and software system is described in detail and the measured density profile is presented as a result.

  20. Development of frequency modulation reflectometer for Korea Superconducting Tokamak Advanced Research tokamak.

    PubMed

    Seo, Seong-Heon; Park, Jinhyung; Wi, H M; Lee, W R; Kim, H S; Lee, T G; Kim, Y S; Kang, Jin-Seob; Bog, M G; Yokota, Y; Mase, A

    2013-08-01

    Frequency modulation reflectometer has been developed to measure the plasma density profile of the Korea Superconducting Tokamak Advanced Research tokamak. Three reflectometers are operating in extraordinary polarization mode in the frequency range of Q band (33.6-54 GHz), V band (48-72 GHz), and W band (72-108 GHz) to measure the density up to 7 × 10(19) m(-3) when the toroidal magnetic field is 2 T on axis. The antenna is installed inside of the vacuum vessel. A new vacuum window is developed by using 50 μm thick mica film and 0.1 mm thick gold gasket. The filter bank of low pass filter, notch filter, and Faraday isolator is used to reject the electron cyclotron heating high power at attenuation of 60 dB. The full frequency band is swept in 20 μs. The mixer output is directly digitized with sampling rate of 100 MSamples/s. The phase is obtained by using wavelet transform. The whole hardware and software system is described in detail and the measured density profile is presented as a result.

  1. A novel multi-channel quadrature Doppler backward scattering reflectometer on the HL-2A tokamak.

    PubMed

    Shi, Zhongbing; Zhong, Wulu; Jiang, Min; Yang, Zengchen; Zhang, Boyu; Shi, Peiwan; Chen, Wei; Wen, Jie; Chen, Chengyuan; Fu, Bingzhong; Liu, Zetian; Ding, Xuantong; Yang, Qingwei; Duan, Xuru

    2016-11-01

    A novel 16-channel fixed frequency Doppler backward scattering (DBS) reflectometer system has been developed on the HL-2A tokamak. This system is based on the filter-based feedback loop microwave source (FFLMS) technique, which has lower phase noise and lower power variation compared with present tunable frequency generation and comb frequency array generation techniques [J. C. Hillesheim et al. Rev. Sci. Instrum. 80, 083507 (2009) and W. A. Peebles et al. Rev. Sci. Instrum. 81, 10D902 (2010)]. The 16-channel DBS system is comprised of four × four-frequency microwave transmitters and direct quadrature demodulation receivers. The working frequencies are 17-24 GHz and 31-38 GHz with the frequency interval of 1 GHz. They are designed to measure the localized intermediate wave-number (k⊥ρ ∼ 1-2, k⊥ ∼ 2-9 cm(-1)) density fluctuations and the poloidal rotation velocity profile of turbulence. The details of the system design and laboratory tests are presented. Preliminary results of Doppler spectra measured by the multi-channel DBS reflectometer systems are obtained. The plasma rotation and turbulence distribution during supersonic molecular beam injection are analyzed.

  2. Performance and data analysis aspects of the new DIII-D monostatic profile reflectometer system

    SciTech Connect

    Zeng, L. Peebles, W. A.; Doyle, E. J.; Rhodes, T. L.; Crocker, N.; Nguyen, X.; Wannberg, C. W.; Wang, G.

    2014-11-15

    A new frequency-modulated profile reflectometer system, featuring a monostatic antenna geometry (using one microwave antenna for both launch and receive), has been installed on the DIII-D tokamak, providing a first experimental test of this measurement approach for profile reflectometry. Significant features of the new system are briefly described in this paper, including the new monostatic arrangement, use of overmoded, broadband transmission waveguide, and dual-polarization combination/demultiplexing. Updated data processing and analysis, and in-service performance aspects of the new monostatic profile reflectometer system are also presented. By using a raytracing code (GENRAY) to determine the approximate trajectory of the probe beam, the electron density (n{sub e}) profile can be successfully reconstructed with L-mode plasmas vertically shifted by more than 10 cm off the vessel midplane. Specifically, it is demonstrated that the new system has a capability to measure n{sub e} profiles with plasma vertical offsets of up to ±17 cm. Examples are also presented of accurate, high time and spatial resolution density profile measurements made over a wide range of DIII-D conditions, e.g., the measured temporal evolution of the density profile across a L-H transition.

  3. Focusing neutron reflectometry: Implementation and experience on the TOF-reflectometer Amor

    NASA Astrophysics Data System (ADS)

    Stahn, J.; Glavic, A.

    2016-06-01

    Neutron reflectometry is a powerful tool to investigate chemical and magnetic depth profiles near surfaces. The advantages of neutrons compared to x-rays are their sensitivity to isotopes, the high penetration capabilities and the high sensitivity to magnetic induction. The biggest disadvantage however is the low flux available, which leads to much longer counting times on much larger samples. In order to boost the performance of neutron reflectometers, a focusing guide system was developed and realised over recent years. Here we report on the application and performance of a down-scaled demonstrator of such a Selene guide, installed as an add-on on the time-of-flight (TOF) reflectometer Amor at the PSI. Due to the limited size of the guide, the flux is concentrated to a footprint of at most 2 mm width. It is thus possible to avoid illumination of contacts even on small samples. Despite the fact that typical samples measured on Amor with a size of 10 × 10mm2 are markedly under illuminated, the presented set-up leads to a reduction in counting time of 80%. The use of the demonstrator thus allows for in-situ or in-operando investigations with a time resolution of a few minutes for a qz range from 0.005Å-1 to 0.08Å-1. Besides a short recapitulation of the concept of focusing reflectometry, a detailed description of the data reduction and its quality is given, followed by an application example.

  4. Architecture for a 1-GHz Digital RADAR

    NASA Technical Reports Server (NTRS)

    Mallik, Udayan

    2011-01-01

    An architecture for a Direct RF-digitization Type Digital Mode RADAR was developed at GSFC in 2008. Two variations of a basic architecture were developed for use on RADAR imaging missions using aircraft and spacecraft. Both systems can operate with a pulse repetition rate up to 10 MHz with 8 received RF samples per pulse repetition interval, or at up to 19 kHz with 4K received RF samples per pulse repetition interval. The first design describes a computer architecture for a Continuous Mode RADAR transceiver with a real-time signal processing and display architecture. The architecture can operate at a high pulse repetition rate without interruption for an infinite amount of time. The second design describes a smaller and less costly burst mode RADAR that can transceive high pulse repetition rate RF signals without interruption for up to 37 seconds. The burst-mode RADAR was designed to operate on an off-line signal processing paradigm. The temporal distribution of RF samples acquired and reported to the RADAR processor remains uniform and free of distortion in both proposed architectures. The majority of the RADAR's electronics is implemented in digital CMOS (complementary metal oxide semiconductor), and analog circuits are restricted to signal amplification operations and analog to digital conversion. An implementation of the proposed systems will create a 1-GHz, Direct RF-digitization Type, L-Band Digital RADAR--the highest band achievable for Nyquist Rate, Direct RF-digitization Systems that do not implement an electronic IF downsample stage (after the receiver signal amplification stage), using commercially available off-the-shelf integrated circuits.

  5. Planetary radar

    NASA Technical Reports Server (NTRS)

    Taylor, R. M.

    1980-01-01

    The radar astronomy activities supported by the Deep Space Network during June, July, and August 1980 are reported. The planetary bodies observed were Venus, Mercury, and the asteroid Toro. Data were obtained at both S and X band, and the observations were considered successful.

  6. Suppression of range sidelobes in bistatic radars

    NASA Astrophysics Data System (ADS)

    McCue, J. J. G.

    1980-03-01

    A bistatic radar is considered in which linear-FM pulses are employed to obtain the needed range resolution while using a long pulse. Range sidelobes of the pulse received over the direct path from the transmitter tend to interfere with the return from the target. It is shown that conventional weighting schemes give little or no suppression of some of the range sidelobes of a linear-FM rectangular pulse passed through a matched filter. This is explained by the irregular spacing of the sidelobes in the pulse when it passes through the matched filter.

  7. Comparison of Background Characteristics of an RCS (Radar Cross Section) Measurement Range Using a CW-Nulling Technique and a Pulse-Gating Technique.

    DTIC Science & Technology

    1985-12-01

    OF ENGI.. G R SIMPSON UNCLASSIFIED DEC 85 RFIT/GE/ENG/85D-49 F/G 1719 N mhhmhhhhl 4 gu LEu • .... ’ . ;% 1, ." -.. . I". Ig 1.2511 4.-. m . ’I’ IU...55 :;. ’ M 4.10 Pulse-Gated Time Domain Response: 8 Inch Sphere Mounted on Target Pedestal...which is what the CW-nulling 4.- - . -o . .. . . . . . . -- I -. ..- -- r Ky ? M -7 system strives to cancel. After the chamber is nulled, the target of

  8. Lunar Radar Cross Section at Low Frequency

    NASA Technical Reports Server (NTRS)

    Rodriguez, P.; Kennedy, E. J.; Kossey, P.; McCarrick, M.; Kaiser, M. L.; Bougeret, J.-L.; Tokarev, Y. V.

    2002-01-01

    Recent bistatic measurements of the lunar radar cross-section have extended the spectrum to long radio wavelength. We have utilized the HF Active Auroral Research Program (HAARP) radar facility near Gakona, Alaska to transmit high power pulses at 8.075 MHz to the Moon; the echo pulses were received onboard the NASA/WIND spacecraft by the WAVES HF receiver. This lunar radar experiment follows our previous use of earth-based HF radar with satellites to conduct space experiments. The spacecraft was approaching the Moon for a scheduled orbit perturbation when our experiment of 13 September 2001 was conducted. During the two-hour experiment, the radial distance of the satellite from the Moon varied from 28 to 24 Rm, where Rm is in lunar radii.

  9. A satellite-based radar wind sensor

    NASA Technical Reports Server (NTRS)

    Xin, Weizhuang

    1991-01-01

    The objective is to investigate the application of Doppler radar systems for global wind measurement. A model of the satellite-based radar wind sounder (RAWS) is discussed, and many critical problems in the designing process, such as the antenna scan pattern, tracking the Doppler shift caused by satellite motion, and backscattering of radar signals from different types of clouds, are discussed along with their computer simulations. In addition, algorithms for measuring mean frequency of radar echoes, such as the Fast Fourier Transform (FFT) estimator, the covariance estimator, and the estimators based on autoregressive models, are discussed. Monte Carlo computer simulations were used to compare the performance of these algorithms. Anti-alias methods are discussed for the FFT and the autoregressive methods. Several algorithms for reducing radar ambiguity were studied, such as random phase coding methods and staggered pulse repitition frequncy (PRF) methods. Computer simulations showed that these methods are not applicable to the RAWS because of the broad spectral widths of the radar echoes from clouds. A waveform modulation method using the concept of spread spectrum and correlation detection was developed to solve the radar ambiguity. Radar ambiguity functions were used to analyze the effective signal-to-noise ratios for the waveform modulation method. The results showed that, with suitable bandwidth product and modulation of the waveform, this method can achieve the desired maximum range and maximum frequency of the radar system.

  10. Countermeasures of Stimulated-Raman-Scattering-Induced Video Distortion in 1.65 μm Optical Time-domain Reflectometer On-line Monitoring 1.55 μm Cable Television System

    NASA Astrophysics Data System (ADS)

    Tsai, Szu-Chi; Tu, Yuan-Kuang; Chen, Yung-Kuang

    2003-07-01

    The countermeasures of stimulated-Raman-scattering (SRS)-induced baseband video distortion in the 1.65 μm optical time-domain reflectometer (OTDR) on-line monitoring 1.55 μm amplitude modulation with vestigial sideband (AM-VSB) cable television (CATV) transmission system are investigated theoretically and experimentally. The countermeasures entail the reduction in the optical modulation index (OMI) of the AM transmitter, OTDR peak power and/or pulse width. The results of numerical simulations and experimental measurements are in good agreement. Moreover, the countermeasure for eliminating the SRS-induced baseband video distortion by the 1.31 μm OTDR on-line monitoring technique is investigated and demonstrated.

  11. A 10 cm dual frequency Doppler weather radar. Part 1: The radar system

    NASA Astrophysics Data System (ADS)

    Bishop, A. W.; Armstrong, G. M.

    1982-10-01

    Design concepts and test results are summarized for a Doppler weather radar system suitable for precipitation measurements over a wide span of radial velocities and slant ranges, even in the presence of ground clutter. The radar transmits two uniform pulse trains at 2.710 and 2.760 GHz. Uniformly spaced pulses permit ground clutter cancellation of up to 50 dB to be achieved with a three-pole elliptic filter. Pulse spacing at one frequency is consistent with long-range coverage in reflectivity, while spacing of the second is consistent with a wide unambiguous velocity measurement span.

  12. Experiment Automation with a Robot Arm using the Liquids Reflectometer Instrument at the Spallation Neutron Source

    SciTech Connect

    Zolnierczuk, Piotr A; Vacaliuc, Bogdan; Sundaram, Madhan; Parizzi, Andre A; Halbert, Candice E; Hoffmann, Michael C; Greene, Gayle C; Browning, Jim; Ankner, John Francis

    2013-01-01

    The Liquids Reflectometer instrument installed at the Spallation Neutron Source (SNS) enables observations of chemical kinetics, solid-state reactions and phase-transitions of thin film materials at both solid and liquid surfaces. Effective measurement of these behaviors requires each sample to be calibrated dynamically using the neutron beam and the data acquisition system in a feedback loop. Since the SNS is an intense neutron source, the time needed to perform the measurement can be the same as the alignment process, leading to a labor-intensive operation that is exhausting to users. An update to the instrument control system, completed in March 2013, implemented the key features of automated sample alignment and robot-driven sample management, allowing for unattended operation over extended periods, lasting as long as 20 hours. We present a case study of the effort, detailing the mechanical, electrical and software modifications that were made as well as the lessons learned during the integration, verification and testing process.

  13. Reflectometer-based metrology for high-aspect ratio via measurement.

    PubMed

    Ku, Yi-Sha; Yang, Fu Shiang

    2010-03-29

    We develop a modified thin film model with adjustable ratio of the illuminated surface areas for accurate reflectivity calculation of deep via structures. We also propose a method combining a half oblate spheroid model and a reflectance modulation algorithm for extraction of via bottom profile from the measured reflectance spectrum. We demonstrate the use and enhancement of an existing wafer metrology tool, spectral reflectometer by implementing novel theoretical model and measurement algorithm for through-silicon via (TSV) inspection. Our non-destructive solution can measure TSV profile diameters as small as 5 microm and aspect ratios greater than 13:1. The measurement precision is in the range of 0.02 microm. Metrology results from actual 3D interconnect processing wafers are presented.

  14. Development of a cold-neutron reflectometer (CN REF-V) at the HANARO

    NASA Astrophysics Data System (ADS)

    Lee, Jeong-Soo; Koo, Jaseung; So, Ji-Yong; Kim, Tae Ho; Park, Sungkyun

    2015-11-01

    A new neutron reflectometer, CN REF-V, has been installed in the cold-neutron laboratory building at the HANARO, a research reactor in Korea. The instrument has a vertical scattering plane and uses a constant wavelength of λ = 4.7535 Å, and it is monochromated by using pyrolytic graphite (PG) crystals. Its measurable minimum reflectivity and maximum momentum transfer for typical solid films are 10-8 and 0.3 Å-1, respectively. A liquid-nitrogen-cooled beryllium filter is used to remove λ/2 contamination due to the PG (002) crystals. With a gold wire activation analysis method, the neutron flux at its sample position was measured and found to be 5.67 × 105 neutrons/cm2 /s. Reflectivity measurements of thin films were successfully carried out with the instrument. A detailed characterization of the instrument and the results of the reflectivity measurements are described.

  15. Invited Article: Polarization ``Down Under'': The polarized time-of-flight neutron reflectometer PLATYPUS

    NASA Astrophysics Data System (ADS)

    Saerbeck, T.; Klose, F.; Le Brun, A. P.; Füzi, J.; Brule, A.; Nelson, A.; Holt, S. A.; James, M.

    2012-08-01

    This review presents the implementation and full characterization of the polarization equipment of the time-of-flight neutron reflectometer PLATYPUS at the Australian Nuclear Science and Technology Organisation (ANSTO). The functionality and efficiency of individual components are evaluated and found to maintain a high neutron beam polarization with a maximum of 99.3% through polarizing Fe/Si supermirrors. Neutron spin-flippers with efficiencies of 99.7% give full control over the incident and scattered neutron spin direction over the whole wavelength spectrum available in the instrument. The first scientific experiments illustrate data correction mechanisms for finite polarizations and reveal an extraordinarily high reproducibility for measuring magnetic thin film samples. The setup is now fully commissioned and available for users through the neutron beam proposal system of the Bragg Institute at ANSTO.

  16. A Computer Aided Broad Band Impedance Matching Technique Using a Comparison Reflectometer. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Gordy, R. S.

    1972-01-01

    An improved broadband impedance matching technique was developed. The technique is capable of resolving points in the waveguide which generate reflected energy. A version of the comparison reflectometer was developed and fabricated to determine the mean amplitude of the reflection coefficient excited at points in the guide as a function of distance, and the complex reflection coefficient of a specific discontinuity in the guide as a function of frequency. An impedance matching computer program was developed which is capable of impedance matching the characteristics of each disturbance independent of other reflections in the guide. The characteristics of four standard matching elements were compiled, and their associated curves of reflection coefficient and shunt susceptance as a function of frequency are presented. It is concluded that an economical, fast, and reliable impedance matching technique has been established which can provide broadband impedance matches.

  17. Invited article: polarization "down under": the polarized time-of-flight neutron reflectometer PLATYPUS.

    PubMed

    Saerbeck, T; Klose, F; Le Brun, A P; Füzi, J; Brule, A; Nelson, A; Holt, S A; James, M

    2012-08-01

    This review presents the implementation and full characterization of the polarization equipment of the time-of-flight neutron reflectometer PLATYPUS at the Australian Nuclear Science and Technology Organisation (ANSTO). The functionality and efficiency of individual components are evaluated and found to maintain a high neutron beam polarization with a maximum of 99.3% through polarizing Fe/Si supermirrors. Neutron spin-flippers with efficiencies of 99.7% give full control over the incident and scattered neutron spin direction over the whole wavelength spectrum available in the instrument. The first scientific experiments illustrate data correction mechanisms for finite polarizations and reveal an extraordinarily high reproducibility for measuring magnetic thin film samples. The setup is now fully commissioned and available for users through the neutron beam proposal system of the Bragg Institute at ANSTO.

  18. Radars in space

    NASA Technical Reports Server (NTRS)

    Delnore, Victor E.

    1990-01-01

    The capabilities of active microwave devices operating from space (typically, radar, scatterometers, interferometers, and altimeters) are discussed. General radar parameters and basic radar principles are explained. Applications of these parameters and principles are also explained. Trends in space radar technology, and where space radars and active microwave sensors in orbit are going are discussed.

  19. TRMM radar

    NASA Technical Reports Server (NTRS)

    Okamoto, Kenichi

    1993-01-01

    The results of a conceptual design study and the performance of key components of the Bread Board Model (BBM) of the Tropical Rainfall Measuring Mission (TRMM) radar are presented. The radar, which operates at 13.8 GHz and is designed to meet TRMM mission objectives, has a minimum measurable rain rate of 0.5 mm/h with a range resolution of 250 m, a horizontal resolution of about 4 km, and a swath width of 220 km. A 128-element active phased array system is adopted to achieve contiguous scanning within the swath. The basic characteristics of BBM were confirmed by experiments. The development of EM started with the cooperation of NASDA and CRL.

  20. Radar Sounder

    DTIC Science & Technology

    1988-09-01

    over the shorter time period (resulting in a multilook SAR ) with the result that spatial resolution, the usual r~ason for using SAR techniques, degrades...Field - - - ALT 21. Sea Surface Topography - - - SAR , ALT 22. Ocean Waves (sea, swell, surf) V. Good Some V. Good SAR , ALT * with additional lower freq...OLS - Operational Line-scan System radiometer (4-6 GHz?) ALT - Altimeter •* good at low microwave SAR - Synthetic Aperture frequencies Radar + over

  1. Radar channel balancing with commutation

    SciTech Connect

    Doerry, Armin Walter

    2014-02-01

    When multiple channels are employed in a pulse-Doppler radar, achieving and maintaining balance between the channels is problematic. In some circumstances the channels may be commutated to achieve adequate balance. Commutation is the switching, trading, toggling, or multiplexing of the channels between signal paths. Commutation allows modulating the imbalance energy away from the balanced energy in Doppler, where it can be mitigated with filtering.

  2. Methods And System Suppressing Clutter In A Gain-Block, Radar-Responsive Tag System

    DOEpatents

    Ormesher, Richard C.; Axline, Robert M.

    2006-04-18

    Methods and systems reduce clutter interference in a radar-responsive tag system. A radar transmits a series of linear-frequency-modulated pulses and receives echo pulses from nearby terrain and from radar-responsive tags that may be in the imaged scene. Tags in the vicinity of the radar are activated by the radar's pulses. The tags receive and remodulate the radar pulses. Tag processing reverses the direction, in time, of the received waveform's linear frequency modulation. The tag retransmits the remodulated pulses. The radar uses a reversed-chirp de-ramp pulse to process the tag's echo. The invention applies to radar systems compatible with coherent gain-block tags. The invention provides a marked reduction in the strength of residual clutter echoes on each and every echo pulse received by the radar. SAR receiver processing effectively whitens passive-clutter signatures across the range dimension. Clutter suppression of approximately 14 dB is achievable for a typical radar system.

  3. Theory of CW lidar aerosol backscatter measurements and development of a 2.1 microns solid-state pulsed laser radar for aerosol backscatter profiling

    NASA Technical Reports Server (NTRS)

    Kavaya, Michael J.; Henderson, Sammy W.; Frehlich, R. G.

    1991-01-01

    The performance and calibration of a focused, continuous wave, coherent detection CO2 lidar operated for the measurement of atmospheric backscatter coefficient, B(m), was examined. This instrument functions by transmitting infrared (10 micron) light into the atmosphere and collecting the light which is scattered in the rearward direction. Two distinct modes of operation were considered. In volume mode, the scattered light energy from many aerosols is detected simultaneously, whereas in the single particle mode (SPM), the scattered light energy from a single aerosol is detected. The analysis considered possible sources of error for each of these two cases, and also considered the conditions where each technique would have superior performance. The analysis showed that, within reasonable assumptions, the value of B(m) could be accurately measured by either the VM or the SPM method. The understanding of the theory developed during the analysis was also applied to a pulsed CO2 lidar. Preliminary results of field testing of a solid state 2 micron lidar using a CW oscillator is included.

  4. Electromagnetic pulse bombs' defense

    NASA Astrophysics Data System (ADS)

    Chen, Bin; Wang, Yongbin; Li, Juan; Wang, Jianzhong

    2007-11-01

    With the high power microwave devices development, the high power microwave electromagnetic pulse bombs (E-bombs) have become practical abroad. The development of conventional E-bombs devices allows their use in nonnuclear confrontations. E-bombs are powerful enough to damage communication, radar, navigation and computer systems. This paper discusses effects of EMP on electrical system and how to defend the EMP.

  5. Tropical Rainfall Measuring Mission (TRMM) project. VI - Spacecraft, scientific instruments, and launching rocket. Part 4 - TRMM rain radar

    NASA Technical Reports Server (NTRS)

    Meneghini, Robert; Atlas, David; Awaka, Jun; Okamoto, Ken'ichi; Ihara, Toshio; Nakamura, Kenji; Kozu, Toshiaki; Manabe, Takeshi

    1990-01-01

    The basic system parameters for the Tropical Rainfall Measuring Mission (TRMM) radar system are frequency, beamwidth, scan angle, resolution, number of independent samples, pulse repetition frequency, data rate, and so on. These parameters were chosen to satisfy NASA's mission requirements. Six candidates for the TRMM rain radar were studied. The study considered three major competitive items: (1) a pulse-compression radar vs. a conventional radar; (2) an active-array radar with a solid state power amplifier vs. a passive-array radar with a traveling-wave-tube amplifier; and (3) antenna types (planar-array antenna vs. cylindrical parabolic antenna). Basic system parameters such as radar sensitivities, power consumption, weight, and size of these six types are described. Trade-off studies of these cases show that the non-pulse-compression active-array radar with a planar array is considered to be the most suitable candidate for the TRMM rain radar at 13.8 GHz.

  6. MST radar observation in international programs

    NASA Astrophysics Data System (ADS)

    Kato, Susumu

    1993-08-01

    MST radars played an important role in the observation of middle atmosphere dynamics in MAP. The radars have made it possible, for the first time, to observe the precise behaviour of atmospheric gravity waves which had so far been suspected, without definite observations, to contribute to produce weak winds around the mesopause. The facilities then built in various places as in the U.S.A., Germany and Japan detected some crucial behaviors to prove the existence of gravity waves breaking in these heights, showing a release of the momentum as required for producing the weak wind region. Since MAP through MAC to STEP which is now going, MST radars have been increasingly active, with increase of the facilities over the globe, in the observation of atmospheric dynamics from near the ground up to the mesosphere. Besides winds, gravity waves and turbulence, the facilities are now found to be able to observe precise structures of various meteorological disturbances as weather-fronts, typhoon, etc. Even the gap without echoes so far between the middle stratosphere and the lower mesosphere would disappear with an appearance of very powerful facilities in future. Like MST radars, ST radars are well developed. They are also pulsed-doppler radars working on VHF radio waves as MST radars, but less sensitive as to be able to observe only the lower stratosphere and the troposphere. ST radars are economical and widely used for unattended observation and in setting-up networks in international programs. ST radars work as meteor radars simply by installing a small device, Medac, to the original systems. Medium frequency (MF) radars suit mesosphere and lower thermosphere observation; they operate with fairly low power, suitable for continuous observation.

  7. Note on Cumulant Expansions in Rummler Processing of Radar Returns.

    DTIC Science & Technology

    General formulas for wake mean velocity and velocity spread in terms of the radar measured pulse pair correlation coefficient are developed and illustrated for several Doppler spectra, including two that are asymmetric. (Author)

  8. Ambiguity Of Doppler Centroid In Synthetic-Aperture Radar

    NASA Technical Reports Server (NTRS)

    Chang, Chi-Yung; Curlander, John C.

    1991-01-01

    Paper discusses performances of two algorithms for resolution of ambiguity in estimated Doppler centroid frequency of echoes in synthetic-aperture radar. One based on range-cross-correlation technique, other based on multiple-pulse-repetition-frequency technique.

  9. Compact extreme ultraviolet reflectometer for the characterization of grazing incidence optics based on a gas discharge light source

    SciTech Connect

    Bergmann, Klaus; Rosier, Oliver; Metzmacher, Christof

    2005-04-01

    A grazing incidence reflectometer operating in the extreme ultraviolet (EUV) spectral range around 13.5 nm is presented which is making use of a compact xenon pinch plasma light source. The apparatus allows for measuring the absolute reflectivity of a sample for grazing incidence angle in the range from typically 5 deg. to 35 deg. by comparing the EUV diode signal for the reflected light and a reference diode with an accuracy of better than 2%. Design criteria for proper matching of diode apertures and distances with respect to the spatially extended plasma source are presented. The absolute accuracy has been checked by investigating a ruthenium sample with low roughness, which has a reflectivity in the EUV close to the theoretical limit. Comparison to measurements at the EUV-reflectometer of the Physikalisch Technische Bundesanstalt in Berlin at a synchrotron source confirm the absolute accuracy of better than 2% for the reflectivity for the angle interval of interest.

  10. Determination of local thickness values of non-uniform thin films by imaging spectroscopic reflectometer with enhanced spatial resolution

    NASA Astrophysics Data System (ADS)

    Vodák, J.; Nečas, D.; Ohlídal, M.; Ohlídal, I.

    2017-02-01

    In this paper an imaging spectroscopic reflectometer with enhanced spatial resolution is presented. Main features of its design, experimental data acquisition, i.e. maps of thin film spectral dependencies of local reflectance and the local thickness map determination are described. The ability of this instrument to characterize thin film thickness non-uniformity with high gradients is demonstrated on measurements of thin film edges. A comparison with an older device is also presented.

  11. In vitro validation of a hand-held optical reflectometer to measure clinically observed erosive tooth wear.

    PubMed

    Carvalho, Thiago Saads; Assunção, Cristiane Meira; Jost, Fabian; Bürgin, Walter Bruno; Rodrigues, Jonas Almeida; Lussi, Adrian

    2016-08-01

    In this study, we analyzed a newly developed optical reflectometer for measuring erosive tooth wear (ETW) in vitro. Three examiners independently assessed the labial surface of 80 deciduous canines and 75 permanent incisors. One examiner performed visual examinations (BEWE), and the other two used the optical pen-size reflectometer to measure surface reflection intensity (SRI) on the same labial surfaces. The examinations were made in duplicate with at least 1 week interval. Intra- and inter-rater agreements were calculated using weighted kappa analysis for BEWE, and intra-class correlation coefficients (ICC) as well as Bland-Altman plots for SRI. The teeth were separated into without (BEWE 0) or with (BEWE 1-3) ETW, and SRI cut-off points were calculated. Intra-rater agreement for the visual examination was 0.46 and 0.82 for deciduous and permanent teeth, respectively. Inter-rater and intra-rater agreement for SRI were good (ICC > 0.7; p < 0.001). SRI measurements produced high specificity values for deciduous and permanent teeth (≥0.74 and ≥ 0.84, respectively), and lower sensitivity values (≥0.37 and ≥ 0.64, respectively), but permanent teeth had generally higher SRI values (p < 0.05). We observed a significant association between BEWE and SRI (p < 0.05). The optical pen-size reflectometer was able to adequately differentiate ETW on permanent teeth, with highly reliable and reproducible measurements, but ETW on deciduous teeth was less accurately differentiated. The reflectometer is a good candidate for clinical research.

