CO2 laser oscillators for laser radar applications

NASA Technical Reports Server (NTRS)

Freed, C.

1990-01-01

This paper reviews the spectral purity, frequency stability, and long-term stabilization of newly developed CO2 isotope lasers. Extremely high spectral purity, and short-term stability of less than 1.5 x 10 to the -13th have been achieved. A brief description on using CO2 isotope lasers as secondary frequency standards and in optical radar is given. The design and output characteristics of a single frequency, TEM00q mode, variable pulse width, hybrid TE CO2 laser system is also described. The frequency chirp in the output has been measured and almost completely eliminated by means of a novel technique.

Imaging laser radar for high-speed monitoring of the environment

NASA Astrophysics Data System (ADS)

Froehlich, Christoph; Mettenleiter, M.; Haertl, F.

1998-01-01

In order to establish mobile robot operations and to realize survey and inspection tasks, robust and precise measurements of the geometry of the 3D environment is the basis sensor technology. For visual inspection, surface classification, and documentation purposes, however, additional information concerning reflectance of measured objects is necessary. High-speed acquisition of both geometric and visual information is achieved by means of an active laser radar, supporting consistent range and reflectance images. The laser radar developed at Zoller + Froehlich (ZF) is an optical-wavelength system measuring the range between sensor and target surface as well as the reflectance of the target surface, which corresponds to the magnitude of the back scattered laser energy. In contrast to other range sensing devices, the ZF system is designed for high-speed and high- performance operation in real indoor and outdoor environments, emitting a minimum of near-IR laser energy. It integrates a single-point laser measurement system and a mechanical deflection system for 3D environmental measurements. This paper reports details of the laser radar which is designed to cover requirements with medium range applications. It outlines the performance requirements and introduces the two-frequency phase-shift measurement principle. The hardware design of the single-point laser measurement system, including the main modulates, such as the laser head, the high frequency unit and the signal processing unit are discussed in detail. The paper focuses on performance data of the laser radar, including noise, drift over time, precision, and accuracy with measurements. It discusses the influences of ambient light, surface material of the target, and ambient temperature for range accuracy and range precision. Furthermore, experimental results from inspection of tunnels, buildings, monuments and industrial environments are presented. The paper concludes by summarizing results and gives a short

CW Laser radar for combustion diagnostics

NASA Astrophysics Data System (ADS)

Malmqvist, Elin; Brydegaard, Mikkel; Aldén, Marcus; Bood, Joakim

2018-04-01

A CW-laser radar system developed for combustion diagnostics is described. The system is based on triangulation to attain range information. A portable system has been constructed and here we show some result from measurements in various flames, for example Rayleigh scattering thermometry and monitoring of particle distributions with high temporal and spatial resolution. The concept can equally well be based on pulsed lasers, allowing suppression of background emission through gated detection.

DFB laser - External modulator fiber optic delay line for radar applications

NASA Astrophysics Data System (ADS)

Newberg, I. L.; Gee, C. M.; Thurmond, G. D.; Yen, H. W.

1989-09-01

A new application of a long fiber-optic delay line as a radar repeater in a radar test set is described. The experimental 31.6-kilometer fiber-optic link includes an external modulator operating with a distributed-feedback laser and low-loss single-mode fiber matched to the laser wavelength to obtain low dispersion for achieving large bandwidth-length performance. The successful tests, in which pulse compression peak sidelobe measurements are used to confirm the link RF phase linearity and SNR performance, show that fiber-optic links can meet the stringent phase and noise requirements of modern radars at high microwave frequencies.

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.

Data collection and simulation of high range resolution laser radar for surface mine detection

NASA Astrophysics Data System (ADS)

Steinvall, Ove; Chevalier, Tomas; Larsson, Håkan

2006-05-01

Rapid and efficient detection of surface mines, IED's (Improvised Explosive Devices) and UXO (Unexploded Ordnance) is of high priority in military conflicts. High range resolution laser radars combined with passive hyper/multispectral sensors offer an interesting concept to help solving this problem. This paper reports on laser radar data collection of various surface mines in different types of terrain. In order to evaluate the capability of 3D imaging for detecting and classifying the objects of interest a scanning laser radar was used to scan mines and surrounding terrain with high angular and range resolution. These data were then fed into a laser radar model capable of generating range waveforms for a variety of system parameters and combinations of different targets and backgrounds. We can thus simulate a potential system by down sampling to relevant pixel sizes and laser/receiver characteristics. Data, simulations and examples will be presented.

Laser Radar Study Using Resonance Absorption for Remote Detection Of Air Pollutants

NASA Technical Reports Server (NTRS)

Igarashi, Takashi

1973-01-01

A laser radar using resonance absorption has an advantage of increased detection range and sensitivity compared with that achieved by Raman or resonance back scattering. In this paper, new laser radar system using resonance absorption is proposed and results obtained from this laser radar system are discussed. NO2, SO2 gas has an absorption spectrum at 4500 A and 3000 A respectively as shown in Fig. 1. A laser light including at least a set of an absorption peak (lambda)1 and a valley (lambda)2 is emitted into a pollutant atmosphere. The light reflected with a topographical reflector or an atmospheric Mie scattering as distributed reflectors is received and divided into two wavelength components (lambda)1 and (lambda)2. The laser radar system used in the investigation is shown in Fig', 2 and consists of a dye laser transmitter, an optical receiver with a special monochrometer and a digital processer. Table 1 shows the molecular constants of NO2, and SO2 and the dye laser used in this experiment. In this system, the absolute concentration of the pollutant gas can be measured in comparison with a standard gas cell. The concentration of NO2, SO2 as low as 0.1 ppm have been measured at 100 m depth resolution. For a 1 mJ laser output, the observable range of this system achieved up to 300 m using the distributed Mie reflector. The capability and technical limitation of the system will be discussed in detail.

Linear FMCW Laser Radar for Precision Range and Vector Velocity Measurements

NASA Technical Reports Server (NTRS)

Pierrottet, Diego; Amzajerdian, Farzin; Petway, Larry; Barnes, Bruce; Lockhard, George; Rubio, Manuel

2008-01-01

An all fiber linear frequency modulated continuous wave (FMCW) coherent laser radar system is under development with a goal to aide NASA s new Space Exploration initiative for manned and robotic missions to the Moon and Mars. By employing a combination of optical heterodyne and linear frequency modulation techniques and utilizing state-of-the-art fiber optic technologies, highly efficient, compact and reliable laser radar suitable for operation in a space environment is being developed. Linear FMCW lidar has the capability of high-resolution range measurements, and when configured into a multi-channel receiver system it has the capability of obtaining high precision horizontal and vertical velocity measurements. Precision range and vector velocity data are beneficial to navigating planetary landing pods to the preselected site and achieving autonomous, safe soft-landing. The all-fiber coherent laser radar has several important advantages over more conventional pulsed laser altimeters or range finders. One of the advantages of the coherent laser radar is its ability to measure directly the platform velocity by extracting the Doppler shift generated from the motion, as opposed to time of flight range finders where terrain features such as hills, cliffs, or slopes add error to the velocity measurement. Doppler measurements are about two orders of magnitude more accurate than the velocity estimates obtained by pulsed laser altimeters. In addition, most of the components of the device are efficient and reliable commercial off-the-shelf fiber optic telecommunication components. This paper discusses the design and performance of a second-generation brassboard system under development at NASA Langley Research Center as part of the Autonomous Landing and Hazard Avoidance (ALHAT) project.

Active laser radar (lidar) for measurement of corresponding height and reflectance images

NASA Astrophysics Data System (ADS)

Froehlich, Christoph; Mettenleiter, M.; Haertl, F.

1997-08-01

For the survey and inspection of environmental objects, a non-tactile, robust and precise imaging of height and depth is the basis sensor technology. For visual inspection,surface classification, and documentation purposes, however, additional information concerning reflectance of measured objects is necessary. High-speed acquisition of both geometric and visual information is achieved by means of an active laser radar, supporting consistent 3D height and 2D reflectance images. The laser radar is an optical-wavelength system, and is comparable to devices built by ERIM, Odetics, and Perceptron, measuring the range between sensor and target surfaces as well as the reflectance of the target surface, which corresponds to the magnitude of the back scattered laser energy. In contrast to these range sensing devices, the laser radar under consideration is designed for high speed and precise operation in both indoor and outdoor environments, emitting a minimum of near-IR laser energy. It integrates a laser range measurement system and a mechanical deflection system for 3D environmental measurements. This paper reports on design details of the laser radar for surface inspection tasks. It outlines the performance requirements and introduces the measurement principle. The hardware design, including the main modules, such as the laser head, the high frequency unit, the laser beam deflection system, and the digital signal processing unit are discussed.the signal processing unit consists of dedicated signal processors for real-time sensor data preprocessing as well as a sensor computer for high-level image analysis and feature extraction. The paper focuses on performance data of the system, including noise, drift over time, precision, and accuracy with measurements. It discuses the influences of ambient light, surface material of the target, and ambient temperature for range accuracy and range precision. Furthermore, experimental results from inspection of buildings, monuments

A HWIL test facility of infrared imaging laser radar using direct signal injection

NASA Astrophysics Data System (ADS)

Wang, Qian; Lu, Wei; Wang, Chunhui; Wang, Qi

2005-01-01

Laser radar has been widely used these years and the hardware-in-the-loop (HWIL) testing of laser radar become important because of its low cost and high fidelity compare with On-the-Fly testing and whole digital simulation separately. Scene generation and projection two key technologies of hardware-in-the-loop testing of laser radar and is a complicated problem because the 3D images result from time delay. The scene generation process begins with the definition of the target geometry and reflectivity and range. The real-time 3D scene generation computer is a PC based hardware and the 3D target models were modeled using 3dsMAX. The scene generation software was written in C and OpenGL and is executed to extract the Z-buffer from the bit planes to main memory as range image. These pixels contain each target position x, y, z and its respective intensity and range value. Expensive optical injection technologies of scene projection such as LDP array, VCSEL array, DMD and associated scene generation is ongoing. But the optical scene projection is complicated and always unaffordable. In this paper a cheaper test facility was described that uses direct electronic injection to provide rang images for laser radar testing. The electronic delay and pulse shaping circuits inject the scenes directly into the seeker's signal processing unit.

Nineteenth International Laser Radar Conference. Part 2

NASA Technical Reports Server (NTRS)

Singh, Upendra N. (Editor); Ismail, Syed (Editor); Schwemmer, Geary K. (Editor)

1998-01-01

This publication contains extended abstracts of papers presented at the Nineteenth International Laser Radar Conference, held at Annapolis, Maryland, July 6-10, 1998; 260 papers were presented in both oral and poster sessions. The topics of the conference sessions were Aerosol Clouds, Multiple Scattering; Tropospheric Profiling, Stratospheric/Mesospheric Profiling; Wind Profiling; New Lidar Technology and Techniques; Lidar Applications, Including Altimetry and Marine; Space and Future Lidar; and Lidar Commercialization/Eye Safety. This conference reflects the breadth of research activities being conducted in the lidar field. These abstracts address subjects from lidar-based atmospheric investigations, development of new lasers and lidar system technology, and current and future space-based lidar systems.

Nineteenth International Laser Radar Conference. Part 1

NASA Technical Reports Server (NTRS)

Singh, Upendra N. (Editor); Ismail, Syed (Editor); Schwemmer, Geary K. (Editor)

1998-01-01

This publication contains extended abstracts of papers presented at the Nineteenth International Laser Radar Conference, held at Annapolis, Maryland, July 6-10, 1998; 260 papers were presented in both oral and poster sessions. The topics of the conference sessions were Aerosol Clouds, Multiple Scattering; Tropospheric Profiling; Stratospheric/Mesospheric Profiling; Wind Profiling; New Lidar Technology and Techniques; Lidar Applications, including Altimetry and Marine; Space and Future Lidar; and Lidar Commercialization/Eye Safety. This conference reflects the breadth of research activities being conducted in the lidar field. These abstracts address subjects from lidar-based atmospheric investigations, development of new lasers and lidar system technology, and current and future space-based lidar systems.

Optical frequency modulation continuous wave coherent laser radar for spacecraft safe landing vector velocity measurement

NASA Astrophysics Data System (ADS)

Sui, Xiao-lin; Zhou, Shou-huan

2013-05-01

The design and performance of Optical frequency modulation continuous wave (OFMCW) coherent laser radar is presented. By employing a combination of optical heterodyne and linear frequency modulation techniques and utilizing fiber optic technologies, highly efficient, compact and reliable laser radar suitable for operation in a space environment is being developed.We also give a hardware structure of the OFMCW coherent laser radar. We made a detailed analysis of the measurement error. Its accuracy in the speed range is less than 0.5%.Measurement results for the movement of the carrier has also made a detailed assessment. The results show that its acceleration vector has better adaptability. The circuit structure is also given a detailed design. At the end of the article, we give the actual authentication method and experimental results.

Sixteenth International Laser Radar Conference, Part 1

NASA Technical Reports Server (NTRS)

Mccormick, M. Patrick (Editor)

1992-01-01

This publication contains extended abstracts of papers presented at the 16th International Laser Radar Conference. One-hundred ninety-five papers were presented in both oral and poster sessions. The topics of the conference sessions were: (1) Mt. Pinatubo Volcanic Dust Layer Observations; (2) Global Change/Ozone Measurements; (3) GLOBE/LAWS/LITE; (4) Mesospheric Measurements and Measurement Systems; (5) Middle Atmosphere; (6) Wind Measurements and Measurement Systems; (7) Imaging and Ranging; (8) Water Vapor Measurements; (9) Systems and Facilities; and (10) Laser Devices and Technology. This conference reflects the breadth of research activities being conducted in the lidar field. These abstracts address subjects from lidar-based atmospheric investigations relating to global change to the development of new lidar systems and technology.

The Precision Expandable Radar Calibration Sphere (PERCS) With Applications for Laser Imaging and Ranging

NASA Astrophysics Data System (ADS)

Bernhardt, P.; Nicholas, A.; Thomas, L.; Davis, M.; Hoberman, C.; Davis, M.

The Naval Research Laboratory will provide an orbiting calibration sphere to be used with ground-based laser imaging telescopes and HF radio systems. The Precision Expandable Radar Calibration Sphere (PERCS) is a practical, reliable, high-performance HF calibration sphere and laser imaging target to orbit at about 600 km altitude. The sphere will be made of a spherical wire frame with aspect independent radar cross section in the 3 to 35 MHz frequency range. The necessary launch vehicle to place the PERCS in orbit will be provided by the Department of Defense Space Test Program. The expandable calibration target has a stowed diameter of 1 meter and a fully deployed diameter of 10.2 meters. A separate deployment mechanism is provided for the sphere. After deployment, the Precision Expandable Radar Calibration Sphere (PERCS) with 180 vertices will be in a high inclination orbit to scatter radio pulses from a number of ground systems, including (1) over-the-horizon (OTH) radars operated by the United States and Australia; (2) high power HF facilities such as HAARP in Alaska, EISCAT in Norway, and Arecibo in Puerto Rico; (3) the chain of high latitude SuperDARN radars used for auroral region mapping; and (4) HF direction finding for Navy ships. With the PERCS satellite, the accuracy of HF radars can be periodically checked for range, elevation, and azimuth errors. In addition, each of the 360 vertices on the PERCS sphere will support an optical retro-reflector for operations with ground laser facilities used to track satellites. The ground laser systems will be used to measure the precise location of the sphere within one cm accuracy and will provide the spatial orientation of the sphere as well as the rotation rate. The Department of Defense facilities that can use the corner-cube reflectors on the PERCS include (1) the Air Force Maui Optical Site (AMOS), (2) the Starfire Optical Range (SOR), and (3) the NRL Optical Test Facility (OTF).

Non-mechanical beam control for entry, descent and landing laser radar (Conference Presentation)

NASA Astrophysics Data System (ADS)

Stockley, Jay E.; Kluttz, Kelly; Hosting, Lance; Serati, Steve; Bradley, Cullen P.; McManamon, Paul F.; Amzajerdian, Farzin

2017-05-01

Laser radar for entry, descent, and landing (EDL) applications as well as the space docking problem could benefit from a low size, weight, and power (SWaP) beam control system. Moreover, an inertia free approach employing non-mechanical beam control is also attractive for laser radar that is intended to be employed aboard space platforms. We are investigating a non-mechanical beam steering (NMBS) sub-system based on liquid crystal polarization grating (LCPG) technology with emphasis placed on improved throughput and significant weight reduction by combining components and drastically reducing substrate thicknesses. In addition to the advantages of non-mechanical, gimbal free beam control, and greatly improved SWaP, our approach also enables wide area scanning using a scalable architecture. An extraterrestrial application entails additional environmental constraints, consequently an environmental test plan tailored to an EDL mission will also be discussed. In addition, we will present advances in continuous fine steering technology which would complement the coarse steering LCPG technology. A low-SWaP, non-mechanical beam control system could be used in many laser radar remote sensing applications including meteorological studies and agricultural or environmental surveys in addition to the entry, descent, and landing application.

NO plume mapping by laser-radar techniques.

PubMed

Edner, H; Sunesson, A; Svanberg, S

1988-09-01

Mapping of NO plumes by using laser-radar techniques has been demonstrated with a mobile differential absorption lidar system. The system was equipped with a narrow-linewidth Nd:YAG-pumped dye laser that, with doubling and mixing, generated pulse energies of 3-5 mJ at 226 nm, with a linewidth of 1pm. This permitted range-resolved measurements of NO, with a range of about 500 m. The detection limit was estimated to 3 microg/m(3), with an integration interval of 350 m. Spectroscopic studies on the gamma(0, 0) bandhead near 226.8 nm were performed with 1-pm resolution, and the differential absorption cross section was determined to be (6.6 +/- 0.6) x 10(-22) m(2), with a wavelength difference of 12 pm.

[The error analysis and experimental verification of laser radar spectrum detection and terahertz time domain spectroscopy].

PubMed

Liu, Wen-Tao; Li, Jing-Wen; Sun, Zhi-Hui

2010-03-01

Terahertz waves (THz, T-ray) lie between far-infrared and microwave in electromagnetic spectrum with frequency from 0.1 to 10 THz. Many chemical agent explosives show characteristic spectral features in the terahertz. Compared with conventional methods of detecting a variety of threats, such as weapons and chemical agent, THz radiation is low frequency and non-ionizing, and does not give rise to safety concerns. The present paper summarizes the latest progress in the application of terahertz time domain spectroscopy (THz-TDS) to chemical agent explosives. A kind of device on laser radar detecting and real time spectrum measuring was designed which measures the laser spectrum on the bases of Fourier optics and optical signal processing. Wedge interferometer was used as the beam splitter to wipe off the background light and detect the laser and measure the spectrum. The result indicates that 10 ns laser radar pulse can be detected and many factors affecting experiments are also introduced. The combination of laser radar spectrum detecting, THz-TDS, modern pattern recognition and signal processing technology is the developing trend of remote detection for chemical agent explosives.