  12. A novel technique for real-time estimation of edge pedestal density gradients via reflectometer time delay data

    SciTech Connect

    Zeng, L. Doyle, E. J.; Rhodes, T. L.; Wang, G.; Sung, C.; Peebles, W. A.; Bobrek, M.

    2016-11-15

    A new model-based technique for fast estimation of the pedestal electron density gradient has been developed. The technique uses ordinary mode polarization profile reflectometer time delay data and does not require direct profile inversion. Because of its simple data processing, the technique can be readily implemented via a Field-Programmable Gate Array, so as to provide a real-time density gradient estimate, suitable for use in plasma control systems such as envisioned for ITER, and possibly for DIII-D and Experimental Advanced Superconducting Tokamak. The method is based on a simple edge plasma model with a linear pedestal density gradient and low scrape-off-layer density. By measuring reflectometer time delays for three adjacent frequencies, the pedestal density gradient can be estimated analytically via the new approach. Using existing DIII-D profile reflectometer data, the estimated density gradients obtained from the new technique are found to be in good agreement with the actual density gradients for a number of dynamic DIII-D plasma conditions.

  13. Upgrades to the NSTX SOL reflectometer to study plasma-antenna coupling and RF-edge interactions

    NASA Astrophysics Data System (ADS)

    Lau, Cornwall; Wilgen, John B.; Caughman, John B.; Hanson, Greg R.; Hosea, Joel; Perkins, Rory; Ryan, Phil; Taylor, Gary

    2014-10-01

    The goal of the Oak Ridge National Laboratory (ORNL) scrape-off-layer (SOL) reflectometer is to measure the density profiles and fluctuations in front of the HHFW antenna on NSTX-U to help understand plasma-antenna coupling and RF-edge interactions, such as profile modifications due to field-aligned power losses and/or parametric decay instabilities. Originally designed for NSTX conditions, the reflectometer is being upgraded to operate at the increased magnetic fields of NSTX-U. General upgrades will be discussed. Most importantly, due to the doubling of the magnetic field for NSTX-U, the use of the current 6-27 GHz X-mode R cutoff on NSTX needs to be reconsidered. If only the X-mode R-cutoff is used, the operating frequencies will need to be modified, requiring significant hardware modifications to both the electronics and reflectometer launchers. It will be shown that the frequencies will not need to be modified for NSTX-U operation if both X-mode L and R cutoffs are measured. The measured SOL density profiles are intended to be used as inputs into RF simulation codes, and one such simulation using COMSOL multiphysics is being developed to understand the electric fields in front of the antenna for cold plasma conditions. Progress on the COMSOL simulation will be reported.

  14. A novel technique for real-time estimation of edge pedestal density gradients via reflectometer time delay data

    NASA Astrophysics Data System (ADS)

    Zeng, L.; Doyle, E. J.; Rhodes, T. L.; Wang, G.; Sung, C.; Peebles, W. A.; Bobrek, M.

    2016-11-01

    A new model-based technique for fast estimation of the pedestal electron density gradient has been developed. The technique uses ordinary mode polarization profile reflectometer time delay data and does not require direct profile inversion. Because of its simple data processing, the technique can be readily implemented via a Field-Programmable Gate Array, so as to provide a real-time density gradient estimate, suitable for use in plasma control systems such as envisioned for ITER, and possibly for DIII-D and Experimental Advanced Superconducting Tokamak. The method is based on a simple edge plasma model with a linear pedestal density gradient and low scrape-off-layer density. By measuring reflectometer time delays for three adjacent frequencies, the pedestal density gradient can be estimated analytically via the new approach. Using existing DIII-D profile reflectometer data, the estimated density gradients obtained from the new technique are found to be in good agreement with the actual density gradients for a number of dynamic DIII-D plasma conditions.

  15. Measurement of the ICRF wave propagation in the internal region of plasmas by using reflectometers on GAMMA10

    NASA Astrophysics Data System (ADS)

    Okada, T.; Ikezoe, R.; Ichimura, M.; Hirata, M.; Sakamoto, M.; Sumida, S.; Iwamoto, Y.; Jang, S.; Itagaki, J.; Onodera, Y.; Yoshikawa, M.; Kohagura, J.; Shima, Y.; Nakashima, Y.

    2015-11-01

    ICRF waves is one of valuable tools for producing and heating plasmas. On GAMMA10, ions are mainly heated by the ICRF waves with the absorption of the cyclotron resonance layers. ICRF waves of 6.36, 9.9 and 10.3 MHz are normally used to be compatible with the magnetic mirror configuration and damped at the resonance layers of the central cell, east and west anchor cells, respectively. These waves are usually excited by ICRF antennas installed in the central cell and propagate to each resonance layer. It is essential for the ongoing divertor simulation experiments on GAMMA 10 to investigate wave excitation, propagation and absorption. We observe the electron density fluctuations accompanied with the ICRF waves by using microwave reflectometer systems. It is confirmed that the wave of 6.36 MHz is further damped near the resonance layer in the internal region. The waves of 9.9 / 10.3 MHz excited in the east / west anchor cells interferes with the wave from the central cell. The interfered wave is controlled with antenna phasing by the phase difference between both antennas in the central and the anchor cell. The wave intensity measured by reflectometers depends clearly on the phase difference. In this talk, the availability of wave measurement with reflectometers is shown, and the wave propagation in the internal region of plasmas on GAMMA 10 is reported. This work is partly supported by JSPS, Japan (25400531, 15K17797) and by NIFS, Japan (NIFS15KUGM101).

  16. Reduction of Stationary Clutter in Radar,

    DTIC Science & Technology

    1980-10-30

    desired object. In radar, such interference is called passive interference. Since this interrerence is derived from stationary objects or rrom objects...conjunction with IAGC) is the so- called detector balance bias 2 [2.1;2.2]. Also, detectors with logarithmic characterisitics are used. Application of...considerable area in space. Thus, applying the so- called discriminator of pulse length, which lets through only pulses of length similar to that of the

  17. Radar Absorbing Material Design

    DTIC Science & Technology

    2003-09-01

    simulations of coated plates were performed to estimate the effectiveness of the absorbing layers in reducing radar cross section . The reduction in monostatic... radar cross section value is shown by plotting the radar cross section of the plate with and without radar absorbing material. ε t 15. NUMBER OF

  18. Research on the performance of multifunctional distributed optical fiber sensing system based on the combination of Brillouin optical time-domain analysis and phase-sensitive optical time-domain reflectometer

    NASA Astrophysics Data System (ADS)

    Zhan, Yage; Liu, Hong; Shen, Ziyang; Yu, Qiao; Zhang, Hongyang

    2016-07-01

    There are many similarities between Brillouin optical time-domain analysis and phase-sensitive optical time-domain reflectometer in system topological structure. A multifunctional distributed optical fiber sensing system based on their similarities and the combination of their topological structure is presented. The system can monitor strain and temperature, as well as detect and locate the intrusions or disturbances along the sensing fiber. Suppose that X is the width of the optical pulse incident into the sensing fiber with the unit of nanosecond and Y is the minimum detectable distance with the unit of meter between two intrusions that are being detected simultaneously. The experiment results show that y changes linearly with x according to the equation: y=0.103x-0.452. By optimizing device parameters of the system, strain measurement accuracy of 3.17 μɛ and the temperature measurement accuracy of 0.45°C have been realized when the optical pulse width is 30 ns. On the other hand, two intrusions have been detected and located simultaneously with this multifunctional system. The results show that the pulse width and the minimum distance between two intrusions (Lmin) have a linear relationship. The theoretical analyses and the experiment results show it is applicable to use this multifunctional system for strain and temperature monitoring, and intrusion detecting.

  19. Radar and Lidar Radar DEM

    NASA Technical Reports Server (NTRS)

    Liskovich, Diana; Simard, Marc

    2011-01-01

    Using radar and lidar data, the aim is to improve 3D rendering of terrain, including digital elevation models (DEM) and estimates of vegetation height and biomass in a variety of forest types and terrains. The 3D mapping of vegetation structure and the analysis are useful to determine the role of forest in climate change (carbon cycle), in providing habitat and as a provider of socio-economic services. This in turn will lead to potential for development of more effective land-use management. The first part of the project was to characterize the Shuttle Radar Topography Mission DEM error with respect to ICESat/GLAS point estimates of elevation. We investigated potential trends with latitude, canopy height, signal to noise ratio (SNR), number of LiDAR waveform peaks, and maximum peak width. Scatter plots were produced for each variable and were fitted with 1st and 2nd degree polynomials. Higher order trends were visually inspected through filtering with a mean and median filter. We also assessed trends in the DEM error variance. Finally, a map showing how DEM error was geographically distributed globally was created.

  20. Planetary landing-zone reconnaissance using ice-penetrating radar data: Concept validation in Antarctica

    NASA Astrophysics Data System (ADS)

    Grima, Cyril; Schroeder, Dustin M.; Blankenship, Donald D.; Young, Duncan A.

    2014-11-01

    The potential for a nadir-looking radar sounder to retrieve significant surface roughness/permittivity information valuable for planetary landing site selection is demonstrated using data from an airborne survey of the Thwaites Glacier Catchment, West Antarctica using the High Capability Airborne Radar Sounder (HiCARS). The statistical method introduced by Grima et al. (2012. Icarus 220, 84-99. http://dx.doi.org/10.1007/s11214-012-9916-y) for surface characterization is applied systematically along the survey flights. The coherent and incoherent components of the surface signal, along with an internally generated confidence factor, are extracted and mapped in order to show how a radar sounder can be used as both a reflectometer and a scatterometer to identify regions of low surface roughness compatible with a planetary lander. These signal components are used with a backscattering model to produce a landing risk assessment map by considering the following surface properties: Root mean square (RMS) heights, RMS slopes, roughness homogeneity/stationarity over the landing ellipse, and soil porosity. Comparing these radar-derived surface properties with simultaneously acquired nadir-looking imagery and laser-altimetry validates this method. The ability to assess all of these parameters with an ice penetrating radar expands the demonstrated capability of a principle instrument in icy planet satellite science to include statistical reconnaissance of the surface roughness to identify suitable sites for a follow-on lander mission.

  1. Ground radar detection of meteoroids in space

    NASA Technical Reports Server (NTRS)

    Kessler, D. J.; Landry, P. M.; Gabbard, J. R.; Moran, J. L. T.

    1980-01-01

    A special test to lower the detection threshold for satellite fragments potentially dangerous to spacecraft was carried out by NORAD for NASA, using modified radar software. The Perimeter Acquisition Radar Attack Characterization System, a large, planar face, phased radar, operates at a nominal 430 MHz and produces 120 pulses per second, 45 of which were dedicated to search. In a time period of 8.4 hours of observations over three days, over 6000 objects were detected and tracked of which 37 were determined to have velocities greater than escape velocity. Six of these were larger objects with radar cross sections greater than 0.1 sq m and were probably orbiting satellites. A table gives the flux of both observed groups.

  2. Ground-based laser radar measurements of satellite vibrations.

    PubMed

    Schultz, K I; Fisher, S

    1992-12-20

    Vibration signatures from the low-power atmospheric compensation (LACE) satellite are obtained by using the MIT Lincoln Laboratory Firepond coherent CO(2) laser radar facility located in Westford, Mass. The LACE satellite is equipped with IR germanium retroreflectors on deployable/retractable booms to enhance ground-based IR laser radar measurements of on-orbit boom vibrations. Analysis of pulsed cw laser radar measurements of the satellite during and subsequent to boom retraction indicates the presence of a complex time-varying model structure. The observed vibration spectra include vibration modes not previously predicted. These data represent the first observations of satellite vibration modes from a ground-based laser radar.

  3. Survey of Ultra-wideband Radar

    NASA Astrophysics Data System (ADS)

    Mokole, Eric L.; Hansen, Pete

    The development of UWB radar over the last four decades is very briefly summarized. A discussion of the meaning of UWB is followed by a short history of UWB radar developments and discussions of key supporting technologies and current UWB radars. Selected UWB radars and the associated applications are highlighted. Applications include detecting and imaging buried mines, detecting and mapping underground utilities, detecting and imaging objects obscured by foliage, through-wall detection in urban areas, short-range detection of suicide bombs, and the characterization of the impulse responses of various artificial and naturally occurring scattering objects. In particular, the Naval Research Laboratory's experimental, low-power, dual-polarized, short-pulse, ultra-high resolution radar is used to discuss applications and issues of UWB radar. Some crucial issues that are problematic to UWB radar are spectral availability, electromagnetic interference and compatibility, difficulties with waveform control/shaping, hardware limitations in the transmission chain, and the unreliability of high-power sources for sustained use above 2 GHz.

  4. The Who, What, Where and When of Radar Targeting: Key Note Speech

    DTIC Science & Technology

    2005-05-01

    imaging radar seeker • Aim point selection • Pulsed Doppler, polarisation diverse, pulse compression • Monopulse angular discrimination • LPI ...The Who, What, Where and When of Radar Targeting. Key Note speech/presentation, MATRIX 2005 workshop NATO SHAPE School, Oberammergau, Germany...review including: • The problems of ATR using mmW radar and some of the techniques traditionally applied. This establishes the state-of-the-art. This

  5. Current test results for the Athena radar responsive tag

    NASA Astrophysics Data System (ADS)

    Ormesher, Richard C.; Martinez, Ana; Plummer, Kenneth W.; Erlandson, David; Delaware, Sheri; Clark, David R.

    2006-05-01

    Sandia National Laboratories has teamed with General Atomics and Sierra Monolithics to develop the Athena tag for the Army's Radar Tag Engagement (RaTE) program. The radar-responsive Athena tag can be used for Blue Force tracking and Combat Identification (CID) as well as data collection, identification, and geolocation applications. The Athena tag is small (~4.5" x 2.4" x 4.2"), battery-powered, and has an integral antenna. Once remotely activated by a Synthetic Aperture Radar (SAR) or Moving Target Indicator (MTI) radar, the tag transponds modulated pulses to the radar at a low transmit power. The Athena tag can operate Ku-band and X-band airborne SAR and MTI radars. This paper presents results from current tag development testing activities. Topics covered include recent field tests results from the AN/APY-8 Lynx, F16/APG-66, and F15E/APG-63 V(1) radars and other Fire Control radars. Results show that the Athena tag successfully works with multiple radar platforms, in multiple radar modes, and for multiple applications. Radar-responsive tags such as Athena have numerous applications in military and government arenas. Military applications include battlefield situational awareness, combat identification, targeting, personnel recovery, and unattended ground sensors. Government applications exist in nonproliferation, counter-drug, search-and-rescue, and land-mapping activities.

  6. Detecting and mitigating wind turbine clutter for airspace radar systems.

    PubMed

    Wang, Wen-Qin

    2013-01-01

    It is well recognized that a wind turbine has a large radar cross-section (RCS) and, due to the movement of the blades, the wind turbine will generate a Doppler frequency shift. This scattering behavior may cause severe interferences on existing radar systems including static ground-based radars and spaceborne or airborne radars. To resolve this problem, efficient techniques or algorithms should be developed to mitigate the effects of wind farms on radars. Herein, one transponder-based mitigation technique is presented. The transponder is not a new concept, which has been proposed for calibrating high-resolution imaging radars. It modulates the radar signal in a manner that the retransmitted signals can be separated from the scene echoes. As wind farms often occupy only a small area, mitigation processing in the whole radar operation will be redundant and cost inefficient. Hence, this paper uses a transponder to determine whether the radar is impacted by the wind farms. If so, the effects of wind farms are then mitigated with subsequent Kalman filtering or plot target extraction algorithms. Taking airborne synthetic aperture radar (SAR) and pulse Doppler radar as the examples, this paper provides the corresponding system configuration and processing algorithms. The effectiveness of the mitigation technique is validated by numerical simulation results.

  7. Detecting and Mitigating Wind Turbine Clutter for Airspace Radar Systems

    PubMed Central

    2013-01-01

    It is well recognized that a wind turbine has a large radar cross-section (RCS) and, due to the movement of the blades, the wind turbine will generate a Doppler frequency shift. This scattering behavior may cause severe interferences on existing radar systems including static ground-based radars and spaceborne or airborne radars. To resolve this problem, efficient techniques or algorithms should be developed to mitigate the effects of wind farms on radars. Herein, one transponder-based mitigation technique is presented. The transponder is not a new concept, which has been proposed for calibrating high-resolution imaging radars. It modulates the radar signal in a manner that the retransmitted signals can be separated from the scene echoes. As wind farms often occupy only a small area, mitigation processing in the whole radar operation will be redundant and cost inefficient. Hence, this paper uses a transponder to determine whether the radar is impacted by the wind farms. If so, the effects of wind farms are then mitigated with subsequent Kalman filtering or plot target extraction algorithms. Taking airborne synthetic aperture radar (SAR) and pulse Doppler radar as the examples, this paper provides the corresponding system configuration and processing algorithms. The effectiveness of the mitigation technique is validated by numerical simulation results. PMID:24385880

  8. C(G)-Band and X(I)-Band Noncoherent Radar Transponder Performance Specification Standard

    DTIC Science & Technology

    2014-06-01

    type transponder sets that any instrumentation tracking radar on any test range may use. 15. SUBJECT TERMS Electronic Trajectory Measurements Group...requirements for both C(G)-band and X(I)-band, noncoherent, pulse-type transponder sets that any instrumentation tracking radar on any test range may...Coherent Radar Transponder Performance Specification Standard, RCC 262-14, is to provide a complete and overall standard for radar tracking transponder

  9. Measuring Mars' Atmospheric Neutral Density from 160 to 320km altitude with the MGS Electron Reflectometer

    NASA Astrophysics Data System (ADS)

    Lillis, R. J.; Mitchell, D. L.; Lin, R. P.; Acuna, M. H.

    2003-12-01

    The Magnetometer/Electron Reflectometer (MAG/ER) experiment aboard Mars Global Surveyor (MGS) samples the local electron population's distribution in energy and pitch angle (angle between electron velocity and local magneticfield direction) at the mapping orbit altitude of ~400km. We develop a single-particle model of the electrons' interaction with the neutral atmosphere and motion along open field-lines connecting the solar wind to remnant crustal magnetization. Electron reflection from magnetic gradients and absorption due to inelastic collisons with atmospheric neutrals results in characteristic pitch angle (PA) distributions for open field lines. By assuming the validity of spherical harmonic expansions (Cain, Arkani-hamed) in the strongest field regions of Mars (such as Terra Sirenum), we trace the electron paths and fit these PA distributions to our model to constrain the scale height and base density of the neutral atmosphere in the interaction region, which is between 160 and 320km altitude. We analyse ~2 martian years of MGS mapping Orbit Data and present the first measurements of Mars' exospheric neutral density. We track density variations over season, latitude and solar cycle and compare with predictions from Mars Thermosphere Global Circulation Model (MTGCM) simulations and with MGS acceleromater data. Our results will help to constrain the upper boundaries of GCMs and assist orbital decay calculations for low-orbiting spacecraft, such as the 2005 Mars Reconnaissance Orbiter.

  10. The Southwest Research Institute ultraviolet reflectance chamber (SwURC): a far ultraviolet reflectometer

    NASA Astrophysics Data System (ADS)

    Winters, Gregory S.; Retherford, Kurt D.; Davis, Michael W.; Escobedo, Stephen M.; Bassett, Eric C.; Patrick, Edward L.; Nagengast, Maggie E.; Fairbanks, Matthew H.; Miles, Paul F.; Parker, Joel W.; Gladstone, G. Randall; Slater, David C.; Stern, S. Alan

    2012-10-01

    We designed and assembled a highly capable UV reflectometer chamber and data acquisition system to provide bidirectional scattering data of various surfaces and materials. This chamber was initially conceived to create laboratory-based UV reflectance measurements of water frost on lunar soil/regolith simulants, to support interpretation of UV reflectance data from the Lyman Alpha Mapping Project ("LAMP") instrument on-board the NASA Lunar Reconnaissance Orbiter spacecraft. A deuterium lamp illuminates surfaces and materials at a fixed 45° incident beam angle over the 115 to 200 nm range via a monochromator, while a photomultiplier tube detector is scanned to cover emission angles -85° to +85° (with a gap from -60° to -30°, due to the detector blocking the incident beam). Liquid nitrogen cools the material/sample mount when desired. The chamber can be configured to test a wide range of samples and materials using sample trays and holders. Test surfaces to date include aluminum mirrors, water ice, reflectance standards, and frozen mixtures of water and lunar soil/regolith stimulant. Future UV measurements planned include Apollo lunar samples, meteorite samples, other ices, minerals, and optical surfaces. Since this chamber may well be able to provide useful research data for groups outside Southwest Research Institute, we plan to take requests from and collaborate with others in the UV and surface reflection research community.

  11. Self-adaptive sampling rate data acquisition in JET's correlation reflectometer

    SciTech Connect

    Arcas, G. de; Lopez, J. M.; Ruiz, M.; Barrera, E.; Vega, J.; Fonseca, A.

    2008-10-15

    Data acquisition systems with self-adaptive sampling rate capabilities have been proposed as a solution to reduce the shear amount of data collected in every discharge of present fusion devices. This paper discusses the design of such a system for its use in the KG8B correlation reflectometer at JET. The system, which is based on the ITMS platform, continuously adapts the sample rate during the acquisition depending on the signal bandwidth. Data are acquired continuously at the expected maximum sample rate and transferred to a memory buffer in the host processor. Thereafter the rest of the process is based on software. Data are read from the memory buffer in blocks and for each block an intelligent decimation algorithm is applied. The decimation algorithm determines the signal bandwidth for each block in order to choose the optimum sample rate for that block, and from there the decimation factor to be used. Memory buffers are used to adapt the throughput of the three main software modules (data acquisition, processing, and storage) following a typical producer-consumer architecture. The system optimizes the amount of data collected while maintaining the same information. Design issues are discussed and results of performance evaluation are presented.

  12. Self-adaptive sampling rate data acquisition in JET's correlation reflectometer.

    PubMed

    de Arcas, G; López, J M; Ruiz, M; Barrera, E; Vega, J; Murari, A; Fonseca, A

    2008-10-01

    Data acquisition systems with self-adaptive sampling rate capabilities have been proposed as a solution to reduce the shear amount of data collected in every discharge of present fusion devices. This paper discusses the design of such a system for its use in the KG8B correlation reflectometer at JET. The system, which is based on the ITMS platform, continuously adapts the sample rate during the acquisition depending on the signal bandwidth. Data are acquired continuously at the expected maximum sample rate and transferred to a memory buffer in the host processor. Thereafter the rest of the process is based on software. Data are read from the memory buffer in blocks and for each block an intelligent decimation algorithm is applied. The decimation algorithm determines the signal bandwidth for each block in order to choose the optimum sample rate for that block, and from there the decimation factor to be used. Memory buffers are used to adapt the throughput of the three main software modules (data acquisition, processing, and storage) following a typical producer-consumer architecture. The system optimizes the amount of data collected while maintaining the same information. Design issues are discussed and results of performance evaluation are presented.

  13. Quantitative measurement of dynamic nanostrain based on a phase-sensitive optical time domain reflectometer.

    PubMed

    Dong, Yongkang; Chen, Xi; Liu, Erhu; Fu, Cheng; Zhang, Hongying; Lu, Zhiwei

    2016-10-01

    A sensing system is proposed for quantitative measurement of large-range dynamic nanostrain based on a phase-sensitive optical time domain reflectometer, where the coherent detection and I/Q demodulation methods are employed to demodulate both the phase and the amplitude of the Rayleigh scattering light in real time. A nanopositioning translation stage is utilized to apply precise nanostrain to fiber. By measuring phase differences between two adjacent sections, the quantitative nanostrain with a large measurement range is demonstrated; this is also a method to measure the strain parameter of refractive index. For the Panda polarization-maintaining fiber under test in the experiment, the strain parameter of phase difference is measured to be 8.714  mrad/(nε·m), while the strain parameter of refractive index is measured to be -0.3751ε-1. As a proof of the concept, the dynamic strain sensing with a range of 10-1000 nε is experimentally demonstrated, and the strain resolution is 1 or 2 nε, corresponding to 5 or 2.5 m spatial resolution, respectively. The experimental measurement also shows a triangular wave with a 12-Hz vibrating frequency and a 100-nε strain amplitude as well as a 188-Hz resonant signal of the tensile section.

  14. Technical overview of the millimeter-wave imaging reflectometer on the DIII-D tokamak (invited)

    NASA Astrophysics Data System (ADS)

    Muscatello, C. M.; Domier, C. W.; Hu, X.; Kramer, G. J.; Luhmann, N. C.; Ren, X.; Riemenschneider, P.; Spear, A.; Tobias, B. J.; Valeo, E.; Yu, L.

    2014-11-01

    The two-dimensional mm-wave imaging reflectometer (MIR) on DIII-D is a multi-faceted device for diagnosing electron density fluctuations in fusion plasmas. Its multi-channel, multi-frequency capabilities and high sensitivity permit visualization and quantitative diagnosis of density perturbations, including correlation length, wavenumber, mode propagation velocity, and dispersion. The two-dimensional capabilities of MIR are made possible with 12 vertically separated sightlines and four-frequency operation (corresponding to four radial channels). The 48-channel DIII-D MIR system has a tunable source that can be stepped in 500 μs increments over a range of 56 to 74 GHz. An innovative optical design keeps both on-axis and off-axis channels focused at the cutoff surface, permitting imaging over an extended poloidal region. The integrity of the MIR optical design is confirmed by comparing Gaussian beam calculations to laboratory measurements of the transmitter beam pattern and receiver antenna patterns. Measurements are presented during the density ramp of a plasma discharge to demonstrate unfocused and focused MIR signals.

  15. Development of inside launch reflectometer systems on the DIII-D tokamak (abstract)a)

    NASA Astrophysics Data System (ADS)

    Doyle, E. J.; Rhodes, T. L.; Doane, J. L.; Peebles, W. A.

    1995-01-01

    Inside launch (high field side) reflectometry is necessary for routine core access on DIII-D and is a very attractive option for ITER and TPX. For high temperature reactor relevant plasmas, relativistic corrections for the left-hand cutoff (inside launched) are relatively small, whereas these substantially affect the location of the normal right hand cutoff. On DIII-D, core access using the right hand cutoff is restricted to low density plasmas, while O-mode polarization is incompatible with flat H-mode density profiles. Routine core access can, however, be obtained using the left-hand cutoff and inside launch. On ITER and TPX, outside launch X-mode systems need to operate at high frequency, ˜100-250 GHz, such that the left-hand cutoff, which is at much lower frequency, ˜0-75 GHz, is an attractive option for high density operation. In addition, inside launch reflectometry can be used to investigate plasma asymmetries; on DIII-D an inboard/outboard asymmetry in turbulence response is observed at the L-H transition. An upgraded inside launch reflectometer system was recently installed on DIII-D, specifically to investigate the use of the left hand X-mode cutoff and inside launch for profile and turbulence measurements in reactor relevant plasmas. This system will also provide routine core access for reflectometry on DIII-D.

  16. Development of inside launch reflectometer systems on the DIII-D tokamaka)

    NASA Astrophysics Data System (ADS)

    Doyle, E. J.; Rhodes, T. L.; Doane, J. L.; Peebles, W. A.

    1995-02-01

    Inside launch (high field side) reflectometry is necessary for routine core access on DIII-D and is a very attractive option for ITER and TPX. For high temperature reactor relevant plasmas, relativistic corrections for the left-hand cutoff (inside launched) are relatively small, whereas these substantially affect the location of the normal right hand cutoff. On DIII-D, core access using the right hand cutoff is restricted to low density plasmas, while O-mode polarization is incompatible with flat H-mode density profiles. Routine core access can, however, be obtained using the left-hand cutoff and inside launch. On ITER and TPX, outside launch X-mode systems need to operate at high frequency, ˜100-250 GHz, such that the left-hand cutoff, which is at much lower frequency, ˜0-75 GHz, is an attractive option for high density operation. In addition, inside launch reflectometry can be used to investigate plasma asymmetries; on DIII-D an inboard/outboard asymmetry in turbulence response is observed at the L-H transition. An upgraded inside launch reflectometer system was recently installed on DIII-D, specifically to investigate the use of the left hand X-mode cutoff and inside launch for profile and turbulence measurements in reactor relevant plasmas. This system will also provide routine core access for reflectometry on DIII-D.

  17. Technical overview of the millimeter-wave imaging reflectometer on the DIII-D tokamak (invited)

    DOE PAGES

    Muscatello, Christopher M.; Domier, Calvin W.; Hu, Xing; ...

    2014-07-22

    The two-dimensional mm-wave imaging reflectometer (MIR) on DIII-D is a multi-faceted device for diagnosing electron density fluctuations in fusion plasmas. Its multi-channel, multi-frequency capabilities and high sensitivity permit visualization and quantitative diagnosis of density perturbations, including correlation length, wavenumber, mode propagation velocity, and dispersion. The two-dimensional capabilities of MIR are made possible with twelve vertically separated sightlines and four-frequency operation (corresponding to four radial channels). The 48-channel DIII-D MIR system has a tunable source that can be stepped in 500 µs increments over a range of 56 to 74 GHz. An innovative optical design keeps both on-axis and off-axis channelsmore » focused at the cutoff surface, permitting imaging over an extended poloidal region. As a result, the integrity of the MIR optical design is confirmed by comparing Gaussian beam calculations to laboratory measurements of the transmitter beam pattern and receiver antenna patterns.« less

  18. Technical overview of the millimeter-wave imaging reflectometer on the DIII-D tokamak (invited)

    SciTech Connect

    Muscatello, Christopher M.; Domier, Calvin W.; Hu, Xing; Kramer, Gerrit J.; Luhmann, Jr., Nelville C.; Ren, Xiaoxin; Riemenschneider, P.; Spear, Alex; Tobias, Benjamin J.; Valeo, Ernest; Yu, L.

    2014-07-22

    The two-dimensional mm-wave imaging reflectometer (MIR) on DIII-D is a multi-faceted device for diagnosing electron density fluctuations in fusion plasmas. Its multi-channel, multi-frequency capabilities and high sensitivity permit visualization and quantitative diagnosis of density perturbations, including correlation length, wavenumber, mode propagation velocity, and dispersion. The two-dimensional capabilities of MIR are made possible with twelve vertically separated sightlines and four-frequency operation (corresponding to four radial channels). The 48-channel DIII-D MIR system has a tunable source that can be stepped in 500 µs increments over a range of 56 to 74 GHz. An innovative optical design keeps both on-axis and off-axis channels focused at the cutoff surface, permitting imaging over an extended poloidal region. As a result, the integrity of the MIR optical design is confirmed by comparing Gaussian beam calculations to laboratory measurements of the transmitter beam pattern and receiver antenna patterns.

  19. Control of laser wavelength tuning and its application in coherent optical time domain reflectometer

    NASA Astrophysics Data System (ADS)

    Lu, Lidong; Sun, Xiaoyan; Li, Binglin

    2017-02-01

    A laser diode temperature control scheme is adopted to achieve the laser wavelength tuning of a narrow linewidth laser, which sends commands by serial communication to change the laser diode temperature. The laser diode temperature is presented by the temperature sensitive resistance. And then the laser wavelength tuning method is also used in a coherent optical time domain reflectometer (C-OTDR) to reduce the coherent Rayleigh noise (CRN) caused by the coherence of the narrow linewidth laser. As the serial communication for the laser wavelength tuning is time-consuming which costs at least 10ms to finish the wavelength tuning once, the measurement time and efficiency of the C-OTDR should be considered. And then the relationship between the times for the laser wavelength changing and the CRN fluctuation is experimentally studied to balance the measurement time consumption and the measurement results, which illustrates that the laser wavelength needs not be changed in each measurement period of the C-OTDR and it can also obtain the ideal result to change the laser wavelength every 500 measurement periods. In traditional C-OTDR, by serial communication, the laser wavelength is changed in each measurement period and the total measurement periods are 218, so by the new scheme it can save about 2600 seconds to achieve an ideal measurement, which is of high efficiency.

  20. Measuring grazing-angle DHR with the infrared grazing angle reflectometer

    NASA Astrophysics Data System (ADS)

    Benson, Michael R.; Marciniak, Michael A.; Burks, Jeffrey W.

    2012-10-01

    The Infrared Grazing Angle Reflectometer allows measurement of Directional Hemispherical Reflectance (DHR) at very high angles of incidence (30 to 85 degrees) and at wavelengths ranging from 4.3 to 10.8 microns. A hemi-ellipsoidal mirror redirects the reflected light and reflects it on to a novel five-sided pyroelectric detector. The incident light intensity is measured and used in calculating the DHR of the sample. In this paper, the theory of operation of this detector is derived, and used to simulate the operation of the system. This simulation of the detector shows errors of 3% or less for both diffuse and specular samples, compared to the theoretical DHR. The calibration method defined in this paper allows for high accuracy and ease of use without knowing the specific attributes of the optics used in the system. Finally, collected DHR data is compared with the simulated data for comparison. Comparing the measured data to the simulation shows that the model correctly predicts the locations and trends of the scattered energy.

  1. Technical overview of the millimeter-wave imaging reflectometer on the DIII-D tokamak (invited).

    PubMed

    Muscatello, C M; Domier, C W; Hu, X; Kramer, G J; Luhmann, N C; Ren, X; Riemenschneider, P; Spear, A; Tobias, B J; Valeo, E; Yu, L

    2014-11-01

    The two-dimensional mm-wave imaging reflectometer (MIR) on DIII-D is a multi-faceted device for diagnosing electron density fluctuations in fusion plasmas. Its multi-channel, multi-frequency capabilities and high sensitivity permit visualization and quantitative diagnosis of density perturbations, including correlation length, wavenumber, mode propagation velocity, and dispersion. The two-dimensional capabilities of MIR are made possible with 12 vertically separated sightlines and four-frequency operation (corresponding to four radial channels). The 48-channel DIII-D MIR system has a tunable source that can be stepped in 500 μs increments over a range of 56 to 74 GHz. An innovative optical design keeps both on-axis and off-axis channels focused at the cutoff surface, permitting imaging over an extended poloidal region. The integrity of the MIR optical design is confirmed by comparing Gaussian beam calculations to laboratory measurements of the transmitter beam pattern and receiver antenna patterns. Measurements are presented during the density ramp of a plasma discharge to demonstrate unfocused and focused MIR signals.

  2. Technical overview of the millimeter-wave imaging reflectometer on the DIII-D tokamak (invited)

    SciTech Connect

    Muscatello, C. M. Domier, C. W.; Hu, X.; Luhmann, N. C.; Ren, X.; Riemenschneider, P.; Spear, A.; Valeo, E.; Yu, L.; Kramer, G. J.; Tobias, B. J.

    2014-11-15

    The two-dimensional mm-wave imaging reflectometer (MIR) on DIII-D is a multi-faceted device for diagnosing electron density fluctuations in fusion plasmas. Its multi-channel, multi-frequency capabilities and high sensitivity permit visualization and quantitative diagnosis of density perturbations, including correlation length, wavenumber, mode propagation velocity, and dispersion. The two-dimensional capabilities of MIR are made possible with 12 vertically separated sightlines and four-frequency operation (corresponding to four radial channels). The 48-channel DIII-D MIR system has a tunable source that can be stepped in 500 μs increments over a range of 56 to 74 GHz. An innovative optical design keeps both on-axis and off-axis channels focused at the cutoff surface, permitting imaging over an extended poloidal region. The integrity of the MIR optical design is confirmed by comparing Gaussian beam calculations to laboratory measurements of the transmitter beam pattern and receiver antenna patterns. Measurements are presented during the density ramp of a plasma discharge to demonstrate unfocused and focused MIR signals.

  3. Airborne Differential Doppler Weather Radar

    NASA Technical Reports Server (NTRS)

    Meneghini, R.; Bidwell, S.; Liao, L.; Rincon, R.; Heymsfield, G.; Hildebrand, Peter H. (Technical Monitor)

    2001-01-01

    The Precipitation Radar aboard the Tropical Rain Measuring Mission (TRMM) Satellite has shown the potential for spaceborne sensing of snow and rain by means of an incoherent pulsed radar operating at 13.8 GHz. The primary advantage of radar relative to passive instruments arises from the fact that the radar can image the 3-dimensional structure of storms. As a consequence, the radar data can be used to determine the vertical rain structure, rain type (convective/stratiform) effective storm height, and location of the melting layer. The radar, moreover, can be used to detect snow and improve the estimation of rain rate over land. To move toward spaceborne weather radars that can be deployed routinely as part of an instrument set consisting of passive and active sensors will require the development of less expensive, lighter-weight radars that consume less power. At the same time, the addition of a second frequency and an upgrade to Doppler capability are features that are needed to retrieve information on the characteristics of the drop size distribution, vertical air motion and storm dynamics. One approach to the problem is to use a single broad-band transmitter-receiver and antenna where two narrow-band frequencies are spaced apart by 5% to 10% of the center frequency. Use of Ka-band frequencies (26.5 GHz - 40 GHz) affords two advantages: adequate spatial resolution can be attained with a relatively small antenna and the differential reflectivity and mean Doppler signals are directly related to the median mass diameter of the snow and raindrop size distributions. The differential mean Doppler signal has the additional property that this quantity depends only on that part of the radial speed of the hydrometeors that is drop-size dependent. In principle, the mean and differential mean Doppler from a near-nadir viewing radar can be used to retrieve vertical air motion as well as the total mean radial velocity. In the paper, we present theoretical calculations for the

  4. Airborne Differential Doppler Weather Radar

    NASA Technical Reports Server (NTRS)

    Meneghini, R.; Bidwell, S.; Liao, L.; Rincon, R.; Heymsfield, G.; Hildebrand, Peter H. (Technical Monitor)

    2001-01-01

    The Precipitation Radar aboard the Tropical Rain Measuring Mission (TRMM) Satellite has shown the potential for spaceborne sensing of snow and rain by means of an incoherent pulsed radar operating at 13.8 GHz. The primary advantage of radar relative to passive instruments arises from the fact that the radar can image the 3-dimensional structure of storms. As a consequence, the radar data can be used to determine the vertical rain structure, rain type (convective/stratiform) effective storm height, and location of the melting layer. The radar, moreover, can be used to detect snow and improve the estimation of rain rate over land. To move toward spaceborne weather radars that can be deployed routinely as part of an instrument set consisting of passive and active sensors will require the development of less expensive, lighter-weight radars that consume less power. At the same time, the addition of a second frequency and an upgrade to Doppler capability are features that are needed to retrieve information on the characteristics of the drop size distribution, vertical air motion and storm dynamics. One approach to the problem is to use a single broad-band transmitter-receiver and antenna where two narrow-band frequencies are spaced apart by 5% to 10% of the center frequency. Use of Ka-band frequencies (26.5 GHz - 40 GHz) affords two advantages: adequate spatial resolution can be attained with a relatively small antenna and the differential reflectivity and mean Doppler signals are directly related to the median mass diameter of the snow and raindrop size distributions. The differential mean Doppler signal has the additional property that this quantity depends only on that part of the radial speed of the hydrometeors that is drop-size dependent. In principle, the mean and differential mean Doppler from a near-nadir viewing radar can be used to retrieve vertical air motion as well as the total mean radial velocity. In the paper, we present theoretical calculations for the

  5. Radar systems for a polar mission, volume 1

    NASA Technical Reports Server (NTRS)

    Moore, R. K.; Claassen, J. P.; Erickson, R. L.; Fong, R. K. T.; Komen, M. J.; Mccauley, J.; Mcmillan, S. B.; Parashar, S. K.

    1977-01-01

    The application of synthetic aperture radar (SAR) in monitoring and managing earth resources is examined. Synthetic aperture radars form a class of side-looking airborne radar, often referred to as coherent SLAR, which permits fine-resolution radar imagery to be generated at long operating ranges by the use of signal processing techniques. By orienting the antenna beam orthogonal to the motion of the spacecraft carrying the radar, a one-dimensional imagery ray system is converted into a two-dimensional or terrain imaging system. The radar's ability to distinguish - or resolve - closely spaced transverse objects is determined by the length of the pulse. The transmitter components receivers, and the mixer are described in details.

  6. Integrated laser/radar satellite ranging and tracking system

    NASA Technical Reports Server (NTRS)

    Hoge, F. E.

    1974-01-01

    A laser satellite ranging system that is mounted upon and integrated with a microwave tracking radar is reported. The 1-pulse/sec ruby laser transmitter is attached directly to the radar's elevation axis and radiates through a new opening in the radar's parabolic dish. The laser photomultiplier tube receiver utilizes the radar's existing 20-cm diam f/11 boresight telescope and observes through a similar symmetrically located opening in the dish. The laser system possesses separate ranging system electronics but shares the radar's timing, computer, and data handling/recording systems. The basic concept of the laser/radar is outlined together with a listing of the numerous advantages over present singular laser range-finding systems. The developmental laser hardware is described along with preliminary range-finding results and expectations.

  7. The proposed flatland radar

    NASA Technical Reports Server (NTRS)

    Green, J. L.; Gage, K. S.; Vanzandt, T. E.; Nastrom, G. D.

    1986-01-01

    A flexible very high frequency (VHF) stratosphere-troposphere (ST) radar configured for meteorological research is to be constructed near Urbana, Illinois. Measurement of small vertical velocities associated with synoptic-scale meteorology can be performed. A large Doppler microwave radar (CHILL) is located a few km from the site of the proposed ST radar. Since the microwave radar can measure the location and velocity of hydrometeors and the VHF ST radar can measure clear (or cloudy) air velocities, simultaneous observations by these two radars of stratiform or convective weather systems would provide valuable meteorological information.

  8. Generating nonlinear FM chirp radar signals by multiple integrations

    DOEpatents

    Doerry, Armin W [Albuquerque, NM

    2011-02-01

    A phase component of a nonlinear frequency modulated (NLFM) chirp radar pulse can be produced by performing digital integration operations over a time interval defined by the pulse width. Each digital integration operation includes applying to a respectively corresponding input parameter value a respectively corresponding number of instances of digital integration.

  9. On-field distributed first-order PMD measurement based on pOTDR and optical pulse width sweep.

    PubMed

    Franciscangelis, Carolina; Floridia, Claudio; Simões, Glauco C C P; Schmmidt, Fernando; Fruett, Fabiano

    2015-05-18

    A method for PMD distributed localization and estimation based on polarization optical time domain reflectometer technique, pOTDR and pulse width sweep is used on-field for the first time. The method consists in launching light pulses with variable widths in an optical fiber under test and then analyzes the Rayleigh backscattered signal spatial power distribution after passing through a polarizer. Both localization and PMD magnitude are function of OTDR pulse width and can be obtained from the ripple analysis, enabling the characterization of the fiber links.

  10. Reflectometer end station for synchrotron calibrations of Advanced X-ray Astrophysics Facility flight optics and for spectrometric research applications

    SciTech Connect

    Graessle, D.E.; Fitch, J.J.; Ingram, R.; Zhang Juda, J. ); Blake, R.L. )

    1995-02-01

    Preparations have been underway to construct and test a facility for grazing incidence reflectance calibrations of flat mirrors at the National Synchrotron Light Source. The purpose is to conduct calibrations on witness flats to the coating process of the flight mirrors for NASA's Advanced X-ray Astrophysics Facility (AXAF). The x-ray energy range required is 50 eV--12 keV. Three monochromatic beamlines (X8C, X8A, U3A) will provide energy tunability over this entire range. The goal is to calibrate the AXAF flight mirrors with uncertainties approaching 1%. A portable end station with a precision-positioning reflectometer has been developed for this work. We have resolved the vacuum cleanliness requirements to preserve the coating integrity of the flats with the strict grazing-angle certainty requirements placed on the rotational control system of the reflectometer. A precision positioning table permits alignment of the system to the synchrotron beam to within 10 arcsec; the reflectometer's rotational control system can then produce grazing angle accuracy to within less than 2 arcsec, provided that the electron orbit is stable. At 10--12 keV, this degree of angular accuracy is necessary to achieve the calibration accuracy required for AXAF. However the most important energy regions for the synchrotron calibration are in the 2000--3200 eV range, where the [ital M]-edge absorption features of the coating element, iridium, appear, and the 300--700 eV range of the Ir [ital N] edges. The detail versus energy exhibited in these features cannot be traced adequately without a tunable energy source, which necessitates a synchrotron for this work. We present the mechanical designs, motion control systems, detection and measurement capabilities, and selected procedures for our measurements, as well as reflectance data.

  11. Radar sensors for automotive collision warning and avoidance

    NASA Astrophysics Data System (ADS)

    Grosch, Theodore O.

    1995-06-01

    Many different sensors and systems, from sonar to machine vision, have been installed on ground vehicles and automobiles. This paper describes the use of radar to improve driving safety and convenience. Radars are valuable sensors for all weather operation and experiments with automotive radar sensors have been conducted for over 40 years. This paper shows the advantages and disadvantages of applying microwave and millimeter wave radar to obstacle detection and collision avoidance in a roadway environment. The performance differences between avoidance and warning sensors are discussed and a problem set is devised for a typical forward-looking collision warning application. Various radar systems have been applied to this problem that include pulse and continuous wave transceivers. These system types are evaluated as to their suitability as a collision warning sensor. The various possible solutions are reduced to a small number of candidate radar types, and one such radar was chosen for full scale development. A low cost frequency modulated/continuous wave radar system was developed for automotive collision warning. The radar is attached to the sun visor inside the vehicle, and has been in operation for over four years. The radar monitors the range and range-rate of other vehicles and obstacles, and warns the driver when it perceives that a dangerous situation is developing. A system description and measured data is presented that shows how the 24.075 to 24.175 GHz band can be used for an adequate early warning system.

  12. Ultra-short pulse generator

    DOEpatents

    McEwan, Thomas E.

    1993-01-01

    An inexpensive pulse generating circuit is disclosed that generates ultra-short, 200 picosecond, and high voltage 100 kW, pulses suitable for wideband radar and other wideband applications. The circuit implements a nonlinear transmission line with series inductors and variable capacitors coupled to ground made from reverse biased diodes to sharpen and increase the amplitude of a high-voltage power MOSFET driver input pulse until it causes non-destructive transit time breakdown in a final avalanche shockwave diode, which increases and sharpens the pulse even more.

  13. Ultra-short pulse generator

    DOEpatents

    McEwan, T.E.

    1993-12-28

    An inexpensive pulse generating circuit is disclosed that generates ultra-short, 200 picosecond, and high voltage 100 kW, pulses suitable for wideband radar and other wideband applications. The circuit implements a nonlinear transmission line with series inductors and variable capacitors coupled to ground made from reverse biased diodes to sharpen and increase the amplitude of a high-voltage power MOSFET driver input pulse until it causes non-destructive transit time breakdown in a final avalanche shock wave diode, which increases and sharpens the pulse even more. 5 figures.

  14. Measuring Mars' Atmospheric Neutral Density from 160 to 220km with the MGS Electron Reflectometer

    NASA Astrophysics Data System (ADS)

    Lillis, R.; Engel, J.; Mitchell, D.; Brain, D.; Lin, R.; Bougher, S.; Acuna, M.

    2005-08-01

    The Magnetometer/Electron Reflectometer (MAG/ER) experiment aboard Mars Global Surveyor (MGS) samples the local electron population's distribution in energy and pitch angle (angle between electron velocity and local magnetic field direction) at the mapping orbit altitude of ˜400km. We develop a single-particle model of the electrons' interaction with the neutral atmosphere and motion along open field-lines connecting the solar wind to remnant crustal magnetization. Electron reflection from magnetic gradients and absorption due to inelastic collisons with atmospheric neutrals results in characteristic pitch angle (PA) distributions for open field lines. By assuming the validity of spherical harmonic expansions (Cain et al, 2003) in the strongest field regions of Mars (such as Terra Sirenum), we trace the electron paths and fit these PA distributions to our model to constrain the scale height and density of the neutral atmosphere in the region of greatest absorption, 160-220km. We analyse almost 3 martian years of MGS mapping Orbit Data and present the first measurements of Mars' neutral density above 180km. Although the uncertainties in single measurements are quite large, averaging over many measurements over a period of weeks allows us to see long-term trends. Major results are: 1) a mean density of 0.03 kg/km3 at 160km with a month-averaged variation of ˜40%, 2) a very strong annual seasonal variation, confirmed by periodogram and least-squares fit and 3) increasing seasonal density variability with distance from the equator. We see broad general agreement with predictions from Mars Thermosphere Global Circulation Model (MTGCM) simulations [Bougher et al, 2004] and with inferred densities from MGS Doppler tracking data [Tracadas et al, 2001]. Our results will help to constrain the upper boundaries of GCMs and assist orbital decay calculations for low-orbiting spacecraft, such as the 2005 Mars Reconnaissance Orbiter. We thank the NASA Jet Propulsion Laboratory

  15. Bubble velocity, diameter, and void fraction measurements in a multiphase flow using fiber optic reflectometer

    NASA Astrophysics Data System (ADS)

    Lim, Ho-Joon; Chang, Kuang-An; Su, Chin B.; Chen, Chi-Yueh

    2008-12-01

    A fiber optic reflectometer (FOR) technique featuring a single fiber probe is investigated for its feasibility of measuring the bubble velocity, diameter, and void fraction in a multiphase flow. The method is based on the interference of the scattered signal from the bubble surface with the Fresnel reflection signal from the tip of the optical fiber. Void fraction is obtained with a high accuracy if an appropriate correction is applied to compensate the underestimated measurement value. Velocity information is accurately obtained from the reflected signals before the fiber tip touches the bubble surface so that several factors affecting the traditional dual-tip probes such as blinding, crawling, and drifting effects due to the interaction between the probe and bubbles can be prevented. The coherent signals reflected from both the front and rear ends of a bubble can provide velocity information. Deceleration of rising bubbles and particles due to the presence of the fiber probe is observed when they are very close to the fiber tip. With the residence time obtained, the bubble chord length can be determined by analyzing the coherent signal for velocity determination before the deceleration starts. The bubble diameters are directly obtained from analyzing the signals of the bubbles that contain velocity information. The chord lengths of these bubbles measured by FOR represent the bubble diameters when the bubble shape is spherical or represent the minor axes when the bubble shape is ellipsoidal. The velocity and size of bubbles obtained from the FOR measurements are compared with those obtained simultaneously using a high speed camera.

  16. Radar cross calibration investigation TAMU radar polarimeter calibration measurements

    NASA Technical Reports Server (NTRS)

    Blanchard, A. J.; Newton, R. W.; Bong, S.; Kronke, C.; Warren, G. L.; Carey, D.

    1982-01-01

    A short pulse, 20 MHz bandwidth, three frequency radar polarimeter system (RPS) operates at center frequencies of 10.003 GHz, 4.75 GHz, and 1.6 GHz and utilizes dual polarized transmit and receive antennas for each frequency. The basic lay-out of the RPS is different from other truck mounted systems in that it uses a pulse compression IF section common to all three RF heads. Separate transmit and receive antennas are used to improve the cross-polarization isolation at each particular frequency. The receive is a digitally controlled gain modulated subsystem and is interfaced directly with a microprocesser computer for control and data manipulation. Antenna focusing distance, focusing each antenna pair, rf head stability, and polarization characteristics of RPS antennas are discussed. Platform and data acquisition procedures are described.

  17. New versions of instrument tuning program and visualization of spectra for reflectometers at the IBR-2 reactor

    NASA Astrophysics Data System (ADS)

    Kirilov, A. S.

    2016-01-01

    This article is devoted to the main features of the tuning program (ICE) and the spectra visualization program (SpectraViewer) used at reflectometers of the IBR-2, Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, (FLNP JINR). The ICE program is implemented as an add-on for the control of Sonix+ software and is designed to adjust the instrument before the main measurement. The SpectraViewer program is also used on other instruments. Programs have been written using the PyQt and the graphics library matplotlib. The work has been carried out at the FLNP JINR.

  18. AND/R: Advanced neutron diffractometer/reflectometer for investigation of thin films and multilayers for the life sciences

    SciTech Connect

    Dura, Joseph A.; Pierce, Donald J.; Majkrzak, Charles F.; Maliszewskyj, Nicholas C.; McGillivray, Duncan J.; Loesche, Mathias; O'Donovan, Kevin V.; Mihailescu, Mihaela; Perez-Salas, Ursula; Worcester, David L.; White, Stephen H.

    2006-07-15

    An elastic neutron scattering instrument, the advanced neutron diffractometer/reflectometer (AND/R), has recently been commissioned at the National Institute of Standards and Technology Center for Neutron Research. The AND/R is the centerpiece of the Cold Neutrons for Biology and Technology partnership, which is dedicated to the structural characterization of thin films and multilayers of biological interest. The instrument is capable of measuring both specular and nonspecular reflectivity, as well as crystalline or semicrystalline diffraction at wave-vector transfers up to approximately 2.20 A{sup -1}. A detailed description of this flexible instrument and its performance characteristics in various operating modes are given.

  19. Electro-optic modulator feedback control in phase-sensitive optical time-domain reflectometer distributed sensor.

    PubMed

    Hui, Xiaonan; Zheng, Shilie; Zhou, Jinhai; Xu, Chen; Chi, Hao; Jin, Xiaofeng; Zhang, Xianmin

    2013-12-10

    We propose a novel method to control the electro-optic modulator (EOM) applied in the phase-sensitive optical time-domain reflectometer (ϕ-OTDR) distributed sensor system, which uses the data of the OTDR curves rather than applying an independent control module. We explain the relationship between the accumulation value of the OTDR curve and the EOM's extinction ratio, and utilize this relationship to feedback control the EOM. The experimental results show that it can compensate the drift of the EOM, and make the modulator run with a high extinction ratio for a long time. And this method can also ratify a small jump of the EOM's bias point.

  20. Current and future capabilities of the neutron reflectometer MIRROR at Oak Ridge National Laboratory's High Flux Isotope Reactor

    NASA Astrophysics Data System (ADS)

    Hamilton, W. A.; Smith, G. S.; Taylor, G. B.; Larkins, B. M.; Porcar, L.

    2006-11-01

    The peripatetic ORNL HFIR Center for Neutron Scattering reflectometer instrument MIRROR has recently been re-installed in an interim beam line position in the reactor beam room. In 2006 an upgraded version of the instrument will move to a high intensity guide hall position fed by the new HFIR cold source. In this short note, we present some aspects of current instrument operation-particularly with respect to data reduction from the instrument's linear reflection plane detector-with examples of ongoing research and analysis, and a brief outline of the expected capabilities of the fully upgraded guide hall instrument.

  1. Development of Surfaces Optically Suitable for Flat Solar Panels. [using a reflectometer which separately evaluates spectral and diffuse reflectivities of surfaces

    NASA Technical Reports Server (NTRS)

    1979-01-01

    A reflectometer which can separately evaluate the spectral and diffuse reflectivities of surfaces is described. A phase locked detection system for the reflectometer is also described. A selective coating on aluminum potentially useful for flat plate solar collector applications is presented. The coating is composed of strongly bound copper oxide (divalent) and is formed by an etching process performed on an aluminum alloy with high copper content. Fabrication costs are expected to be small due to the one stop fabrication process. A number of conclusions gathered from the literature as to the required optical properties of flat plate solar collectors are discussed.

  2. Magnetism reflectometer study shows LiF layers improve efficiency in spin valve devices

    SciTech Connect

    Bardoel, Agatha A; Lauter, Valeria; Szulczewski, Greg J

    2012-01-01

    New, more efficient materials for spin valves - a device used in magnetic sensors, random access memories, and hard disk drives - may be on the way based on research using the magnetism reflectometer at Oak Ridge National Laboratory (ORNL). Spin valve devices work by means of two or more conducting magnetic material layers that alternate their electrical resistance depending on the layers alignment. Giant magnetoresistance is a quantum mechanical effect first observed in thin film structures about 20 years ago. The effect is observed as a significant change in electrical resistance, depending on whether the magnetization of adjacent ferromagnetic layers is in a parallel or an antiparallel magnetic alignment. 'What we are doing here is developing new materials. The search for new materials suitable for injecting and transferring carriers with a preferential spin orientation is most important for the development of spintronics,' said Valeria Lauter, lead instrument scientist on the magnetism reflectometer at the Spallation Neutron Source (SNS), who collaborated on the experiment. The researchers discovered that the conductivity of such materials is improved when an organic polymer semiconductor layer is placed between the magnetic materials. Organic semiconductors are now the material of choice for future spin valve devices because they preserve spin coherence over longer times and distances than conventional semiconductors. While research into spin valves has been ongoing, research into organic semiconductors is recent. Previous research has shown that a 'conductivity mismatch' exists in spin valve systems in which ferromagnetic metal electrodes interface with such organic semiconductors as Alq3 ({pi}-conjugated molecule tris(8-hydroxy-quinoline) aluminium). This mismatch limits the efficient injection of the electrons from the electrodes at the interface with the semiconductor material. However, lithium fluoride (LiF), commonly used in light-emitting diodes, has

  3. Attenuation of front-end reflections in an impulse radar using high-speed switching

    NASA Astrophysics Data System (ADS)

    Mazzaro, Gregory J.; Ressler, Marc A.; Smith, Gregory D.