Comparison of Surface Elevation Changes of the Greenland and Antarctic Ice Sheets from Radar and Laser Altimetry

NASA Technical Reports Server (NTRS)

Zwally, H. Jay; Brenner, Anita C.; Barbieri, Kristine; DiMarzio, John P.; Li, Jun; Robbins, John; Saba, Jack L.; Yi, Donghui

2012-01-01

A primary purpose of satellite altimeter measurements is determination of the mass balances of the Greenland and Antarctic ice sheets and changes with time by measurement of changes in the surface elevations. Since the early 1990's, important measurements for this purpose have been made by radar altimeters on ERS-l and 2, Envisat, and CryoSat and a laser altimeter on ICESat. One principal factor limiting direct comparisons between radar and laser measurements is the variable penetration depth of the radar signal and the corresponding location of the effective depth of the radar-measured elevation beneath the surface, in contrast to the laser-measured surface elevation. Although the radar penetration depth varies significantly both spatially and temporally, empirical corrections have been developed to account for this effect. Another limiting factor in direct comparisons is caused by differences in the size of the laser and radar footprints and their respective horizontal locations on the surface. Nevertheless, derived changes in elevation, dHldt, and time-series of elevation, H(t), have been shown to be comparable. For comparisons at different times, corrections for elevation changes caused by variations in the rate offrrn compaction have also been developed. Comparisons between the H(t) and the average dH/dt at some specific locations, such as the Vostok region of East Antarctic, show good agreement among results from ERS-l and 2, Envisat, and ICESat. However, Greenland maps of dHidt from Envisat and ICESat for the same time periods (2003-2008) show some areas of significant differences as well as areas of good agreement. Possible causes of residual differences are investigated and described.

Laser radar cross-section estimation from high-resolution image data.

PubMed

Osche, G R; Seeber, K N; Lok, Y F; Young, D S

1992-05-10

A methodology for the estimation of ladar cross sections from high-resolution image data of geometrically complex targets is presented. Coherent CO(2) laser radar was used to generate high-resolution amplitude imagery of a UC-8 Buffalo test aircraft at a range of 1.3 km at nine different aspect angles. The average target ladar cross section was synthesized from these data and calculated to be sigma(T) = 15.4 dBsm, which is similar to the expected microwave radar cross sections. The aspect angle dependence of the cross section shows pronounced peaks at nose on and broadside, which are also in agreement with radar results. Strong variations in both the mean amplitude and the statistical distributions of amplitude with the aspect angle have also been observed. The relative mix of diffuse and specular returns causes significant deviations from a simple Lambertian or Swerling II target, especially at broadside where large normal surfaces are present.

Simulation of laser radar tooling ball measurements: focus dependence

NASA Astrophysics Data System (ADS)

Smith, Daniel G.; Slotwinski, Anthony; Hedges, Thomas

2015-10-01

The Nikon Metrology Laser Radar system focuses a beam from a fiber to a target object and receives the light scattered from the target through the same fiber. The system can, among other things, make highly accurate measurements of the position of a tooling ball by locating the angular position of peak signal quality, which is related to the fiber coupling efficiency. This article explores the relationship between fiber coupling efficiency and focus condition.

The effectiveness of laser and radar based enforcement programs for deterrence of speeding

DOT National Transportation Integrated Search

1997-02-01

This report documents the results of a study to determine the community-wide effectiveness of laser-based speed enforcement programs relative to radar-based programs. Jurisdiction-wide speeding enforcement programs were implemented and evaluated in t...

Agile beam laser radar using computational imaging for robotic perception

NASA Astrophysics Data System (ADS)

Powers, Michael A.; Stann, Barry L.; Giza, Mark M.

2015-05-01

This paper introduces a new concept that applies computational imaging techniques to laser radar for robotic perception. We observe that nearly all contemporary laser radars for robotic (i.e., autonomous) applications use pixel basis scanning where there is a one-to-one correspondence between world coordinates and the measurements directly produced by the instrument. In such systems this is accomplished through beam scanning and/or the imaging properties of focal-plane optics. While these pixel-basis measurements yield point clouds suitable for straightforward human interpretation, the purpose of robotic perception is the extraction of meaningful features from a scene, making human interpretability and its attendant constraints mostly unnecessary. The imposing size, weight, power and cost of contemporary systems is problematic, and relief from factors that increase these metrics is important to the practicality of robotic systems. We present a system concept free from pixel basis sampling constraints that promotes efficient and adaptable sensing modes. The cornerstone of our approach is agile and arbitrary beam formation that, when combined with a generalized mathematical framework for imaging, is suited to the particular challenges and opportunities of robotic perception systems. Our hardware concept looks toward future systems with optical device technology closely resembling modern electronically-scanned-array radar that may be years away from practicality. We present the design concept and results from a prototype system constructed and tested in a laboratory environment using a combination of developed hardware and surrogate devices for beam formation. The technological status and prognosis for key components in the system is discussed.

Experimental evaluation of penetration capabilities of a Geiger-mode APD array laser radar system

NASA Astrophysics Data System (ADS)

Jonsson, Per; Tulldahl, Michael; Hedborg, Julia; Henriksson, Markus; Sjöqvist, Lars

2017-10-01

Laser radar 3D imaging has the potential to improve target recognition in many scenarios. One case that is challenging for most optical sensors is to recognize targets hidden in vegetation or behind camouflage. The range resolution of timeof- flight 3D sensors allows segmentation of obscuration and target if the surfaces are separated far enough so that they can be resolved as two distances. Systems based on time-correlated single-photon counting (TCSPC) have the potential to resolve surfaces closer to each other compared to laser radar systems based on proportional mode detection technologies and is therefore especially interesting. Photon counting detection is commonly performed with Geigermode Avalanche Photodiodes (GmAPD) that have the disadvantage that they can only detect one photon per laser pulse per pixel. A strong return from an obscuring object may saturate the detector and thus limit the possibility to detect the hidden target even if photons from the target reach the detector. The operational range where good foliage penetration is observed is therefore relatively narrow for GmAPD systems. In this paper we investigate the penetration capability through semi-transparent surfaces for a laser radar with a 128×32 pixel GmAPD array and a 1542 nm wavelength laser operating at a pulse repetition frequency of 90 kHz. In the evaluation a screen was placed behind different canvases with varying transmissions and the detected signals from the surfaces for different laser intensities were measured. The maximum return from the second surface occurs when the total detection probability is around 0.65-0.75 per pulse. At higher laser excitation power the signal from the second surface decreases. To optimize the foliage penetration capability it is thus necessary to adaptively control the laser power to keep the returned signal within this region. In addition to the experimental results, simulations to study the influence of the pulse energy on penetration through

Measurement of trace stratospheric constituents with a balloon borne laser radar

NASA Technical Reports Server (NTRS)

Heaps, William S.; Mcgee, Thomas J.

1990-01-01

The objective of this research was to measure the concentration of the stratospheric hydroxyl radical and related chemical species as a function of altitude, season, and time of day. Although hydroxyl plays a very important role in the chemistry controlling stratospheric ozone, little is known about its behavior because it has been a difficult species to measure. The instrument employed in this program was a laser radar, employing the technique of remote laser induced fluorescence. This instrument offers a number of attractive features including extreme specificity and sensitivity, a straightforward relationship between observed quantity and the desired concentration, and immunity to self-contamination.

Experimental and rendering-based investigation of laser radar cross sections of small unmanned aerial vehicles

NASA Astrophysics Data System (ADS)

Laurenzis, Martin; Bacher, Emmanuel; Christnacher, Frank

2017-12-01

Laser imaging systems are prominent candidates for detection and tracking of small unmanned aerial vehicles (UAVs) in current and future security scenarios. Laser reflection characteristics for laser imaging (e.g., laser gated viewing) of small UAVs are investigated to determine their laser radar cross section (LRCS) by analyzing the intensity distribution of laser reflection in high resolution images. For the first time, LRCSs are determined in a combined experimental and computational approaches by high resolution laser gated viewing and three-dimensional rendering. An optimized simple surface model is calculated taking into account diffuse and specular reflectance properties based on the Oren-Nayar and the Cook-Torrance reflectance models, respectively.

HgCdTe photomixers for CO2 laser radar systems

NASA Technical Reports Server (NTRS)

Bratt, Peter R.

1992-01-01

The Santa Barbara Research Center has developed a variety of high speed HgCdTe photodetectors for use in CO2 laser radar systems. These detectors have outstanding performance and can be made available in production quantities. Many of them have been employed in a variety of systems applications over the past ten years. In this paper, we briefly describe the detector technology, summarize the state-of-the-art, and indicate some practical applications.

Self-contained eye-safe laser radar using an erbium-doped fiber laser

NASA Astrophysics Data System (ADS)

Driscoll, Thomas A.; Radecki, Dan J.; Tindal, Nan E.; Corriveau, John P.; Denman, Richard

2003-07-01

An Eye-safe Laser Radar has been developed under White Sands Missile Range sponsorship. The SEAL system, the Self-contained Eyesafe Autonomous Laser system, is designed to measure target position within a 0.5 meter box. Targets are augmented with Scotchlite for ranging out to 6 km and augmented with a retroreflector for targets out to 20 km. The data latency is less than 1.5 ms, and the position update rate is 1 kHz. The system is air-cooled, contained in a single 200-lb, 6-cubic-foot box, and uses less than 600 watts of prime power. The angle-angle-range data will be used to measure target dynamics and to control a tracking mount. The optical system is built around a diode-pumped, erbium-doped fiber laser rated at 1.5 watts average power at 10 kHz repetition rate with 25 nsec pulse duration. An 8 inch-diameter, F/2.84 telescope is relayed to a quadrant detector at F/0.85 giving a 5 mrad field of view. Two detectors have been evaluated, a Germanium PIN diode and an Intevac TE-IPD. The receiver electronics uses a DSP network of 6 SHARC processors to implement ranging and angle error algorithms along with an Optical AGC, including beam divergence/FOV control loops.Laboratory measurements of the laser characteristics, and system range and angle accuracies will be compared to simulations. Field measurements against actual targets will be presented.

Maximum angular accuracy of pulsed laser radar in photocounting limit.

PubMed

Elbaum, M; Diament, P; King, M; Edelson, W

1977-07-01

To estimate the angular position of targets with pulsed laser radars, their images may be sensed with a fourquadrant noncoherent detector and the image photocounting distribution processed to obtain the angular estimates. The limits imposed on the accuracy of angular estimation by signal and background radiation shot noise, dark current noise, and target cross-section fluctuations are calculated. Maximum likelihood estimates of angular positions are derived for optically rough and specular targets and their performances compared with theoretical lower bounds.

Laser radar range and detection performance for MEMS corner cube retroreflector arrays

NASA Astrophysics Data System (ADS)

Grasso, Robert J.; Odhner, Jefferson E.; Stewart, Hamilton; McDaniel, Robert V.

2004-12-01

BAE SYSTEMS reports on a program to characterize the performance of MEMS corner cube retroreflector arrays under laser illumination. These arrays have significant military and commercial application in the areas of: 1) target identification; 2) target tracking; 3) target location; 4) identification friend-or-foe (IFF); 5) parcel tracking, and; 6) search and rescue assistance. BAE SYSTEMS has theoretically determined the feasibility of these devices to learn if sufficient signal-to-noise performance exists to permit a cooperative laser radar sensor to be considered for device location and interrogation. Results indicate that modest power-apertures are required to achieve SNR performance consistent with high probability of detection and low false alarm rates.

Laser radar range and detection performance for MEMS corner cube retroreflector arrays

NASA Astrophysics Data System (ADS)

Grasso, Robert J.; Jost, Steven R.; Smith, M. J.; McDaniel, Robert V.

2004-01-01

BAE SYSTEMS reports on a program to characterize the performance of MEMS corner cube retroreflector arrays under laser illumination. These arrays have significant military and commercial application in the areas of: (1) target identification; (2) target tracking; (3) target location; (4) identification friend-or-foe (IFF); (5) parcel tracking, and; (6) search and rescue assistance. BAE SYSTEMS has theoretically determined the feasibility of these devices to learn if sufficient signal-to-noise performance exists to permit a cooperative laser radar sensor to be considered for device location and interrogation. Results indicate that modest power-apertures are required to achieve SNR performance consistent with high probability of detection and low false alarm rates.

Two Dimensional Positioning and Heading Solution for Flying Vehicles using a Line-Scanning Laser Radar (LADAR)

DTIC Science & Technology

2011-03-24

6 2.4.1 Reference Frames . . . . . . . . . . . . . . . . . 6 2.4.2 Line and Feature Extraction . . . . . . . . . . . 7 2.4.3 SLAM ...Positioning System . . . . . . . . . . . . . . . . . . 1 LADAR Laser Radar . . . . . . . . . . . . . . . . . . . . . . . . . . 1 LiDAR Light Detection and...Ranging . . . . . . . . . . . . . . . . 2 SLAM Simultaneous Localization and Mapping . . . . . . . . . . 2 ANT Advanced Navigation Technology

Comparing helicopter-borne profiling radar with airborne laser scanner data for forest structure estimation.

NASA Astrophysics Data System (ADS)

Piermattei, Livia; Hollaus, Markus; Pfeifer, Norbert; Chen, Yuwei; Karjalainen, Mika; Hakala, Teemu; Hyyppä, Juha; Wagner, Wolfgang

2017-04-01

Forests are complex ecosystems that show substantial variation with respect to climate, management regime, stand history, disturbance, and needs of local communities. The dynamic processes of growth and disturbance are reflected in the structural components of forests that include the canopy vertical structure and geometry (e.g. size, height, and form), tree position and species diversity. Current remote-sensing systems to measure forest structural attributes include passive optical sensors and active sensors. The technological capabilities of active remote sensing like the ability to penetrate the vegetation and provide information about its vertical structure has promoted an extensive use of LiDAR (Light Detection And Ranging) and radar (RAdio Detection And Ranging) system over the last 20 years. LiDAR measurements from aircraft (airborne laser scanning, ALS) currently represents the primary data source for three-dimensional information on forest vertical structure. Contrary, despite the potential of radar remote sensing, their use is not yet established in forest monitoring. In order to better understand the interaction of pulsed radar with the forest canopy, and to increase the feasibility of this system, the Finnish Geospatial Research Institute has developed a helicopter-borne profiling radar system, called TomoRadar. TomoRadar is capable of recording a canopy-penetrating profile of forests. To georeference the radar measurements the system was equipped with a global navigation satellite system and an inertial measurement unit with a centimeter level accuracy of the flight trajectory. The TomoRadar operates at Ku-band, (wave lengths λ 1.5cm) with two separated parabolic antennas providing co- and cross-polarization modes. The purpose of this work is to investigate the capability of the TomoRadar system, for estimating the forest vertical profile, terrain topography and tree height. We analysed 600 m TomoRadar crosspolarized (i.e. horizontal - vertical

Laser one-dimensional range profile and the laser two-dimensional range profile of cylinders

NASA Astrophysics Data System (ADS)

Gong, Yanjun; Wang, Mingjun; Gong, Lei

2015-10-01

Laser one-dimensional range profile, that is scattering power from pulse laser scattering of target, is a radar imaging technology. The laser two-dimensional range profile is two-dimensional scattering imaging of pulse laser of target. Laser one-dimensional range profile and laser two-dimensional range profile are called laser range profile(LRP). The laser range profile can reflect the characteristics of the target shape and surface material. These techniques were motivated by applications of laser radar to target discrimination in ballistic missile defense. The radar equation of pulse laser is given in this paper. This paper demonstrates the analytical model of laser range profile of cylinder based on the radar equation of the pulse laser. Simulations results of laser one-dimensional range profiles of some cylinders are given. Laser range profiles of cylinder, whose surface material with diffuse lambertian reflectance, is given in this paper. Laser range profiles of different pulse width of cylinder are given in this paper. The influences of geometric parameters, pulse width, attitude on the range profiles are analyzed.

Research on effect of rough surface on FMCW laser radar range accuracy

NASA Astrophysics Data System (ADS)

Tao, Huirong

2018-03-01

The non-cooperative targets large scale measurement system based on frequency-modulated continuous-wave (FMCW) laser detection and ranging technology has broad application prospects. It is easy to automate measurement without cooperative targets. However, the complexity and diversity of the surface characteristics of the measured surface directly affects the measurement accuracy. First, the theoretical analysis of range accuracy for a FMCW laser radar was studied, the relationship between surface reflectivity and accuracy was obtained. Then, to verify the effect of surface reflectance for ranging accuracy, a standard tool ball and three standard roughness samples were measured within 7 m to 24 m. The uncertainty of each target was obtained. The results show that the measurement accuracy is found to increase as the surface reflectivity gets larger. Good agreements were obtained between theoretical analysis and measurements from rough surfaces. Otherwise, when the laser spot diameter is smaller than the surface correlation length, a multi-point averaged measurement can reduce the measurement uncertainty. The experimental results show that this method is feasible.

Comparison of Retracking Algorithms Using Airborne Radar and Laser Altimeter Measurements of the Greenland Ice Sheet

NASA Technical Reports Server (NTRS)

Ferraro, Ellen J.; Swift, Calvin T.

1995-01-01

This paper compares four continental ice sheet radar altimeter retracking algorithms using airborne radar and laser altimeter data taken over the Greenland ice sheet in 1991. The refurbished Advanced Application Flight Experiment (AAFE) airborne radar altimeter has a large range window and stores the entire return waveform during flight. Once the return waveforms are retracked, or post-processed to obtain the most accurate altitude measurement possible, they are compared with the high-precision Airborne Oceanographic Lidar (AOL) altimeter measurements. The AAFE waveforms show evidence of varying degrees of both surface and volume scattering from different regions of the Greenland ice sheet. The AOL laser altimeter, however, obtains a return only from the surface of the ice sheet. Retracking altimeter waveforms with a surface scattering model results in a good correlation with the laser measurements in the wet and dry-snow zones, but in the percolation region of the ice sheet, the deviation between the two data sets is large due to the effects of subsurface and volume scattering. The Martin et al model results in a lower bias than the surface scattering model, but still shows an increase in the noise level in the percolation zone. Using an Offset Center of Gravity algorithm to retrack altimeter waveforms results in measurements that are only slightly affected by subsurface and volume scattering and, despite a higher bias, this algorithm works well in all regions of the ice sheet. A cubic spline provides retracked altitudes that agree with AOL measurements over all regions of Greenland. This method is not sensitive to changes in the scattering mechanisms of the ice sheet and it has the lowest noise level and bias of all the retracking methods presented.

Comparison of stimulated and spontaneous laser-radar methods for the remote sensing of ocean physical properties

NASA Astrophysics Data System (ADS)

Leonard, Donald A.; Sweeney, Harold E.

1990-09-01

The physical properties of ocean water, in the top few ten meters, are of great interest in the scientific, engineering, and general oceanographic communities. Subsurface profiles of temperature, salinity, and sound speed measured by laser radar in real time on a synoptic basis over a wide area from an airborne platform would provide valuable information complementary to the data that is now readily available. The laser-radar technique specifically applicable to ocean sensing uses spectroscopic analysis of the inelastic backscattered optical signal. Two methods have received considerable attention for remote sensing and both have been demonstrated in field experiments. These are spontaneous Raman1 and spontaneous Brillouin2 scattering. A discussion of these two processes and a comparison of their properties that are useful for remote sensing was presented3 at SPIE Ocean Optics IX. This paper compares ocean remote sensing using stimulated Brillouin scattering (SBS) and stimulated Raman scattering (SRS) processes with better known spontaneous methods. The results of laboratory measurements of temperature using SBS and some preliminary results of SRS are presented with extensions to performance estimates of potential field systems.