    2011-06-01

    Pulse reflection between front-end components is a common problem for impulse radar systems. Such reflections arise because radio frequency components are rarely impedance-matched over an ultra-wide bandwidth. Any mismatch between components causes a portion of the impulse to reflect within the radar front-end. If the reflection couples into the transmit antenna, the radar emits an unintended, delayed and distorted replica of the intended radar transmission. These undesired transmissions reflect from the radar environment, produce echoes in the radar image, and generate false alarms in the vicinity of actual targets. The proposed solution for eliminating these echoes, without redesigning the transmit antenna, is to dissipate pulse reflections in a matched load before they are emitted. A high-speed switch directs the desired pulse to the antenna and redirects the undesired reflection from the antenna to a matched load. The Synchronous Impulse Reconstruction (SIRE) radar developed by the Army Research Laboratory (ARL) is the case-study. This paper reviews the current front-end design, provides a recent radar image which displays the aforementioned echoes, and describes the switch-cable-load circuit solution for eliminating the echoes. The consequences of inserting each portion of the new hardware into the radar front-end are explained. Measurements on the front-end with the high-speed switch show an attenuation of the undesired pulse transmissions of more than 18 dB and an attenuation in the desired pulse transmission of less than 3 dB.

  4. Method and Apparatus for Reading Two Dimensional Identification Symbols Using Radar Techniques

    NASA Technical Reports Server (NTRS)

    Schramm, Harry F., Jr. (Inventor); Roxby, Donald L. (Inventor)

    2003-01-01

    A method and apparatus are provided for sensing two-dimensional identification marks provided on a substrate or embedded within a substrate below a surface of the substrate. Micropower impulse radar is used to transmit a high risetime, short duration pulse to a focussed radar target area of the substrate having the two dimensional identification marks. The method further includes the steps of listening for radar echoes returned from the identification marks during a short listening period window occurring a predetermined time after transmission of the radar pulse. If radar echoes are detected, an image processing step is carried out. If no radar echoes are detected, the method further includes sequentially transmitting further high risetime, short duration pulses, and listening for radar echoes from each of said further pulses after different elapsed times for each of the further pulses until radar echoes are detected. When radar echoes are detected, data based on the detected echoes is processed to produce an image of the identification marks.

  5. Saturated semiconductor optical amplifier phase modulation for long range laser radar applications.

    PubMed

    Carns, Jennifer L; Duncan, Bradley D; Dierking, Matthew P

    2012-08-20

    We investigate the use of a semiconductor optical amplifier operated in the saturation regime as a phase modulator for long range laser radar applications. The nature of the phase and amplitude modulation resulting from a high peak power Gaussian pulse, and the impact this has on the ideal pulse response of a laser radar system, is explored. We also present results of a proof-of-concept laboratory demonstration using phase-modulated pulses to interrogate a stationary target.

  6. Rendezvous radar for the orbital maneuvering vehicle

    NASA Astrophysics Data System (ADS)

    Locke, John W.; Olds, Keith A.; Ohe, Thomas D.

    The rendezvous radar set (RRS) under development will be a key subsystem aboard NASA's new orbital maneuvering vehicle (OMV). The RRS is an X-band all solid-state, monopulse tracking, frequency-hopping, pulse-Doppler radar system. Targets of 1m2 are detected at ranges greater than 4.5 nautical miles, and larger targets are detected at up to 10 nautical miles. The target is then tracked in angle, range, and range rate to a distance of 35 feet from the OMV. In addition to performance and cost, the design drivers for the RRS development have included the minimization of power consumption, size, and weight.

  7. Phase and amplitude errors in FM radars

    NASA Astrophysics Data System (ADS)

    Griffiths, Hugh D.

    The constraints on phase and amplitude errors are determined for various types of FM radar by calculating the range sidelobe levels on the point target response due to the phase and amplitude modulation of the target echo. It is shown that under certain circumstances the constraints on phase linearity appropriate for conventional pulse compression radars are unnecessarily stringent, and quite large phase errors can be tolerated provided the relative delay of the local oscillator with respect to the target echo is small compared with the periodicity of the phase error characteristic. The constraints on amplitude flatness, however, are severe under almost all circumstances.

  8. Weather Radar Technology Development

    DTIC Science & Technology

    1990-08-15

    uelocitV WMs ) data processing systems such as NEXRAD to have a reliable technique for removing ambiguities due to velocity aliasing. Performance of many...intended for automated implementation on radar systems such as the NEXt generation weather RADar ( NEXRAD ) system. Several research areas were addressed...with Doppler radar will soon be realized with the deployment of the NEXRAD radar systems. Some of these large scale storms can have devastating wind

  9. Lunar radar backscatter studies

    NASA Technical Reports Server (NTRS)

    Thompson, T. W.

    1979-01-01

    The lunar surface material in the Plato area is characterized using Earth based visual, infrared, and radar signatures. Radar scattering in the lunar regolith with an existing optical scattering computer program is modeled. Mapping with 1 to 2 km resolution of the Moon using a 70 cm Arecibo radar is presented.

  10. Radar: Human Safety Net

    ERIC Educational Resources Information Center

    Ritz, John M.

    2016-01-01

    Radar is a technology that can be used to detect distant objects not visible to the human eye. A predecessor of radar, called the telemobiloscope, was first used to detect ships in the fog in 1904 off the German coast. Many scientists have worked on the development and refinement of radar (Hertz with electromagnetic waves; Popov with determining…

  11. Radar: Human Safety Net

    ERIC Educational Resources Information Center

    Ritz, John M.

    2016-01-01

    Radar is a technology that can be used to detect distant objects not visible to the human eye. A predecessor of radar, called the telemobiloscope, was first used to detect ships in the fog in 1904 off the German coast. Many scientists have worked on the development and refinement of radar (Hertz with electromagnetic waves; Popov with determining…

  12. Solar Radar Experiments

    DTIC Science & Technology

    1998-01-01

    communications satellites and electric power grids. RELATED PROJECTS Studies with the HAARP radar facility being constructed in Alaska are conducted with...on wave-plasma interactions and also are assessing the possible use of HAARP as a solar radar. REFERENCES James, J. C., Radar studies of the sun, in

  13. Underwater probing with laser radar

    NASA Technical Reports Server (NTRS)

    Carswell, A. I.; Sizgoric, S.

    1975-01-01

    Recent advances in laser and electro optics technology have greatly enhanced the feasibility of active optical probing techniques aimed at the remote sensing of water parameters. This paper describes a LIDAR (laser radar) that has been designed and constructed for underwater probing. The influence of the optical properties of water on the general design parameters of a LIDAR system is considered. Discussion of the specific details in the choice of the constructed LIDAR is given. This system utilizes a cavity dumped argon ion laser transmitter capable of 50 watt peak powers, 10 nanosecond pulses and megahertz pulse repetition rates at 10 different wavelengths in the blue green region of the spectrum. The performance of the system, in proving various types of water, is demonstrated by summarizing the results of initial laboratory and field experiments.

  14. A radar tour of Venus

    NASA Astrophysics Data System (ADS)

    Beatty, J. K.

    1985-06-01

    The surface of Venus is briefly characterized in a summary of results obtained by the Soviet Venera 15 and 16 8-cm synthetic-aperture radars, IR radiometers, and radar altimeters. A series of radar images, mainly from Kotelnikov et al. (1984), are presented and discussed, and the descent vehicles to be released by the two Vega spacecraft as they pass Venus in June 1985 on their way to an encounter with Halley's comet are described. Plans for the missions Phobos (two spacecraft to orbit Mars, rendezvous with Phobos and Deimos, release small instrumented landers, and perform mass spectrometry of vapors released by laser pulses directed at the satellite surfaces, beginning in 1988), a lunar-orbiter mission for 1989-1990, and Vesta (a not-yet-approved 1991 mission comprising a French probe to the asteroid 4 Vesta and perhaps 53 Kalypso and 453 Tea and a Soviet spacecraft to release a kite-supported Venus-atmosphere probe before flying on to an unknown destination) are considered.

  15. Signal Processing Techniques for a Planetary Subsurface Radar Onboard Satellite

    NASA Astrophysics Data System (ADS)

    Yagitani, S.; Ishikawa, T.; Nagano, I.; Kojima, H.; Matsumoto, H.

    2001-12-01

    We are developing a satellite-borne HF ( ~ 10 MHz) radar system to be used to investigate planetary subsurface layered structures. Before deciding the design of a high-performance subsurface radar system, in this study we calculate the propagation and reflection characteristics of various HF radar pulses through subsurface layer models, in order to examine the wave forms and frequencies of the radar pulses suitable to discriminate and pick up weak subsurface echoes buried in stronger surface reflection and scattering echoes. In the numerical calculations the wave form of a transmitted radar pulse is first Fourier-transformed into a number of elementary plane waves having different frequencies, for each of which the propagation and reflection characteristics through subsurface layer models are calculated by a full wave analysis. Then the wave form of the reflected radar echo is constructed by synthesizing all of the elementary plane waves. As the transmitted pulses, we use several different types of wave form modulation to realize the radar pulse compression to improve the signal-to-noise (S/N) ratio and time resolution of the subsurface echoes: the linear FM chirp (conventional), the M (maximal-length) sequence and the complementary sequences. We will discuss the characteristics of these pulse compression techniques, such as the improvement in the S/N ratio and the time resolution to identify the subsurface echoes. We will also present the possibility of applying the Multiple Signal Classification (MUSIC) method to further improve both the S/N ratio and time resolution to extract the weaker subsurface echoes.

  16. MIMO-OFDM signal optimization for SAR imaging radar

    NASA Astrophysics Data System (ADS)

    Baudais, J.-Y.; Méric, S.; Riché, V.; Pottier, É.

    2016-12-01

    This paper investigates the optimization of the coded orthogonal frequency division multiplexing (OFDM) transmitted signal in a synthetic aperture radar (SAR) context. We propose to design OFDM signals to achieve range ambiguity mitigation. Indeed, range ambiguities are well known to be a limitation for SAR systems which operates with pulsed transmitted signal. The ambiguous reflected signal corresponding to one pulse is then detected when the radar has already transmitted the next pulse. In this paper, we demonstrate that the range ambiguity mitigation is possible by using orthogonal transmitted wave as OFDM pulses. The coded OFDM signal is optimized through genetic optimization procedures based on radar image quality parameters. Moreover, we propose to design a multiple-input multiple-output (MIMO) configuration to enhance the noise robustness of a radar system and this configuration is mainly efficient in the case of using orthogonal waves as OFDM pulses. The results we obtain show that OFDM signals outperform conventional radar chirps for range ambiguity suppression and for robustness enhancement in 2 ×2 MIMO configuration.

  17. Probing of high-frequency coherent fluctuations by using a two-channel microwave reflectometer with antenna switching

    NASA Astrophysics Data System (ADS)

    Ikezoe, R.; Ichimura, M.; Itagaki, J.; Hirata, M.; Sumida, S.; Jang, S.; Izumi, K.; Tanaka, A.; Yoshikawa, M.; Kohagura, J.; Sakamoto, M.; Nakashima, Y.

    2016-10-01

    A two-channel microwave reflectometer with capability of fast switching of microwave antennas in array was developed and applied to a hot linear plasma produced in GAMMA 10 to study the behavior of Alfvén waves in a collisionless bounded plasma. High-frequency fluctuations associated with Alfvén-ion-cyclotron (AIC) waves were successfully measured at multi points using this system. It is found that coherent phase fluctuations are obtainable at wide radial and axial region for the AIC waves. In addition, measured phase-difference profile clearly shows standing wave structures. Signature of movement of these nodes is also obtained. These results demonstrate applicability of the developed two-channel reflectometer for assessment of spatial structure of high-frequency waves and also verifies globally expanded coherent structure of the AIC waves in GAMMA 10. Two-point correlation analysis in conjunction with multi-point measurements using antenna switching turns out to be a powerful tool for investigating spatial structure of waves in a hot plasma where traditional solid probes are inadequate. This work was in part supported by Grant-in-Aid for Young Scientists (B) (15K17797) and Scientific Research (C) (25400531), and by Bidirectional Collaborative Research Program of NIFS (NIFS15KUGM101).

  18. X-ray reflectometer for single layer and multilayer coating characterization at 8 keV: An interlaboratory study

    NASA Astrophysics Data System (ADS)

    Gurgew, Danielle N.; Broadway, David M.; Gubarev, Mikhail; Ramsey, Brian D.; Gregory, Don A.

    2016-10-01

    An X-ray reflectometer (XRR) system has been developed at the Marshall Space Flight Center (MSFC) for characterizing various soft and hard X-ray optic coatings. The XRR instrument generates X-ray radiation using a high-output rotating anode source (RAS), operational over a voltage range of 5-35 kV and a current range of 10-150 mA. Copper is used as the target material to produce an X-ray spectrum from which the Kα line at 8.048 keV is isolated for the reflectivity measurements. Five precision slits are mounted along the X-ray beam path to limit the extent of the beam at the sample and to adjust the resolution in the measurements. A goniometer consisting of two precision rotary stages controls the positions of the coating sample and the X-ray detector with respect to the beam. The detector itself is a high performance silicon drift detector used to achieve high count rate efficiency to attain good statistics in the reflectivity measurement at larger grazing angles. The X-ray reflectometer system design and capabilities are described in detail. Verification of the system is obtained through an interlaboratory study in which reflectivity measurements of a multilayer coating made at MSFC are compared with those made at two external laboratories.

  19. A simultaneous multiple angle-wavelength dispersive X-ray reflectometer using a bent-twisted polychromator crystal.

    PubMed

    Matsushita, Tadashi; Arakawa, Etsuo; Voegeli, Wolfgang; Yano, Yohko F

    2013-01-01

    An X-ray reflectometer has been developed, which can simultaneously measure the whole specular X-ray reflectivity curve with no need for rotation of the sample, detector or monochromator crystal during the measurement. A bent-twisted crystal polychromator is used to realise a convergent X-ray beam which has continuously varying energy E (wavelength λ) and glancing angle α to the sample surface as a function of horizontal direction. This convergent beam is reflected in the vertical direction by the sample placed horizontally at the focus and then diverges horizontally and vertically. The normalized intensity distribution of the reflected beam measured downstream of the specimen with a two-dimensional pixel array detector (PILATUS 100K) represents the reflectivity curve. Specular X-ray reflectivity curves were measured from a commercially available silicon (100) wafer, a thin gold film coated on a silicon single-crystal substrate and the surface of liquid ethylene glycol with data collection times of 0.01 to 1000 s using synchrotron radiation from a bending-magnet source of a 6.5 GeV electron storage ring. A typical value of the simultaneously covered range of the momentum transfer was 0.01-0.45 Å(-1) for the silicon wafer sample. The potential of this reflectometer for time-resolved X-ray studies of irreversible structural changes is discussed.

  20. X-ray reflectometer for single layer and multilayer coating characterization at 8 keV: An interlaboratory study.

    PubMed

    Gurgew, Danielle N; Broadway, David M; Gubarev, Mikhail; Ramsey, Brian D; Gregory, Don A

    2016-10-01

    An X-ray reflectometer (XRR) system has been developed at the Marshall Space Flight Center (MSFC) for characterizing various soft and hard X-ray optic coatings. The XRR instrument generates X-ray radiation using a high-output rotating anode source (RAS), operational over a voltage range of 5-35 kV and a current range of 10-150 mA. Copper is used as the target material to produce an X-ray spectrum from which the Kα line at 8.048 keV is isolated for the reflectivity measurements. Five precision slits are mounted along the X-ray beam path to limit the extent of the beam at the sample and to adjust the resolution in the measurements. A goniometer consisting of two precision rotary stages controls the positions of the coating sample and the X-ray detector with respect to the beam. The detector itself is a high performance silicon drift detector used to achieve high count rate efficiency to attain good statistics in the reflectivity measurement at larger grazing angles. The X-ray reflectometer system design and capabilities are described in detail. Verification of the system is obtained through an interlaboratory study in which reflectivity measurements of a multilayer coating made at MSFC are compared with those made at two external laboratories.

  1. A simultaneous multiple angle-wavelength dispersive X-ray reflectometer using a bent-twisted polychromator crystal

    PubMed Central

    Matsushita, Tadashi; Arakawa, Etsuo; Voegeli, Wolfgang; Yano, Yohko F.

    2013-01-01

    An X-ray reflectometer has been developed, which can simultaneously measure the whole specular X-ray reflectivity curve with no need for rotation of the sample, detector or monochromator crystal during the measurement. A bent-twisted crystal polychromator is used to realise a convergent X-ray beam which has continuously varying energy E (wavelength λ) and glancing angle α to the sample surface as a function of horizontal direction. This convergent beam is reflected in the vertical direction by the sample placed horizontally at the focus and then diverges horizontally and vertically. The normalized intensity distribution of the reflected beam measured downstream of the specimen with a two-dimensional pixel array detector (PILATUS 100K) represents the reflectivity curve. Specular X-ray reflectivity curves were measured from a commercially available silicon (100) wafer, a thin gold film coated on a silicon single-crystal substrate and the surface of liquid ethylene glycol with data collection times of 0.01 to 1000 s using synchrotron radiation from a bending-magnet source of a 6.5 GeV electron storage ring. A typical value of the simultaneously covered range of the momentum transfer was 0.01–0.45 Å−1 for the silicon wafer sample. The potential of this reflectometer for time-resolved X-ray studies of irreversible structural changes is discussed. PMID:23254659

  2. Transponder-Aided Joint Calibration and Synchronization Compensation for Distributed Radar Systems

    PubMed Central

    Wang, Wen-Qin

    2015-01-01

    High-precision radiometric calibration and synchronization compensation must be provided for distributed radar system due to separate transmitters and receivers. This paper proposes a transponder-aided joint radiometric calibration, motion compensation and synchronization for distributed radar remote sensing. As the transponder signal can be separated from the normal radar returns, it is used to calibrate the distributed radar for radiometry. Meanwhile, the distributed radar motion compensation and synchronization compensation algorithms are presented by utilizing the transponder signals. This method requires no hardware modifications to both the normal radar transmitter and receiver and no change to the operating pulse repetition frequency (PRF). The distributed radar radiometric calibration and synchronization compensation require only one transponder, but the motion compensation requires six transponders because there are six independent variables in the distributed radar geometry. Furthermore, a maximum likelihood method is used to estimate the transponder signal parameters. The proposed methods are verified by simulation results. PMID:25794158

  3. Transponder-aided joint calibration and synchronization compensation for distributed radar systems.

    PubMed

    Wang, Wen-Qin

    2015-01-01

    High-precision radiometric calibration and synchronization compensation must be provided for distributed radar system due to separate transmitters and receivers. This paper proposes a transponder-aided joint radiometric calibration, motion compensation and synchronization for distributed radar remote sensing. As the transponder signal can be separated from the normal radar returns, it is used to calibrate the distributed radar for radiometry. Meanwhile, the distributed radar motion compensation and synchronization compensation algorithms are presented by utilizing the transponder signals. This method requires no hardware modifications to both the normal radar transmitter and receiver and no change to the operating pulse repetition frequency (PRF). The distributed radar radiometric calibration and synchronization compensation require only one transponder, but the motion compensation requires six transponders because there are six independent variables in the distributed radar geometry. Furthermore, a maximum likelihood method is used to estimate the transponder signal parameters. The proposed methods are verified by simulation results.

  4. Radar stage uncertainty

    USGS Publications Warehouse

    Fulford, J.M.; Davies, W.J.

    2005-01-01

    The U.S. Geological Survey is investigating the performance of radars used for stage (or water-level) measurement. This paper presents a comparison of estimated uncertainties and data for radar water-level measurements with float, bubbler, and wire weight water-level measurements. The radar sensor was also temperature-tested in a laboratory. The uncertainty estimates indicate that radar measurements are more accurate than uncorrected pressure sensors at higher water stages, but are less accurate than pressure sensors at low stages. Field data at two sites indicate that radar sensors may have a small negative bias. Comparison of field radar measurements with wire weight measurements found that the radar tends to measure slightly lower values as stage increases. Copyright ASCE 2005.

  5. Eye-safe coherent laser radar system at 2.1 microns using Tm,Ho:YAG lasers

    NASA Technical Reports Server (NTRS)

    Henderson, Sammy W.; Hale, Charley P.; Magee, James R.; Kavaya, Michael J.; Huffaker, A. V.

    1991-01-01

    An eye-safe pulsed coherent laser radar has been developed by using single-frequency Tm,Ho:YAG lasers and heterodyne detection. Returns from a mountainside located 145 km from the laser radar system and the measurement of wind velocity to ranges exceeding 20 km have been demonstrated with transmitted pulse energies of 22 mJ.

  6. Modern Radar Techniques for Geophysical Applications: Two Examples

    NASA Technical Reports Server (NTRS)

    Arokiasamy, B. J.; Bianchi, C.; Sciacca, U.; Tutone, G.; Zirizzotti, A.; Zuccheretti, E.

    2005-01-01

    The last decade of the evolution of radar was heavily influenced by the rapid increase in the information processing capabilities. Advances in solid state radio HF devices, digital technology, computing architectures and software offered the designers to develop very efficient radars. In designing modern radars the emphasis goes towards the simplification of the system hardware, reduction of overall power, which is compensated by coding and real time signal processing techniques. Radars are commonly employed in geophysical radio soundings like probing the ionosphere; stratosphere-mesosphere measurement, weather forecast, GPR and radio-glaciology etc. In the laboratorio di Geofisica Ambientale of the Istituto Nazionale di Geofisica e Vulcanologia (INGV), Rome, Italy, we developed two pulse compression radars. The first is a HF radar called AIS-INGV; Advanced Ionospheric Sounder designed both for the purpose of research and for routine service of the HF radio wave propagation forecast. The second is a VHF radar called GLACIORADAR, which will be substituting the high power envelope radar used by the Italian Glaciological group. This will be employed in studying the sub glacial structures of Antarctica, giving information about layering, the bed rock and sub glacial lakes if present. These are low power radars, which heavily rely on advanced hardware and powerful real time signal processing. Additional information is included in the original extended abstract.

  7. 2. VIEW SOUTHWEST, prime search radar tower, height finder radar ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. VIEW SOUTHWEST, prime search radar tower, height finder radar towards, height finder radar towers, and radar tower (unknown function) - Fort Custer Military Reservation, P-67 Radar Station, .25 mile north of Dickman Road, east of Clark Road, Battle Creek, Calhoun County, MI

  8. Description and availability of airborne Doppler radar data

    NASA Technical Reports Server (NTRS)

    Harrah, S. D.; Bracalente, E. M.; Schaffner, P. R.; Baxa, E. G.

    1993-01-01

    An airborne, forward-looking, pulse, Doppler radar has been developed in conjunction with the joint FAA/NASA Wind Shear Program. This radar represents a first in an emerging technology. The radar was developed to assess the applicability of an airborne radar to detect low altitude hazardous wind shears for civil aviation applications. Such a radar must be capable of looking down into the ground clutter environment and extracting wind estimates from relatively low reflectivity weather targets. These weather targets often have reflectivities several orders of magnitude lower than the surrounding ground clutter. The NASA radar design incorporates numerous technological and engineering achievements in order to accomplish this task. The basic R/T unit evolved from a standard Collins 708 weather radar, which supports specific pulse widths of 1-7 microns and Pulse Repetition Frequencies (PRF) of less than 1-10 kHz. It was modified to allow for the output of the first IF signal, which fed a NASA developed receiver/detector subsystem. The NASA receiver incorporated a distributed, high-speed digital attenuator, producing a range bin to range bin automatic gain control system with 65 dB of dynamic range. Using group speed information supplied by the aircraft's navigation system, the radar signal is frequency demodulated back to base band (zero Doppler relative to stationary ground). The In-phase & Quadrature-phase (I/Q) components of the measured voltage signal are then digitized by a 12-bit A-D converter (producing an additional 36 dB of dynamic range). The raw I/Q signal for each range bin is then recorded (along with the current radar & aircraft state parameters) by a high-speed Kodak tape recorder.

  9. W-band ARM Cloud Radar (WACR) Handbook

    SciTech Connect

    Widener, KB; Johnson, K

    2005-01-05

    The W-band Atmospheric Radiation Measurement (ARM) Program Cloud Radar (WACR) systems are zenith pointing Doppler radars that probe the extent and composition of clouds at 95.04 GHz. The main purpose of this radar is to determine cloud boundaries (e.g., cloud bottoms and tops). This radar reports estimates for the first three spectra moments for each range gate up to 15 km. The 0th moment is reflectivity, the 1st moment is radial velocity, and the 2nd moment is spectral width. Also available are the raw spectra files. Unlike the millimeter wavelength cloud radar (MMCR), the WACR does not use pulse coding and operates in only copolarization and cross-polarization modes.

  10. Radar signal categorization using a neural network

    NASA Technical Reports Server (NTRS)

    Anderson, James A.; Gately, Michael T.; Penz, P. Andrew; Collins, Dean R.

    1991-01-01

    Neural networks were used to analyze a complex simulated radar environment which contains noisy radar pulses generated by many different emitters. The neural network used is an energy minimizing network (the BSB model) which forms energy minima - attractors in the network dynamical system - based on learned input data. The system first determines how many emitters are present (the deinterleaving problem). Pulses from individual simulated emitters give rise to separate stable attractors in the network. Once individual emitters are characterized, it is possible to make tentative identifications of them based on their observed parameters. As a test of this idea, a neural network was used to form a small data base that potentially could make emitter identifications.

  11. Wideband Waveform Design principles for Solid-state Weather Radars

    SciTech Connect

    Bharadwaj, Nitin; Chandrasekar, V.

    2012-01-01

    The use of solid-state transmitter is becoming a key part of the strategy to realize a network of low cost electronically steered radars. However, solid-state transmitters have low peak powers and this necessitates the use of pulse compression waveforms. In this paper a frequency diversity wideband waveforms design is proposed to mitigate low sensitivity of solid-state transmitters. In addition, the waveforms mitigate the range eclipsing problem associated with long pulse compression. An analysis of the performance of pulse compression using mismatched compression filters designed to minimize side lobe levels is presented. The impact of range side lobe level on the retrieval of Doppler moments are presented. Realistic simulations are performed based on CSU-CHILL radar data and Center for Collaborative Adaptive Sensing of the Atmosphere (CASA) Integrated Project I (IP1) radar data.

  12. Suppression Of Range Sidelobes In Spaceborne Rain-Mapping Radar

    NASA Technical Reports Server (NTRS)

    Im, Eastwood; Wilson, William J.; Li, Fuk K.; Tanner, Alan B.; Durden, Stephen L.; Denning, Richard F.

    1994-01-01

    Adequate suppression of range sidelobes in chirp pulse-compression radar system for spaceborne rain-mapping application demonstrated in operation of aircraft version of system. Radar system operates at center frequency of 13.8 GHz, developed for operation aboard NASA DC-8 aircraft to measure vertical rainfall-rate profiles and rain-cell dimensions. Sidelobes suppressed by at least 55 dB. Technique applied to other frequencies, therefore, useful in other radar systems in which low sidelobes at mid to far range needed.

  13. Signal Processing System for the CASA Integrated Project I Radars

    SciTech Connect

    Bharadwaj, Nitin; Chandrasekar, V.; Junyent, Francesc

    2010-09-01

    This paper describes the waveform design space and signal processing system for dual-polarization Doppler weather radar operating at X band. The performance of the waveforms is presented with ground clutter suppression capability and mitigation of range velocity ambiguity. The operational waveform is designed based on operational requirements and system/hardware requirements. A dual Pulse Repetition Frequency (PRF) waveform was developed and implemented for the first generation X-band radars deployed by the Center for Collaborative Adaptive Sensing of the Atmosphere (CASA). This paper presents an evaluation of the performance of the waveforms based on simulations and data collected by the first-generation CASA radars during operations.

  14. CloudSat: the Cloud Profiling Radar Mission

    NASA Technical Reports Server (NTRS)

    Im, Eastwood; Durden, Stephen L.; Tanelli, Simone

    2006-01-01

    The Cloud Profiling Radar (CPR), the primary science instrument of the CloudSat Mission, is a 94-GHz nadir-looking radar that measures the power backscattered by clouds as a function of distance from the radar. This instrument will acquire a global time series of vertical cloud structure at 500-m vertical resolution and 1.4-km horizontal resolution. CPR will operate in a short-pulse mode and will yield measurements at a minimum detectable sensitivity of -28 dBZ.

  15. Operation of a Radar Altimeter over the Greenland Ice Sheet

    NASA Technical Reports Server (NTRS)

    Grund, Matthew D.

    1996-01-01

    This thesis presents documentation for the Advanced Application Flight Experiment (AAFE) pulse compression radar altimeter and its role in the NASA Multisensor Airborne Altimetry Experiment over Greenland in 1993. The AAFE Altimeter is a Ku-band microwave radar which has demonstrated 14 centimeter range precision in operation over arctic ice. Recent repairs and improvements were required to make the Greenland missions possible. Transmitter, receiver and software modifications, as well as the integration of a GPS receiver are thoroughly documented. Procedures for installation, and operation of the radar are described. Finally, suggestions are made for further system improvements.

  16. Radar Based Navigation in Unknown Terrain

    DTIC Science & Technology

    2012-12-31

    loss and reflector backscatter. . 41 8. Matched filter output of an OFDM pulse reflecting off a perfect reflector at a range of 140 meters...30]. In these studies, the presence of digital terrain elevation data (DTED) is assumed. The data collected from the radar is correlated to DTED...spectrum between the discrete points is highly correlated . Fig. 5 shows another OFDM symbol which is modulated with an example communications signal

  17. Rendezvous radar for the orbital maneuvering vehicle

    NASA Technical Reports Server (NTRS)

    Locke, John W.; Olds, Keith; Parks, Howard

    1991-01-01

    This paper describes the development of the Rendezvous Radar Set (RRS) for the Orbital Maneuvering Vehicle (OMV) for the National Aeronautics and Space Administration (NASA). The RRS was to be used to locate, and then provide vectoring information to, target satellites (or Shuttle or Space Station) to aid the OMV in making a minimum-fuel-consumption approach and rendezvous. The RRS design is that of an X-Band, all solid-state, monopulse tracking, frequency hopping, pulse-Doppler radar system. The development of the radar was terminated when the OMV prime contract to TRW was terminated by NASA. At the time of the termination, the development was in the circuit design stage. The system design was virtually completed, the PDR had been held. The RRS design was based on Motorola's experiences, both in the design and production of radar systems for the US Army and in the design and production of hi-rel communications systems for NASA space programs. Experience in these fields was combined with the latest digital signal processor and micro-processor technology to design a light-weight, low-power, spaceborne radar. The antenna and antenna positioner (gimbals) technology developed for the RRS is now being used in the satellite-to-satellite communication link design for Motorola's Iridium telecommunications system.

  18. Rendezvous radar for the orbital maneuvering vehicle

    NASA Astrophysics Data System (ADS)

    Locke, John W.; Olds, Keith; Parks, Howard

    This paper describes the development of the Rendezvous Radar Set (RRS) for the Orbital Maneuvering Vehicle (OMV) for the National Aeronautics and Space Administration (NASA). The RRS was to be used to locate, and then provide vectoring information to, target satellites (or Shuttle or Space Station) to aid the OMV in making a minimum-fuel-consumption approach and rendezvous. The RRS design is that of an X-Band, all solid-state, monopulse tracking, frequency hopping, pulse-Doppler radar system. The development of the radar was terminated when the OMV prime contract to TRW was terminated by NASA. At the time of the termination, the development was in the circuit design stage. The system design was virtually completed, the PDR had been held. The RRS design was based on Motorola's experiences, both in the design and production of radar systems for the US Army and in the design and production of hi-rel communications systems for NASA space programs. Experience in these fields was combined with the latest digital signal processor and micro-processor technology to design a light-weight, low-power, spaceborne radar. The antenna and antenna positioner (gimbals) technology developed for the RRS is now being used in the satellite-to-satellite communication link design for Motorola's Iridium telecommunications system.

  19. 3. VIEW NORTHWEST, height finder radar towers, and radar tower ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. VIEW NORTHWEST, height finder radar towers, and radar tower (unknown function) - Fort Custer Military Reservation, P-67 Radar Station, .25 mile north of Dickman Road, east of Clark Road, Battle Creek, Calhoun County, MI

  20. 30. Perimeter acquisition radar building room #318, showing radar control. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    30. Perimeter acquisition radar building room #318, showing radar control. Console and line printers - Stanley R. Mickelsen Safeguard Complex, Perimeter Acquisition Radar Building, Limited Access Area, between Limited Access Patrol Road & Service Road A, Nekoma, Cavalier County, ND

  1. Phased-array radar for airborne systems

    NASA Astrophysics Data System (ADS)

    Tahim, Raghbir S.; Foshee, James J.; Chang, Kai

    2003-09-01

    Phased array antenna systems, which support high pulse rates and high transmit power, are well suited for radar and large-scale surveillance. Sensors and communication systems can function as the eyes and ears for ballistic missile defense applications, providing early warning of attack, target detection and identification, target tracking, and countermeasure decision. In such applications, active array radar systems that contain solid-state transmitter sources and low-noise preamplifiers for transmission and reception are preferred over the conventional radar antennas, because the phased array radar offers the advantages of power management and efficiency, reliability, signal reception, beam steering target detection. The current phased array radar designs are very large, complex and expensive and less efficient because of high RF losses in the phase control circuits used for beam scan. Several thousands of phase shifters and drivers may be required for a single system thus making the system very complex and expensive. This paper describes the phased array radar system based on high power T/R modules, wide-band radiating planar antenna elements and very low loss wide-band phase control circuits (requiring reduced power levels) for beam scan. The phase shifter design is based on micro-strip feed lines perturbed by the proximity of voltage controlled piezoelectric transducer (PET). Measured results have shown an added insertion loss of less than 1 dB for a phase shift of 450 degrees from 2 to 20 GHz. The new wideband phased array radar design provides significant reduction in size cost and weight. Compared to the conventional phased array systems, the cost saving is more than 15 to 1.

  2. Echo tracker/range finder for radars and sonars

    NASA Technical Reports Server (NTRS)

    Constantinides, N. J. (Inventor)

    1982-01-01

    An echo tracker/range finder or altimeter is described. The pulse repetition frequency (PFR) of a predetermined plurality of transmitted pulses is adjusted so that echo pulses received from a reflecting object are positioned between transmitted pulses and divided their interpulse time interval into two time intervals having a predetermined ratio with respect to each other. The invention described provides a means whereby the arrival time of a plurality of echo pulses is defined as the time at which a composite echo pulse formed of a sum of the individual echo pulses has the highest amplitude. The invention is applicable to radar systems, sonar systems, or any other kind of system in which pulses are transmitted and echoes received therefrom.

  3. Planetary radar studies

    NASA Technical Reports Server (NTRS)

    Thompson, T. W.; Cutts, J. A.

    1981-01-01

    A catalog of lunar and radar anomalies was generated to provide a base for comparison with Venusian radar signatures. The relationships between lunar radar anomalies and regolith processes were investigated, and a consortium was formed to compare lunar and Venusian radar images of craters. Time was scheduled at the Arecibo Observatory to use the 430 MHz radar to obtain high resolution radar maps of six areas of the lunar suface. Data from 1978 observations of Mare Serenitas and Plato are being analyzed on a PDP 11/70 computer to construct the computer program library necessary for the eventual reduction of the May 1981 and subsequent data acquisitions. Papers accepted for publication are presented.

  4. Laser radar in robotics

    SciTech Connect

    Carmer, D.C.; Peterson, L.M.

    1996-02-01

    In this paper the authors describe the basic operating principles of laser radar sensors and the typical algorithms used to process laser radar imagery for robotic applications. The authors review 12 laser radar sensors to illustrate the variety of systems that have been applied to robotic applications wherein information extracted from the laser radar data is used to automatically control a mechanism or process. Next, they describe selected robotic applications in seven areas: autonomous vehicle navigation, walking machine foot placement, automated service vehicles, manufacturing and inspection, automotive, military, and agriculture. They conclude with a discussion of the status of laser radar technology and suggest trends seen in the application of laser radar sensors to robotics. Many new applications are expected as the maturity level progresses and system costs are reduced.

  5. Historical sketch: Radar geology

    NASA Technical Reports Server (NTRS)

    Macdonald, H.

    1980-01-01

    A chronological assessment is given of the broad spectra of technology associated with radar geology. Particular attention is given to the most recent developments made in the areas of microwave Earth resources applications and geologic remote sensing from aircraft and satellite. The significance of space derived radar in geologic investigations is discussed and the scientific basis for exploiting the sensitivity of radar signals to various aspects of geologic terrain is given.

  6. Bistatic-radar investigation

    NASA Technical Reports Server (NTRS)

    Howard, H. T.; Tyler, G. L.

    1972-01-01

    A bistatic-radar study during the Apollo 15 flight is reviewed, with the orbiting command module as one terminal. Bistatic-radar slopes are compared to geological maps of Copernicus and Riphaeus mountain regions and Kepler region. Basic theory is discussed, including the radar echoes composed of the sum of the reflections from the moon area that is mutually visible from the spacecraft and earth. A signal receiving system and data processing system are outlined schematically.

  7. Wide swath SAR and radar altimeter

    NASA Astrophysics Data System (ADS)

    Malliot, Harold A.

    The conceptual design of a spaceborne, high-resolution, wide-swath synthetic aperture radar (SAR) and radar altimeter that can be implemented in L, C or X band or in a combination of bands is described. The design uses active planar array antennas to form mulitple independent beams that cover swaths of up to 700 km. A dual C/X-band array can be used. From an altitude of 800 km, up to five beams provide contiguous SAR coverage tracks. A sixth beam, directed at nadir, is used for radar altimetery. Any combination of SAR beams can be selected and they can be scanned in elevation and azimuth to optimize image geometry and resolution. All beams transmit, simultaneously, 66.2-microsec pulses at a pulse repetition frequency (PRF) of 1365 Hz. The multiple-look cross-track-resolved distance ranges from 6.5 m to 7.8 m, and the azimuth-resolved distance ranges from 6 to 11 m over a 491 km swath made up to four tracks. The altimeter beam transmits linear frequency modulated pulses with a bandwidth of 320 MHz and can obtain an altitude precision of 4.2 cm.

  8. Observation and Theory of the Radar Aurora

    NASA Astrophysics Data System (ADS)

    Sahr, John David

    1990-01-01

    Plasma density irregularities occurring near the Aurora Borealis cause scattering of HF, VHF, and UHF radio waves. The scattering is so strong that a small radar, such a the Cornell University Portable Radar Interferometer (CUPRI), can easily detect this "radar aurora." Analysis of the resulting radar signal provides great detail about the spatial and temporal characteristics of these auroral E region irregularities. We present observations of the radar aurora from recent campaigns in northern Sweden. After reviewing the basic theory and observations of auroral electrojet irregularities, we introduce a simple nonlinear fluid theory of electrojet ion-acoustic waves, and reduce it to a form of the "three-wave interaction" equations. This theory provides a simple mechanism for excitation of linearly stable waves at large aspect and flow angles, as well as a prediction of the power spectra that a coherent scatter radar should observe. In addition, this theory may be able account for "type 3" waves without resorting to ion gyro modes, such as the electrostatic ion-cyclotron wave. During the course of our research we have generated a simple new radar transmitting mode and signal processing algorithm which very simply solves a frequency aliasing problem that often occurs in CUPRI auroral radar studies when a single-pulse spectral mode is used. Several new radar data analysis routines have been developed, including principally the "cross-beam image" and scatter plots of the second versus first moments of the power spectrum of the irregularities. Analysis of vertical interferometer data shows that "type 3" waves originate at ordinary electrojet altitudes, not in the upper E region, from which we conclude that the electrostatic ion-cyclotron mode does not generate "type 3" waves. The measured height of type 3 waves and other spectral analyses provide support for our pure ion -acoustic theory of type 3 waves. In closing, we offer suggestions for hardware improvements to the

  9. Observation and theory of the radar aurora

    NASA Astrophysics Data System (ADS)

    Sahr, John David

    Plasma density irregularities occurring near the Aurora Borealis cause scattering of HF, VHF, and UHF radio waves. The scattering is so strong that a small radar, such as the Cornell University Portable Radar Interferometer (CUPRI), can easily detect this radar aurora. Analysis of the resulting radar signal provides great detail about the spatial and temporal characteristics of these auroral E region irregularities. Observations are presented of the radar aurora from recent campaigns in northern Sweden. After reviewing the basic theory and observations of auroral electrojet irregularities, a simple nonlinear fluid theory of electrojet ion-acoustic waves is introduced, and reduced to a form of the three-wave interaction equations. This theory provides a simple mechanism for excitation of linearly stable waves at large aspect and flow angles, as well as a prediction of the power spectra that a coherent scatter radar should observe. In addition, this theory may be able to account for type 3 waves without resorting to ion gyro modes, such as the electrostatic ion-cyclotron wave. During the course of the research a simple new radar transmitting mode and signal processing algorithm was generated which very simply solves a frequency aliasing problem that often occurs in CUPRI auroral radar studies when a single-pulse spectral mode is used. Several new radar data analysis routines were developed, including the principally cross-beam image and scatter plots of the second versus first moments of the power spectrum of the irregularities. Analysis of vertical interferometer data shows that type 3 waves originate at ordinary electrojet altitudes, not in the upper E region, from which it is concluded that the electrostatic ion-cyclotron mode does not generate type 3 waves. The measured height of type 3 waves and other spectral analyses provide support for the pure ion-acoustic theory of type 3 waves. Suggestions are offered for hardware improvements to the CUPRI radar, new

  10. UAS-Based Radar Sounding of Ice

    NASA Astrophysics Data System (ADS)

    Hale, R. D.; Keshmiri, S.; Leuschen, C.; Ewing, M.; Yan, J. B.; Rodriguez-Morales, F.; Gogineni, S.

    2014-12-01

    The University of Kansas Center for Remote Sensing of Ice Sheets developed two Unmanned Aerial Systems (UASs) to support polar research. We developed a mid-range UAS, called the Meridian, for operating a radar depth sounder/imager at 195 MHz with an eight-element antenna array. The Meridian weighs 1,100 lbs, has a 26-foot wingspan, and a range of 950 nm at its full payload capacity of 120 lbs. Ice-penetrating radar performance drove the configuration design, though additional payloads and sensors were considered to ensure adaptation to multi-mission science payloads. We also developed a short range UAS called the G1X for operating a low-frequency radar sounder that operates at 14 and 35 MHz. The G1X weighs 85 lbs, has a 17-foot wingspan, and a range of about 60 nm per gallon of fuel. The dual-frequency HF/VHF radar depth sounder transmits at 100 W peak power at a pulse repetition frequency of 10 KHz and weighs approximately 4.5 lbs. We conducted flight tests of the G1X integrated with the radar at the Sub-glacial Lake Whillans ice stream and the WISSARD drill site. The tests included pilot-controlled and fully autonomous flights to collect data over closely-spaced lines to synthesize a 2-D aperture. We obtained clear bed echoes with a signal-to-noise (S/N) ratio of more than 50 dB at this location. These are the first-ever successful soundings of glacial ice with a UAS-based radar. Although ice attenuation losses in this location are low in comparison to more challenging targets, in-field performance improvements to the UAS and HF/VHF radar system enabled significant gains in the signal-to-noise ratio, such that the system can now be demonstrated on more challenging outlet glaciers. We are upgrading the G1X UAS and radar system for further tests and data collection in Greenland. We are reducing the weight and volume of the radar, which, when coupled with further reductions in airframe and avionics weight and a larger fuel bladder, will offer extended range. Finally

  11. Introduction to Radar Polarimetry

    DTIC Science & Technology

    1991-04-23

    to VI° - SSýSh = fSMI2. But according to the radar formula [143, the power is proportional to the radar cross section , in this case af. Hence we are...knowledge the scattering matrix S can be rewritten as where the phases 4 of the measured voltages and the radar cross sections are made explicit. c...absolute phase the scattering matrix consists ef 8 - 2 - 1 = 5 independent parameters: three radar cross sections and two phase ]ifferences (see Eq.(5.6

  12. Origins of radar

    NASA Astrophysics Data System (ADS)

    Hill, R. D.

    Sessions on the history of thunderstorm and lightning research were held December 11, 1985, at the AGU Fall Meeting in San Francisco, Calif. At that time, since it was well known that lightning researchers were intimately involved in the development of radar and since the 50th anniversary of radar in the United States was at hand, it was suggested that a session on the history of meteorological radar would be appropriate and interesting. The following contribution was presented in the History of Meteorological Radar session May 22, 1986, at the AGU Spring Meeting in Baltimore, Md.

  13. Distinguishing between similar tubular objects using pulse reflectometry: a study of trumpet and cornet leadpipes

    NASA Astrophysics Data System (ADS)

    Buick, J. M.; Kemp, J.; Sharp, D. B.; van Walstijn, M.; Campbell, D. M.; Smith, R. A.

    2002-05-01

    This paper considers the measurement of the internal radius of a number of similar, short, tubular leadpipes using pulse reflectometry. Pulse reflectometry is an acoustical technique for measuring the internal bore of a tubular object by analysing the reflections which occur when an acoustical pulse is directed into the object. The leadpipes are designed to form the initial, or lead, part of a trumpet or cornet and their internal radii differ by less than 0.1 mm between similar pipes. The ability of the reflectometer to detect these small differences, which are considered by players to produce a noticeable difference in the sound of an instrument, are investigated. It is seen that the pulse reflectometer is able to distinguish between leadpipes with different nominal radii varying by as little as 0.03 mm, demonstrating its potential in the study of musical instruments and showing that it can be used as a diagnostic tool by the instrument manufacturer to detect defects which are significant enough to acoustically alter performance. The absolute accuracy of the radius measurements is also considered at the end of the leadpipe, where the uncertainty is ±0.05 mm.

  14. Simulation of error in optical radar range measurements.

    PubMed

    Der, S; Redman, B; Chellappa, R

    1997-09-20

    We describe a computer simulation of atmospheric and target effects on the accuracy of range measurements using pulsed laser radars with p-i-n or avalanche photodiodes for direct detection. The computer simulation produces simulated images as a function of a wide variety of atmospheric, target, and sensor parameters for laser radars with range accuracies smaller than the pulse width. The simulation allows arbitrary target geometries and simulates speckle, turbulence, and near-field and far-field effects. We compare simulation results with actual range error data collected in field tests.

  15. Discriminating spurious signals in radar data using multiple channels

    NASA Astrophysics Data System (ADS)

    Doerry, A. W.; Bickel, D. L.

    2017-05-01

    Spurious energy in received radar data is unanticipated and undesired signal relevant to radar target signatures, usually a consequence of nonideal component and circuit behavior, perhaps due to I/Q imbalance, nonlinear component behavior, additive interference (e.g. cross-talk, etc.), or other sources. The manifestation of the spurious energy in a range-Doppler map or image can often be influenced by appropriate pulse-to-pulse phase modulation. Comparing multiple images having been processed with the same data but different signal paths and modulations allows identifying undesired spurs and then cropping or apodizing them.

  16. Aircraft and satellite measurement of ocean wave directional spectra using scanning-beam microwave radars

    NASA Technical Reports Server (NTRS)

    Jackson, F. C.; Walton, W. T.; Baker, P. L.

    1982-01-01

    A microwave radar technique for remotely measuring the vector wave number spectrum of the ocean surface is described. The technique, which employs short-pulse, noncoherent radars in a conical scan mode near vertical incidence, is shown to be suitable for both aircraft and satellite application, the technique was validated at 10 km aircraft altitude, where we have found excellent agreement between buoy and radar-inferred absolute wave height spectra.

  17. Implementation of the new multichannel X-mode edge density profile reflectometer for the ICRF antenna on ASDEX Upgrade

    NASA Astrophysics Data System (ADS)

    Aguiam, D. E.; Silva, A.; Bobkov, V.; Carvalho, P. J.; Carvalho, P. F.; Cavazzana, R.; Conway, G. D.; D'Arcangelo, O.; Fattorini, L.; Faugel, H.; Fernandes, A.; Fünfgelder, H.; Gonçalves, B.; Guimarais, L.; De Masi, G.; Meneses, L.; Noterdaeme, J. M.; Pereira, R. C.; Rocchi, G.; Santos, J. M.; Tuccillo, A. A.; Tudisco, O.

    2016-11-01

    A new multichannel frequency modulated continuous-wave reflectometry diagnostic has been successfully installed and commissioned on ASDEX Upgrade to measure the plasma edge electron density profile evolution in front of the Ion Cyclotron Range of Frequencies (ICRF) antenna. The design of the new three-strap ICRF antenna integrates ten pairs (sending and receiving) of microwave reflectometry antennas. The multichannel reflectometer can use three of these to measure the edge electron density profiles up to 2 × 1019 m-3, at different poloidal locations, allowing the direct study of the local plasma layers in front of the ICRF antenna. ICRF power coupling, operational effects, and poloidal variations of the plasma density profile can be consistently studied for the first time. In this work the diagnostic hardware architecture is described and the obtained density profile measurements were used to track outer radial plasma position and plasma shape.

  18. KWS-3, the new focusing-mirror ultra small-angle neutron scattering instrument and reflectometer at Jülich

    NASA Astrophysics Data System (ADS)

    Kentzinger, E.; Dohmen, L.; Alefeld, B.; Rücker, U.; Stellbrink, J.; Ioffe, A.; Richter, D.; Brückel, Th.

    2004-07-01

    In Jülich, a new high-resolution small-angle neutron scattering (SANS) instrument and reflectometer has been built. The principle of this instrument is a one-to-one image of an entrance aperture on a 2D position-sensitive detector by neutron reflection on a double-focusing toroidal mirror. It permits to perform SANS studies with a scattering wave vector resolution between 10-3 and 10-4Å-1 with considerable intensity advantages over pinhole-SANS instruments. To date, KWS-3 is the worldwide unique SANS instrument running on this principle. We present here the characterization of the image produced by the mirror and a measurement of the scattering from a diffraction grating.

  19. Study of ITER plasma position reflectometer using a two-dimensional full-wave finite-difference time domain code

    SciTech Connect

    Silva, F. da

    2008-10-15

    The EU will supply the plasma position reflectometer for ITER. The system will have channels located at different poloidal positions, some of them obliquely viewing a plasma which has a poloidal density divergence and curvature, both adverse conditions for profile measurements. To understand the impact of such topology in the reconstruction of density profiles a full-wave two-dimensional finite-difference time domain O-mode code with the capability for frequency sweep was used. Simulations show that the reconstructed density profiles still meet the ITER radial accuracy specifications for plasma position (1 cm), except for the highest densities. Other adverse effects such as multireflections induced by the blanket, density fluctuations, and MHD activity were considered and a first understanding on their impact obtained.

  20. A field-deployable spectral reflectometer to characterize surfaces in the infrared from the NIR to the LWIR

    NASA Astrophysics Data System (ADS)

    Moreau, Louis; Bourque, Hugo; Ouellet, Réal; Roy, Claude; Vallières, Christian; Thériault, Guillaume

    2011-06-01

    ABB Bomem has recently designed a field-deployable reflectometer to measure the diffuse spectral reflectance of surfaces from 0.7 μm to 13.5 μm. Its spectral resolution is adjustable and can be as fine as 4 cm-1. The instrument is designed to field and laboratory operation. It is portable and battery-operated. In its simplest mode, the instrument is automated and can be operated by non-specialist personnel with minimal training. The instrument was designed to build a spectral database of different surfaces in various conditions (different humidity, temperature, texture, mixing, etc.) and in the presence of various interfering chemicals (oils, solvents, etc.). The instrument has its own built-in infrared sources. The sources illuminate the ground area to be measured. The instrument has also two built-in reference diffusers: a Spectralon diffuser and an Infragold diffuser.

  1. Reconstruction of the Density Profile for the EAST Tokamak Based on Polarimeter/Interferometer and Microwave Reflectometer Systems

    NASA Astrophysics Data System (ADS)

    Zhu, Xiang; Zeng, Long; Liu, Haiqing; Jie, Yinxian; Zhang, Shoubiao; Hu, Jiansheng; Gao, Xiang

    2015-09-01

    A plasma density profile reconstruction procedure based on the Park matrix method has been developed for both circular and elongated plasma configuration on the Experimental Advanced Superconducting Tokamak (EAST). This method incorporates the line integrated electron density measured by the HCN interferometer and polarimeter/interferometer (POINT) system, the equilibrium fit (EFIT) based on magnetic measurements and the edge electron density profile provided by the microwave reflectometer. It is shown that when the magnetic flux surfaces are slightly corrected, the fitting error is less than 5% in comparison with the measurement data. supported by the National Magnetic Confinement Fusion Science Program of China (Nos. 2013GB106003, 2014GB106004 and 2014GB106002) and National Natural Science Foundation of China (Nos. 11475221 and 11105184)

  2. Implementation of the new multichannel X-mode edge density profile reflectometer for the ICRF antenna on ASDEX Upgrade

    SciTech Connect

    Aguiam, D. E. Silva, A.; Carvalho, P. J.; Carvalho, P. F.; Fernandes, A.; Gonçalves, B.; Guimarais, L.; Meneses, L.; Pereira, R. C.; Santos, J. M.; Bobkov, V.; Conway, G. D.; Faugel, H.; Fünfgelder, H.; Cavazzana, R.; De Masi, G.; D’Arcangelo, O.; Rocchi, G.; Tuccillo, A. A.; and others

    2016-11-15

    A new multichannel frequency modulated continuous-wave reflectometry diagnostic has been successfully installed and commissioned on ASDEX Upgrade to measure the plasma edge electron density profile evolution in front of the Ion Cyclotron Range of Frequencies (ICRF) antenna. The design of the new three-strap ICRF antenna integrates ten pairs (sending and receiving) of microwave reflectometry antennas. The multichannel reflectometer can use three of these to measure the edge electron density profiles up to 2 × 10{sup 19} m{sup −3}, at different poloidal locations, allowing the direct study of the local plasma layers in front of the ICRF antenna. ICRF power coupling, operational effects, and poloidal variations of the plasma density profile can be consistently studied for the first time. In this work the diagnostic hardware architecture is described and the obtained density profile measurements were used to track outer radial plasma position and plasma shape.

  3. Application of a portable 3He-based polarization insert at a time-of-flight neutron reflectometer

    NASA Astrophysics Data System (ADS)

    Kreuzpaintner, Wolfgang; Masalovich, Sergey; Moulin, Jean-François; Wiedemann, Birgit; Ye, Jingfan; Mayr, Sina; Paul, Amitesh; Haese, Martin; Pomm, Matthias; Böni, Peter

    2017-03-01

    The suitability of a transportable 3He-spin filter as temporary broadband polarizer for a Time-of-Flight neutron reflectometer is demonstrated. A simple two-wavelength method for characterisation of a 3He-spin filter is proposed, which can be applied even if the absolute transmittance of the 3He-spin filter cannot be accurately determined. We demonstrate the data treatment procedure for extracting the spin-up and spin-down neutron reflectivity from measurements obtained with a time dependent 3He polarization. The extraction of a very weak magnetic signal from reflectivity data, measured on the in-situ grown magnetic heterostructure Fe1nm /Cu20nm /Sisubstrate in an externally applied magnetic field of 30 mT is presented and compared to similar measurements on the growth stage Cu20nm /Sisubstrate of the very same sample, which does not yet contain any magnetic material.

  4. Front-end antenna system design for the ITER low-field-side reflectometer system using GENRAY ray tracing

    NASA Astrophysics Data System (ADS)

    Wang, G.; Doyle, E. J.; Peebles, W. A.

    2016-11-01

    A monostatic antenna array arrangement has been designed for the microwave front-end of the ITER low-field-side reflectometer (LFSR) system. This paper presents details of the antenna coupling coefficient analyses performed using GENRAY, a 3-D ray tracing code, to evaluate the plasma height accommodation capability of such an antenna array design. Utilizing modeled data for the plasma equilibrium and profiles for the ITER baseline and half-field scenarios, a design study was performed for measurement locations varying from the plasma edge to inside the top of the pedestal. A front-end antenna configuration is recommended for the ITER LFSR system based on the results of this coupling analysis.

  5. Combined radar and telemetry system

    DOEpatents

    Rodenbeck, Christopher T.; Young, Derek; Chou, Tina; Hsieh, Lung-Hwa; Conover, Kurt; Heintzleman, Richard

    2017-08-01

    A combined radar and telemetry system is described. The combined radar and telemetry system includes a processing unit that executes instructions, where the instructions define a radar waveform and a telemetry waveform. The processor outputs a digital baseband signal based upon the instructions, where the digital baseband signal is based upon the radar waveform and the telemetry waveform. A radar and telemetry circuit transmits, simultaneously, a radar signal and telemetry signal based upon the digital baseband signal.

  6. Ultrawideband radar clutter measurements of forested terrain, 1991--1992

    SciTech Connect

    Sheen, D.M.; Severtsen, R.H.; Prince, J.M.; Davis, K.C.; Collins, H.D.

    1993-06-01

    The ultrawideband (UWB) radar clutter measurements project was conducted to provide radar clutter data for new ultrawideband radar systems which are currently under development. A particular goal of this project is to determine if conventional narrow band clutter data may be extrapolated to the UWB case. This report documents measurements conducted in 1991 and additional measurements conducted in 1992. The original project consisted of clutter measurements of forested terrain in the Olympic National Forest near Sequim, WA. The impulse radar system used a 30 kW peak impulse source with a 2 Gigasample/second digitizer to form a UHF (300--1000 MHz) ultrawideband impulse radar system. Additional measurements were conducted in parallel using a Systems Planning Corporation (SPC) step-chirp radar system. This system utilized pulse widths of 1330 nanoseconds over a bandwidth of 300--1000 MHz to obtain similar resolution to the impulse system. Due to the slow digitizer data throughput in the impulse radar system, data collection rates were significantly higher using the step-chirp system. Additional forest clutter measurements were undertaken in 1992 to increase the amount of data available, and especially to increase the amount of data from the impulse radar system.