Capturing atmospheric effects on 3D millimeter wave radar propagation patterns

NASA Astrophysics Data System (ADS)

Cook, Richard D.; Fiorino, Steven T.; Keefer, Kevin J.; Stringer, Jeremy

2016-05-01

Traditional radar propagation modeling is done using a path transmittance with little to no input for weather and atmospheric conditions. As radar advances into the millimeter wave (MMW) regime, atmospheric effects such as attenuation and refraction become more pronounced than at traditional radar wavelengths. The DoD High Energy Laser Joint Technology Offices High Energy Laser End-to-End Operational Simulation (HELEEOS) in combination with the Laser Environmental Effects Definition and Reference (LEEDR) code have shown great promise simulating atmospheric effects on laser propagation. Indeed, the LEEDR radiative transfer code has been validated in the UV through RF. Our research attempts to apply these models to characterize the far field radar pattern in three dimensions as a signal propagates from an antenna towards a point in space. Furthermore, we do so using realistic three dimensional atmospheric profiles. The results from these simulations are compared to those from traditional radar propagation software packages. In summary, a fast running method has been investigated which can be incorporated into computational models to enhance understanding and prediction of MMW propagation through various atmospheric and weather conditions.

Servomechanism for Doppler shift compensation in optical correlator for synthetic aperture radar

NASA Technical Reports Server (NTRS)

Constaninides, N. J.; Bicknell, T. J. (Inventor)

1980-01-01

A method and apparatus for correcting Doppler shifts in synthetic aperture radar data is described. An optical correlator for synthetic aperture radar data has a means for directing a laser beam at a signal film having radar return pulse intensity information recorded on it. A resultant laser beam passes through a range telescope, an azimuth telescope, and a Fourier transform filter located between the range and azimuth telescopes, and forms an image for recording on an image film. A compensation means for Doppler shift in the radar return pulse intensity information includes a beam splitter for reflecting the modulated laser beam, after having passed through the Fourier transform filter, to a detection screen having two photodiodes mounted on it.

Real-time multi-target ranging based on chaotic polarization laser radars in the drive-response VCSELs.

PubMed

Zhong, Dongzhou; Xu, Geliang; Luo, Wei; Xiao, Zhenzhen

2017-09-04

According to the principle of complete chaos synchronization and the theory of Hilbert phase transformation, we propose a novel real-time multi-target ranging scheme by using chaotic polarization laser radar in the drive-response vertical-cavity surface-emitting lasers (VCSELs). In the scheme, to ensure each polarization component (PC) of the master VCSEL (MVCSEL) to be synchronized steadily with that of the slave VCSEL, the output x-PC and y-PC from the MVCSEL in the drive system and those in the response system are modulated by the linear electro-optic effect simultaneously. Under this condition, by simulating the influences of some key parameters of the system on the synchronization quality and the relative errors of the two-target ranging, related operating parameters can be optimized. The x-PC and the y-PC, as two chaotic radar sources, are used to implement the real-time ranging for two targets. It is found that the measured distances of the two targets at arbitrary position exhibit strong real-time stability and only slight jitter. Their resolutions are up to millimeters, and their relative errors are very small and less than 2.7%.

Heterodyne efficiency for a coherent laser radar with diffuse or aerosol targets

NASA Technical Reports Server (NTRS)

Frehlich, R. G.

1993-01-01

The performance of a Coherent Laser Radar is determined by the statistics of the coherent Doppler signal. The heterodyne efficiency is an excellent indication of performance because it is an absolute measure of beam alignment and is independent of the transmitter power, the target backscatter coefficient, the atmospheric attenuation, and the detector quantum efficiency and gain. The theoretical calculation of heterodyne efficiency for an optimal monostatic lidar with a circular aperture and Gaussian transmit laser is presented including beam misalignment in the far-field and near-field regimes. The statistical behavior of estimates of the heterodyne efficiency using a calibration hard target are considered. For space based applications, a biased estimate of heterodyne efficiency is proposed that removes the variability due to the random surface return but retains the sensitivity to misalignment. Physical insight is provided by simulation of the fields on the detector surface. The required detector calibration is also discussed.

Design considerations for eye-safe single-aperture laser radars

NASA Astrophysics Data System (ADS)

Starodubov, D.; McCormick, K.; Volfson, L.

2015-05-01

The design considerations for low cost, shock resistant, compact and efficient laser radars and ranging systems are discussed. The reviewed approach with single optical aperture allows reducing the size, weight and power of the system. Additional design benefits include improved stability, reliability and rigidity of the overall system. The proposed modular architecture provides simplified way of varying the performance parameters of the range finder product family by selecting the sets of specific illumination and detection modules. The performance operation challenges are presented. The implementation of non-reciprocal optical elements is considered. The cross talk between illumination and detection channels for single aperture design is reviewed. 3D imaging capability for the ranging applications is considered. The simplified assembly and testing process for single aperture range finders that allows to mass produce the design are discussed. The eye safety of the range finder operation is summarized.

Digital Elevation Models of Greenland based on combined radar and laser altimetry as well as high-resolution stereoscopic imagery

NASA Astrophysics Data System (ADS)

Levinsen, J. F.; Smith, B. E.; Sandberg Sorensen, L.; Khvorostovsky, K.; Simonsen, S. B.; Forsberg, R.

2015-12-01

A number of Digital Elevation Models (DEMs) of Greenland exist, each of which are applicable for different purposes. This study presents two such DEMs: One developed by merging contemporary radar and laser altimeter data, and one derived from high-resolution stereoscopic imagery. All products are made freely available. The former DEM covers the entire Greenland. It is specific to the year 2010, providing it with an advantage over previous models suffering from either a reduced spatial/ temporal data coverage or errors from surface elevation changes (SEC) occurring during data acquisition. Radar data are acquired with Envisat and CryoSat-2, and laser data with the Ice, Cloud, and land Elevation Satellite, the Land, Vegetation, and Ice Sensor, and the Airborne Topographic Mapper. Correcting radar data for errors from slope effects and surface penetration of the echoes, and merging these with laser data, yields a DEM capable of resolving both surface depressions as well as topographic features at higher altitudes. The spatial resolution is 2 x 2 km, making the DEM ideal for application in surface mass balance studies, SEC detection from radar altimetry, or for correcting such data for slope-induced errors. The other DEM is developed in a pilot study building the expertise to map all ice-free parts of Greenland. The work combines WorldView-2 and -3 as well as GeoEye1 imagery from 2014 and 2015 over the Disko, Narsaq, Tassilaq, and Zackenberg regions. The novelty of the work is the determination of the product specifications after elaborate discussions with interested parties from government institutions, the tourist industry, etc. Thus, a 10 m DEM, 1.5 m orthophotos, and vector maps are produced. This opens to the possibility of using orthophotos with up-to-date contour lines or for deriving updated coastlines to aid, e.g., emergency management. This allows for a product development directly in line with the needs of parties with specific interests in Greenland.

A Short Range, High Accuracy Radar Ranging System,

DTIC Science & Technology

1984-12-01

may be of any type and can perform the same functions as any other type of radar (pulsed or continuous wave (CW), coherent or noncoherent , etc.). The...use of an optical carrier frequency 4 enables laser radars to take advantage of the benefits inherent in higher frequencies: higher bandwidths allow...results that are inaccurate or incorrect. Also, directing a laser beam at an aircraft cockpit from a range of 25 feet would pose a serious safety

Millimeter wave radars raise weapon IQ

NASA Astrophysics Data System (ADS)

Lerner, E. J.

1985-02-01

The problems encountered by laser and IR homing devices for guided munitions may be tractable with warhead-mounted mm-wave radars. Operating at about 100 GHz and having several kilometers range, mm-wave radars see through darkness, fog, rain and smoke. The radar must be coupled with an analyzer that discerns moving and stationary targets and higher priority targets. The target lock-on can include shut-off of the transmitter and reception of naturally-generated mm-waves bouncing off the target when in the terminal phase of the flight. Monopulse transmitters have simplified the radar design, although mass production of finline small radar units has yet to be accomplished, particularly in combining GaAs, ferrites and other materials on one monolithic chip.

Calculation method for laser radar cross sections of rotationally symmetric targets.

PubMed

Cao, Yunhua; Du, Yongzhi; Bai, Lu; Wu, Zhensen; Li, Haiying; Li, Yanhui

2017-07-01

The laser radar cross section (LRCS) is a key parameter in the study of target scattering characteristics. In this paper, a practical method for calculating LRCSs of rotationally symmetric targets is presented. Monostatic LRCSs for four kinds of rotationally symmetric targets (cone, rotating ellipsoid, super ellipsoid, and blunt cone) are calculated, and the results verify the feasibility of the method. Compared with the results for the triangular patch method, the correctness of the method is verified, and several advantages of the method are highlighted. For instance, the method does not require geometric modeling and patch discretization. The method uses a generatrix model and double integral, and its calculation is concise and accurate. This work provides a theory analysis for the rapid calculation of LRCS for common basic targets.

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.

Laser radar system for obstacle avoidance

NASA Astrophysics Data System (ADS)

Bers, Karlheinz; Schulz, Karl R.; Armbruster, Walter

2005-09-01

The threat of hostile surveillance and weapon systems require military aircraft to fly under extreme conditions such as low altitude, high speed, poor visibility and incomplete terrain information. The probability of collision with natural and man-made obstacles during such contour missions is high if detection capability is restricted to conventional vision aids. Forward-looking scanning laser radars which are build by the EADS company and presently being flight tested and evaluated at German proving grounds, provide a possible solution, having a large field of view, high angular and range resolution, a high pulse repetition rate, and sufficient pulse energy to register returns from objects at distances of military relevance with a high hit-and-detect probability. The development of advanced 3d-scene analysis algorithms had increased the recognition probability and reduced the false alarm rate by using more readily recognizable objects such as terrain, poles, pylons, trees, etc. to generate a parametric description of the terrain surface as well as the class, position, orientation, size and shape of all objects in the scene. The sensor system and the implemented algorithms can be used for other applications such as terrain following, autonomous obstacle avoidance, and automatic target recognition. This paper describes different 3D-imaging ladar sensors with unique system architecture but different components matched for different military application. Emphasis is laid on an obstacle warning system with a high probability of detection of thin wires, the real time processing of the measured range image data, obstacle classification und visualization.

Transmitter and receiver antenna gain analysis for laser radar and communication systems

NASA Technical Reports Server (NTRS)

Klein, B. J.; Degnan, J. J.

1973-01-01

A comprehensive and fairly self-contained study of centrally obscured optical transmitting and receiving antennas is presented and is intended for use by the laser radar and communication systems designer. The material is presented in a format which allows the rapid and accurate evaluation of antenna gain. The Fresnel approximation to scalar wave theory is reviewed and the antenna analysis proceeds in terms of the power gain. Conventional range equations may then be used to calculate the power budget. The transmitter calculations, resulting in near and far field antenna gain patterns, assumes the antenna is illuminated by a laser operating in the fundamental cavity mode. A simple equation is derived for matching the incident source distribution to a general antenna configuration for maximum on-axis gain. An interpretation of the resultant gain curves allows a number of auxiliary design curves to be drawn which display the losses in antenna gain due to pointing errors and the cone angle of the outgoing beam as a function of antenna size and central obscuration. The use of telescope defocusing as an approach to spreading the beam for target acquisition is compared to some alternate methods.

Long microwave delay fiber-optic link for radar testing

NASA Astrophysics Data System (ADS)

Newberg, I. L.; Gee, C. M.; Thurmond, G. D.; Yen, H. W.

1990-05-01

A long fiberoptic delay line is used as a radar repeater to improve radar testing capabilities. The first known generation of 152 microsec delayed ideal target at X-band (10 GHz) frequencies having the phase stability and signal-to-noise ratio (SNR) needed for testing modern high-resolution Doppler radars is demonstrated with a 31.6-km experimental externally modulated fiberoptic link with a distributed-feedback (DFB) laser. The test application, link configuration, and link testing are discussed.

Optically pre-amplified lidar-radar

NASA Astrophysics Data System (ADS)

Morvan, Loic; Dolfi, Daniel; Huignard, Jean-Pierre

2001-09-01

We present the concept of an optically pre-amplified intensity modulated lidar, where the modulation frequency is in the microwave domain (1-10 GHz). Such a system permits to combine directivity of laser beams with mature radar processing. As an intensity modulated or dual-frequency laser beam is directed on a target, the backscattered intensity is collected by an optical system, pass through an optical preamplifier, and is detected on a high speed photodiode in a direct detection scheme. A radar type processing permits then to extract range, speed and identification information. The association of spatially multimode amplifier and direct detection allows low sensitivity to atmospheric turbulence and large field of view. We demonstrated theoretically that optical pre-amplification can greatly enhance sensitivity, even in spatially multimode amplifiers, such as free-space amplifier or multimode doped fiber. Computed range estimates based on this concept are presented. Laboratory demonstrations using 1 to 3 GHz modulated laser sources and >20 dB gain in multimode amplifiers are detailed. Preliminary experimental results on range and speed measurements and possible use for large amplitude vibrometry will be presented.

GeoSAR: A Radar Terrain Mapping System for the New Millennium

NASA Technical Reports Server (NTRS)

Thompson, Thomas; vanZyl, Jakob; Hensley, Scott; Reis, James; Munjy, Riadh; Burton, John; Yoha, Robert

2000-01-01

GeoSAR Geographic Synthetic Aperture Radar) is a new 3 year effort to build a unique, dual-frequency, airborne Interferometric SAR for mapping of terrain. This is being pursued via a Consortium of the Jet Propulsion Laboratory (JPL), Calgis, Inc., and the California Department of Conservation. The airborne portion of this system will operate on a Calgis Gulfstream-II aircraft outfitted with P- and X-band Interferometric SARs. The ground portions of this system will be a suite of Flight Planning Software, an IFSAR Processor and a Radar-GIS Workstation. The airborne P-band and X-band radars will be constructed by JPL with the goal of obtaining foliage penetration at the longer P-band wavelengths. The P-band and X-band radar will operate at frequencies of 350 Mhz and 9.71 Ghz with bandwidths of either 80 or 160 Mhz. The airborne radars will be complemented with airborne laser system for measuring antenna positions. Aircraft flight lines and radar operating instructions will be computed with the Flight Planning Software The ground processing will be a two-step step process. First, the raw radar data will be processed into radar images and interferometer derived Digital Elevation Models (DEMs). Second, these radar images and DEMs will be processed with a Radar GIS Workstation which performs processes such as Projection Transformations, Registration, Geometric Adjustment, Mosaicking, Merging and Database Management. JPL will construct the IFSAR Processor and Calgis, Inc. will construct the Radar GIS Workstation. The GeoSAR Project was underway in November 1996 with a goal of having the radars and laser systems fully integrated onto the Calgis Gulfstream-II aircraft in early 1999. Then, Engineering Checkout and Calibration-Characterization Flights will be conducted through November 1999. The system will be completed at the end of 1999 and ready for routine operations in the year 2000.

Radar Sensing for Intelligent Vehicles in Urban Environments

PubMed Central

Reina, Giulio; Johnson, David; Underwood, James

2015-01-01

Radar overcomes the shortcomings of laser, stereovision, and sonar because it can operate successfully in dusty, foggy, blizzard-blinding, and poorly lit scenarios. This paper presents a novel method for ground and obstacle segmentation based on radar sensing. The algorithm operates directly in the sensor frame, without the need for a separate synchronised navigation source, calibration parameters describing the location of the radar in the vehicle frame, or the geometric restrictions made in the previous main method in the field. Experimental results are presented in various urban scenarios to validate this approach, showing its potential applicability for advanced driving assistance systems and autonomous vehicle operations. PMID:26102493

Radar Sensing for Intelligent Vehicles in Urban Environments.

PubMed

Reina, Giulio; Johnson, David; Underwood, James

2015-06-19

Radar overcomes the shortcomings of laser, stereovision, and sonar because it can operate successfully in dusty, foggy, blizzard-blinding, and poorly lit scenarios. This paper presents a novel method for ground and obstacle segmentation based on radar sensing. The algorithm operates directly in the sensor frame, without the need for a separate synchronised navigation source, calibration parameters describing the location of the radar in the vehicle frame, or the geometric restrictions made in the previous main method in the field. Experimental results are presented in various urban scenarios to validate this approach, showing its potential applicability for advanced driving assistance systems and autonomous vehicle operations.

Laser range profile of cones

NASA Astrophysics Data System (ADS)

Zhou, Wenzhen; Gong, Yanjun; Wang, Mingjun; Gong, Lei

2016-10-01

technology. Laser one-dimensional range profile can reflect the characteristics of the target shape and surface material. These techniques were motivated by applications of laser radar to target discrimination in ballistic missile defense. The radar equation of pulse laser about cone is given in this paper. This paper demonstrates the analytical model of laser one-dimensional range profile of cone based on the radar equation of the pulse laser. Simulations results of laser one-dimensional range profiles of some cones are given. Laser one-dimensional range profiles of cone, whose surface material with diffuse lambertian reflectance, is given in this paper. Laser one-dimensional range profiles of cone, whose surface mater with diffuse materials whose retroreflectance can be modeled closely with an exponential term that decays with increasing incidence angles, is given in this paper. Laser one-dimensional range profiles of different pulse width of cone is given in this paper. The influences of surface material, pulse width, attitude on the one-dimensional range are analyzed. The laser two-dimensional range profile is two-dimensional scattering imaging of pulse laser of target. The two-dimensional range profile of roughness target can provide range resolved information. An analytical model of two-dimensional laser range profile of cone is proposed. The simulations of two-dimensional laser range profiles of some cones are given. Laser two-dimensional range profiles of cone, whose surface mater with diffuse lambertian reflectance, is given in this paper. Laser two-dimensional range profiles of cone, whose surface mater with diffuse materials whose retroreflectance can be modeled closely with an exponential term that decays with increasing incidence angles, is given in this paper. The influence of pulse width, surface material on laser two-dimensional range profile is analyzed. Laser one-dimensional range profile and laser two-dimensional range profile are called as laser

Radar Thickness Measurements over the Southern Part of the Greenland Ice Sheet

NASA Technical Reports Server (NTRS)

Chuah, Teong Sek; Gogineni, Siva Prasad; Allen, Christopher; Wohletz, Brad; Wong, Y. C.; Ng, P. Y.; Ajayi, E.

1996-01-01

We performed ice thickness measurements over the southern part of the Greenland ice sheet during June and July 1993. We used an airborne coherent radar depth sounder for these measurements. The radar was operated from a NASA P-3 aircraft equipped with GPS receivers. Radar data were collected in conjunction with laser altimeter and microwave altimeter measurements of ice surface elevation. This report provides radio echograms and thickness profiles from data collected during 1993.

Laser radar studies: A study of the feasibility of remote measurement of atmospheric density and turbidity by means of rotational Raman scattering of laser light

NASA Technical Reports Server (NTRS)

Reiss, N.; Schotland, R. M.

1973-01-01

A remote sensing technique is described which utilizes elastic scattering and rotational Raman scattering of laser light in the atmosphere to obtain soundings of turbidity, transmissivity and density. A scheme is devised whereby, through selective weighting of the rotational Raman lines, the effect of atmospheric temperature structure may be eliminated. The close spectral proximity of the elastic and Raman-scattered signals, combined with the fact that the Raman scattering is quite weak, produces special requirements for the spectroscopic and light-gathering components of a rotational Raman laser radar system. These requirements are investigated. A computation of typical signal-to-noise ratios is made. It is shown that daytime signal-to-noise ratios greater than 10 db are to be expected for observation heights of 5 km and below. For nighttime work, 10 db signal-to-noise ratios are achievable to altitudes as high as 15 km.

Finding the Enemy: Using 3-D Laser Radar (LADAR) Imaging for Real Time Combat Identification of Ground Targets in an Obscured Environment

DTIC Science & Technology

2010-04-01

AIR COMMAND AND STAFF COLLEGE AIR UNIVERSITY FINDING THE ENEMY: USING 3-D LASER RADAR (LADAR) IMAGING FOR REAL TIME COMBAT...Faculty In Partial Fulfillment of Graduation Requirements Advisor: Lt Col Terry Bullard Maxwell Air Force Base, Alabama April 2010...position of the US government or the Department of Defense. In accordance with Air Force Instruction 51-303, it is not copyrighted, but is the property of

Novel eye-safe line scanning 3D laser-radar

NASA Astrophysics Data System (ADS)

Eberle, B.; Kern, Tobias; Hammer, Marcus; Schwanke, Ullrich; Nowak, Heinrich

2014-10-01

Today, the civil market provides quite a number of different 3D-Sensors covering ranges up to 1 km. Typically these sensors are based on single element detectors which suffer from the drawback of spatial resolution at larger distances. Tasks demanding reliable object classification at long ranges can be fulfilled only by sensors consisting of detector arrays. They ensure sufficient frame rates and high spatial resolution. Worldwide there are many efforts in developing 3D-detectors, based on two-dimensional arrays. This paper presents first results on the performance of a recently developed 3D imaging laser radar sensor, working in the short wave infrared (SWIR) at 1.5 μm. It consists of a novel Cadmium Mercury Telluride (CMT) linear array APD detector with 384x1 elements at a pitch of 25 μm, developed by AIM Infrarot Module GmbH. The APD elements are designed to work in the linear (non-Geiger) mode. Each pixel will provide the time of flight measurement, and, due to the linear detection mode, allowing the detection of three successive echoes. The resolution in depth is 15 cm, the maximum repetition rate is 4 kHz. We discuss various sensor concepts regarding possible applications and their dependence on system parameters like field of view, frame rate, spatial resolution and range of operation.

Effect of H-wave polarization on laser radar detection of partially convex targets in random media.

PubMed

El-Ocla, Hosam

2010-07-01

A study on the performance of laser radar cross section (LRCS) of conducting targets with large sizes is investigated numerically in free space and random media. The LRCS is calculated using a boundary value method with beam wave incidence and H-wave polarization. Considered are those elements that contribute to the LRCS problem including random medium strength, target configuration, and beam width. The effect of the creeping waves, stimulated by H-polarization, on the LRCS behavior is manifested. Targets taking large sizes of up to five wavelengths are sufficiently larger than the beam width and are sufficient for considering fairly complex targets. Scatterers are assumed to have analytical partially convex contours with inflection points.

All-optical central-frequency-programmable and bandwidth-tailorable radar

PubMed Central

Zou, Weiwen; Zhang, Hao; Long, Xin; Zhang, Siteng; Cui, Yuanjun; Chen, Jianping

2016-01-01

Radar has been widely used for military, security, and rescue purposes, and modern radar should be reconfigurable at multi-bands and have programmable central frequencies and considerable bandwidth agility. Microwave photonics or photonics-assisted radio-frequency technology is a unique solution to providing such capabilities. Here, we demonstrate an all-optical central-frequency-programmable and bandwidth-tailorable radar architecture that provides a coherent system and utilizes one mode-locked laser for both signal generation and reception. Heterodyning of two individually filtered optical pulses that are pre-chirped via wavelength-to-time mapping generates a wideband linearly chirped radar signal. The working bands can be flexibly tailored with the desired bandwidth at a user-preferred carrier frequency. Radar echoes are first modulated onto the pre-chirped optical pulse, which is also used for signal generation, and then stretched in time or compressed in frequency several fold based on the time-stretch principle. Thus, digitization is facilitated without loss of detection ability. We believe that our results demonstrate an innovative radar architecture with an ultra-high-range resolution. PMID:26795596

New phase method of measuring particle size with laser Doppler radar

NASA Astrophysics Data System (ADS)

Zemlianskii, Vladimir M.

1996-06-01

A vast field of non-contact metrology, vibrometry, dynamics and microdynamics problems solved on the basis of laser Doppler method resulted in the development of great variety of laser Doppler radar (LDR). In coherent LDR few beams with various polarization are generally adopted, that are directed at the zone of measurement, through which the probing air stream moves. Studies of various coherent LDR demonstrated that polarization-phase effects of scattering can in some cases considerably effect on the signal-to-noise ratio of the Doppler signal. On the other side using phase effects can simultaneous measurement of size and velocity of spherical particles. New possibilities for improving the accuracy of measuring spherical particles' sizes come to light when application is made in coherent LDR of two waves- probing and one out of the types of symmetrical reception of scattered radiation, during which phase-conjugate signals are formed. The theoretical analysis on the basis of the scattering theory showed, that in symmetrical reception of scattered radiation with respect to the planes OXZ and OYZ output signal of the photoreceiver contains two high- frequency signal components, which in relation to parameters of the probing and size, can either be in phase or antiphase. Results of numerical modeling are presented: amplitude of high frequency signal, coefficient of phase and polarization matching of mixed waves, the depths of photocurrent modulation and also signal's phase in relation to the angle between the probing beams. Phase method of determining particle's sizes based on the use of two wavelengths probing and symmetrical reception of scattered radiation in which conditions for the formation of phase conjugated high-frequency signals are satisfied is presented.

Analysis of detection performance of multi band laser beam analyzer

NASA Astrophysics Data System (ADS)

Du, Baolin; Chen, Xiaomei; Hu, Leili

2017-10-01

Compared with microwave radar, Laser radar has high resolution, strong anti-interference ability and good hiding ability, so it becomes the focus of laser technology engineering application. A large scale Laser radar cross section (LRCS) measurement system is designed and experimentally tested. First, the boundary conditions are measured and the long range laser echo power is estimated according to the actual requirements. The estimation results show that the echo power is greater than the detector's response power. Secondly, a large scale LRCS measurement system is designed according to the demonstration and estimation. The system mainly consists of laser shaping, beam emitting device, laser echo receiving device and integrated control device. Finally, according to the designed lidar cross section measurement system, the scattering cross section of target is simulated and tested. The simulation results are basically the same as the test results, and the correctness of the system is proved.

Using raindrop size distributions from different types of disdrometer to establish weather radar algorithms

NASA Astrophysics Data System (ADS)

Baldini, Luca; Adirosi, Elisa; Roberto, Nicoletta; Vulpiani, Gianfranco; Russo, Fabio; Napolitano, Francesco

2015-04-01

Radar precipitation retrieval uses several relationships that parameterize precipitation properties (like rainfall rate and liquid water content and attenuation (in case of radars at attenuated frequencies such as those at C- and X- band) as a function of combinations of radar measurements. The uncertainty in such relations highly affects the uncertainty precipitation and attenuation estimates. A commonly used method to derive such relationships is to apply regression methods to precipitation measurements and radar observables simulated from datasets of drop size distributions (DSD) using microphysical and electromagnetic assumptions. DSD datasets are determined both by theoretical considerations (i.e. based on the assumption that the radar always samples raindrops whose sizes follow a gamma distribution) or from experimental measurements collected throughout the years by disdrometers. In principle, using long-term disdrometer measurements provide parameterizations more representative of a specific climatology. However, instrumental errors, specific of a disdrometer, can affect the results. In this study, different weather radar algorithms resulting from DSDs collected by diverse types of disdrometers, namely 2D video disdrometer, first and second generation of OTT Parsivel laser disdrometer, and Thies Clima laser disdrometer, in the area of Rome (Italy) are presented and discussed to establish at what extent dual-polarization radar algorithms derived from experimental DSD datasets are influenced by the different error structure of the different type of disdrometers used to collect the data.

Light Detection and Ranging (LIDAR) From Space - Laser Altimeters

NASA Technical Reports Server (NTRS)

Sun, Xiaoli

2016-01-01

Light detection and ranging, or lidar, is like radar but atoptical wavelengths. The principle of operation and theirapplications in remote sensing are similar. Lidars havemany advantages over radars in instrument designs andapplications because of the much shorter laser wavelengthsand narrower beams. The lidar transmitters and receiveroptics are much smaller than radar antenna dishes. Thespatial resolution of lidar measurement is much finer thanthat of radar because of the much smaller footprint size onground. Lidar measurements usually give a better temporalresolution because the laser pulses can be much narrowerthan radio frequency (RF) signals. The major limitation oflidar is the ability to penetrate clouds and ground surfaces.

The Effects of Laser Phase Noise on Laser Radar Performance

DTIC Science & Technology

1992-12-01

Laboratory 5. Figure 3 shows Allan variance plots of the above ultrastable C02 laser which has an open Fabry - Perot cavity 5. The open and solid circles...the same measurement time -r) by more than 10 dB. Therefore, the root Allan variance for the Fabry - Perot cavity ultrastable C02 laser can be...variance so that the SSB phase noise for the Fabry - Perot cavity ultrastable CO 2 laser is about 20 dB (because of the squaring operation) below that of the

Pulsed Submillimeter Laser Program.

DTIC Science & Technology

1979-05-15

number of interrelated subsystems required for a heterodyning FIR radar were investigated. The work focused on optically pumped FIR lasers which... laser pressure. Figure 9 illustrates the effect on optical shape of raising laser pressure. It can be seen that considerable pulse shortening occurs as...range in which single transverse mode operation of a TE CO2 laser has been achieved. For the purposes of this program the optical cavity was

Lasers '92; Proceedings of the International Conference on Lasers and Applications, 15th, Houston, TX, Dec. 7-10, 1992

NASA Technical Reports Server (NTRS)

Wang, Charles P. (Editor)

1993-01-01

Papers from the conference are presented, and the topics covered include the following: x-ray lasers, excimer lasers, chemical lasers, high power lasers, blue-green lasers, dye lasers, solid state lasers, semiconductor lasers, gas and discharge lasers, carbon dioxide lasers, ultrafast phenomena, nonlinear optics, quantum optics, dynamic gratings and wave mixing, laser radar, lasers in medicine, optical filters and laser communication, optical techniques and instruments, laser material interaction, and industrial and manufacturing applications.

Binary selectable detector holdoff circuit: Design, testing, and application. [to laser radar data acquisition system

NASA Technical Reports Server (NTRS)

Kadrmas, K. A.

1973-01-01

A very high speed switching circuit, part of a laser radar data acquisition system, has been designed and tested. The primary function of this circuit was to provide computer controlled switching of photodiode detector preamplifier power supply voltages, typically less than plus or minus 20 volts, in approximately 10 nanoseconds. Thus, in actual use, detector and/or detector preamplifier damage can be avoided as a result of sudden extremely large values of backscattered radiation being detected, such as might be due to short range, very thin atmospheric dust layers. Switching of the power supply voltages was chosen over direct switching the photodiode detector input to the preamplifier, based on system noise considerations. Also, the circuit provides a synchronized trigger pulse output for triggering devices such as the Biomation Model 8100 100 MHz analog to digital converter.

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.

Prospects for quantum cascade lasers as transmitters and local oscillators in coherent terahertz transmitter/receiver systems

NASA Astrophysics Data System (ADS)

Waldman, Jerry; Danylov, Andriy A.; Goyette, Thomas M.; Coulombe, Michael J.; Giles, Robert H.; Gatesman, Andrew J.; Goodhue, William D.; Li, Jin; Linden, Kurt J.; Nixon, William E.

2009-02-01

Coherent terahertz radar systems, using CO2 laser-pumped molecular lasers have been used during the past decade for radar scale modeling applications, as well as proof-of-principle demonstrations of remote detection of concealed weapons. The presentation will consider the potential for replacement of molecular laser sources by quantum cascade lasers. While the temporal and spatial characteristics of current THz QCLs limit their applicability, rapid progress is being made in resolving these issues. Specifications for satisfying the requirements of coherent short-range THz radars will be reviewed and the feasibility of incorporating existing QCL devices into such systems will be described.

A high sensitive 66 dB linear dynamic range receiver for 3-D laser radar

NASA Astrophysics Data System (ADS)

Ma, Rui; Zheng, Hao; Zhu, Zhangming

2017-08-01

This study presents a CMOS receiver chip realized in 0.18 μm standard CMOS technology and intended for high precision 3-D laser radar. The chip includes an adjustable gain transimpedance pre-amplifier, a post-amplifier and two timing comparators. An additional feedback is employed in the regulated cascode transimpedance amplifier to decrease the input impedance, and a variable gain transimpedance amplifier controlled by digital switches and analog multiplexer is utilized to realize four gain modes, extending the input dynamic range. The measurement shows that the highest transimpedance of the channel is 50 k {{Ω }}, the uncompensated walk error is 1.44 ns in a wide linear dynamic range of 66 dB (1:2000), and the input referred noise current is 2.3 pA/\\sqrt{{Hz}} (rms), resulting in a very low detectable input current of 1 μA with SNR = 5.

Comparing Goldstone Solar System Radar Earth-based Observations of Mars with Orbital Datasets

NASA Technical Reports Server (NTRS)

Haldemann, A. F. C.; Larsen, K. W.; Jurgens, R. F.; Slade, M. A.

2005-01-01

The Goldstone Solar System Radar (GSSR) has collected a self-consistent set of delay-Doppler near-nadir radar echo data from Mars since 1988. Prior to the Mars Global Surveyor (MGS) Mars Orbiter Laser Altimeter (MOLA) global topography for Mars, these radar data provided local elevation information, along with radar scattering information with global coverage. Two kinds of GSSR Mars delay-Doppler data exist: low 5 km x 150 km resolution and, more recently, high (5 to 10 km) spatial resolution. Radar data, and non-imaging delay-Doppler data in particular, requires significant data processing to extract elevation, reflectivity and roughness of the reflecting surface. Interpretation of these parameters, while limited by the complexities of electromagnetic scattering, provide information directly relevant to geophysical and geomorphic analyses of Mars. In this presentation we want to demonstrate how to compare GSSR delay-Doppler data to other Mars datasets, including some idiosyncracies of the radar data. Additional information is included in the original extended abstract.

Airborne Visible Laser Optical Communications Program (AVLOC)

NASA Technical Reports Server (NTRS)

Ward, J. H.

1975-01-01

The design, development, and operation of airborne and ground-based laser communications and laser radar hardware is described in support of the Airborne Visible Laser Optical Communication program. The major emphasis is placed on the development of a highly flexible test bed for the evaluation of laser communications systems techniques and components in an operational environment.

Investigation of High Linearity DFB Lasers for Analog Communications

DTIC Science & Technology

1998-02-01

personal communication systems (PCS) service and phased array radar. In this thesis, we examine the dynamic range and distortion for a Fujitsu DFB laser. We...PCS) service and phased array radar. In this thesis, we examine the dynamic range and distortion for a Fujitsu DFB laser. We extract parameters from...is dependent upon the coupling coefficient, as discussed in Chapter 3. Spatial hole burning is more important at lower frequencies (owing to finite

Color (RGB) imaging laser radar

NASA Astrophysics Data System (ADS)

Ferri De Collibus, M.; Bartolini, L.; Fornetti, G.; Francucci, M.; Guarneri, M.; Nuvoli, M.; Paglia, E.; Ricci, R.

2008-03-01

We present a new color (RGB) imaging 3D laser scanner prototype recently developed in ENEA, Italy). The sensor is based on AM range finding technique and uses three distinct beams (650nm, 532nm and 450nm respectively) in monostatic configuration. During a scan the laser beams are simultaneously swept over the target, yielding range and three separated channels (R, G and B) of reflectance information for each sampled point. This information, organized in range and reflectance images, is then elaborated to produce very high definition color pictures and faithful, natively colored 3D models. Notable characteristics of the system are the absence of shadows in the acquired reflectance images - due to the system's monostatic setup and intrinsic self-illumination capability - and high noise rejection, achieved by using a narrow field of view and interferential filters. The system is also very accurate in range determination (accuracy better than 10 -4) at distances up to several meters. These unprecedented features make the system particularly suited to applications in the domain of cultural heritage preservation, where it could be used by conservators for examining in detail the status of degradation of frescoed walls, monuments and paintings, even at several meters of distance and in hardly accessible locations. After providing some theoretical background, we describe the general architecture and operation modes of the color 3D laser scanner, by reporting and discussing first experimental results and comparing high-definition color images produced by the instrument with photographs of the same subjects taken with a Nikon D70 digital camera.

Automatic Rejection Of Multimode Laser Pulses

NASA Technical Reports Server (NTRS)

Tratt, David M.; Menzies, Robert T.; Esproles, Carlos

1991-01-01

Characteristic modulation detected, enabling rejection of multimode signals. Monitoring circuit senses multiple longitudinal mode oscillation of transversely excited, atmospheric-pressure (TEA) CO2 laser. Facility developed for inclusion into coherent detection laser radar (LIDAR) system. However, circuit described of use in any experiment where desireable to record data only when laser operates in single longitudinal mode.

Models of the diffuse radar backscatter from Mars

NASA Technical Reports Server (NTRS)

England, A. W.; Austin, R. T.

1991-01-01

The topographies of several debris flow units near the Mount St. Helens Volcano were measured at lateral scales of millimeters to meters in September 1990. The objective was to measure the surface roughness of the debris flows at scales smaller than, on the order of, and larger that the radar wavelength of common remote sensing radars. A laser profiling system and surveying instruments were used to obtain elevation data for square areas that varied in size from 10 to 32 cm. The elevation data were converted to estimates of the power spectrum of surface roughness. The conversions were based upon standard periodogram techniques, and upon a modified spectral estimation technique that was developed.

Enhancing Europa surface characterization with ice penetrating radar: A Comparative study in Antarctica

NASA Astrophysics Data System (ADS)

Curra, C.; Arnold, E.; Karwoski, B.; Grima, C.; Schroeder, D. M.; Young, D. A.; Blankenship, D. D.

2013-12-01

The shape and composition of the surface of Europa result from multiple processes, most of them involving direct and indirect interactions between the liquid and solid phases of its outer water layer. The surface ice composition is likely to reflect the material exchanged with the sub-glacial ocean and potentially holds signatures of organic compounds that could demonstrate the ability of the icy moon to sustain life. Therefore, the most likely targets for in-situ landing missions are primarily located in complex terrains disrupted by exchange mechanisms with the ocean/lenses of sub-glacial liquid water. Any landing site selection process to ensure a safe delivery of a future lander, will then have to confidently characterize its surface roughness. We evaluate the capability of an ice-penetrating radar to characterize the roughness using a statistical method applied to the surface echoes. Our approach is to compare radar-derived data with nadir-imagery and laser altimetry simultaneously acquired on an airborne platform over Marie Byrd Land, West Antarctica, during the 2012-13 GIMBLE survey. The radar is the High-Capability Radar Sounder 2 (HiCARS 2, 60 MHz) system operated by the University of Texas Institute for Geophysics (UTIG), with specifications similar to the Ice Penetrating Radar (IPR) of the Europa Clipper project. Surface textures as seen by simultaneously collected nadir imagery are manually classified, allowing individual contrast stretching for better identification. We identified crevasse fields, blue ice patches, and families of wind-blown patterns. Homogeneity/heterogeneity of the textures has also been an important classification criterion. The various textures are geolocated and compared to the evolution and amplitude of laser-derived and radar-derived roughness. Similarities and discrepancies between these three datasets are illustrated and analyzed to qualitatively constrain radar sensitivity to the surface textures. The result allows for a

Coordinated Radar Resource Management for Networked Phased Array Radars

DTIC Science & Technology

2014-12-01

Coordinated radar resource management for networked phased array radars Peter W. Moo and Zhen Ding Radar Sensing & Exploitation Section Defence...15] P.W. Moo . Scheduling for multifunction radar via two-slope benefit functions. Radar, Sonar Navigation, IET, 5(8):884 –894, Oct. 2011. [16] M.I

Compressive Sensing for Radar and Radar Sensor Networks

DTIC Science & Technology

2013-12-02

Zero Correlation Zone Sequence Pair Sets for MIMO Radar Inspired by recent advances in MIMO radar, we apply orthogonal phase coded waveforms to MIMO ...radar system in order to gain better range resolution and target direction finding performance [2]. We provide and investigate a generalized MIMO radar...ZCZ) sequence-Pair Set (ZCZPS). We also study the MIMO radar ambiguity function of the system using phase coded waveforms, based on which we analyze

I. I. Rabi, Nuclear Magnetic Resonance (NMR), and Radar

Science.gov Websites

dropdown arrow Site Map A-Z Index Menu Synopsis I. I. Rabi, Nuclear Magnetic Resonance (NMR), and Radar Nobel Prize in Physics "for his resonance method for recording the magnetic properties of atomic the atomic clock, the laser and the diagnostic scanning of the human body by nuclear magnetic

Laser diodes for sensing applications: adaptive cruise control and more

NASA Astrophysics Data System (ADS)

Heerlein, Joerg; Morgott, Stefan; Ferstl, Christian

2005-02-01

Adaptive Cruise Controls (ACC) and pre-crash sensors require an intelligent eye which can recognize traffic situations and deliver a 3-dimensional view. Both microwave RADAR and "Light RADAR" (LIDAR) systems are well suited as sensors. In order to utilize the advantages of LIDARs -- such as lower cost, simpler assembly and high reliability -- the key component, the laser diode, is of primary importance. Here, we present laser diodes which meet the requirements of the automotive industry.