  7. Laboratory demonstration of an effective range sidelobe suppression technique for spaceborne rain radars

    NASA Technical Reports Server (NTRS)

    Im, E.; Tanner, A.; Wilson, W.; Denning, R.; Durden, S.; Li, F.

    1991-01-01

    A 13.8 GHz linear frequency-modulated pulse compression radar electronics system for spaceborne and airborne radar rain mapping applications has been built and tested. Preliminary test results indicate that the far range sidelobes can be suppressed to the desired -60 B level in the laboratory environment.

  8. Laboratory demonstration of an effective range sidelobe suppression technique for spaceborne rain radars

    NASA Astrophysics Data System (ADS)

    Im, E.; Tanner, A.; Wilson, W.; Denning, R.; Durden, S.; Li, F.

    A 13.8 GHz linear frequency-modulated pulse compression radar electronics system for spaceborne and airborne radar rain mapping applications has been built and tested. Preliminary test results indicate that the far range sidelobes can be suppressed to the desired -60 B level in the laboratory environment.

  9. Ultrashort-pulse reflectometry (invited)

    NASA Astrophysics Data System (ADS)

    Domier, C. W.; Luhmann, N. C., Jr.; Chou, A. E.; Zhang, W.-M.; Romanowsky, A. J.

    1995-01-01

    Time-of-flight radar diagnostics are envisaged as having great potential for determining electron density profiles in next generation tokamaks such as TPX and ITER. Ultrashort-pulse radar reflectometry is a promising new time-of-flight diagnostic capable of making instantaneous density profile determination utilizing a single source and a single set of measurements. A proof-of-principle eight channel system has been constructed for use on the CCT tokamak at UCLA, and has undergone extensive testing in the laboratory.

  10. Digital controller for the Wave Propagation Laboratory's VHF and UHF wind-profiling radars

    NASA Astrophysics Data System (ADS)

    Moran, K.

    1984-09-01

    Principles are described for operation of a digital system that is used to control the operations of a multiple beam stratospheric-tropospheric (ST) radar system. The digital system, referred to as the radar controller, contains the digital logic for generating the necessary pulse sequences for modulation of the radar transmitter, gating the radar's receiver channels, and sequencing the antenna beams. The radar controller also performs digital-to-analog conversion and coherent averaging of the receiver necessary for signal detection in ST radars. The radar controller is controlled internally by a Z80 microprocessor, and the entire system functions as a peripheral device to a host minicomputer. Block diagrams and detailed circuit schematics for all the custom designed electronics are included.

  11. Micropower impulse radar technology and applications

    SciTech Connect

    Mast, J., LLNL

    1998-04-15

    The LLNL-developed Micropower Impulse Radar (MIR) technology has quickly gone from laboratory concept to embedded circuitry in numerous government and commercial systems in the last few years[l]. The main ideas behind MIR, invented by T. McEwan in the Laser Program, are the generation and detection systems for extremely low- power ultra-wideband pulses in the gigaHertz regime using low-cost components. These ideas, coupled with new antenna systems, timing and radio-frequency (RF) circuitry, computer interfaces, and signal processing, have provided the catalyst for a new generation of compact radar systems. Over the past several years we have concentrated on a number of applications of MIR which address a number of remote-sensing applications relevant to emerging programs in defense, transportation, medical, and environmental research. Some of the past commercial successes have been widely publicized [2] and are only now starting to become available for market. Over 30 patents have been filed and over 15 licenses have been signed on various aspects of the MIR technology. In addition, higher performance systems are under development for specific laboratory programs and government reimbursables. The MIR is an ultra- wideband, range-gated radar system that provides the enabling hardware technology used in the research areas mentioned above. It has numerous performance parameters that can be Selected by careful design to fit the requirements. We have improved the baseline, short- range, MIR system to demonstrate its effectiveness. The radar operates over the hand from approximately I to 4 GHz with pulse repetition frequencies up to 10 MHz. It provides a potential range resolution of I cm at ranges of greater than 20 m. We have developed a suite of algorithms for using MIR for image formation. These algorithms currently support Synthetic aperture and multistate array geometries. This baseline MIR radar imaging system has been used for several programmatic applications.

  12. The PROUST radar

    NASA Technical Reports Server (NTRS)

    Bertin, F.; Glass, M.; Ney, R.; Petitdidier, M.

    1986-01-01

    The Stratosphere-Troposphere (ST) radar called PROUST works at 935 MHz using the same klystron and antenna as the coherent-scatter radar. The use of this equipment for ST work has required some important modifications of the transmitting system and the development of receiving, data processing and acquisition (1984,1985) equipment. The modifications are discussed.

  13. Synchronization in multistatic radar

    NASA Astrophysics Data System (ADS)

    Jubrink, H. G.

    1993-08-01

    This report gives a summary of multistatic radar principles and synchronization methods. Different methods are described using direct and indirect synchronization. The report also presents a general review of synchronization methods for the future. Two LORAN C receivers have been analyzed for use as local reference oscillators in multistatic radar.

  14. Quantum radar cross sections

    NASA Astrophysics Data System (ADS)

    Lanzagorta, Marco

    2010-06-01

    The radar cross section σC is an objective measure of the "radar visibility" of an object. As such, σC is an important concept for the correct characterization of the operational performance of radar systems. Furthermore, σC is equally essential for the design and development of stealth weapon systems and platforms. Recent years have seen the theoretical development of quantum radars, that is, radars that operate with a small number of photons. In this regime, the radar-target interaction is described through photon-atom scattering processes governed by the laws of quantum electrodynamics. As such, it is theoretically inconsistent to use the same σC to characterize the performance of a quantum radar. In this paper we define a quantum radar cross section σQ based on quantum electrodynamics and interferometric considerations. We discuss the theoretical challenges of defining σQ, as well as computer simulations of σC and σQ for simple targets.

  15. Polarization Radar Processing Technology

    DTIC Science & Technology

    1989-10-01

    Oi"C FILE ( J qII RADC-TR-89-144 In-House Report October 1989 AD-A215 242 POLARIZATION RADAR PROCESSING TECHNOLOGY Kenneth C. Stiefvater, Russell D...NO. NO. NO. ACCESSION NO. 62702F 4506 11 58 11. TITLE (Include Security Classification) POLARIZATION RADAR PROCESSING TECHNOLOGY 12. PERSONAL AUTHOR(S

  16. Radar illusion via metamaterials

    NASA Astrophysics Data System (ADS)

    Jiang, Wei Xiang; Cui, Tie Jun

    2011-02-01

    An optical illusion is an image of a real target perceived by the eye that is deceptive or misleading due to a physiological illusion or a specific visual trick. The recently developed metamaterials provide efficient approaches to generate a perfect optical illusion. However, all existing research on metamaterial illusions has been limited to theory and numerical simulations. Here, we propose the concept of a radar illusion, which can make the electromagnetic (EM) image of a target gathered by radar look like a different target, and we realize a radar illusion device experimentally to change the radar image of a metallic target into a dielectric target with predesigned size and material parameters. It is well known that the radar signatures of metallic and dielectric objects are significantly different. However, when a metallic target is enclosed by the proposed illusion device, its EM scattering characteristics will be identical to that of a predesigned dielectric object under the illumination of radar waves. Such an illusion device will confuse the radar, and hence the real EM properties of the metallic target cannot be perceived. We designed and fabricated the radar illusion device using artificial metamaterials in the microwave frequency, and good illusion performances are observed in the experimental results.

  17. Noncooperative rendezvous radar system

    NASA Technical Reports Server (NTRS)

    1974-01-01

    A fire control radar system was developed, assembled, and modified. The baseline system and modified angle tracking system are described along with the performance characteristics of the baseline and modified systems. Proposed changes to provide additional techniques for radar evaluation are presented along with flight test data.

  18. Java Radar Analysis Tool

    NASA Technical Reports Server (NTRS)

    Zaczek, Mariusz P.

    2005-01-01

    Java Radar Analysis Tool (JRAT) is a computer program for analyzing two-dimensional (2D) scatter plots derived from radar returns showing pieces of the disintegrating Space Shuttle Columbia. JRAT can also be applied to similar plots representing radar returns showing aviation accidents, and to scatter plots in general. The 2D scatter plots include overhead map views and side altitude views. The superposition of points in these views makes searching difficult. JRAT enables three-dimensional (3D) viewing: by use of a mouse and keyboard, the user can rotate to any desired viewing angle. The 3D view can include overlaid trajectories and search footprints to enhance situational awareness in searching for pieces. JRAT also enables playback: time-tagged radar-return data can be displayed in time order and an animated 3D model can be moved through the scene to show the locations of the Columbia (or other vehicle) at the times of the corresponding radar events. The combination of overlays and playback enables the user to correlate a radar return with a position of the vehicle to determine whether the return is valid. JRAT can optionally filter single radar returns, enabling the user to selectively hide or highlight a desired radar return.

  19. Determination of radar MTF

    SciTech Connect

    Chambers, D.

    1994-11-15

    The ultimate goal of the Current Meter Array (CMA) is to be able to compare the current patterns detected with the array with radar images of the water surface. The internal wave current patterns modulate the waves on the water surface giving a detectable modulation of the radar cross-section (RCS). The function relating the RCS modulations to the current patterns is the Modulation Transfer Function (MTF). By comparing radar images directly with co-located CMA measurements the MTF can be determined. In this talk radar images and CMA measurements from a recent experiment at Loch Linnhe, Scotland, will be used to make the first direct determination of MTF for an X and S band radar at low grazing angles. The technical problems associated with comparing radar images to CMA data will be explained and the solution method discussed. The results suggest the both current and strain rate contribute equally to the radar modulation for X band. For S band, the strain rate contributes more than the current. The magnitude of the MTF and the RCS modulations are consistent with previous estimates when the wind is blowing perpendicular to the radar look direction.

  20. Improved Timing Scheme for Spaceborne Precipitation Radar

    NASA Technical Reports Server (NTRS)

    Berkun, Andrew; Fischman, Mark

    2004-01-01

    An improved timing scheme has been conceived for operation of a scanning satellite-borne rain-measuring radar system. The scheme allows a real-time-generated solution, which is required for auto targeting. The current timing scheme used in radar satellites involves pre-computing a solution that allows the instrument to catch all transmitted pulses without transmitting and receiving at the same time. Satellite altitude requires many pulses in flight at any time, and the timing solution to prevent transmit and receive operations from colliding is usually found iteratively. The proposed satellite has a large number of scanning beams each with a different range to target and few pulses per beam. Furthermore, the satellite will be self-targeting, so the selection of which beams are used will change from sweep to sweep. The proposed timing solution guarantees no echo collisions, can be generated using simple FPGA-based hardware in real time, and can be mathematically shown to deliver the maximum number of pulses per second, given the timing constraints. The timing solution is computed every sweep, and consists of three phases: (1) a build-up phase, (2) a feedback phase, and (3) a build-down phase. Before the build-up phase can begin, the beams to be transmitted are sorted in numerical order. The numerical order of the beams is also the order from shortest range to longest range. Sorting the list guarantees no pulse collisions. The build-up phase begins by transmitting the first pulse from the first beam on the list. Transmission of this pulse starts a delay counter, which stores the beam number and the time delay to the beginning of the receive window for that beam. The timing generator waits just long enough to complete the transmit pulse plus one receive window, then sends out the second pulse. The second pulse starts a second delay counter, which stores its beam number and time delay. This process continues until an output from the first timer indicates there is less

  1. Equatorial MU Radar project

    NASA Astrophysics Data System (ADS)

    Yamamoto, Mamoru; Hashiguchi, H.; Tsuda, Toshitaka; Yamamoto, Masayuki

    Research Institute for Sustainable Humanosphere, Kyoto University (RISH) has been studying the atmosphere by using radars. The first big facility was the MU (Middle and Upper atmosphere) radar installed in Shiga, Japan in 1984. This is one of the most powerful and multi-functional radar, and is successful of revealing importance of atmospheric waves for the dynamical vertical coupling processes. The next big radar was the Equatorial Atmosphere Radar (EAR) installed at Kototabang, West Sumatra, Indonesia in 2001. The EAR was operated under close collaboration with LAPAN (Indonesia National Institute for Aeronautics and Space), and conducted the long-term continuous observations of the equatorial atmosphere/ionosphere for more than 10 years. The MU radar and the EAR are both utilized for inter-university and international collaborative research program for long time. National Institute for Polar Research (NIPR) joined EISCAT Scientific Association together with Nagoya University, and developed the PANSY radar at Syowa base in Antarctica as a joint project with University of Tokyo. These are the efforts of radar study of the atmosphere/ionosphere in the polar region. Now we can find that Japan holds a global network of big atmospheric/ionospheric radars. The EAR has the limitation of lower sensitivity compared with the other big radars shown above. RISH now proposes a plan of Equatorial MU Radar (EMU) that is to establish the MU-radar class radar next to the EAR. The EMU will have an active phased array antenna with the 163m diameter and 1055 cross-element Yagis. Total output power of the EMU will be more than 500kW. The EMU can detect turbulent echoes from the mesosphere (60-80km). In the ionosphere incoherent-scatter observations of plasma density, drift, and temperature would be possible. Multi-channel receivers will realize radar-imaging observations. The EMU is one of the key facilities in the project "Study of coupling processes in the solar-terrestrial system

  2. Intelligent radar data processing

    NASA Astrophysics Data System (ADS)

    Holzbaur, Ulrich D.

    The application of artificial intelligence principles to the processing of radar signals is considered theoretically. The main capabilities required are learning and adaptation in a changing environment, processing and modeling information (especially dynamics and uncertainty), and decision-making based on all available information (taking its reliability into account). For the application to combat-aircraft radar systems, the tasks include the combination of data from different types of sensors, reacting to electronic counter-countermeasures, evaluation of how much data should be acquired (energy and radiation management), control of the radar, tracking, and identification. Also discussed are related uses such as monitoring the avionics systems, supporting pilot decisions with respect to the radar system, and general applications in radar-system R&D.

  3. Micropower impulse radar imaging

    SciTech Connect

    Hall, M.S.

    1995-11-01

    From designs developed at the Lawrence Livermore National Laboratory (LLNL) in radar and imaging technologies, there exists the potential for a variety of applications in both public and private sectors. Presently tests are being conducted for the detection of buried mines and the analysis of civil structures. These new systems use a patented ultra-wide band (impulse) radar technology known as Micropower Impulse Radar (GPR) imaging systems. LLNL has also developed signal processing software capable of producing 2-D and 3-D images of objects embedded in materials such as soil, wood and concrete. My assignment while at LLNL has focused on the testing of different radar configurations and applications, as well as assisting in the creation of computer algorithms which enable the radar to scan target areas of different geometeries.

  4. Spaceborne weather radar

    NASA Technical Reports Server (NTRS)

    Meneghini, Robert; Kozu, Toshiaki

    1990-01-01

    The present work on the development status of spaceborne weather radar systems and services discusses radar instrument complementarities, the current forms of equations for the characterization of such aspects of weather radar performance as surface and mirror-image returns, polarimetry, and Doppler considerations, and such essential factors in spaceborne weather radar design as frequency selection, scanning modes, and the application of SAR to rain detection. Attention is then given to radar signal absorption by the various atmospheric gases, rain drop size distribution and wind velocity determinations, and the characteristics of clouds, as well as the range of available estimation methods for backscattering, single- and dual-wavelength attenuation, and polarimetric and climatological characteristics.

  5. Meteorological radar calibration

    NASA Technical Reports Server (NTRS)

    Hodge, D. B.

    1978-01-01

    A meteorological radar calibration technique is developed. It is found that the integrated, range corrected, received power saturates under intense rain conditions in a manner analogous to that encountered for the radiometric path temperature. Furthermore, it is found that this saturation condition establishes a bound which may be used to determine an absolution radar calibration for the case of radars operating at attenuating wavelengths. In the case of less intense rainfall or for radars at nonattenuating wavelengths, the relationship for direct calibration in terms of an independent measurement of radiometric path temperature is developed. This approach offers the advantage that the calibration is in terms of an independent measurement of the rainfall through the same elevated region as that viewed by the radar.

  6. Multiple arrested synthetic aperture radar

    NASA Astrophysics Data System (ADS)

    Shuster, J. S.

    1981-05-01

    This report contains the formulation and analysis of an airborne synthetic aperture rate scheme which employs a multiplicity of antennas with the displaced phase center antenna technique to detect slowly moving targets embedded in a severe clutter environment. The radar is evaluated using the target to clutter power ratio as the measure of performance. Noise is ignored in the analysis. An optimization scheme which maximizes this ratio is employed to obtain the optimum processor weighting. The performance of the MASAR processor with optimum weights is compared against that using target weights (composed of the target signal) and that using binomial weights (which, effectively, form an n-pulse canceller). Both the target and the clutter are modeled with the electric field backscattering coefficient. The target is modeled simply as a deterministically moving point scatterer with the same albedo as a point of clutter. The clutter is modeled as a homogeneous, isotropic, two dimensional, spatiotemporal random field for which only the correlation properties are required. The analysis shows that this radar, with its optimum weighting scheme, is a promising synthetic aperture concept for the detection of slowly moving targets immersed in strong clutter environments.

  7. Progress in coherent laser radar

    NASA Technical Reports Server (NTRS)

    Vaughan, J. M.

    1986-01-01

    Considerable progress with coherent laser radar has been made over the last few years, most notably perhaps in the available range of high performance devices and components and the confidence with which systems may now be taken into the field for prolonged periods of operation. Some of this increasing maturity was evident at the 3rd Topical Meeting on Coherent Laser Radar: Technology and Applications. Topics included in discussions were: mesoscale wind fields, nocturnal valley drainage and clear air down bursts; airborne Doppler lidar studies and comparison of ground and airborne wind measurement; wind measurement over the sea for comparison with satellite borne microwave sensors; transport of wake vortices at airfield; coherent DIAL methods; a newly assembled Nd-YAG coherent lidar system; backscatter profiles in the atmosphere and wavelength dependence over the 9 to 11 micrometer region; beam propagation; rock and soil classification with an airborne 4-laser system; technology of a global wind profiling system; target calibration; ranging and imaging with coherent pulsed and CW system; signal fluctuations and speckle. Some of these activities are briefly reviewed.

  8. Scale model ultrawideband impulse radar

    NASA Astrophysics Data System (ADS)

    Morgan, Michael A.

    1993-05-01

    The Transient Electromagnetic Scattering Laboratory (TESL) is described which employs a unique dual-channel ultra-wideband impulsive illuminating source. This is a free-field facility where targets are suspended within an anechoic chamber. A highly coherent primal step pulse is amplified by two GaAs wideband power amplifiers having complementary passbands which feed individual wideband horn antennas. This yields an effective 1 - 12 GHz impulse bandwidth. A high speed digital processing oscilloscope samples the output of a single receiving horn. The TESL has facilitated research into radar target identification using complex natural resonances. Theory and operational characteristics of the facility are discussed and technical improvements are described which have yielded significant improvement in both the effective bandwidth and the signal-to-noise ratio of transient scattering measurements. Experimental validations are shown which illustrate the level of fidelity attainable and consideration is given to recent enhancements, including an increase of measurement bandwidth to 50 GHz.

  9. Ground validation of Dual Precipitation Radar (DPR) on GPM by rapid scan Phased Array weahter Radar (PAR)

    NASA Astrophysics Data System (ADS)

    Hirano, Y.; Mega, T.; Shimamura, S.; Wu, T.; Kikuchi, H.; Ushio, T.; Yoshikawa, E.; Chandra, C. V.

    2014-12-01

    The core observatory satellite of the Global Precipitation Measurement (GPM) mission was launched on February 27th 2014. The Dual-frequency Precipitation Radar (DPR) on the GPM core observatory is the succession of the TRMM Precipitation Radar (PR). The DPR consists of a Ku-band precipitation radar and a Ka-band precipitation radar. The DPR is expected to be more sensitive than the PR especially in the measurement of light rainfall and snowfall in high latitude regions. Because of the difference of spatial and temporal resolutions, Space Radar (SR) and conventional type of Ground Radar (GR) are hard to compare.The SR observes each point of earth in short time, for example one footprint is an observation in some microseconds. Rain-gauge measurements have accurate rainfall rate, but rain-gage observes small area and accumulated rainfall in some minutes. The conventional GR can cover a wide area, however, a volume scan requires several minutes. The Phased Array weather Radar (PAR) is developed by Osaka University, Toshiba, and NICT. The PAR is a weather-radar on X-band within 100m range sampling. High spatial and temporal resolution is achieved by the PAR with pulse compression and the digital beam-forming technique. The PAR transmits a wide beam and receives narrow beams by using digital beam forming. Then, the PAR observes many elevation angles from a single pulse. The time of each volume scan is 10-30 seconds in operation, typically 30 seconds. The study shows comparisons between the DPR and the PAR by more similar spatial and temporal resolution. The rainfall region of DPR is similar to the one of PAR. Correlation coefficient of both radar reflectivity suggests more than 0.8 in the 20km range of PAR. As a result, it is considered that DPR can observe with high accuracy. We present the case study which DPR overpassed the PAR observation region in detail.

  10. 4. VIEW NORTHEAST, radar tower (unknown function), prime search radar ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. VIEW NORTHEAST, radar tower (unknown function), prime search radar tower, emergency power building, and height finder radar tower - Fort Custer Military Reservation, P-67 Radar Station, .25 mile north of Dickman Road, east of Clark Road, Battle Creek, Calhoun County, MI

  11. 5. VIEW EAST, height finder radar towers, radar tower (unknown ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    5. VIEW EAST, height finder radar towers, radar tower (unknown function), prime search radar tower, operations building, and central heating plant - Fort Custer Military Reservation, P-67 Radar Station, .25 mile north of Dickman Road, east of Clark Road, Battle Creek, Calhoun County, MI

  12. Modeling and experiments with a subsea laser radar system

    NASA Astrophysics Data System (ADS)

    Bjarnar, Morten L.; Klepsvik, John O.; Nilsen, Jan E.

    1991-12-01

    Subsea laser radar has a potential for accurate 3-D imaging in water. A prototype system has been developed at Seatex A/S in Norway as a prestudy for the design of an underwater laser radar scanning system. Parallel to the experimental studies, a numerical radiometric model has been developed as an aid in the system design. This model simulates a raster scanning laser radar system for in-water use. Thus this parametric model allows for analysis and predictions of the performance of such a sensor system. Experiments have been conducted to test a prototype laser radar system. The experimental system tested uses a Q-switched, frequency doubled, Nd:YAG solid state laser operating at a wavelength of 532 nm, which is close to optimal for use in water due to the small light attenuation around this wavelength in seawater. The laser has an energy output of 6 (mu) J per pulse 1 kHz pulse repetition frequency (PRF) and the receiver aperture is approximately 17 cm2. The laser radar prototype was mounted onto an accurate pan and tilt unit in order to test the 3-D imaging capabilities. The ultimate goal of the development is to provide an optical 3-D imaging tool for distances comparable to high frequency sonars with a range capability of approximately 30 - 50 m. The results from these experiments are presented. The present implementation of the scanning laser radar model is described and some outputs from the simulation are shown.

  13. Fundamental radar properties: hidden variables in space-time

    NASA Astrophysics Data System (ADS)

    Gabriel, Andrew K.

    2002-05-01

    A derivation of the properties of pulsed radiative imaging systems is presented with examples drawn from conventional, synthetic aperture, and interferometric radar. A geometric construction of the space and time components of a radar observation yields a simple underlying structural equivalence among many of the properties of radar, including resolution, range ambiguity, azimuth aliasing, signal strength, speckle, layover, Doppler shifts, obliquity and slant range resolution, finite antenna size, atmospheric delays, and beam- and pulse-limited configurations. The same simple structure is shown to account for many interferometric properties of radar: height resolution, image decorrelation, surface velocity detection, and surface deformation measurement. What emerges is a simple, unified description of the complex phenomena of radar observations. The formulation comes from fundamental physical concepts in relativistic field theory, of which the essential elements are presented. In the terminology of physics, radar properties are projections of hidden variables-curved worldlines from a broken symmetry in Minkowski space-time-onto a time-serial receiver.

  14. 3D measurements in the polar mesosphere using coherent radar imaging

    NASA Astrophysics Data System (ADS)

    Zecha, M.; Sommer, S.; Rapp, M.; Stober, G.; Latteck, R.

    2012-12-01

    Radars provide the opportunity of continuous measurements in the interesting area of the polar mesosphere. Usually the spatial resolution of measurements by pulsed VHF radars is limited by the radar beam width, transmitting pulse length, and sampling time. Due to these technical restrictions the typical small-scale structures in the mesosphere often cannot be resolved. Furthermore the quality of the estimation of dynamic atmosphere parameters is reduced if the position and direction of scatter returns cannot determined exactly. Radar interferometry methods have been developed to reduce these limitations. The coherent radar imaging method gives a high resolving image of the scatter structure insight the radar beam volume. In recent years the VHF radar MAARSY was installed in Andenes/Norway (69°N). This new radar was designed to allow improved three-dimensional observations in the atmosphere. It consists of 433 Yagis and allows a minimum beam width of about 4 degree. The beam direction can be changed pulse-by-pulse freely in azimuth angle and practicable up to 40 degree in zenith angle. The pulse length can be varied from a couple of km down to 50 m. Up to 16 receiving channels of spaced antennas can be used. In this presentation we show the detection of the angles-of-arrival of radar echoes and the correction of the wind measurements. We demonstrate the improvement of measurement results by using coherent radar imaging. The differences to the results of conventional methods depend on the beam width, range resolution, antenna distances, and beam tilting. We show that the application of interferometry is necessary to improve considerably the quality of 3D-measurement results. Furthermore we demonstrate the synthesis of high resolved images to get a real 3D image of the mesosphere.

  15. Radar Imaging with a Network of Digital Noise Radar Systems

    DTIC Science & Technology

    2009-03-01

    III. Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 3.1 Radar Range Equation and Radar Cross Section . . . . . 29 3.2 UWB...noise radar system. This particular ap- plication tracked a corner reflector that moved from a range of 40 ft to 185 ft from the radar while using an...target scenario and the resulting SAR image. In this test, a radar was placed outside a room with a trihedral reflector placed on the other side of the

  16. Radar remote sensing in biology

    USGS Publications Warehouse

    Moore, Richard K.; Simonett, David S.

    1967-01-01

    The present status of research on discrimination of natural and cultivated vegetation using radar imaging systems is sketched. The value of multiple polarization radar in improved discrimination of vegetation types over monoscopic radars is also documented. Possible future use of multi-frequency, multi-polarization radar systems for all weather agricultural survey is noted.

  17. Spaceborne meteorological radar studies

    NASA Technical Reports Server (NTRS)

    Meneghini, R.

    1988-01-01

    Various radar designs and methods are studied for the estimation of rainfall parameters from space. An immediate goal is to support the development of the spaceborne radar that has been proposed for the Tropical Rain Measuring Mission (TRMM). The effort is divided into two activities: a cooperative airborne rain measuring experiment with the Radio Research Laboratory of Japan (RRL), and the modelling of spaceborne weather radars. An airborne rain measuring experiment was conducted at Wallops Flight Facility in 1985 to 1986 using the dual-wavelength radar/radiometer developed by RRL. The data are presently being used to test a number of methods that are relevant to spaceborne weather radars. An example is shown of path-averaged rain rates as estimated from three methods: the standard reflectivity rain rate method (Z-R), a dual-wavelength method, and a surface reference method. The results from the experiment shows for the first time the feasibility of using attenuation methods from space. The purposes of the modelling are twofold: to understand in a quantitative manner the relationships between a particular radar design and its capability for estimating precipitation parameters and to help devise and test new methods. The models are being used to study the impact of various TRMM radar designs on the accuracy of rain rate estimation as well as to test the performance of range-profiling algorithms, the mirror-image method, and some recently devised graphical methods for the estimation of the drop size distribution.

  18. Radar applications overview

    NASA Astrophysics Data System (ADS)

    Greenspan, Marshall

    1996-06-01

    During the fifty years since its initial development as a means of providing early warning of airborne attacks against allied countries during World War II, radar systems have developed to the point of being highly mobile and versatile systems capable of supporting a wide variety of remote sensing applications. Instead of being tied to stationary land-based sites, radar systems have found their way into highly mobile land vehicles as well as into aircraft, missiles, and ships of all sizes. Of all these applications, however, the most exciting revolution has occurred in the airborne platform arena where advanced technology radars can be found in all shapes and sizes...ranging from the large AWACS and Joint STARS long range surveillance and targeting systems to small millimeter wave multi-spectral sensors on smart weapons that can detect and identify their targets through the use of highly sophisticated digital signal processing hardware and software. This paper presents an overview of these radar applications with the emphasis on modern airborne sensors that span the RF spectrum. It will identify and describe the factors that influence the parameters of low frequency and ultra wide band radars designed to penetrate ground and dense foliage environments and locate within them buried mines, enemy armor, and other concealed or camouflaged weapons of war. It will similarly examine the factors that lead to the development of airborne radar systems that support long range extended endurance airborne surveillance platforms designed to detect and precision-located both small high speed airborne threats as well as highly mobile time critical moving and stationary surface vehicles. The mission needs and associated radar design impacts will be contrasted with those of radar systems designed for high maneuverability rapid acquisition tactical strike warfare platforms, and shorter range cued air-to-surface weapons with integral smart radar sensors.

  19. Radar frequency radiation

    NASA Astrophysics Data System (ADS)

    Malowicki, E.

    1981-11-01

    A method is presented for the determination of radar frequency radiation power densities that the PAVE PAWS radar system could produce in its air and ground environment. The effort was prompted by the concern of the people in the vicinity of OTIS AFB MA and BEALE AFB CA about the possible radar frequency radiation hazard of the PAVE PAWS radar. The method is based on the following main assumptions that: (a) the total field can be computed as the vector summation of the individual fields due to each antenna element; (b) the individual field can be calculated using distances for which the field point is in the far field of the antenna element. An RFR computer program was coded for the RADC HE 6180 digital computer and exercised to calculate the radiation levels in the air and ground space for the present baseline and the possible Six DB and 10 DB growth systems of the PAVE PAWS radar system at OTIS AFB MA. The average radiation levels due to the surveillance fence were computed for three regions: in the air space in front of the radar, at the radar hazard fence at OTIS AFB MA and at representative ground points in the OTIS AFB vicinity. It was concluded that the radar frequency radiation of PAVE PAWS does not present a hazard to personnel provided there is no entry to the air hazard zone or to the area within the hazard fence. The method developed offers a cost effective way to determine radiation levels from a phased array radar especially in the near field and transition regions.

  20. Radar investigation of asteroids

    NASA Technical Reports Server (NTRS)

    Ostro, S. J.

    1981-01-01

    Software to support all stages of asteroid radar observation and data analysis is developed. First-order analysis of all data in hand is complete. Estimates of radar cross sections, circular polarization ratios, and limb-to-limb echo spectral bandwidths for asteroids 7 Iris, 16 Psyche, 97 Klotho, 1862 Apollo, and 1915 Quetzalcoatl are reported. Radar observations of two previously unobserved asteroids were conducted. An Aten asteroid, 2100 Ra-Shalom, with the smallest known semimajor axis (0.83) was detected. Preliminary data reduction indicates a circular polarization ratio comparable to those of Apollo, Quetzalcoatl, and Toro.

  1. Radar investigation of asteroids

    NASA Technical Reports Server (NTRS)

    Ostro, S. J.

    1984-01-01

    The initial radar observations of the mainbelt asteroids 9 Metis, 27 Euterpe, and 60 Echo are examined. For each target, data are taken simultaneously in the same sense of circular polarization as transmitted as well as in the opposite (OC) sense. Estimates of the radar cross sections provide estimates of the circular polarization ratio, and the normalized OC radar cross section. The circular polarization ratio, is comparable to values measured for other large S type asteroids and for a few much smaller, Earth approaching objects, most of the echo is due to single reflection backscattering from smooth surface elements.

  2. Radar investigation of asteroids

    NASA Astrophysics Data System (ADS)

    Ostro, S. J.

    1981-11-01

    Software to support all stages of asteroid radar observation and data analysis is developed. First-order analysis of all data in hand is complete. Estimates of radar cross sections, circular polarization ratios, and limb-to-limb echo spectral bandwidths for asteroids 7 Iris, 16 Psyche, 97 Klotho, 1862 Apollo, and 1915 Quetzalcoatl are reported. Radar observations of two previously unobserved asteroids were conducted. An Aten asteroid, 2100 Ra-Shalom, with the smallest known semimajor axis (0.83) was detected. Preliminary data reduction indicates a circular polarization ratio comparable to those of Apollo, Quetzalcoatl, and Toro.

  3. Radar Remote Sensing

    NASA Technical Reports Server (NTRS)

    Rosen, Paul A.

    2012-01-01

    This lecture was just a taste of radar remote sensing techniques and applications. Other important areas include Stereo radar grammetry. PolInSAR for volumetric structure mapping. Agricultural monitoring, soil moisture, ice-mapping, etc. The broad range of sensor types, frequencies of observation and availability of sensors have enabled radar sensors to make significant contributions in a wide area of earth and planetary remote sensing sciences. The range of applications, both qualitative and quantitative, continue to expand with each new generation of sensors.

  4. Radar investigation of asteroids

    NASA Technical Reports Server (NTRS)

    Ostro, S. J.

    1981-01-01

    Efforts were focused on: (1) acquisition of radar data at Arecibo; (2) examination of raw data; (3) reduction of the unmodulated data to background-free, calibrated spectra; (4) integration and coherent analyses of the phase-coded data; and (5) calculation of Doppler shifts and preliminary values for echo limb-to-limb bandwidths, radar cross sections, and circular polarization ratios. Asteroids observed to data have radar properties distinct from those of the rocky terrestrial planets and those of the icy Galilean satellites.

  5. EISCAT Svalbard radar

    NASA Astrophysics Data System (ADS)

    Lehtinen, Markku; Kangas, Jorma

    1992-02-01

    The main fields of interest of the Finnish scientists in EISCAT research are listed. Finnish interests in the Polar Cap Radar (PMR) and areas where the Finnish contribution could be important are addressed: radar techniques; sporadic E layers in the polar cap; atmospheric models; auroral studies in the polar cap; nonthermal plasmas in the F region; coordinated measurements with the Cluster satellites; studies of the ionospheric traveling; convection vortices; polar cap absorption; studies of lower atmosphere; educational program. A report on the design specification of an ionospheric and atmospheric radar facility based on the archipelago of Svalbard (Norway) is summarized.

  6. Asteroid radar astrometry

    NASA Technical Reports Server (NTRS)

    Ostro, S. J.; Jurgens, R. F.; Rosema, K. D.; Winkler, R.; Yeomans, D. K.; Campbell, D. B.; Chandler, J. F.; Shapiro, I. I.; Hine, A. A.; Velez, R.

    1991-01-01

    Measurements of time delay and Doppler frequency are reported for asteroid-radar echoes obtained at Arecibo and Goldstone during 1980-1990. Radar astrometry is presented for 23 near-earth asteroids and three mainbelt asteroids. These measurements, which are orthogonal to optical, angular-position measurements, and typically have a fractional precision between 10 to the -5th and 10 to the -8th, permit significant improvement in estimates of orbits and hence in the accuracy of prediction ephemerides. Estimates are also reported of radar cross-section and circular polarization ratio for all asteroids observed astrometrically during 1980-1990.

  7. A microprogrammable radar controller

    NASA Technical Reports Server (NTRS)

    Law, D. C.

    1986-01-01

    The Wave Propagation Lab. has completed the design and construction of a microprogrammable radar controller for atmospheric wind profiling. Unlike some radar controllers using state machines or hardwired logic for radar timing, this design is a high speed programmable sequencer with signal processing resources. A block diagram of the device is shown. The device is a single 8 1/2 inch by 10 1/2 inch printed circuit board and consists of three main subsections: (1) the host computer interface; (2) the microprogram sequencer; and (3) the signal processing circuitry. Each of these subsections are described in detail.

  8. Calculations of radar backscattering coefficient of vegetation-covered soils

    NASA Technical Reports Server (NTRS)

    Mo, T.; Schmugge, T. J.; Jackson, T. J. (Principal Investigator)

    1983-01-01

    A model for simulating the measured backscattering coefficient of vegetation-covered soil surfaces includes both coherent and incoherent components of the backscattered radar pulses from a rough sil surface. The effect of vegetation canopy scattering is also incorporated into the model by making the radar pulse subject to two-way attenuation and volume scattering when it passes through the vegetation layer. Model results agree well with the measured angular distributions of the radar backscattering coefficient for HH polarization at the 1.6 GHz and 4.75 GHz frequencies over grass-covered fields. It was found that the coherent scattering component is very important at angles near nadir, while the vegetation volume scattering is dominant at incident angles 30 degrees.

  9. Micro-Doppler processing for ultra-wideband radar data

    NASA Astrophysics Data System (ADS)

    Smith, Graeme E.; Ahmad, Fauzia; Amin, Moeness G.

    2012-06-01

    In this paper, we describe an operational pulse Doppler radar imaging system for indoor target localization and classification, and show how a target's micro-Doppler signature (μDS) can be processed when ultra-wideband (UWB) waveforms are employed. Unlike narrowband radars where time-frequency signal representations can be applied to reveal the target time-Doppler frequency signatures, the UWB system permits joint range-time-frequency representation (JRTFR). JRTFR outputs the data in a 3D domain representing range, frequency, and time, allowing both the μDS and high range resolution (HRR) signatures to be observed. We delineate the relationship between the μDS and the HRR signature, showing how they would form a complimentary joint feature for classification. We use real-data to demonstrate the effectiveness of the UWB pulse-Doppler radar, combined with nonstationary signal analyses, in gaining valuable insights into human positioning and motions.

  10. Development of Radar Control system for Multi-mode Active Phased Array Radar for atmospheric probing

    NASA Astrophysics Data System (ADS)

    Yasodha, Polisetti; Jayaraman, Achuthan; Thriveni, A.

    2016-07-01

    TR modules, (ii) radar operation software which facilitates experimental parameter setting and operating the radar in different modes, (iii) beam steering software which computes the amplitude co-efficients and phases required for each TR module, for forming the beams selected for radar operation with the desired shape and (iv) Calibration software for calibrating the radar by measuring the differential insertion phase and amplitudes in all 1024 Transmit and Receive paths and correcting them. The TR module configuring software is a major task as it needs to control 1024 TR modules, which are located in the field about 150 m away from the RC system in the control room. Each TR module has a processor identified with a dedicated IP address, along with memory to store the instructions and parameters required for radar operation. A communication link is designed using Gigabit Ethernet (GbE) switches to realise 1 to 1024 way switching network. RC system computer communicates with the each processor using its IP address and establishes connection, via 1 to 1024 port GbE switching network. The experimental parameters data are pre-loaded parallely into all the TR modules along with the phase shifter data required for beam steering using this network. A reference timing pulse is sent to all the TR modules simultaneously, which indicates the start of radar operation. RC system also monitors the status parameters from the TR modules indicating their health during radar operation at regular intervals, via GbE switching network. Beam steering software generates the phase shift required for each TR module for the beams selected for operation. Radar operational software calls the phase shift data required for beam steering and adds it to the calibration phase obtained through calibration software and loads the resultant phase data into TR modules. Timed command/data transfer to/from subsystems and synchronisation of subsystems is essential for proper real-time operation of the

  11. River discharge measurements by using helicopter-mounted radar

    USGS Publications Warehouse

    Melcher, N.B.; Costa, J.E.; Haeni, F.P.; Cheng, R.T.; Thurman, E.M.; Buursink, M.; Spicer, K.R.; Hayes, E.; Plant, W.J.; Keller, W.C.; Hayes, K.

    2002-01-01

    The United States Geological Survey and the University of Washington collaborated on a series of initial experiments on the Lewis, Toutle, and Cowlitz Rivers during September 2000 and a detailed experiment on the Cowlitz River during May 2001 to determine the feasibility of using helicopter-mounted radar to measure river discharge. Surface velocities were measured using a pulsed Doppler radar, and river depth was measured using ground-penetrating radar. Surface velocities were converted to mean velocities, and horizontal registration of both velocity and depth measurements enabled the calculation of river discharge. The magnitude of the uncertainty in velocity and depth indicate that the method error is in the range of 5 percent. The results of this experiment indicate that helicopter-mounted radar can make the rapid, accurate discharge measurements that are needed in remote locations and during regional floods.

  12. Phase correlator reduces mm-wave radar cost

    NASA Astrophysics Data System (ADS)

    Weiss, R., Sr.; Hobbs, P.; Locatelli, J.

    1986-03-01

    A technique involving the IC storage of magnetron phase for reference has been developed to make possible the use of the low-cost efficient magnetron in obtaining phase coherent signals for pulse Doppler radar. In the new external coherence method, the recorded random midpulse-region phase is compared with the frequency of the echo allowing Doppler information, free of phase noise, to be extracted. The gated magnetron was tested at Ka-band in a 35-GHz radar, and good agreement with the CP-4 5.5 GHz radar was shown. With good accuracy down to 10 cm/s, the present system, especially in the mm-wave region, has important applications to meteorological and military radar.

  13. Complementary Waveforms for Sidelobe Suppression and Radar Polarimetry

    DTIC Science & Technology

    2010-01-01

    at all delays other than zero. Almost a decade after their invention, Welti rediscovered complementary sequences (there are his D-codes) [6] and... Welti , “Quaternary codes for pulsed radar,” IRE Trans. Inform. Theory, vol. IT-6, no. 3, pp. 400–408, June 1960. [7] M. R. Ducoff and B. W. Tietjen

  14. Study of an airborne Doppler radar: Project Asterix

    NASA Astrophysics Data System (ADS)

    Testud, Jacques; Baudin, F.; Amayenc, P.

    Specifications for an airborne Doppler radar for meteorological applications are given. The following areas are covered: (1) principle for measuring three-dimensional speed field; (2) pulse pattern and detectability; (3) antenna; (4) processing of data; (5) analog system; (6) data control and recording; (7) attitude control and vibrations; and (8) logistics.

  15. Study to investigate and evaluate means of optimizing the radar function for the space shuttle

    NASA Technical Reports Server (NTRS)

    1976-01-01

    A detailed analysis of the spiral scan was performed for antenna sizes ranging from 20 inches to 36 inches in diameter and for search angles characteristic of both the radar and the communication acquisition modes. The power budgets for passive target radar detection were calculated for antenna diameters ranging from 20 to 36 inches. Dwell times commensurate with spiral scan were used for these budget calculations. The signal design for the candidate pulse Doppler system is summarized. Ground return analysis carried out for the passive target radar mode is examined, and the details are presented. A concluding description of the proposed candidate radar/communication system configuration is given.

  16. Studies on Radar Sensor Networks

    DTIC Science & Technology

    2007-08-08

    through-foliage target detection using UWB radar sensor network based on real-world data; 2. Foliage clutter modeling using UWB radars; 3. Outdoor UWB...channel modeling based on field data; 4. Multi-target detection using radar sensor networks (theoretical studies); 5. SVD-QR and graph theory for MIMO...Foliage clutter modeling using UWB radars; 3. Outdoor UWB channel modeling based on field data; 4. Multi-target detection using radar sensor networks

  17. Space radar image of New York City

    NASA Technical Reports Server (NTRS)

    1995-01-01

    This radar image of the New York city metropolitan area. The island of Manhattan appears in the center of the image. The green-colored rectangle on Manhattan is Central Park. This image was acquired by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/ X-SAR) aboard the space shuttle Endeavour on October 10, 1994. North is toward the upper right. The area shown is 75.0 kilometers by 48.8 kilometers (46.5 miles by 30.2 miles). The image is centered at 40.7 degrees north latitude and 73.8 degrees west longitude. In general, light blue areas correspond to dense urban development, green areas to moderately vegetated zones and black areas to bodies of water. The Hudson River is the black strip that runs from the left edge to the upper right corner of the image. It separates New Jersey, in the upper left of the image, from New York. The Atlantic Ocean is at the bottom of the image where two barrier islands along the southern shore of Long Island are also visible. John F. Kennedy International Airport is visible above these islands. Long Island Sound, separating Long Island from Connecticut, is the dark area right of the center of the image. Many bridges are visible in the image, including the Verrazano Narrows, George Washington and Brooklyn bridges. The radar illumination is from the left of the image; this causes some urban zones to appear red because the streets are at a perpendicular angle to the radar pulse. The colors in this image were obtained using the following radar channels: red represents the L-band (horizontally transmitted and received); green represents the L-band (horizontally transmitted, vertically received); blue represents the C-band (horizontally transmitted, vertically received). Radar images like this one could be used as a tool for city planners and resource managers to map and monitor land use patterns. The radar imaging systems can clearly detect the variety of landscapes in the area, as well as the density of urban

  18. Space radar image of New York City

    NASA Technical Reports Server (NTRS)

    1995-01-01

    This radar image of the New York city metropolitan area. The island of Manhattan appears in the center of the image. The green-colored rectangle on Manhattan is Central Park. This image was acquired by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/ X-SAR) aboard the space shuttle Endeavour on October 10, 1994. North is toward the upper right. The area shown is 75.0 kilometers by 48.8 kilometers (46.5 miles by 30.2 miles). The image is centered at 40.7 degrees north latitude and 73.8 degrees west longitude. In general, light blue areas correspond to dense urban development, green areas to moderately vegetated zones and black areas to bodies of water. The Hudson River is the black strip that runs from the left edge to the upper right corner of the image. It separates New Jersey, in the upper left of the image, from New York. The Atlantic Ocean is at the bottom of the image where two barrier islands along the southern shore of Long Island are also visible. John F. Kennedy International Airport is visible above these islands. Long Island Sound, separating Long Island from Connecticut, is the dark area right of the center of the image. Many bridges are visible in the image, including the Verrazano Narrows, George Washington and Brooklyn bridges. The radar illumination is from the left of the image; this causes some urban zones to appear red because the streets are at a perpendicular angle to the radar pulse. The colors in this image were obtained using the following radar channels: red represents the L-band (horizontally transmitted and received); green represents the L-band (horizontally transmitted, vertically received); blue represents the C-band (horizontally transmitted, vertically received). Radar images like this one could be used as a tool for city planners and resource managers to map and monitor land use patterns. The radar imaging systems can clearly detect the variety of landscapes in the area, as well as the density of urban

  19. Theoretical distribution of range data obtained by laser radar and its applications

    NASA Astrophysics Data System (ADS)

    Haijiao, Jiang; Jiancheng, Lai; Wei, Yan; Chunyong, Wang; Zhenhua, Li

    2013-02-01

    This paper addresses the distribution of range data obtained by laser radar. An analytical solution of the range distribution was obtained for direct detection laser radar using constant threshold discriminator based on the time-of-flight principle. The analytical solution was verified by experiments and simulations. The results show that the derived analytical function can describe the probability density distribution of the range data obtained by laser radar with a constant threshold discriminator. The probability density distribution of the range data is proportional to the probability density function of the noise and to the slope of the rising edge of the laser echo pulse. The probability density distributions of the range data obtained by laser radar with different pulse shapes, amplitudes, widths and thresholds are also presented. These factors are important for improvements in the design of laser radar systems.

  20. Laser Radar Animation

    NASA Image and Video Library

    Laser and radar instruments aboard NASA aircraft provide measurements of the snow and ice surface and down to the bedrock under the ice. Lasers, with a shorter wavelength, measure the surface eleva...

  1. Radar investigation of asteroids

    NASA Technical Reports Server (NTRS)

    Ostro, S. J.

    1983-01-01

    For 80 Sappho, 356 Liguria, 694 Ekard, and 2340 Hathor, data were taken simultaneously in the same sense of circular polarization as transmitted (SC) as well as in the opposite (OC) sense. Graphs show the average OC and SC radar echo power spectra soothed to a resolution of EFB Hz and plotted against Doppler frequency. Radar observations of the peculiar object 2201 Oljato reveal an unusual set of echo power spectra. The albedo and polarization ratio remain fairly constant but the bandwidths range from approximately 0.8 Hz to 1.4 Hz and the spectral shapes vary dramatically. Echo characteristics within any one date's approximately 2.5-hr observation period do not fluctuate very much. Laboratory measurements of the radar frequency electrical properties of particulate metal-plus-silicate mixtures can be combined with radar albedo estimates to constrain the bulk density and metal weight, fraction in a hypothetical asteroid regolith having the same particle size distribution as lab samples.

  2. Multispectral imaging radar

    NASA Technical Reports Server (NTRS)

    Porcello, L. J.; Rendleman, R. A.

    1972-01-01

    A side-looking radar, installed in a C-46 aircraft, was modified to provide it with an initial multispectral imaging capability. The radar is capable of radiating at either of two wavelengths, these being approximately 3 cm and 30 cm, with either horizontal or vertical polarization on each wavelength. Both the horizontally- and vertically-polarized components of the reflected signal can be observed for each wavelength/polarization transmitter configuration. At present, two-wavelength observation of a terrain region can be accomplished within the same day, but not with truly simultaneous observation on both wavelengths. A multiplex circuit to permit this simultaneous observation has been designed. A brief description of the modified radar system and its operating parameters is presented. Emphasis is then placed on initial flight test data and preliminary interpretation. Some considerations pertinent to the calibration of such radars are presented in passing.

  3. Proof of Concept: Development of Snow Liquid Water Content Profiler Using CS650 Reflectometers at Caribou, ME, USA

    PubMed Central

    Pérez Díaz, Carlos L.; Muñoz, Jonathan; Lakhankar, Tarendra; Khanbilvardi, Reza; Romanov, Peter

    2017-01-01

    The quantity of liquid water in the snowpack defines its wetness. The temporal evolution of snow wetness’s plays a significant role in wet-snow avalanche prediction, meltwater release, and water availability estimations and assessments within a river basin. However, it remains a difficult task and a demanding issue to measure the snowpack’s liquid water content (LWC) and its temporal evolution with conventional in situ techniques. We propose an approach based on the use of time-domain reflectometry (TDR) and CS650 soil water content reflectometers to measure the snowpack’s LWC and temperature profiles. For this purpose, we created an easily-applicable, low-cost, automated, and continuous LWC profiling instrument using reflectometers at the Cooperative Remote Sensing Science and Technology Center-Snow Analysis and Field Experiment (CREST-SAFE) in Caribou, ME, USA, and tested it during the snow melt period (February–April) immediately after installation in 2014. Snow Thermal Model (SNTHERM) LWC simulations forced with CREST-SAFE meteorological data were used to evaluate the accuracy of the instrument. Results showed overall good agreement, but clearly indicated inaccuracy under wet snow conditions. For this reason, we present two (for dry and wet snow) statistical relationships between snow LWC and dielectric permittivity similar to Topp’s equation for the LWC of mineral soils. These equations were validated using CREST-SAFE in situ data from winter 2015. Results displayed high agreement when compared to LWC estimates obtained using empirical formulas developed in previous studies, and minor improvement over wet snow LWC estimates. Additionally, the equations seemed to be able to capture the snowpack state (i.e., onset of melt, medium, and maximum saturation). Lastly, field test results show advantages, such as: automated, continuous measurements, the temperature profiling of the snowpack, and the possible categorization of its state. However, future work

  4. Proof of Concept: Development of Snow Liquid Water Content Profiler Using CS650 Reflectometers at Caribou, ME, USA.

    PubMed

    Pérez Díaz, Carlos L; Muñoz, Jonathan; Lakhankar, Tarendra; Khanbilvardi, Reza; Romanov, Peter

    2017-03-21

    The quantity of liquid water in the snowpack defines its wetness. The temporal evolution of snow wetness's plays a significant role in wet-snow avalanche prediction, meltwater release, and water availability estimations and assessments within a river basin. However, it remains a difficult task and a demanding issue to measure the snowpack's liquid water content (LWC) and its temporal evolution with conventional in situ techniques. We propose an approach based on the use of time-domain reflectometry (TDR) and CS650 soil water content reflectometers to measure the snowpack's LWC and temperature profiles. For this purpose, we created an easily-applicable, low-cost, automated, and continuous LWC profiling instrument using reflectometers at the Cooperative Remote Sensing Science and Technology Center-Snow Analysis and Field Experiment (CREST-SAFE) in Caribou, ME, USA, and tested it during the snow melt period (February-April) immediately after installation in 2014. Snow Thermal Model (SNTHERM) LWC simulations forced with CREST-SAFE meteorological data were used to evaluate the accuracy of the instrument. Results showed overall good agreement, but clearly indicated inaccuracy under wet snow conditions. For this reason, we present two (for dry and wet snow) statistical relationships between snow LWC and dielectric permittivity similar to Topp's equation for the LWC of mineral soils. These equations were validated using CREST-SAFE in situ data from winter 2015. Results displayed high agreement when compared to LWC estimates obtained using empirical formulas developed in previous studies, and minor improvement over wet snow LWC estimates. Additionally, the equations seemed to be able to capture the snowpack state (i.e., onset of melt, medium, and maximum saturation). Lastly, field test results show advantages, such as: automated, continuous measurements, the temperature profiling of the snowpack, and the possible categorization of its state. However, future work should

  5. Statistical MIMO Radar

    DTIC Science & Technology

    2004-12-20

    improve the radar’s performance. MIMO radar utilizes multiple antennas at both the transmitter and receiver. It can be applied in monostatic or bistatic...signal at the output of the beamformer equals , , HE t x y x y t t M E y t x y x M r a b s n a b        20y s t n t S- MIMO Radar

  6. Active radar stealth device

    NASA Astrophysics Data System (ADS)

    Cain, R. N.; Corda, Albert J.

    1991-07-01

    This patent discloses an active radar stealth device mounted on a host platform for minimizing the radar cross-section of the host platform. A coating which is essentially microwave transparent is attached to the surface of a host platform and is exposed to an incident microwave field. A plurality of detector/emitter pairs contained within the coating detect and actively cancel, respectively, the microwave field at each respective detector/emitter pair.

  7. Airborne MIMO GMTI Radar

    DTIC Science & Technology

    2011-03-31

    applications [1], [2], [3], [4]. [5]. [6]. [7]. [8]. [9]. [10]. [11]. [12]. Conventional phased array radars form a single coherent transmit beam and...intentionally left blank. 1. INTRODUCTION Conventional phased - array radars form a single coherent transmit beam and measure the backscattered response... steering vector for a SI MO array with nr"/? receiver phase centers located at positions xm + y„. This is how the MIMO virtual array arises. The waveforms

  8. Radar Cross Section Measurements

    DTIC Science & Technology

    1986-09-30

    Radar 54 17. Measured Range Sidelobe Performance of Chirp Radar 56 18. Range and Cross Range Image of Target Dror.’ŕ Vehicle 57 19. Incoherent rms...the measured range resolution, 4.9 in, closely agrees with the theoretical performance for this weighting. The measured range sidelobe performance...Interval 4.89in. 2% kHz 300 kHz 310 kHz (b) Expanded Scale + 5 ft from Target Figure 17. Measured Range Sidelobe Performance of

  9. Cassini Radar hardware technologies

    SciTech Connect

    Wheeler, K.; Renick, P.

    1996-03-01

    The hardware development portion of the Cassini Radar task is complete. The flight model Digital Assembly and Energy Storage Assembly have been integrated and tested, as has the engineering/qualification model Radio Frequency Electronics Assembly. Integration of the flight model Radio Frequency Electronics Assembly is ready to begin. The intent of this paper is to describe some of the more interesting technologies implemented in the electronics to achieve the requirements of the Cassini Radar experiment. {copyright} {ital 1996 American Institute of Physics.}

  10. On wave radar measurement

    NASA Astrophysics Data System (ADS)

    Ewans, Kevin; Feld, Graham; Jonathan, Philip

    2014-09-01

    The SAAB REX WaveRadar sensor is widely used for platform-based wave measurement systems by the offshore oil and gas industry. It offers in situ surface elevation wave measurements at relatively low operational costs. Furthermore, there is adequate flexibility in sampling rates, allowing in principle sampling frequencies from 1 to 10 Hz, but with an angular microwave beam width of 10° and an implied ocean surface footprint in the order of metres, significant limitations on the spatial and temporal resolution might be expected. Indeed there are reports that the accuracy of the measurements from wave radars may not be as good as expected. We review the functionality of a WaveRadar using numerical simulations to better understand how WaveRadar estimates compare with known surface elevations. In addition, we review recent field measurements made with a WaveRadar set at the maximum sampling frequency, in the light of the expected functionality and the numerical simulations, and we include inter-comparisons between SAAB radars and buoy measurements for locations in the North Sea.

  11. Phase coded, micro-power impulse radar motion sensor

    DOEpatents

    McEwan, Thomas E.

    1996-01-01

    A motion sensing, micro-power impulse radar MIR impresses on the transmitted signal, or the received pulse timing signal, one or more frequencies lower than the pulse repetition frequency, that become intermediate frequencies in a "IF homodyne" receiver. Thus, many advantages of classical RF receivers can be thereby be realized with ultra-wide band radar. The sensor includes a transmitter which transmits a sequence of electromagnetic pulses in response to a transmit timing signal at a nominal pulse repetition frequency. A receiver samples echoes of the sequence of electromagnetic pulses from objects within the field with controlled timing, in response to a receive timing signal, and generates a sample signal in response to the samples. A timing circuit supplies the transmit timing signal to the transmitter and supplies the receive timing signal to the receiver. The relative timing of the transmit timing signal and the receive timing signal is modulated between a first relative delay and a second relative delay at an intermediate frequency, causing the receiver to sample the echoes such that the time between transmissions of pulses in the sequence and samples by the receiver is modulated at the intermediate frequency. Modulation may be executed by modulating the pulse repetition frequency which drives the transmitter, by modulating the delay circuitry which controls the relative timing of the sample strobe, or by modulating amplitude of the transmitted pulses. The electromagnetic pulses will have a nominal center frequency related to pulse width, and the first relative delay and the second relative delay between which the timing signals are modulated, differ by less than the nominal pulse width, and preferably by about one-quarter wavelength at the nominal center frequency of the transmitted pulses.