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

Frequency-agile dual-frequency lidar for integrated coherent radar-lidar architectures.

PubMed

Vercesi, Valeria; Onori, Daniel; Laghezza, Francesco; Scotti, Filippo; Bogoni, Antonella; Scaffardi, Mirco

2015-04-01

We propose a novel architecture for implementing a dual-frequency lidar (DFL) exploiting differential Doppler shift measurement. The two frequency tones, needed for target velocity measurements, are selected from the spectrum of a mode-locked laser operating in the C-band. The tones' separation is easily controlled by using a programmable wavelength selective switch, thus allowing for a dynamic trade-off among robustness to atmospheric turbulence and sensitivity. Speed measurements for different tone separations equal to 10, 40, 80, and 160 GHz are demonstrated, proving the system's capability of working in different configurations. Thanks to the acquisition system based on an analog-to-digital converter and digital-signal processing, real-time velocity measurements are demonstrated. The MLL-based proposed architecture enables the integration of the DFL with a photonic-based radar that exploits the same laser for generating and receiving radio-frequency signal with high performance, thus allowing for simultaneous or complementary target observations by exploiting the advantages of both radar and lidar.

GLACIER MONITORING SYSTEM IN COLOMBIA - complementing glaciological measurements with laser-scanning and ground-penetrating radar surveys

NASA Astrophysics Data System (ADS)

Ceballos, Jorge; Micheletti, Natan; Rabatel, Antoine; Mölg, Nico; Zemp, Michael

2015-04-01

Colombia (South America) has six small glaciers (total glacierized area of 45 Km2); their geographical location, close to zero latitude, makes them very sensitive to climate changes. An extensive monitoring program is being performed since 2006 on two glaciers, with international cooperation supports. This presentation summarizes the results of glacier changes in Colombia and includes the latest results obtained within the CATCOS Project - Phase 1 (Capacity Building and Twinning for Climate Observing Systems) signed between Colombia and Switzerland, and within the Joint Mixte Laboratory GREAT-ICE (IRD - France), with the application of LiDAR technology and GPR-based ice thickness measurements at Conejeras Glacier. Conejeras Glacier (Lat. N. 4° 48' 56"; Long. W. 75° 22' 22"; Alt. Max. 4915m.; Alt. Min. 4730m. Area 0.2 Km2) is located on the north-western side of Santa Isabel Volcano. This glacier belongs to global glacier monitoring network of the World Glacier Monitoring Service (WGMS-ID: 2721). The surface mass balance is calculated monthly using the direct glaciological method. Between April 2006 and May 2014, Conejeras Glacier showed a cumulative loss of -21 m w.e. The CATCOS Project allowed to improve the glacier monitoring system in Colombia with two main actions: (1) a terrestrial laser scanner survey (RIEGL VZ-6000 terrestrial laser scanner, property of Universities of Lausanne and Fribourg); and (2) ice thickness measurements (Blue System Integration Ltd. Ice Penetrating Radar of property of IRD). The terrestrial laser-scanning survey allowed to realize an accurate digital terrain model of the glacier surface with 13 million points and a decimetric resolution. Ice thickness measurements showed an average glacier thickness of 22 meters and a maximum of 52 meters.

Range imaging laser radar

DOEpatents

Scott, Marion W.

1990-01-01

A laser source is operated continuously and modulated periodically (typicy sinusoidally). A receiver imposes another periodic modulation on the received optical signal, the modulated signal being detected by an array of detectors of the integrating type. Range to the target determined by measuring the phase shift of the intensity modulation on the received optical beam relative to a reference. The receiver comprises a photoemitter for converting the reflected, periodically modulated, return beam to an accordingly modulated electron stream. The electron stream is modulated by a local demodulation signal source and subsequently converted back to a photon stream by a detector. A charge coupled device (CCD) array then averages and samples the photon stream to provide an electrical signal in accordance with the photon stream.

Range imaging laser radar

DOEpatents

Scott, M.W.

1990-06-19

A laser source is operated continuously and modulated periodically (typically sinusoidally). A receiver imposes another periodic modulation on the received optical signal, the modulated signal being detected by an array of detectors of the integrating type. Range to the target determined by measuring the phase shift of the intensity modulation on the received optical beam relative to a reference. The receiver comprises a photoemitter for converting the reflected, periodically modulated, return beam to an accordingly modulated electron stream. The electron stream is modulated by a local demodulation signal source and subsequently converted back to a photon stream by a detector. A charge coupled device (CCD) array then averages and samples the photon stream to provide an electrical signal in accordance with the photon stream. 2 figs.

Radar based autonomous sensor module

NASA Astrophysics Data System (ADS)

Styles, Tim

2016-10-01

Most surveillance systems combine camera sensors with other detection sensors that trigger an alert to a human operator when an object is detected. The detection sensors typically require careful installation and configuration for each application and there is a significant burden on the operator to react to each alert by viewing camera video feeds. A demonstration system known as Sensing for Asset Protection with Integrated Electronic Networked Technology (SAPIENT) has been developed to address these issues using Autonomous Sensor Modules (ASM) and a central High Level Decision Making Module (HLDMM) that can fuse the detections from multiple sensors. This paper describes the 24 GHz radar based ASM, which provides an all-weather, low power and license exempt solution to the problem of wide area surveillance. The radar module autonomously configures itself in response to tasks provided by the HLDMM, steering the transmit beam and setting range resolution and power levels for optimum performance. The results show the detection and classification performance for pedestrians and vehicles in an area of interest, which can be modified by the HLDMM without physical adjustment. The module uses range-Doppler processing for reliable detection of moving objects and combines Radar Cross Section and micro-Doppler characteristics for object classification. Objects are classified as pedestrian or vehicle, with vehicle sub classes based on size. Detections are reported only if the object is detected in a task coverage area and it is classified as an object of interest. The system was shown in a perimeter protection scenario using multiple radar ASMs, laser scanners, thermal cameras and visible band cameras. This combination of sensors enabled the HLDMM to generate reliable alerts with improved discrimination of objects and behaviours of interest.

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

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

Surface Roughness of the Moon Derived from Multi-frequency Radar Data

NASA Astrophysics Data System (ADS)

Fa, W.

2011-12-01

Surface roughness of the Moon provides important information concerning both significant questions about lunar surface processes and engineering constrains for human outposts and rover trafficabillity. Impact-related phenomena change the morphology and roughness of lunar surface, and therefore surface roughness provides clues to the formation and modification mechanisms of impact craters. Since the Apollo era, lunar surface roughness has been studied using different approaches, such as direct estimation from lunar surface digital topographic relief, and indirect analysis of Earth-based radar echo strengths. Submillimeter scale roughness at Apollo landing sites has been studied by computer stereophotogrammetry analysis of Apollo Lunar Surface Closeup Camera (ALSCC) pictures, whereas roughness at meter to kilometer scale has been studied using laser altimeter data from recent missions. Though these studies shown lunar surface roughness is scale dependent that can be described by fractal statistics, roughness at centimeter scale has not been studied yet. In this study, lunar surface roughnesses at centimeter scale are investigated using Earth-based 70 cm Arecibo radar data and miniature synthetic aperture radar (Mini-SAR) data at S- and X-band (with wavelengths 12.6 cm and 4.12 cm). Both observations and theoretical modeling show that radar echo strengths are mostly dominated by scattering from the surface and shallow buried rocks. Given the different penetration depths of radar waves at these frequencies (< 30 m for 70 cm wavelength, < 3 m at S-band, and < 1 m at X-band), radar echo strengths at S- and X-band will yield surface roughness directly, whereas radar echo at 70-cm will give an upper limit of lunar surface roughness. The integral equation method is used to model radar scattering from the rough lunar surface, and dielectric constant of regolith and surface roughness are two dominate factors. The complex dielectric constant of regolith is first estimated

Planetary surface roughness derived from ice penetrating radar data: Method and concept validation in Antarctica

NASA Astrophysics Data System (ADS)

Grima, C.; Schroeder, D. M.; Blankenship, D. D.; Young, D. A.

2013-12-01

Geological and climatic processes shaping the landscape of planetary bodies imprint the surface with particular textures, i.e. continuous topographic entities at meters to decameters scales where the surface elevation is dominated by a stochastic behavior. The so-called roughness is a proxy to get insights into the type of surface terrain and its ongoing evolution. It is also an important descriptor involved in landing site selection processes to ensure the safe delivery of a lander/rover over a stable work zone. Planetary surface roughnesses are usually derived from point-to-point elevation models acquired by laser altimetry or stereo-imagery. However, in the last decade, nadir-looking penetrating radars have become another remote-sensing technology commonly used for planetary surface and sub-surface characterization (e.g. MARSIS/SHARAD on Mars, LRS on the Moon, and Ice Penetrating Radars for future missions to Europa). Here, we present a statistical method to extract the reflected and scattered components embedded in the surface echoes of HF (3-30 MHz) and VHF (30-300 MHz) penetrating radars in order to derive significant roughness information. We demonstrate the reliability of the method with an application to a radar dataset acquired during the 2004-05 austral summer campaign of the Airborne Geophysical Survey of the Amundsen Sea Embayment, Antarctica, (AGASEA) project with the High-Capability Radar Sounder (HiCARS, 60 MHz) system operated by the University of Texas Institute for Geophysics (UTIG). Results are thoroughly compared with simultaneously acquired laser altimetry and nadir imagery of the surface. We emphasize the possibilities and advantages of the method in light of the future exploration of the Europa and Ganymede icy moons by multi-frequency ice penetrating radars.

Radar research at The Pennsylvania State University Radar and Communications Laboratory

NASA Astrophysics Data System (ADS)

Narayanan, Ram M.

2017-05-01

The Radar and Communications Laboratory (RCL) at The Pennsylvania State University is at the forefront of radar technology and is engaged in cutting edge research in all aspects of radar, including modeling and simulation studies of novel radar paradigms, design and development of new types of radar architectures, and extensive field measurements in realistic scenarios. This paper summarizes the research at The Pennsylvania State University's Radar and Communications Laboratory and relevant collaborative research with several groups over the past 15 years in the field of radar and related technologies, including communications, radio frequency identification (RFID), and spectrum sensing.

Equatorial radar system

NASA Technical Reports Server (NTRS)

Rukao, S.; Tsuda, T.; Sato, T.; Kato, S.

1989-01-01

A large clear air radar with the sensitivity of an incoherent scatter radar for observing the whole equatorial atmosphere up to 1000 km altitude is now being designed in Japan. The radar, called the Equatorial Radar, will be built in Pontianak, Kalimantan Island, Indonesia (0.03 N, 109.3 E). The system is a 47 MHz monostatic Doppler radar with an active phased array configuration similar to that of the MU radar in Japan, which has been in successful operation since 1983. It will have a PA product of more than 5 x 10(9) sq. Wm (P = average transmitter power, A = effective antenna aperture) with sensitivity more than 10 times that of the MU radar. This system configuration enables pulse-to-pulse beam steering within 25 deg from the zenith. As is the case of the MU radar, a variety of sophisticated operations will be made feasible under the supervision of the radar controller. A brief description of the system configuration is presented.

Stable method for estimation of laser ranging

NASA Astrophysics Data System (ADS)

Kurbasova, G. S.; Rykhlova, L. V.

A noise-immunity variant of the least squares method was developed for the preliminary analysis of laser-ranging data. The method takes into account the influence of many physical phenomena accompanying the generation of the laser-ranging signals, their passing through the optical channel, the distribution in the atmosphere, the scattering on the corner reflector, and their registration. The method was demonstrated on the example of Lageos observations made with the Intercosmos laser radar.

The Precision Expandable Radar Calibration Sphere (PERCS) With Applications for Laser Imaging and Ranging

DTIC Science & Technology

2008-09-01

HF facilities such as HAARP in Alaska, EISCAT in Norway, and Arecibo in Puerto Rico; (3) the chain of high latitude SuperDARN radars used for auroral...DF arrays, ground HF transmitters such as the Navy relocatable over the horizon radar (ROTHR) and the Air Force/Navy HAARP system would be employed...United States and Australia; (2) high power HF facilities such as HAARP in Alaska, EISCAT in Norway, and Arecibo in Puerto Rico; (3) the chain of high

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.

Development of carbon dioxide laser doppler instrumentation detection of clear air turbulence

NASA Technical Reports Server (NTRS)

Sonnenschein, C.; Jelalian, A.; Keene, W.

1970-01-01

The analytical, experimental, and developmental aspects of an airborne, pulsed, carbon dioxide laser-optical radar system are described. The laser detects clear air turbulence and performs Doppler measurements of this air-motion phenomenon. Conclusions and recommendations arising from the development of the laser system are presented.

Analysis of Airborne Radar Altimetry Measurements of the Greenland Ice Sheet

NASA Technical Reports Server (NTRS)

Ferraro, Ellen J.

1994-01-01

This dissertation presents an analysis of airborne altimetry measurements taken over the Greenland ice sheet with the 13.9 GHz Advanced Application Flight Experiment (AAFE) pulse compression radar altimeter. This Ku-band instrument was refurbished in 1990 by the Microwave Remote Sensing Laboratory at the University of Massachusetts to obtain high-resolution altitude measurements and to improve the tracking, speed, storage and display capabilities of the radar. In 1991 and 1993, the AAFE altimeter took part in the NASA Multisensor Airborne Altimetry Experiments over Greenland, along with two NASA laser altimeters. Altitude results from both experiments are presented along with comparisons to the laser altimeter and calibration passes over the Sondrestroem runway in Greenland. Although it is too early to make a conclusion about the growth or decay of the ice sheet, these results show that the instrument is capable of measuring small-scale surface changes to within 14 centimeters. In addition, results from these experiments reveal that the radar is sensitive to the different diagenetic regions of the ice sheet. Return waveforms from the wet- snow, percolation and dry-snow zones show varying effects of both surface scattering and sub-surface or volume scattering. Models of each of the diagenetic regions of Greenland are presented along with parameters such as rms surface roughness, rms surface slope and attenuation coefficient of the snow pack obtained by fitting the models to actual return waveforms.

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.

Laser Looking at Earth

NASA Technical Reports Server (NTRS)

1999-01-01

TerraPoint (TM) LLC is a company that combines the technologies developed at NASA's Goddard Space Flight Center (GSFC) and the Houston Advanced Research Center (HARC) with the concept of topographic real estate imaging. TerraPoint provides its customers with digital, topographical data generated by laser technology rather than commonly used microwave (radar) and photographic technologies. This product's technology merges Goddard's and HARC's laser ranging, global positioning systems, and mapping software into a miniaturized package that can be mounted in a light aircraft.

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

Debris Flux Comparisons From The Goldstone Radar, Haystack Radar, and Hax Radar Prior, During, and After the Last Solar Maximum

NASA Technical Reports Server (NTRS)

Stokely, C. L.; Stansbery, E. G.; Goldstein, R. M.

2006-01-01

The continual monitoring of low Earth orbit (LEO) debris environment using highly sensitive radars is essential for an accurate characterization of these dynamic populations. Debris populations are continually evolving since there are new debris sources, previously unrecognized debris sources, and debris loss mechanisms that are dependent on the dynamic space environment. Such radar data are used to supplement, update, and validate existing orbital debris models. NASA has been utilizing radar observations of the debris environment for over a decade from three complementary radars: the NASA JPL Goldstone radar, the MIT Lincoln Laboratory (MIT/LL) Long Range Imaging Radar (known as the Haystack radar), and the MIT/LL Haystack Auxiliary radar (HAX). All of these systems are highly sensitive radars that operate in a fixed staring mode to statistically sample orbital debris in the LEO environment. Each of these radars is ideally suited to measure debris within a specific size region. The Goldstone radar generally observes objects with sizes from 2 mm to 1 cm. The Haystack radar generally measures from 5 mm to several meters. The HAX radar generally measures from 2 cm to several meters. These overlapping size regions allow a continuous measurement of cumulative debris flux versus diameter from 2 mm to several meters for a given altitude window. This is demonstrated for all three radars by comparing the debris flux versus diameter over 200 km altitude windows for 3 nonconsecutive years from 1998 through 2003. These years correspond to periods before, during, and after the peak of the last solar cycle. Comparing the year to year flux from Haystack for each of these altitude regions indicate statistically significant changes in subsets of the debris populations. Potential causes of these changes are discussed. These analysis results include error bars that represent statistical sampling errors, and are detailed in this paper.

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.

Simulation of a weather radar display for over-water airborne radar approaches

NASA Technical Reports Server (NTRS)

Clary, G. R.

1983-01-01

Airborne radar approach (ARA) concepts are being investigated as a part of NASA's Rotorcraft All-Weather Operations Research Program on advanced guidance and navigation methods. This research is being conducted using both piloted simulations and flight test evaluations. For the piloted simulations, a mathematical model of the airborne radar was developed for over-water ARAs to offshore platforms. This simulated flight scenario requires radar simulation of point targets, such as oil rigs and ships, distributed sea clutter, and transponder beacon replies. Radar theory, weather radar characteristics, and empirical data derived from in-flight radar photographs are combined to model a civil weather/mapping radar typical of those used in offshore rotorcraft operations. The resulting radar simulation is realistic and provides the needed simulation capability for ongoing ARA research.

A novel multi-dimensional absolute distance measurement system using a basic frequency modulated continuous wave radar and an external cavity laser with trilateration metrology

NASA Astrophysics Data System (ADS)

Xiong, Xingting; Qu, Xinghua; Zhang, Fumin

2018-01-01

We propose and describe a novel multi-dimensional absolute distance measurement system. This system incorporates a basic frequency modulated continuous wave (FMCW) radar and an second external cavity laser (ECL). Through the use of trilateration, the system in our paper can provide 3D resolution inherently range. However, the measured optical path length differences (OPD) is often variable in industrial environments and this will causes Doppler effect, which has greatly impact on the measurement result. With using the second ECL, the system can correct the Doppler effect to ensure the precision of absolute distance measurement. Result of the simulation will prove the influence of Doppler effect.

Planetary radar studies. [radar mapping of the Moon and radar signatures of lunar and Venus craters

NASA Technical Reports Server (NTRS)

Thompson, T. W.; Cutts, J. A.

1981-01-01

Progress made in studying the evolution of Venusian craters and the evolution of infrared and radar signatures of lunar crater interiors is reported. Comparison of radar images of craters on Venus and the Moon present evidence for a steady state Venus crater population. Successful observations at the Arecibo Observatory yielded good data on five nights when data for a mix of inner and limb areas were acquired. Lunar craters with radar bright ejects are discussed. An overview of infrared radar crater catalogs in the data base is included.

Apollo experience report: Lunar module landing radar and rendezvous radar

NASA Technical Reports Server (NTRS)

Rozas, P.; Cunningham, A. R.

1972-01-01

A developmental history of the Apollo lunar module landing and rendezvous radar subsystems is presented. The Apollo radar subsystems are discussed from initial concept planning to flight configuration testing. The major radar subsystem accomplishments and problems are discussed.

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

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.

Radar-based rainfall estimation: Improving Z/R relations through comparison of drop size distributions, rainfall rates and radar reflectivity patterns

NASA Astrophysics Data System (ADS)

Neuper, Malte; Ehret, Uwe

2014-05-01

The relation between the measured radar reflectivity factor Z and surface rainfall intensity R - the Z/R relation - is profoundly complex, so that in general one speaks about radar-based quantitative precipitation estimation (QPE) rather than exact measurement. Like in Plato's Allegory of the Cave, what we observe in the end is only the 'shadow' of the true rainfall field through a very small backscatter of an electromagnetic signal emitted by the radar, which we hope has been actually reflected by hydrometeors. The meteorological relevant and valuable Information is gained only indirectly by more or less justified assumptions. One of these assumptions concerns the drop size distribution, through which the rain intensity is finally associated with the measured radar reflectivity factor Z. The real drop size distribution is however subject to large spatial and temporal variability, and consequently so is the true Z/R relation. Better knowledge of the true spatio-temporal Z/R structure therefore has the potential to improve radar-based QPE compared to the common practice of applying a single or a few standard Z/R relations. To this end, we use observations from six laser-optic disdrometers, two vertically pointing micro rain radars, 205 rain gauges, one rawindsonde station and two C-band Doppler radars installed or operated in and near the Attert catchment (Luxembourg). The C-band radars and the rawindsonde station are operated by the Belgian and German Weather Services, the rain gauge data was partly provided by the French, Dutch, Belgian, German Weather Services and the Ministry of Agriculture of Luxembourg and the other equipment was installed as part of the interdisciplinary DFG research project CAOS (Catchment as Organized Systems). With the various data sets correlation analyzes were executed. In order to get a notion on the different appearance of the reflectivity patterns in the radar image, first of all various simple distribution indices (for example the

Radar orthogonality and radar length in Finsler and metric spacetime geometry

NASA Astrophysics Data System (ADS)

Pfeifer, Christian

2014-09-01

The radar experiment connects the geometry of spacetime with an observers measurement of spatial length. We investigate the radar experiment on Finsler spacetimes which leads to a general definition of radar orthogonality and radar length. The directions radar orthogonal to an observer form the spatial equal time surface an observer experiences and the radar length is the physical length the observer associates to spatial objects. We demonstrate these concepts on a forth order polynomial Finsler spacetime geometry which may emerge from area metric or premetric linear electrodynamics or in quantum gravity phenomenology. In an explicit generalization of Minkowski spacetime geometry we derive the deviation from the Euclidean spatial length measure in an observers rest frame explicitly.

Nonlinear automatic landing control of unmanned aerial vehicles on moving platforms via a 3D laser radar

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hervas, Jaime Rubio; Tang, Hui; Reyhanoglu, Mahmut

2014-12-10

This paper presents a motion tracking and control system for automatically landing Unmanned Aerial Vehicles (UAVs) on an oscillating platform using Laser Radar (LADAR) observations. The system itself is assumed to be mounted on a ship deck. A full nonlinear mathematical model is first introduced for the UAV. The ship motion is characterized by a Fourier transform based method which includes a realistic characterization of the sea waves. LADAR observation models are introduced and an algorithm to process those observations for yielding the relative state between the vessel and the UAV is presented, from which the UAV's state relative tomore » an inertial frame can be obtained and used for feedback purposes. A sliding mode control algorithm is derived for tracking a landing trajectory defined by a set of desired waypoints. An extended Kalman filter (EKF) is proposed to account for process and observation noises in the design of a state estimator. The effectiveness of the control algorithm is illustrated through a simulation example.« less

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.

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.

Recommendation on Transition from Primary/Secondary Radar to Secondary- Only Radar Capability

DTIC Science & Technology

1994-10-01

Radar Beacon Performance Monitor RCIU Remote Control Interface Unit RCL Remote Communications Link R E&D Research, Engineering and Development RML Radar...rate. 3.1.2.5 Maintenance The current LRRs have limited remote maintenance monitoring (RMM) capabilities via the Remote Control Interface Unit ( RCIU ...1, -2 and FPS-20 radars required an upgrade of some of the radar subsystems, namely the RCIU to respond as an RMS and the CD to interface with radar

Reconfigurable L-Band Radar

NASA Technical Reports Server (NTRS)

Rincon, Rafael F.

2008-01-01

The reconfigurable L-Band radar is an ongoing development at NASA/GSFC that exploits the capability inherently in phased array radar systems with a state-of-the-art data acquisition and real-time processor in order to enable multi-mode measurement techniques in a single radar architecture. The development leverages on the L-Band Imaging Scatterometer, a radar system designed for the development and testing of new radar techniques; and the custom-built DBSAR processor, a highly reconfigurable, high speed data acquisition and processing system. The radar modes currently implemented include scatterometer, synthetic aperture radar, and altimetry; and plans to add new modes such as radiometry and bi-static GNSS signals are being formulated. This development is aimed at enhancing the radar remote sensing capabilities for airborne and spaceborne applications in support of Earth Science and planetary exploration This paper describes the design of the radar and processor systems, explains the operational modes, and discusses preliminary measurements and future plans.

Social Radar

DTIC Science & Technology

2012-01-01

RTA HFM-201/RSM PAPER 3 - 1 © 2012 The MITRE Corporation. All Rights Reserved. Social Radar Barry Costa and John Boiney MITRE Corporation...defenders require an integrated set of capabilities that we refer to as a “ social radar.” Such a system would support strategic- to operational-level...situation awareness, alerting, course of action analysis, and measures of effectiveness for each action undertaken. Success of a social radar

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.

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

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.

Three-dimensional laser microvision.

PubMed

Shimotahira, H; Iizuka, K; Chu, S C; Wah, C; Costen, F; Yoshikuni, Y

2001-04-10

A three-dimensional (3-D) optical imaging system offering high resolution in all three dimensions, requiring minimum manipulation and capable of real-time operation, is presented. The system derives its capabilities from use of the superstructure grating laser source in the implementation of a laser step frequency radar for depth information acquisition. A synthetic aperture radar technique was also used to further enhance its lateral resolution as well as extend the depth of focus. High-speed operation was made possible by a dual computer system consisting of a host and a remote microcomputer supported by a dual-channel Small Computer System Interface parallel data transfer system. The system is capable of operating near real time. The 3-D display of a tunneling diode, a microwave integrated circuit, and a see-through image taken by the system operating near real time are included. The depth resolution is 40 mum; lateral resolution with a synthetic aperture approach is a fraction of a micrometer and that without it is approximately 10 mum.

Interpreting Radar View near Mars' South Pole, Orbit 1360

NASA Technical Reports Server (NTRS)

2006-01-01

A radargram from the Shallow Subsurface Radar instrument (SHARAD) on NASA's Mars Reconnaissance Orbiter is shown in the upper-right panel and reveals detailed structure in the polar layered deposits of the south pole of Mars.

The sounding radar collected the data presented here during orbit 1360 of the mission, on Nov. 10, 2006.

The horizontal scale in the radargram is distance along the ground track. It can be referenced to the ground track map shown in the lower right. The radar traversed from about 74 degrees to 85 degrees south latitude, or about 650 kilometers (400 miles). The ground track map shows elevation measured by the Mars Orbiter Laser Altimeter on NASA's Mars Global Surveyor orbiter. Green indicates low elevation; reddish-white indicates higher elevation. The traverse proceeds up onto a plateau formed by the layers.

The vertical scale on the radargram is time delay of the radar signals reflected back to Mars Reconnaissance Orbiter from the surface and subsurface. For reference, using an assumed velocity of the radar waves in the subsurface, time is converted to depth below the surface at one place: about 800 meters (2,600 feet) to one of the strongest subsurface reflectors. This reflector marks the base of the polar layered deposits. The color scale varies from black for weak reflections to white for strong reflections.

The middle panel shows mapping of the major subsurface reflectors, some of which can be traced for a distance of 100 kilometers (60 miles) or more. The layering manifests the recent climate history of Mars, recorded by the deposition and removal of ice and dust.

The Shallow Subsurface Radar was provided by the Italian Space Agency (ASI). Its operations are led by the University of Rome and its data are analyzed by a joint U.S.-Italian science team. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology, Pasadena, manages the Mars Reconnaissance Orbiter for the NASA Science

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

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.

Space Radar Image of Ubar Optical/Radar

NASA Image and Video Library

1998-04-28

This pair of images from space shows a portion of the southern Empty Quarter of the Arabian Peninsula in the country of Oman. On the left is a radar image of the region around the site of the fabled Lost City of Ubar, discovered in 1992 with the aid of remote sensing data. On the right is an enhanced optical image taken by the shuttle astronauts. Ubar existed from about 2800 BC to about 300 AD. and was a remote desert outpost where caravans were assembled for the transport of frankincense across the desert. The actual site of the fortress of the Lost City of Ubar, currently under excavation, is too small to show in either image. However, tracks leading to the site, and surrounding tracks, show as prominent, but diffuse, reddish streaks in the radar image. Although used in modern times, field investigations show many of these tracks were in use in ancient times as well. Mapping of these tracks on regional remote sensing images provided by the Landsat satellite was a key to recognizing the site as Ubar. The prominent magenta colored area is a region of large sand dunes. The green areas are limestone rocks, which form a rocky desert floor. A major wadi, or dry stream bed, runs across the scene and appears as a white line. The radar images, and ongoing field investigations, will help shed light on an early civilization about which little in known. The radar image was taken by the Spaceborne Imaging Radar C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) and is centered at 18 degrees North latitude and 53 degrees East longitude. The image covers an area about 50 kilometers by 100 kilometers (31 miles by 62 miles). The colors in the image are assigned to different frequencies and polarizations of the radar as follows: red is L-band, horizontally transmitted, horizontally received; blue is C-band horizontally transmitted, horizontally received; green is L-band horizontally transmitted, vertically received. SIR-C/X-SAR, a joint mission of the German, Italian and the United

41. Perimeter acquisition radar building radar element and coaxial display, ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

41. Perimeter acquisition radar building radar element and coaxial display, with drawing of typical antenna section. Drawing, from left to right, shows element, aluminum ground plane, cable connectors and hardware, cable, and back-up ring. Grey area is the concrete wall - Stanley R. Mickelsen Safeguard Complex, Perimeter Acquisition Radar Building, Limited Access Area, between Limited Access Patrol Road & Service Road A, Nekoma, Cavalier County, ND

Preliminary VHF radar and high-data-rate optical turbulence profile observations using a balloon-ring platform

NASA Astrophysics Data System (ADS)

Eaton, Frank D.; Nastrom, Gregory D.; Kyrazis, Demos T.; Black, Don G.; Black, Wiley T.; Black, R. Alastair

2009-08-01

A recent measurement campaign at Vandenberg Air Force Base, Calif. involved taking simultaneous observations with a VHF radar and high-data-rate (1-micron diameter) platinum wires to sense optical turbulence (from temperature fluctuations). The radar observations produce profiles of the refractive index structure parameter (C2n ), the turbulent kinetic energy (σ2t ), the eddy dissipation rate (ɛ), the inner scale (lo ), the outer scale (Lo ) of turbulence, and wind speed and direction to an altitude of 20 km AGL. The fine wire measurements were taken from the surface with several sensors mounted on a balloon-ring platform sampling in excess of 3 kHz to balloon burst altitudes (typically above 25 km AGL). The main objectives of this effort are to compare the two measurement techniques and to obtain observations that can address several fundamental turbulence issues of the real turbulent atmosphere related to laser beam propagation. To date, modeling and simulation of laser beam propagation through atmospheric turbulence have relied upon a traditional theoretical basis that assumes the existence of homogeneous, isotropic, stationary, and Kolmogorov turbulence. Results presented from the radar observations include C2n, σ2t, ɛ, lo, and the standard deviation of vertical velocity (σw). A comparison of the profiles of C2n obtained from the two measurement techniques is shown and discussed. A time series of temperature data obtained from a fine wire probe traversing one radar range gate is presented and discussed. Future measurement and analysis efforts are presented.

Remote steering of laser beams by radar- and laser-induced refractive-index gradients in the atmosphere Remote steering of laser beams

NASA Astrophysics Data System (ADS)

Zheltikov, A. M.; Shneider, M. N.; Voronin, A. A.; Sokolov, A. V.; Scully, M. O.

2012-01-01

Refractive-index gradients induced in the atmospheric air by properly tailored laser and microwave fields are shown to enable a remote steering of laser beams. Heating-assisted modulation of the refractive index of the air by microwave radiation is shown to support small-angle laser-beam bending with bending angles on the order of 10-2. Ionization of the atmospheric air by dyads of femto- and nanosecond laser pulses, on the other hand, can provide beam deflection angles in excess of π/5, offering an attractive strategy for radiation transfer, free-space communications, and laser-based standoff detection.

51. View of upper radar scanner switch in radar scanner ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

51. View of upper radar scanner switch in radar scanner building 105 from upper catwalk level showing emanating waveguides from upper switch (upper one-fourth of photograph) and emanating waveguides from lower radar scanner switch in vertical runs. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

Spaceborne radar observations: A guide for Magellan radar-image analysis

NASA Technical Reports Server (NTRS)

Ford, J. P.; Blom, R. G.; Crisp, J. A.; Elachi, Charles; Farr, T. G.; Saunders, R. Stephen; Theilig, E. E.; Wall, S. D.; Yewell, S. B.

1989-01-01

Geologic analyses of spaceborne radar images of Earth are reviewed and summarized with respect to detecting, mapping, and interpreting impact craters, volcanic landforms, eolian and subsurface features, and tectonic landforms. Interpretations are illustrated mostly with Seasat synthetic aperture radar and shuttle-imaging-radar images. Analogies are drawn for the potential interpretation of radar images of Venus, with emphasis on the effects of variation in Magellan look angle with Venusian latitude. In each landform category, differences in feature perception and interpretive capability are related to variations in imaging geometry, spatial resolution, and wavelength of the imaging radar systems. Impact craters and other radially symmetrical features may show apparent bilateral symmetry parallel to the illumination vector at low look angles. The styles of eruption and the emplacement of major and minor volcanic constructs can be interpreted from morphological features observed in images. Radar responses that are governed by small-scale surface roughness may serve to distinguish flow types, but do not provide unambiguous information. Imaging of sand dunes is rigorously constrained by specific angular relations between the illumination vector and the orientation and angle of repose of the dune faces, but is independent of radar wavelength. With a single look angle, conditions that enable shallow subsurface imaging to occur do not provide the information necessary to determine whether the radar has recorded surface or subsurface features. The topographic linearity of many tectonic landforms is enhanced on images at regional and local scales, but the detection of structural detail is a strong function of illumination direction. Nontopographic tectonic lineaments may appear in response to contrasts in small-surface roughness or dielectric constant. The breakpoint for rough surfaces will vary by about 25 percent through the Magellan viewing geometries from low to high

Lasers, their development, and applications at M.I.T. Lincoln Laboratory

NASA Technical Reports Server (NTRS)

Rediker, R. H.; Melngailis, I.; Mooradian, A.

1984-01-01

A historical account of the work on lasers at MIT Lincoln Laboratory is presented. Highlighted are the efforts that led to the coinvention of the semiconductor laser and the Laboratory's later role in establishing the feasibility of GaInAsP/InP semiconductor lasers for use in fiber telecommunications at 1.3-1.5 micron wavelengths. Descriptions of other important developments include tunable lead-salt semiconductor and solid-state lasers for spectroscopy and LIDAR applications, respectively, as well as ultrastable CO2 lasers for coherent infrared radar.

Space Radar Image of Long Island Optical/Radar

NASA Technical Reports Server (NTRS)

1994-01-01

This pair of images of the Long Island, New York region is a comparison of an optical photograph (top) and a radar image (bottom), both taken in darkness in April 1994. The photograph at the top was taken by the Endeavour astronauts at about 3 a.m. Eastern time on April 20, 1994. The image at the bottom was acquired at about the same time four days earlier on April 16,1994 by the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) system aboard the space shuttle Endeavour. Both images show an area approximately 100 kilometers by 40 kilometers (62 miles by 25 miles) that is centered at 40.7 degrees North latitude and 73.5 degrees West longitude. North is toward the upper right. The optical image is dominated by city lights, which are particularly bright in the densely developed urban areas of New York City located on the left half of the photo. The brightest white zones appear on the island of Manhattan in the left center, and Central Park can be seen as a darker area in the middle of Manhattan. To the northeast (right) of the city, suburban Long Island appears as a less densely illuminated area, with the brightest zones occurring along major transportation and development corridors. Since radar is an active sensing system that provides its own illumination, the radar image shows a great amount of surface detail, despite the night-time acquisition. The colors in the radar image were obtained using the following radar channels: red represents the L-band (horizontally transmitted and received); green represents the L-band (horizontally transmitted and vertically received); blue represents the C-band (horizontally transmitted and vertically received). In this image, the water surface - the Atlantic Ocean along the bottom edge and Long Island Sound shown at the top edge - appears red because small waves at the surface strongly reflect the horizontally transmitted and received L-band radar signal. Networks of highways and railroad lines are clearly

Space Radar Image of Long Island Optical/Radar

NASA Image and Video Library

1999-05-01

This pair of images of the Long Island, New York region is a comparison of an optical photograph (top) and a radar image (bottom), both taken in darkness in April 1994. The photograph at the top was taken by the Endeavour astronauts at about 3 a.m. Eastern time on April 20, 1994. The image at the bottom was acquired at about the same time four days earlier on April 16,1994 by the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) system aboard the space shuttle Endeavour. Both images show an area approximately 100 kilometers by 40 kilometers (62 miles by 25 miles) that is centered at 40.7 degrees North latitude and 73.5 degrees West longitude. North is toward the upper right. The optical image is dominated by city lights, which are particularly bright in the densely developed urban areas of New York City located on the left half of the photo. The brightest white zones appear on the island of Manhattan in the left center, and Central Park can be seen as a darker area in the middle of Manhattan. To the northeast (right) of the city, suburban Long Island appears as a less densely illuminated area, with the brightest zones occurring along major transportation and development corridors. Since radar is an active sensing system that provides its own illumination, the radar image shows a great amount of surface detail, despite the night-time acquisition. The colors in the radar image were obtained using the following radar channels: red represents the L-band (horizontally transmitted and received); green represents the L-band (horizontally transmitted and vertically received); blue represents the C-band (horizontally transmitted and vertically received). In this image, the water surface - the Atlantic Ocean along the bottom edge and Long Island Sound shown at the top edge - appears red because small waves at the surface strongly reflect the horizontally transmitted and received L-band radar signal. Networks of highways and railroad lines are clearly

Systems and Methods for Radar Data Communication

NASA Technical Reports Server (NTRS)

Bunch, Brian (Inventor); Szeto, Roland (Inventor); Miller, Brad (Inventor)

2013-01-01

A radar information processing system is operable to process high bandwidth radar information received from a radar system into low bandwidth radar information that may be communicated to a low bandwidth connection coupled to an electronic flight bag (EFB). An exemplary embodiment receives radar information from a radar system, the radar information communicated from the radar system at a first bandwidth; processes the received radar information into processed radar information, the processed radar information configured for communication over a connection operable at a second bandwidth, the second bandwidth lower than the first bandwidth; and communicates the radar information from a radar system, the radar information communicated from the radar system at a first bandwidth.