  12. Phase coded, micro-power impulse radar motion sensor

    DOEpatents

    McEwan, T.E.

    1996-05-21

    A motion sensing, micro-power impulse radar MIR impresses on the transmitted signal, or the received pulse timing signal, one or more frequencies lower than the pulse repetition frequency, that become intermediate frequencies in a ``IF homodyne`` receiver. Thus, many advantages of classical RF receivers can be thereby be realized with ultra-wide band radar. The sensor includes a transmitter which transmits a sequence of electromagnetic pulses in response to a transmit timing signal at a nominal pulse repetition frequency. A receiver samples echoes of the sequence of electromagnetic pulses from objects within the field with controlled timing, in response to a receive timing signal, and generates a sample signal in response to the samples. A timing circuit supplies the transmit timing signal to the transmitter and supplies the receive timing signal to the receiver. The relative timing of the transmit timing signal and the receive timing signal is modulated between a first relative delay and a second relative delay at an intermediate frequency, causing the receiver to sample the echoes such that the time between transmissions of pulses in the sequence and samples by the receiver is modulated at the intermediate frequency. Modulation may be executed by modulating the pulse repetition frequency which drives the transmitter, by modulating the delay circuitry which controls the relative timing of the sample strobe, or by modulating amplitude of the transmitted pulses. The electromagnetic pulses will have a nominal center frequency related to pulse width, and the first relative delay and the second relative delay between which the timing signals are modulated, differ by less than the nominal pulse width, and preferably by about one-quarter wavelength at the nominal center frequency of the transmitted pulses. 5 figs.

  13. Radar Symposium, 7th, Universitaet Ulm, Federal Republic of Germany, Oct. 10-12, 1989, Reports

    NASA Astrophysics Data System (ADS)

    Baur, K.

    Various papers on radar are presented. Individual topics addressed include: aspects of long-wave radiation, future NATO identification systems, experimental X-band SAR, results of first tests of the ROSAR method, concept and results of the azimuth Quick-Look Processor for the SAR aircraft, specification of an inertial navigation system for experimental SAR, detection of slowly moving targets with airborne radar, fast method for disturbance-free two-dimensional ISAR imaging, development and optimization of a coastal radar system, determination of orientation accuracy in curving trajectories, radome structures for high-frequency applications. Also discussed are: monolithically integrated GaAs switching circuits for the millimeter wave range, new pulse compression methods for periodically phase-coded signal transmission, architectures of programmable radar signal processors, evaluation of the period length of periodic signals, interactive simulation system for multisensor systems, intelligent radar data processing, knowledge-based components of a tracking system, radar signatures of highly resolving millimeter wave sensors.

  14. Laser radar technology and applications; Proceedings of the Meeting, Quebec, Canada, June 3-5, 1986

    NASA Astrophysics Data System (ADS)

    Cruickshank, James M.; Harney, Robert C.

    1986-01-01

    Various papers on laser radar technology and applications are presented. The topics considered include: eye-safe solid lasers for lidar applications, practical DF laser for ranging applications, ultrafast surface barrier photodetectors, performance analyses for peak-detecting laser radars, multiple scattering for laser beams propagating in a layered atmosphere, laser radar cross section of objects immersed in the earth's atmosphere, measurements of pulse coherence in mode-locked TEA-CO2 lasers, and single longitudinal mode operation of a continuously tunable high pressure TE-CO2. Also discussed are: amplitude-modulated laser system for distance and displacement measurement, minilaser rangefinder, laser docking system radar flight experiment, improved optical resonator for laser radars, design of frequency-stable TEA-CO2 lasers, HgCdTe photodiodes for heterodyne applications, acoustooptic spectrum analyzer for laser radar applications, laser cloud mapper and its applications, scanning lidar bathymeter for water depth measurement, and fluorescence lidar for land and sea remote sensing.

  15. Radiometric calibration of the SwRI ultraviolet reflectance chamber (SwURC) far-ultraviolet reflectometer

    NASA Astrophysics Data System (ADS)

    Karnes, Preston L.; Retherford, Kurt D.; Winters, Gregory S.; Bassett, Eric C.; Escobedo, Stephen M.; Patrick, Edward L.; Richter, Amanda; Davis, Michael W.; Miles, Paul F.; Parker, Joel W.; Gladstone, G. Randall; Greathouse, Thomas K.; Schindhelm, Eric R.; Feaga, Lori M.; Stern, S. Alan

    2013-09-01

    The Southwest Research Institute Ultraviolet Reflectance Chamber (SwURC) is a highly capable UV reflectometer chamber and data acquisition system designed to provide bidirectional scattering data of various surfaces and materials. The chamber provides laboratory-based UV reflectance measurements of water frost/ice, lunar soils, simulants, and analogs to support interpretation of UV reflectance data from the Lyman Alpha Mapping Project (LAMP) Lunar Reconnaissance Orbiter (LRO). A deuterium lamp illuminates a monochromator with a nominal wavelength range of 115 nm to 210 nm. The detector scans emission angles -85° to +85°in the principal plane. Liquid nitrogen passed through the sample mount enables constant refrigeration of tray temperatures down to 78 K to form water ice and other volatile samples. The SwURC can be configured to examine a wide range of samples and materials through the use of custom removable sample trays, connectors, and holders. Calibration reference standard measurements reported here include Al/MgF2 coated mirrors for specular reflection and Fluorilon for diffuse reflectances. This calibration work is a precursor to reports of experiments measuring the far-UV reflectance of water frost, lunar simulants, and Apollo soil sample 10084 in support of LRO-LAMP.

  16. BioRef: a versatile time-of-flight reflectometer for soft matter applications at Helmholtz-Zentrum Berlin.

    PubMed

    Strobl, M; Steitz, R; Kreuzer, M; Rose, M; Herrlich, H; Mezei, F; Grunze, M; Dahint, R

    2011-05-01

    BioRef is a versatile novel time-of-flight reflectometer featuring a sample environment for in situ infrared spectroscopy at the reactor neutron source BER II of the Helmholtz Zentrum Berlin für Materialien und Energie (HZB). After two years of design and construction phase the instrument has recently undergone commissioning and is now available for specular and off-specular neutron reflectivity measurements. BioRef is especially dedicated to the investigation of soft matter systems and studies at the solid-liquid interface. Due to flexible resolution modes and variable addressable wavelength bands that allow for focusing onto a selected scattering vector range, BioRef enables a broad range of surface and interface investigations and even kinetic studies with subsecond time resolution. The instrumental settings can be tailored to the specific requirements of a wide range of applications. The performance is demonstrated by several reference measurements, and the unique option of in situ on-board infrared spectroscopy is illustrated by the example of a phase transition study in a lipid multilayer film.

  17. Strain measurement using a Brillouin optical time domain reflectometer for development of aircraft structure health monitoring system

    NASA Astrophysics Data System (ADS)

    Shimizu, Takayuki; Yari, Takashi; Nagai, Kanehiro; Takeda, Nobuo

    2001-07-01

    We conducted theoretical and experimental approaches for applying Brillouin optical time domain reflectometer (BOTDR) to aircraft and spacecraft structure health monitoring system. Firstly, distributed strain was measured by BOTDR under 3-point bending test and a spatial resolution was enhanced up to 0.5m using Brillouin spectrum analysis and processing though the device used in this experiment had a spatial resolution of 2m normally. Secondly, dynamic strain measurement was executed under cyclic loading conditions. Brillouin spectrum measured under dynamic conditions is equivalent to superposed spectrum using many spectra measured under static loading conditions. As the measured spectrum was decomposed into many spectra in static loading state, the strain amplitude and its ratio could be estimated. Thirdly, strain and temperature could be measured independently using combined system of BOTDR and fiber Bragg grating (FBG) with wavelength division multiplexing (WDM). Additionally, the application of BOTDR sensing system was shown for a prototype carbon fiber reinforced plastic (CFRP) liquid hydrogen (LH2) tank under cryogenic condition.

  18. Evaluating the thermal stability of multi-pass cells' effective optical path length using optical frequency domain reflectometer

    NASA Astrophysics Data System (ADS)

    Gao, Hong; Cao, Xiuhan; Li, Jinyi; Du, Zhenhui

    2016-10-01

    Multi-pass cells (MPCs) are commonly used to improve the sensitivity for trace gas detection using spectroscopy technologies. The determination of Effective Optical Path Length (EOPL) of a MPC is very important and challenging in applications which aim at absolute measurements. It is well-known that the temperature changing will exercise some influence on the MPCs' spatial structure, however, measurements of the influence haven't been reported which might due to the limitation of measuring method. In this paper, we used a direct high-precision measuring method with Optical Frequency Domain Reflectometer (OFDR) to evaluate the thermal stability of a multi-pass cell. To simulate the environment with a large range of temperature changing, this paper gave a series of experiments by setting the temperature control unit in system from 25 to 175 degree Celsius, and the MPC's EOPL was measured simultaneously for the investigation of temperature response. The results showed that the effective optical path length increase monotonically along with the variation of the temperature, and the rising rate is 0.5 mm/ºC with the total length of about 3 meters which should be pay attention to when the ultra-high accuracy results are demanded. To stabilize the EOPL of the system, if it is possible, the environment temperature of gas cell can be controlled with a constant temperature. In practical applications, the real-time monitoring of EOPL with a direct measuring method may be necessary.

  19. Satellite radar altimeters - Present and future oceanographic capabilities

    NASA Technical Reports Server (NTRS)

    Townsend, W. F.; Mcgoogan, J. T.; Walsh, E. J.

    1981-01-01

    Satellite radar altimeters have the ability to provide information related to ocean wave heights, wind speed, and currents. The present investigation has the objective to demonstrate the current capabilities and to indicate ways to increase the information content of the altimeter return through the use of wider bandwidth, higher pulse repetition frequencies (PRF), and multibeam. Altimeters aboard Skylab, Geos-3, and Seasat-1 have provided investigators with valuable experience in translating the radar observables into oceanic parameters. Basically, an altimeter transmits a narrow pulse and measures the time interval until the return energy from the ocean surface is received. That direct measure of the satellite altitude can be interpreted in terms of surface topography. Attention is given to altimeter oceanographic measurements, altimeter return pulse characteristics, satellite pointing and surface slopes, the adaptive tracker for terrain mapping, and a multibeam altimeter.

  20. Can Compressed Sensing Be Applied To Dual-Polarimetric Weather Radars?

    NASA Astrophysics Data System (ADS)

    Mishra, K.; Kruger, A.; Krajewski, W. F.

    2013-12-01

    The recovery of sparsely-sampled signals has long attracted considerable research interest in various fields such as reflection seismology, microscopy, and astronomy. Recently, such recovery techniques have been formalized as a sampling method called compressed sensing (CS) which uses few linear and non-adaptive measurements to reconstruct a signal that is sparse in a known domain. Many radar and remote sensing applications require efficient and rapid data acquisition. CS techniques have, therefore, enormous potential in dramatically changing the way the radar samples and processes data. A number of recent studies have investigated CS for radar applications with emphasis on point target radars, and synthetic aperture radar (SAR) imaging. CS radar holds the promise of compressing-while-sampling, and may yield simpler receiver hardware which uses low-rate ADCs and eliminates pulse compression/matched filter. The need of fewer measurements also implies that a CS radar may need smaller dwell times without significant loss of information. Finally, CS radar data could be used for improving the quality of low-resolution radar observations. In this study, we explore the feasibility of using CS for dual-polarimetric weather radars. In order to recover a signal in CS framework, two conditions must be satisfied: sparsity and incoherence. The sparsity of weather radar measurements can be modeled in several domains such as time, frequency, joint time-frequency domain, or polarimetric measurement domains. The condition of incoherence relates to the measurement process which, in a radar scenario, would imply designing an incoherent transmit waveform or an equivalent scanning strategy with an existing waveform. In this study, we formulate a sparse signal model for precipitation targets as observed by a polarimetric weather radar. The applicability of CS for such a signal model is then examined through simulations of incoherent measurements along with real weather data obtained

  1. 66. VIEW SHOWING HOLD FOR RADAR CABLES AT RADAR SITE, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    66. VIEW SHOWING HOLD FOR RADAR CABLES AT RADAR SITE, LOOKING NORTH Everett Weinreb, photographer, March 1988 - Mount Gleason Nike Missile Site, Angeles National Forest, South of Soledad Canyon, Sylmar, Los Angeles County, CA

  2. Interdisciplinary Earth Science Applications Using Satellite Radar Altimetry

    NASA Astrophysics Data System (ADS)

    Kuo, C.; Shum, C.; Lee, H.; Dai, C.; Yi, Y.

    2012-12-01

    Satellite altimetry was conceived as a space geodetic concept for ocean surface topography mapping in the NASA-sponsored 1969 Williamstown, MA Conference, and was tested as part of the passive and active radar payload (S192), along with a radiometer and a scatterometer, on Skylab-1 in May 14, 1973. Since then, numerous radar and laser satellite altimetry missions orbiting/flying-by the Earth, Mars, Mercury, Titan and the Moon have been launched, evolving from the original scientific objective of marine gravity field mapping to a geodetic tool to address interdisciplinary Earth and planetary sciences. The accuracy of the radar altimeter has improved from 0.9 m RMS for the S-192 Skylab Ku-band compressed-pulse altimeter, to 2 cm RMS (2 second average) for the dual-frequency pulse-limited radar altimetry and associated sensors onboard TOPEX/POSEIDON. Satellite altimetry has evolved into a unique cross-disciplinary geodetic tool in addressing contemporary Earth science problems including sea-level rise, large-scale general ocean circulation, ice-sheet mass balance, terrestrial hydrology, and bathymetry. Here we provide a concise review and describe specific results on the additional recent innovative and unconventional applications of interdisciplinary science research using satellite radar altimetry, including geodynamics, land subsidence, snow depth, wetland and cold region hydrology.

  3. Packet radar spectrum recovery for physiological signals.

    PubMed

    Yavari, Ehsan; Padasdao, Bryson; Lubecke, Victor; Boric-Lubecke, Olga

    2013-01-01

    Packet Doppler radar is investigated for extracting physiological signals. System on Chip is employed as a signal source in packet mode, and it transmits signals intermittently at 2.405 GHz to save power. Reflected signals are demodulated directly by spectral analysis of received pulses in the baseband. Spectral subtraction, using data from an empty room, is applied to extract the periodic movement. It was experimentally demonstrated that frequency of the periodic motion can be accurately extracted using this technique. Proposed approach reduces the computation complexity of the signal processing part effectively.

  4. WEATHER RADAR RESEARCH AND STORM DYNAMICS.

    DTIC Science & Technology

    METEOROLOGICAL RADAR, STORMS), (*WEATHER FORECASTING, METEOROLOGICAL RADAR), (*STORMS, BIBLIOGRAPHIES), TORNADOES , CYCLONES, METEOROLOGY, ATMOSPHERIC PRECIPITATION, RAINFALL, WIND, TROPICAL CYCLONES, HAIL

  5. PULSE SORTER

    DOEpatents

    Wade, E.J.

    1958-07-29

    An apparatus is described for counting and recording the number of electrical pulses occurring in each of a timed sequence of groups of pulses. The particular feature of the invention resides in a novel timing circuit of the univibrator type which provides very accurately timed pulses for opening each of a series of coincidence channels in sequence. The univibrator is shown incorporated in a pulse analyzing system wherein a series of pulse counting channels are periodically opened in order, one at a time, for a predetermtned open time interval, so that only one channel will be open at the time of occurrence of any of the electrical pulses to be sorted.

  6. A barrier radar concept

    NASA Astrophysics Data System (ADS)

    Marshall, J.; Ball, C.; Weissman, I.

    A description is given of a low power, light-weight radar that can be quickly set up and operated on batteries for extended periods of time to detect airborne intruders. With low equipment and operating costs, it becomes practical to employ a multiplicity of such radars to provide an unbroken intrusion fence over the desired perimeter. Each radar establishes a single transmitted fan beam extending vertically from horizon to horizon. The beam is generated by a two-face array antenna built in an A-frame configuration and is shaped, through phasing of the array elements, to concentrate the transmitter power in a manner consistent with the expected operating altitude ceiling of the targets of interest. The angular width of this beam in the dimension transverse to the fan depends on the radar transmission frequency and the antenna aperture dimension, but is typically wide enough so that a target at the maximum altitude or range will require tens of seconds to pass through the beam. A large number of independent samples of radar data will thus be available to provide many opportunities for target detection.

  7. Wind turbine impact on operational weather radar I/Q data: characterisation and filtering

    NASA Astrophysics Data System (ADS)

    Norin, Lars

    2017-05-01

    For the past 2 decades wind turbines have been growing in number all over the world as a response to the increasing demand for renewable energy. However, the rapid expansion of wind turbines presents a problem for many radar systems, including weather radars. Wind turbines in the line of sight of a weather radar can have a negative impact on the radar's measurements. As weather radars are important instruments for meteorological offices, finding a way for wind turbines and weather radars to co-exist would be of great societal value.Doppler weather radars base their measurements on in-phase and quadrature phase (I/Q) data. In this work a month's worth of recordings of high-resolution I/Q data from an operational Swedish C-band weather radar are presented. The impact of point targets, such as masts and wind turbines, on the I/Q data is analysed and characterised. It is shown that the impact of point targets on single radar pulses, when normalised by amplitude, is manifested as a distinct and highly repeatable signature. The shape of this signature is found to be independent of the size, shape and yaw angle of the wind turbine. It is further demonstrated how the robustness of the point target signature can be used to identify and filter out the impact of wind turbines in the radar's signal processor.

  8. Gadanki Ionospheric Radar Interferometer (GIRI): System Description, Capabilities and Observations

    NASA Astrophysics Data System (ADS)

    Durga rao, Meka; Jayaraman, Achuthan; Patra, Amit; Kamaraj, Pandian; Jayaraj, Katta; Raghavendra, J.; Yasodha, Polisetti

    2016-07-01

    A 30-MHz radar has been developed at National Atmospheric Research Laboratory for dedicated probing of ionosphere and to study the low latitude ionospheric plasma irregularities. The radar has the beam steering capability to scan a larger part of the sky up to ±45o in East-West direction, which will overcome the limitation of slit camera picture obtained by the fixed beam of the Gadanki MST radar on the ionospheric plasma irregularity/structures. The system is also configured for pulse-to-pulse beam steering, employs multi-channel receiving system to carryout Interferometry/Imaging experiments. The radar system employs 20x8 phased antenna array, Direct Digital Synthesizers to generate pulse coded excitation signals, high power solid-state Transmit-Receive modules to generate a peak power of 150 kW, low loss coaxial beam forming and feeder network and multi-channel direct IF digital receiver. Round-the-clock observations are being made with uninterrupted operations and high quality E-and F-Region Range-Time-Intensity and conical maps are obtained with the system. In this paper we present, the system design philosophy, realization, initial observations and also the capability of the system to augment for Meteor observations.

  9. Coordinated Radar Resource Management for Networked Phased Array Radars

    DTIC Science & Technology

    2014-12-01

    Research and Development Canada Ottawa, Canada K1A 0Z4 Email: Peter.Moo@drdc-rddc.gc.ca Abstract A phased array radar has the ability to rapidly and...search and Development Canada (DRDC) Ottawa to analyse the performance of radar resource management techniques for naval radars operating in a littoral

  10. 33. Perimeter acquisition radar building room #320, perimeter acquisition radar ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    33. Perimeter acquisition radar building room #320, perimeter acquisition radar operations center (PAROC), contains the tactical command and control group equipment required to control the par site. Showing spacetrack monitor console - Stanley R. Mickelsen Safeguard Complex, Perimeter Acquisition Radar Building, Limited Access Area, between Limited Access Patrol Road & Service Road A, Nekoma, Cavalier County, ND

  11. Phase modulating the Urbana radar

    NASA Technical Reports Server (NTRS)

    Herrington, L. J., Jr.; Bowhill, S. A.

    1983-01-01

    The design and operation of a switched phase modulation system for the Urbana Radar System are discussed. The system is implemented and demonstrated using a simple procedure. The radar system and circuits are described and analyzed.

  12. Microwave and Pulsed Power

    SciTech Connect

    Freytag, E.K.

    1993-03-01

    The goals of the Microwave and Pulsed Power thrust area are to identify realizable research and development efforts and to conduct high-quality research in those pulse power and microwave technologies that support existing and emerging programmatic requirements at Lawrence Livermore National Laboratory (LLNL). Our main objective is to work on nationally important problems while enhancing our basic understanding of enabling technologies such as component design and testing, compact systems packaging, exploratory physics experiments, and advanced systems integration and performance. During FY-92, we concentrated our research efforts on the six project areas described in this report. (1) We are investigating the superior electronic and thermal properties of diamond that may make it an ideal material for a high-power, solid-state switch. (2) We are studying the feasibility of using advanced Ground Penetrating Imaging Radar technology for reliable non-destructive evaluation of bridges and other high-value concrete structures. These studies include conceptual designs, modeling, experimental verifications, and image reconstruction of simulated radar data. (3) We are exploring the efficiency of pulsed plasma processing techniques used for the removal of NO{sub x} from various effluent sources. (4) We have finished the investigation of the properties of a magnetically delayed low-pressure gas switch, which was designed here at LLNL. (5) We are applying statistical electromagnetic theory techniques to help assess microwave effects on electronic subsystems, by using a mode stirred chamber as our measurement tool. (6) We are investigating the generation of perfluoroisobutylene (PFIB) in proposed CFC replacement fluids when they are subjected to high electrical stresses and breakdown environments.

  13. Microwave and pulsed power

    NASA Astrophysics Data System (ADS)

    Freytag, E. K.

    1993-03-01

    The goals of the Microwave and Pulsed Power thrust area are to identify realizable research and development efforts and to conduct high-quality research in those pulse power and microwave technologies that support existing and emerging programmatic requirements at Lawrence Livermore National Laboratory (LLNL). Our main objective is to work on nationally important problems while enhancing our basic understanding of enabling technologies such as component design and testing, compact systems packaging, exploratory physics experiments, and advanced systems integration and performance. During FY-92, we concentrated our research efforts on the six project areas described in this report. We are investigating the superior electronic and thermal properties of diamond that may make it an ideal material for a high-power, solid-state switch. We are studying the feasibility of using advanced Ground Penetrating Imaging Radar technology for reliable non-destructive evaluation of bridges and other high-value concrete structures. These studies include conceptual designs, modeling, experimental verifications, and image reconstruction of simulated radar data. We are exploring the efficiency of pulsed plasma processing techniques used for the removal of NO(x) from various effluent sources. We have finished the investigation of the properties of a magnetically delayed low-pressure gas switch, which was designed here at LLNL. We are applying statistical electromagnetic theory techniques to help assess microwave effects on electronic subsystems, by using a mode stirred chamber as our measurement tool. We are investigating the generation of perfluoroisobutylene (PFIB) in proposed CFC replacement fluids when they are subjected to high electrical stresses and breakdown environments.

  14. The MST Radar Technique

    NASA Technical Reports Server (NTRS)

    Balsley, B. B.

    1985-01-01

    The past ten year have witnessed the development of a new radar technique to examine the structure and dynamics of the atmosphere between roughly 1 to 100 km on a continuous basis. The technique is known as the MST (for Mesosphere-Stratosphere-Troposphere) technique and is usable in all weather conditions, being unaffected by precipitation or cloud cover. MST radars make use of scattering from small scale structure in the atmospheric refractive index, with scales of the order of one-half the radar wavelength. Pertinent scale sizes for middle atmospheric studies typically range between a fraction of a meter and a few meters. The structure itself arises primarily from atmospheric turbulence. The technique is briefly described along with the meteorological parameters it measures.

  15. Radar for tracer particles

    NASA Astrophysics Data System (ADS)

    Ott, Felix; Herminghaus, Stephan; Huang, Kai

    2017-05-01

    We introduce a radar system capable of tracking a 5 mm spherical target continuously in three dimensions. The 10 GHz (X-band) radar system has a transmission power of 1 W and operates in the near field of the horn antennae. By comparing the phase shift of the electromagnetic wave traveling through the free space with an IQ-mixer, we obtain the relative movement of the target with respect to the antennae. From the azimuth and inclination angles of the receiving antennae obtained in the calibration, we reconstruct the target trajectory in a three-dimensional Cartesian system. Finally, we test the tracking algorithm with target moving in circular as well as in pendulum motions and discuss the capability of the radar system.

  16. World's largest radar

    NASA Astrophysics Data System (ADS)

    White, J.

    1982-05-01

    The design, construction, and performance characteristics of an ionospheric sounding radar with a 1000-foot diameter (20 acre) antenna built at Arecibo are reviewed. The Arecibo Observatory facility can be used as a radar with transmission and reception at both 430 and 2380 MHz. The CW S-band transmitter consists of a Varian klystron with 2.5 MW peak, 450 kW average power capability. A dual channel receiver uses a maser amplifier. The UHF radar transmitter, employing two klystrons for 2.5 MW peak, 150 average power, is located in the ground station adjacent to the antenna, and the microwave energy is supplied to the feed structure via a waveguide line. The Arecibo antenna beamwidth is about 0.05 deg at 1420 MHz, with a solid angle about 0.002 square degrees; the instrument can easily detect a galaxy like the Milky Way at a distance of 700 million light years.

  17. Pulse Oximetry

    MedlinePlus

    ... www.thoracic.org amount of gases (oxygen and carbon dioxide) that are in your blood. To get an ... Also, a pulse oximeter does not measure your carbon dioxide level. How accurate is the pulse oximeter? The ...

  18. Capabilities and limitations of the Sondrestrom radar for ST observations

    NASA Technical Reports Server (NTRS)

    Watkins, B. J.

    1983-01-01

    The Sondrestrom radar is located on the western side of Greenland near the U.S. air base and Danish community at Sondre Stromfjord. The radar was previously located at Chatanika, Alaska where its primary role was incoherent-scatter studies of the auroral ionosphere. Stratosphere/troposphere studies have occupied a very small portion of the radar observing schedule. The high operating frequency (1290 MHz) implies that the radar may only be used for turbulence-scatter studies in the troposphere and lower stratosphere. While the inner scale sizes of turbulence imply that the radar should be able to obtain data up to at least 20 km, in practice about 15 km seems to be the usual limit, due to lack of system sensitivity. However, this upper height limit varies from day to day and data have been obtained up to 23 km when a long (50 micro sec) pulse has been used. At high latitudes the tropopause is typically about 8 to 11 km altitude, therefore the radar is particularly suited to studies at tropopause heights. Additionally capabilities and limitations are discussed along with transmitter, receiver and antenna characteristics.

  19. A wing pod-based millimeter wavelength airborne cloud radar

    NASA Astrophysics Data System (ADS)

    Vivekanandan, J.; Ellis, S.; Tsai, P.; Loew, E.; Lee, W. C.; Emmett, J.; Dixon, M.; Burghart, C.; Rauenbuehler, S.

    2015-04-01

    This paper describes a novel, airborne pod-based millimeter wavelength radar. Its frequency of operation is 94 GHz (3 mm wavelength). The radar has been designed to fly on the NCAR Gulfstream V HIAPER aircraft; however, it could be deployed on other similarly equipped aircraft. The pod-based configuration occupies minimum cabin space and maximizes scan coverage. The radar system is capable of collecting observations in a staring mode between zenith and nadir or in a scanning mode. Standard pulse-pair estimates of moments and raw time series of backscattered signals are recorded. The radar system design and characteristics, as well as techniques for calibrating reflectivity and correcting Doppler velocity for aircraft attitude and motion are described. The radar can alternatively be deployed in a ground-based configuration, housed in the 20 ft shipping container it shares with the High Spectral Resolution Lidar (HSRL). The radar was tested both on the ground and in flight. Preliminary measurements of Doppler and polarization measurements were collected and examples are presented.

  20. A wing pod-based millimeter wavelength airborne cloud radar

    NASA Astrophysics Data System (ADS)

    Vivekanandan, J.; Ellis, S.; Tsai, P.; Loew, E.; Lee, W.-C.; Emmett, J.; Dixon, M.; Burghart, C.; Rauenbuehler, S.

    2015-08-01

    This paper describes a novel, airborne pod-based millimeter (mm) wavelength radar. Its frequency of operation is 94 GHz (3 mm wavelength). The radar has been designed to fly on the NCAR Gulfstream V HIAPER aircraft; however, it could be deployed on other similarly equipped aircraft. The pod-based configuration occupies minimum cabin space and maximizes scan coverage. The radar system is capable of collecting observations in a staring mode between zenith and nadir or in a scanning mode. Standard pulse-pair estimates of moments and raw time series of backscattered signals are recorded. The radar system design and characteristics as well as techniques for calibrating reflectivity and correcting Doppler velocity for aircraft attitude and motion are described. The radar can alternatively be deployed in a ground-based configuration, housed in the 20 ft shipping container it shares with the High Spectral Resolution Lidar (HSRL). The radar was tested both on the ground and in flight. Preliminary measurements of Doppler and polarization measurements were collected and examples are presented.