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.

FIRE_CI2_ETL_RADAR

Atmospheric Science Data Center

2015-11-25

FIRE_CI2_ETL_RADAR Project Title:  FIRE II CIRRUS Discipline:  ... Platform:  Ground Station Instrument:  Radar Spatial Coverage:  (37.06, -95.34) Spatial ... Order Data Guide Documents:  ETL_RADAR Guide Readme Files:  Readme ETL_RADAR (PS) ...

Phased-array laser radar: Concept and application

NASA Technical Reports Server (NTRS)

Kadrmas, K. A.

1973-01-01

The design and construction of a coaxial transmitter-receiver combination was investigated. Major emphasis was placed on simple permanent optical alignment, transmitter-receiver field of view matching, use of a pulsed gas laser as a transmitter maximum optical efficiency, complete digital control of data acquisition, and optical mount pointing and tracking. Also a means of expanding the coaxial transmitter-receiver concept to allow phased-array lidar, par-lidar was described.

Interpreting Radar View near Mars' South Pole, Orbit 1334

NASA Technical Reports Server (NTRS)

2006-01-01

A radargram from the Shallow Subsurface Radar instrument (SHARAD) on NASA's Mars Reconnaissance Orbiter is shown in the upper-right panel and reveals detailed structure in the polar layered deposits of the south pole of Mars.

The sounding radar collected the data presented here during orbit 1334 of the mission, on Nov. 8, 2006.

The horizontal scale in the radargram is distance along the ground track. It can be referenced to the ground track map shown in the lower right. The radar traversed from about 75 to 85 degrees south latitude, or about 590 kilometers (370 miles). The ground track map shows elevation measured by the Mars Orbiter Laser Altimeter on NASA's Mars Global Surveyor orbiter. Green indicates low elevation; reddish-white indicates higher elevation. The traverse proceeds up onto a plateau formed by the layers.

The vertical scale on the radargram is time delay of the radar signals reflected back to Mars Reconnaissance Orbiter from the surface and subsurface. For reference, using an assumed velocity of the radar waves in the subsurface, time is converted to depth below the surface at one place: about 1,500 meters (5,000 feet) to one of the deeper subsurface reflectors. The color scale varies from black for weak reflections to white for strong reflections.

The middle panel shows mapping of the major subsurface reflectors, some of which can be traced for a distance of 100 kilometers (60 miles) or more. The layers are not all horizontal and the reflectors are not always parallel to one another. Some of this is due to variations in surface elevation, which produce differing velocity path lengths for different reflector depths. However, some of this behavior is due to spatial variations in the deposition and removal of material in the layered deposits, a result of the recent climate history of Mars.

The Shallow Subsurface Radar was provided by the Italian Space Agency (ASI). Its operations are led by the University of Rome and its

Model studies of laser absorption computed tomography for remote air pollution measurement

NASA Technical Reports Server (NTRS)

Wolfe, D. C., Jr.; Byer, R. L.

1982-01-01

Model studies of the potential of laser absorption-computed tomography are presented which demonstrate the possibility of sensitive remote atmospheric pollutant measurements, over kilometer-sized areas, with two-dimensional resolution, at modest laser source powers. An analysis of this tomographic reconstruction process as a function of measurement SNR, laser power, range, and system geometry, shows that the system is able to yield two-dimensional maps of pollutant concentrations at ranges and resolutions superior to those attainable with existing, direct-detection laser radars.

Segmentation, classification, and pose estimation of military vehicles in low resolution laser radar images

NASA Astrophysics Data System (ADS)

Neulist, Joerg; Armbruster, Walter

2005-05-01

Model-based object recognition in range imagery typically involves matching the image data to the expected model data for each feasible model and pose hypothesis. Since the matching procedure is computationally expensive, the key to efficient object recognition is the reduction of the set of feasible hypotheses. This is particularly important for military vehicles, which may consist of several large moving parts such as the hull, turret, and gun of a tank, and hence require an eight or higher dimensional pose space to be searched. The presented paper outlines techniques for reducing the set of feasible hypotheses based on an estimation of target dimensions and orientation. Furthermore, the presence of a turret and a main gun and their orientations are determined. The vehicle parts dimensions as well as their error estimates restrict the number of model hypotheses whereas the position and orientation estimates and their error bounds reduce the number of pose hypotheses needing to be verified. The techniques are applied to several hundred laser radar images of eight different military vehicles with various part classifications and orientations. On-target resolution in azimuth, elevation and range is about 30 cm. The range images contain up to 20% dropouts due to atmospheric absorption. Additionally some target retro-reflectors produce outliers due to signal crosstalk. The presented algorithms are extremely robust with respect to these and other error sources. The hypothesis space for hull orientation is reduced to about 5 degrees as is the error for turret rotation and gun elevation, provided the main gun is visible.

RADAR performance experiments

NASA Technical Reports Server (NTRS)

Leroux, C.; Bertin, F.; Mounir, H.

1991-01-01

Theoretical studies and experimental results obtained at Coulommiers airport showed the capability of Proust radar to detect wind shears, in clear air condition as well as in presence of clouds or rain. Several examples are presented: in a blocking highs situation an atmospheric wave system at the Brunt-Vaisala frequency can be clearly distinguished; in a situation of clouds without rain the limit between clear air and clouds can be easily seen; and a windshear associated with a gust front in rainy conditions is shown. A comparison of 30 cm clear air radar Proust and 5 cm weather Doppler radar Ronsard will allow to select the best candidate for wind shear detection, taking into account the low sensibility to ground clutter of Ronsard radar.

46 CFR 121.404 - Radars.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 4 2010-10-01 2010-10-01 false Radars. 121.404 Section 121.404 Shipping COAST GUARD... Navigation Equipment § 121.404 Radars. (a) Except as allowed by paragraph (b) of this section, all self... radar system for surface navigation with a radar screen mounted at the primary operating station. (b...

46 CFR 121.404 - Radars.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 4 2011-10-01 2011-10-01 false Radars. 121.404 Section 121.404 Shipping COAST GUARD... Navigation Equipment § 121.404 Radars. (a) Except as allowed by paragraph (b) of this section, all self... radar system for surface navigation with a radar screen mounted at the primary operating station. (b...

46 CFR 121.404 - Radars.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 4 2014-10-01 2014-10-01 false Radars. 121.404 Section 121.404 Shipping COAST GUARD... Navigation Equipment § 121.404 Radars. (a) Except as allowed by paragraph (b) of this section, all self... radar system for surface navigation with a radar screen mounted at the primary operating station. (b...

46 CFR 121.404 - Radars.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 4 2013-10-01 2013-10-01 false Radars. 121.404 Section 121.404 Shipping COAST GUARD... Navigation Equipment § 121.404 Radars. (a) Except as allowed by paragraph (b) of this section, all self... radar system for surface navigation with a radar screen mounted at the primary operating station. (b...

46 CFR 121.404 - Radars.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 4 2012-10-01 2012-10-01 false Radars. 121.404 Section 121.404 Shipping COAST GUARD... Navigation Equipment § 121.404 Radars. (a) Except as allowed by paragraph (b) of this section, all self... radar system for surface navigation with a radar screen mounted at the primary operating station. (b...

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.

Injection-seeded operation of a Q-switched Cr,Tm,Ho:YAG laser

NASA Technical Reports Server (NTRS)

Henderson, Sammy W.; Hale, Charley P.; Magee, James R.

1991-01-01

Single-frequency Tm,Ho:YAG lasers operating near 2 microns are attractive sources for several applications including eye-safe laser radar (lidar) and pumping of AgGaSe2 parametric oscillators for efficient generation of longer wavelengths. As part of a program to develop a coherent lidar system using Tm,Ho:YAG lasers, a diode laser-pumped tunable CW single-longitudinal-mode (SLM) Cr:Tm:Ho:YAG laser and a flashlamp-pumped single-transverse-mode Q-switched Cr,Tm,Ho:YAG laser were developed. The CW laser was used to injection-seed the flashlamp-pumped laser, resulting in SLM Q-switched output. Operational characteristics of the CW and Q-switched lasers and injection-seeding results are reported.

Application of airborne laser scanner measurements of ocean roughness to the calibration and validation of a satellite bistatic radar experiment

NASA Astrophysics Data System (ADS)

Parrin, J.; Garrison, J. L.

2006-12-01

A high-resolution airborne laser scanner, from the National Center for Airborne Laser Mapping (NCALM) was used to profile the ocean surface in an attempt to experimentally measure the ocean height spectrum down to wavelengths as small as a few centimetres. In October of 2005, three data collections were scheduled, during overpasses of the UK-DMC satellite, off the coast of Virginia. UK-DMC carries an experimental bistatic radar receiver, which uses Global Navigation Satellite System (GNSS) signals as illumination sources. Most models for reflected GNSS signals relate the shape of the signal correlation waveforms to the ocean roughness, parameterized as a probability distribution (PDF) of surface slopes. This statistical description of the ocean surface must first be filtered to wavelengths greater than some fraction of the GNSS wavelength of 19 cm. Past experimental campaigns have used more common in-situ measurements, such as wind speed, for comparison with GNSS waveforms. These types of measurements will require the assumption of some empirical model for the ocean height spectrum, allowing the computation of the filtered slope statistics. Proposed applications of reflected GNSS signals include the correction of ocean roughness effects in passive microwave radiometry. To evaluate the feasibility of GNSS reflections for this measurement, it is important to make a more direct measurement of the ocean surface slope statistics, without the assumption of a spectrum model. In these experiments, a direct measurement of this spectrum was attempted, using the NCALM system. The laser scanner was operated on a low altitude (500 m) aircraft, at the highest sample rate (33KHz), generating ocean height measurements with an along-track separation of a few millimetres. The laser illuminates a spot on the ocean surface that is smaller than 10 cm, however, limiting the smallest resolvable wavelength to something on that order. Laser data were collected along multiple flight lines

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

Modern multi-mode active phased array radars require highly efficient radar control system for hassle free real time radar operation. The requirement comes due to the distributed architecture of the active phased array radar, where each antenna element in the array is connected to a dedicated Transmit-Receive (TR) module. Controlling the TR modules, which are generally few hundreds in number, and functioning them in synchronisation, is a huge task during real time radar operation and should be handled with utmost care. Indian MST Radar, located at NARL, Gadanki, which is established during early 90's, as an outcome of the middle atmospheric program, is a remote sensing instrument for probing the atmosphere. This radar has a semi-active array, consisting of 1024 antenna elements, with limited beam steering, possible only along the principle planes. To overcome the limitations and difficulties, the radar is being augmented into fully active phased array, to accomplish beam agility and multi-mode operations. Each antenna element is excited with a dedicated 1 kW TR module, located in the field and enables to position the radar beam within 20° conical volume. A multi-channel receiver makes the radar to operate in various modes like Doppler Beam Swinging (DBS), Spaced Antenna (SA), Frequency Domain Interferometry (FDI) etc. Present work describes the real-time radar control (RC) system for the above described active phased array radar. The radar control system consists of a Spartan 6 FPGA based Timing and Control Signal Generator (TCSG), and a computer containing the software for controlling all the subsystems of the radar during real-time radar operation and also for calibrating the radar. The main function of the TCSG is to generate the control and timing waveforms required for various subsystems of the radar. Important components of the RC system software are (i) TR module configuring software which does programming, controlling and health parameter monitoring of the

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.

Obstacle penetrating dynamic radar imaging system

DOEpatents

Romero, Carlos E [Livermore, CA; Zumstein, James E [Livermore, CA; Chang, John T [Danville, CA; Leach, Jr Richard R. [Castro Valley, CA

2006-12-12

An obstacle penetrating dynamic radar imaging system for the detection, tracking, and imaging of an individual, animal, or object comprising a multiplicity of low power ultra wideband radar units that produce a set of return radar signals from the individual, animal, or object, and a processing system for said set of return radar signals for detection, tracking, and imaging of the individual, animal, or object. The system provides a radar video system for detecting and tracking an individual, animal, or object by producing a set of return radar signals from the individual, animal, or object with a multiplicity of low power ultra wideband radar units, and processing said set of return radar signals for detecting and tracking of the individual, animal, or object.

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.

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…

Airborne radar surveys of snow depth over Antarctic sea ice during Operation IceBridge

NASA Astrophysics Data System (ADS)

Panzer, B.; Gomez-Garcia, D.; Leuschen, C.; Paden, J. D.; Gogineni, P. S.

2012-12-01

Over the last decade, multiple satellite-based laser and radar altimeters, optimized for polar observations, have been launched with one of the major objectives being the determination of global sea ice thickness and distribution [5, 6]. Estimation of sea-ice thickness from these altimeters relies on freeboard measurements and the presence of snow cover on sea ice affects this estimate. Current means of estimating the snow depth rely on daily precipitation products and/or data from passive microwave sensors [2, 7]. Even a small uncertainty in the snow depth leads to a large uncertainty in the sea-ice thickness estimate. To improve the accuracy of the sea-ice thickness estimates and provide validation for measurements from satellite-based sensors, the Center for Remote Sensing of Ice Sheets deploys the Snow Radar as a part of NASA Operation IceBridge. The Snow Radar is an ultra-wideband, frequency-modulated, continuous-wave radar capable of resolving snow depth on sea ice from 5 cm to more than 2 meters from long-range, airborne platforms [4]. This paper will discuss the algorithm used to directly extract snow depth estimates exclusively using the Snow Radar data set by tracking both the air-snow and snow-ice interfaces. Prior work in this regard used data from a laser altimeter for tracking the air-snow interface or worked under the assumption that the return from the snow-ice interface was greater than that from the air-snow interface due to a larger dielectric contrast, which is not true for thick or higher loss snow cover [1, 3]. This paper will also present snow depth estimates from Snow Radar data during the NASA Operation IceBridge 2010-2011 Antarctic campaigns. In 2010, three sea ice flights were flown, two in the Weddell Sea and one in the Amundsen and Bellingshausen Seas. All three flight lines were repeated in 2011, allowing an annual comparison of snow depth. In 2011, a repeat pass of an earlier flight in the Weddell Sea was flown, allowing for a

German Radar Observation Shuttle Experiment (ROSE)

NASA Technical Reports Server (NTRS)

Sleber, A. J.; Hartl, P.; Haydn, R.; Hildebrandt, G.; Konecny, G.; Muehlfeld, R.

1984-01-01

The success of radar sensors in several different application areas of interest depends on the knowledge of the backscatter of radar waves from the targets of interest, the variance of these interaction mechanisms with respect to changing measurement parameters, and the determination of the influence of he measuring systems on the results. The incidence-angle dependency of the radar cross section of different natural targets is derived. Problems involved by the combination of data gained with different sensors, e.g., MSS-, TM-, SPOTand SAR-images are analyzed. Radar cross-section values gained with ground-based radar spectrometers and spaceborne radar imaging, and non-imaging scatterometers and spaceborne radar images from the same areal target are correlated. The penetration of L-band radar waves into vegetated and nonvegetated surfaces is analyzed.

Using TRMM and GPM precipitation radar for calibration of weather radars in the Philippines

NASA Astrophysics Data System (ADS)

Crisologo, Irene; Bookhagen, Bodo; Smith, Taylor; Heistermann, Maik

2016-04-01

Torrential and sustained rainfall from tropical cyclones, monsoons, and thunderstorms frequently impact the Philippines. In order to predict, assess, and measure storm impact, it is imperative to have a reliable and accurate monitoring system in place. In 2011, the Philippine Atmospheric, Geophysical, and Astronomical Services Administration (PAGASA) established a weather radar network of ten radar devices, eight of which are single-polarization S-band radars and two dual-polarization C-band radars. Because of a low-density hydrometeorological monitoring networks in the Philippines, calibration of weather radars becomes a challenging, but important task. In this study, we explore the potential of scrutinizing the calibration of ground radars by using the observations from the Tropical Rainfall Measuring Mission (TRMM). For this purpose, we compare different TRMM level 1 and 2 orbital products from overpasses over the Philippines, and compare these products to reflectivities observed by the Philippine ground radars. Differences in spatial resolution are addressed by computing adequate zonal statistics of the local radar bins located within the corresponding TRMM cell in space and time. The wradlib package (Heistermann et al. 2013; Heistermann et al. 2015) is used to process the data from the Subic S-band single-polarization weather radar. These data will be analyzed in conjunction with TRMM data for June to August 2012, three months of the wet season. This period includes the enhanced monsoon of 2012, locally called Habagat 2012, which brought sustained intense rainfall and massive floods in several parts of the country including the most populated city of Metro Manila. References Heistermann, M., Jacobi, S., Pfaff, T. (2013): Technical Note: An open source library for processing weather radar data (wradlib). Hydrol. Earth Syst. Sci., 17, 863-871, doi: 10.5194/hess-17-863-2013. Heistermann, M., S. Collis, M. J. Dixon, S. Giangrande, J. J. Helmus, B. Kelley, J

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.

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.

Airborne Radar Observations of Severe Hailstorms: Implications for Future Spaceborne Radar

NASA Technical Reports Server (NTRS)

Heymsfield, Gerald M.; Tian, Lin; Li, Lihua; McLinden, Matthew; Cervantes, Jaime I.

2013-01-01

A new dual-frequency (Ku and Ka band) nadir-pointing Doppler radar on the high-altitude NASA ER-2 aircraft, called the High-Altitude Imaging Wind and Rain Airborne Profiler (HIWRAP), has collected data over severe thunderstorms in Oklahoma and Kansas during the Midlatitude Continental Convective Clouds Experiment (MC3E). The overarching motivation for this study is to understand the behavior of the dualwavelength airborne radar measurements in a global variety of thunderstorms and how these may relate to future spaceborne-radar measurements. HIWRAP is operated at frequencies that are similar to those of the precipitation radar on the Tropical Rainfall Measuring Mission (Ku band) and the upcoming Global Precipitation Measurement mission satellite's dual-frequency (Ku and Ka bands) precipitation radar. The aircraft measurements of strong hailstorms have been combined with ground-based polarimetric measurements to obtain a better understanding of the response of the Ku- and Ka-band radar to the vertical distribution of the hydrometeors, including hail. Data from two flight lines on 24 May 2011 are presented. Doppler velocities were approx. 39m/s2at 10.7-km altitude from the first flight line early on 24 May, and the lower value of approx. 25m/s on a second flight line later in the day. Vertical motions estimated using a fall speed estimate for large graupel and hail suggested that the first storm had an updraft that possibly exceeded 60m/s for the more intense part of the storm. This large updraft speed along with reports of 5-cm hail at the surface, reflectivities reaching 70 dBZ at S band in the storm cores, and hail signals from polarimetric data provide a highly challenging situation for spaceborne-radar measurements in intense convective systems. The Ku- and Ka-band reflectivities rarely exceed approx. 47 and approx. 37 dBZ, respectively, in these storms.

Enhanced Weather Radar (EWxR) System

NASA Technical Reports Server (NTRS)

Kronfeld, Kevin M. (Technical Monitor)

2003-01-01

An airborne weather radar system, the Enhanced Weather Radar (EWxR), with enhanced on-board weather radar data processing was developed and tested. The system features additional weather data that is uplinked from ground-based sources, specialized data processing, and limited automatic radar control to search for hazardous weather. National Weather Service (NWS) ground-based Next Generation Radar (NEXRAD) information is used by the EWxR system to augment the on-board weather radar information. The system will simultaneously display NEXRAD and on-board weather radar information in a split-view format. The on-board weather radar includes an automated or hands-free storm-finding feature that optimizes the radar returns by automatically adjusting the tilt and range settings for the current altitude above the terrain and searches for storm cells near the atmospheric 0-degree isotherm. A rule-based decision aid was developed to automatically characterize cells as hazardous, possibly-hazardous, or non-hazardous based upon attributes of that cell. Cell attributes are determined based on data from the on-board radar and from ground-based radars. A flight path impact prediction algorithm was developed to help pilots to avoid hazardous weather along their flight plan and their mission. During development the system was tested on the NASA B757 aircraft and final tests were conducted on the Rockwell Collins Sabreliner.

Pulsed-discharge carbon dioxide lasers

NASA Technical Reports Server (NTRS)

Willetts, David V.

1990-01-01

The purpose is to attempt a general introduction to pulsed carbon dioxide lasers of the kind used or proposed for laser radar applications. Laser physics is an excellent example of a cross-disciplinary topic, and the molecular spectroscopy, energy transfer, and plasma kinetics of the devices are explored. The concept of stimulated emission and population inversions is introduced, leading on to the molecular spectroscopy of the CO2 molecule. This is followed by a consideration of electron-impact pumping, and the pertinent energy transfer and relaxation processes which go on. Since the devices are plasma pumped, it is necessary to introduce a complex subject, but this is restricted to appropriate physics of glow discharges. Examples of representative devices are shown. The implications of the foregoing to plasma chemistry and gas life are discussed.

Laser doppler and radar interferometer for contactless measurements on unaccessible tie-rods on monumental buildings: Santa Maria della Consolazione Temple in Todi

NASA Astrophysics Data System (ADS)

Gioffré, M.; Cavalagli, N.; Pepi, C.; Trequattrini, M.

2017-01-01

Non-contact measurements can be effectively used in civil engineering to assess the variation of structural performance with time. In the last decades this approach has received considerable interests from researchers working in the field of structural health monitoring (SHM). Indeed, non-contact measurements are very attractive because it is possible to perform non intrusive and non destructive investigations even being at a significant distance from the targets. Within this context, contactless measurements of the tie-rod vibrations in the Santa Maria della Consolazione Temple in Todi (Italy) are presented in this paper. In particular, laser vibrometer and radar interferometer measurements are used to estimate natural frequencies and mode shapes. This information is crucial to obtain the tensile axial force in the tie-rods, which can be used as an indicator of structural integrity or possible failure. Furthermore, a novel approach is proposed where drones (Unmanned Aerial Vehicles) can be successfully used to improve the effectiveness and the accuracy of the experimental activities.

Historical aspects of radar atmospheric dynamics

NASA Technical Reports Server (NTRS)

Kato, Susumu

1989-01-01

A review of the history of radar techniques which have been applied to atmospheric observation is given. The author starts with ionosphere observation with the ionosonde, symbolizing as it does the earliest history of radar observation, and proceeds to later developments in radar observation such as the use of partial reflection, meteor, and incoherent scatter radars. Mesosphere stratosphere troposphere (MST) radars are discussed in terms of lower atmosphere observation.

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.

Consistency analysis and correction of ground-based radar observations using space-borne radar

NASA Astrophysics Data System (ADS)

Zhang, Shuai; Zhu, Yiqing; Wang, Zhenhui; Wang, Yadong

2018-04-01

The lack of an accurate determination of radar constant can introduce biases in ground-based radar (GR) reflectivity factor data, and lead to poor consistency of radar observations. The geometry-matching method was applied to carry out spatial matching of radar data from the Precipitation Radar (PR) on board the Tropical Rainfall Measuring Mission (TRMM) satellite to observations from a GR deployed at Nanjing, China, in their effective sampling volume, with 250 match-up cases obtained from January 2008 to October 2013. The consistency of the GR was evaluated with reference to the TRMM PR, whose stability is established. The results show that the below-bright-band-height data of the Nanjing radar can be split into three periods: Period I from January 2008 to March 2010, Period II from March 2010 to May 2013, and Period III from May 2013 to October 2013. There are distinct differences in overall reflectivity factor between the three periods, and the overall reflectivity factor in period II is smaller by a factor of over 3 dB than in periods I and III, although the overall reflectivity within each period remains relatively stable. Further investigation shows that in period II the difference between the GR and PR observations changed with echo intensity. A best-fit relation between the two radar reflectivity factors provides a linear correction that is applied to the reflectivity of the Nanjing radar, and which is effective in improving its consistency. Rain-gauge data were used to verify the correction, and the estimated precipitation based on the corrected GR reflectivity data was closer to the rain-gauge observations than that without correction.

A 1J LD pumped Nd:YAG pulsed laser system

NASA Astrophysics Data System (ADS)

Yi, Xue-bin; Wang, Bin; Yang, Feng; Li, Jing; Liu, Ya-Ping; Li, Hui-Jun; Wang, Yu; Chen, Ren

2017-11-01

A 1J LD pumped Nd;YAG pulsed laser was designed. The laser uses an oscillation and two-staged amplification structure, and applies diode bar integrated array as side-pump. The TEC temperature control device combing liquid cooling system is organized to control the temperature of the laser system. This study also analyzed the theoretical threshold of working material, the effect of thermal lens and the basic principle of laser amplification. The results showed that the laser system can achieve 1J, 25Hz pulse laser output, and the laser pulse can be output at two width: 6-7ns and 10ns, respectively, and the original beam angle is 1.2mrad. The laser system is characterized by small size, light weight, as well as good stability, which make it being applied in varied fields such as photovoltaic radar platform and etc

A 10 cm Dual Frequency Doppler Weather Radar. Part I. The Radar System.

DTIC Science & Technology

1982-10-25

Evaluation System ( RAMCES )". The step attenuator required for this calibration can be programmed remotely, has low power and temperature coefficients, and...Control and Evaluation System". The Quality Assurance/Fault Location Network makes use of fault location techniques at critical locations in the radar and...quasi-con- tinuous monitoring of radar performance. The Radar Monitor, Control and Evaluation System provides for automated system calibration and

Radar data smoothing filter study

NASA Technical Reports Server (NTRS)

White, J. V.

1984-01-01

The accuracy of the current Wallops Flight Facility (WFF) data smoothing techniques for a variety of radars and payloads is examined. Alternative data reduction techniques are given and recommendations are made for improving radar data processing at WFF. A data adaptive algorithm, based on Kalman filtering and smoothing techniques, is also developed for estimating payload trajectories above the atmosphere from noisy time varying radar data. This algorithm is tested and verified using radar tracking data from WFF.

47 CFR 80.273 - Radar standards.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 47 Telecommunication 5 2012-10-01 2012-10-01 false Radar standards. 80.273 Section 80.273... MARITIME SERVICES Equipment Authorization for Compulsory Ships § 80.273 Radar standards. (a) Radar... with radar must comply with the following standards (all incorporated by reference, see § 80.7): (1...

47 CFR 80.273 - Radar standards.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 47 Telecommunication 5 2014-10-01 2014-10-01 false Radar standards. 80.273 Section 80.273... MARITIME SERVICES Equipment Authorization for Compulsory Ships § 80.273 Radar standards. (a) Radar... with radar must comply with the following standards (all incorporated by reference, see § 80.7): (1...

47 CFR 80.273 - Radar standards.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 47 Telecommunication 5 2013-10-01 2013-10-01 false Radar standards. 80.273 Section 80.273... MARITIME SERVICES Equipment Authorization for Compulsory Ships § 80.273 Radar standards. (a) Radar... with radar must comply with the following standards (all incorporated by reference, see § 80.7): (1...

Magneto-Radar Hidden Metal Detector

DOEpatents

McEwan, Thomas E.

2005-07-05

A varying magnetic field excites slight vibrations in an object and a radar sensor detects the vibrations at a harmonic of the excitation frequency. The synergy of the magnetic excitation and radar detection provides increased detection range compared to conventional magnetic metal detectors. The radar rejects background clutter by responding only to reflecting objects that are vibrating at a harmonic excitation field, thereby significantly improving detection reliability. As an exemplary arrangement, an ultra-wideband micropower impulse radar (MIR) is capable of being employed to provide superior materials penetration while providing range information. The magneto-radar may be applied to pre-screening magnetic resonance imaging (MRI) patients, landmine detection and finding hidden treasures.

Laser Doppler Radar System Calibration and Rainfall Attenuation Measurements

DOT National Transportation Integrated Search

1978-10-01

The atmospheric attenuation and backscatter coefficients have been measured at the 10.6-micrometers wavelength of the CO2 laser in rainstorms. Data are presented to show the increase in attenuation coefficient with rainfall rate. Backscatter coeffici...

Interception of LPI radar signals

NASA Astrophysics Data System (ADS)

Lee, Jim P.

1991-11-01

Most current radars are designed to transmit short duration pulses with relatively high peak power. These radars can be detected easily by the use of relatively modest EW intercept receivers. Three radar functions (search, anti-ship missile (ASM) seeker, and navigation) are examined to evaluate the effectiveness of potential low probability of intercept (LPI) techniques, such as waveform coding, antenna profile control, and power management that a radar may employ against current Electronic Warfare (EW) receivers. The general conclusion is that it is possible to design a LPI radar which is effective against current intercept EW receivers. LPI operation is most easily achieved at close ranges and against a target with a large radar cross section. The general system sensitivity requirement for the detection of current and projected LPI radars is found to be on the order of -100 dBmi which cannot be met by current EW receivers. Finally, three potential LPI receiver architectures, using channelized, superhet, and acousto-optic receivers with narrow RF and video bandwidths are discussed. They have shown some potential in terms of providing the sensitivity and capability in an environment where both conventional and LPI signals are present.

46 CFR 130.310 - Radar.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 4 2011-10-01 2011-10-01 false Radar. 130.310 Section 130.310 Shipping COAST GUARD... EQUIPMENT AND SYSTEMS Navigational Equipment § 130.310 Radar. Each vessel of 100 or more gross tons must be fitted with a general marine radar in the pilothouse. ...

46 CFR 130.310 - Radar.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 4 2010-10-01 2010-10-01 false Radar. 130.310 Section 130.310 Shipping COAST GUARD... EQUIPMENT AND SYSTEMS Navigational Equipment § 130.310 Radar. Each vessel of 100 or more gross tons must be fitted with a general marine radar in the pilothouse. ...

46 CFR 130.310 - Radar.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 4 2013-10-01 2013-10-01 false Radar. 130.310 Section 130.310 Shipping COAST GUARD... EQUIPMENT AND SYSTEMS Navigational Equipment § 130.310 Radar. Each vessel of 100 or more gross tons must be fitted with a general marine radar in the pilothouse. ...

46 CFR 130.310 - Radar.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 4 2014-10-01 2014-10-01 false Radar. 130.310 Section 130.310 Shipping COAST GUARD... EQUIPMENT AND SYSTEMS Navigational Equipment § 130.310 Radar. Each vessel of 100 or more gross tons must be fitted with a general marine radar in the pilothouse. ...

46 CFR 130.310 - Radar.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 4 2012-10-01 2012-10-01 false Radar. 130.310 Section 130.310 Shipping COAST GUARD... EQUIPMENT AND SYSTEMS Navigational Equipment § 130.310 Radar. Each vessel of 100 or more gross tons must be fitted with a general marine radar in the pilothouse. ...

Radar Image of Galapagos Island

NASA Image and Video Library

1996-10-23

This is an image showing part of Isla Isabella in the western Galapagos Islands. It was taken by the L-band radar in HH polarization from the Spaceborne Imaging Radar C/X-Band Synthetic Aperture Radar on the 40th orbit of NASA’s space shuttle Endeavour.

Low-Angle Radar Tracking

DTIC Science & Technology

1976-02-01

Transition from Specular Reflection to Diffuse Scattering. . . 10 Composition of the Electric-Field Vector as Seen at the Radar...r t (16) R • FIGURE P COMPOSITION OF THE ELECTRIC-FIELD VECTOR AS SEEN AT THE RADAR, R, IN FIG. 2. The electric field at the radar, E, is the sum...wavelengths in the VHP and UHF ranges even subsurface characteristics can be important. So in a field experiment one must be careful to measure

All-digital radar architecture

NASA Astrophysics Data System (ADS)

Molchanov, Pavlo A.

2014-10-01

All digital radar architecture requires exclude mechanical scan system. The phase antenna array is necessarily large because the array elements must be co-located with very precise dimensions and will need high accuracy phase processing system for aggregate and distribute T/R modules data to/from antenna elements. Even phase array cannot provide wide field of view. New nature inspired all digital radar architecture proposed. The fly's eye consists of multiple angularly spaced sensors giving the fly simultaneously thee wide-area visual coverage it needs to detect and avoid the threats around him. Fly eye radar antenna array consist multiple directional antennas loose distributed along perimeter of ground vehicle or aircraft and coupled with receiving/transmitting front end modules connected by digital interface to central processor. Non-steering antenna array allows creating all-digital radar with extreme flexible architecture. Fly eye radar architecture provides wide possibility of digital modulation and different waveform generation. Simultaneous correlation and integration of thousands signals per second from each point of surveillance area allows not only detecting of low level signals ((low profile targets), but help to recognize and classify signals (targets) by using diversity signals, polarization modulation and intelligent processing. Proposed all digital radar architecture with distributed directional antenna array can provide a 3D space vector to the jammer by verification direction of arrival for signals sources and as result jam/spoof protection not only for radar systems, but for communication systems and any navigation constellation system, for both encrypted or unencrypted signals, for not limited number or close positioned jammers.

Comparison of radar data versus rainfall data

PubMed Central

Espinosa, B.; Hromadka, T.V.; Perez, R.

2015-01-01

Doppler radar data are increasingly used in rainfall-runoff synthesis studies, perhaps due to radar data availability, among other factors. However, the veracity of the radar data are often a topic of concern. In this paper, three Doppler radar outcomes developed by the United States National Weather Service at three radar sites are examined and compared to actual rain gage data for two separate severe storm events in order to assess accuracy in the published radar estimates of rainfall. Because the subject storms were very intense rainfall events lasting approximately one hour in duration, direct comparisons between the three radar gages themselves can be made, as well as a comparison to rain gage data at a rain gage location subjected to the same storm cells. It is shown that topographic interference with the radar outcomes can be a significant factor leading to differences between radar and rain gage readings, and that care is needed in calibrating radar outcomes using available rain gage data in order to interpolate rainfall estimates between rain gages using the spatial variation observed in the radar readings. The paper establishes and describes•the need for “ground-truthing” of radar data, and•possible errors due to topographic interference. PMID:26649276

Classification and correction of the radar bright band with polarimetric radar

NASA Astrophysics Data System (ADS)

Hall, Will; Rico-Ramirez, Miguel; Kramer, Stefan

2015-04-01

The annular region of enhanced radar reflectivity, known as the Bright Band (BB), occurs when the radar beam intersects a layer of melting hydrometeors. Radar reflectivity is related to rainfall through a power law equation and so this enhanced region can lead to overestimations of rainfall by a factor of up to 5, so it is important to correct for this. The BB region can be identified by using several techniques including hydrometeor classification and freezing level forecasts from mesoscale meteorological models. Advances in dual-polarisation radar measurements and continued research in the field has led to increased accuracy in the ability to identify the melting snow region. A method proposed by Kitchen et al (1994), a form of which is currently used operationally in the UK, utilises idealised Vertical Profiles of Reflectivity (VPR) to correct for the BB enhancement. A simpler and more computationally efficient method involves the formation of an average VPR from multiple elevations for correction that can still cause a significant decrease in error (Vignal 2000). The purpose of this research is to evaluate a method that relies only on analysis of measurements from an operational C-band polarimetric radar without the need for computationally expensive models. Initial results show that LDR is a strong classifier of melting snow with a high Critical Success Index of 97% when compared to the other variables. An algorithm based on idealised VPRs resulted in the largest decrease in error when BB corrected scans are compared to rain gauges and to lower level scans with a reduction in RMSE of 61% for rain-rate measurements. References Kitchen, M., R. Brown, and A. G. Davies, 1994: Real-time correction of weather radar data for the effects of bright band, range and orographic growth in widespread precipitation. Q.J.R. Meteorol. Soc., 120, 1231-1254. Vignal, B. et al, 2000: Three methods to determine profiles of reflectivity from volumetric radar data to correct

Recommendation on transition from primary/secondary radar to secondary-only radar capability

DOT National Transportation Integrated Search

1994-10-01

This recommendation has been prepared to support the FAA decision to deactivate primary Long-range radars and presents a : transition strategy and implementation plan for the transformation of the existing primary/secondary en route radar : system to...

Evaluation of meteorological airborne Doppler radar

NASA Technical Reports Server (NTRS)

Hildebrand, P. H.; Mueller, C. K.

1984-01-01

This paper will discuss the capabilities of airborne Doppler radar for atmospheric sciences research. The evaluation is based on airborne and ground based Doppler radar observations of convective storms. The capability of airborne Doppler radar to measure horizontal and vertical air motions is evaluated. Airborne Doppler radar is shown to be a viable tool for atmospheric sciences research.

Lunar and Venusian radar bright rings

NASA Technical Reports Server (NTRS)

Thompson, T. W.; Saunders, R. S.; Weissman, D. E.

1986-01-01

Twenty-one lunar craters have radar bright ring appearances which are analogous to eleven complete ring features in the earth-based 12.5 cm observations of Venus. Radar ring diameters and widths for the lunar and Venusian features overlap for sizes from 45 to 100 km. Radar bright areas for the lunar craters are associated with the slopes of the inner and outer rim walls, while level crater floors and level ejecta fields beyond the raised portion of the rim have average radar backscatter. It is proposed that the radar bright areas of the Venusian rings are also associated with the slopes on the rims of craters. The lunar craters have evolved to radar bright rings via mass wasting of crater rim walls and via post-impact flooding of crater floors. Aeolian deposits of fine-grained material on Venusian crater floors may produce radar scattering effects similar to lunar crater floor flooding. These Venusian aeolian deposits may preferentially cover blocky crater floors producing a radar bright ring appearance. It is proposed that the Venusian features with complete bright ring appearances and sizes less than 100 km are impact craters. They have the same sizes as lunar craters and could have evolved to radar bright rings via analogous surface processes.

46 CFR 184.404 - Radars.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 7 2011-10-01 2011-10-01 false Radars. 184.404 Section 184.404 Shipping COAST GUARD... MISCELLANEOUS SYSTEMS AND EQUIPMENT Navigation Equipment § 184.404 Radars. (a) A vessel must be fitted with a Federal Communications Commission (FCC) type accepted general marine radar system for surface navigation...

46 CFR 184.404 - Radars.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 7 2010-10-01 2010-10-01 false Radars. 184.404 Section 184.404 Shipping COAST GUARD... MISCELLANEOUS SYSTEMS AND EQUIPMENT Navigation Equipment § 184.404 Radars. (a) A vessel must be fitted with a Federal Communications Commission (FCC) type accepted general marine radar system for surface navigation...

46 CFR 184.404 - Radars.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 7 2014-10-01 2014-10-01 false Radars. 184.404 Section 184.404 Shipping COAST GUARD... MISCELLANEOUS SYSTEMS AND EQUIPMENT Navigation Equipment § 184.404 Radars. (a) A vessel must be fitted with a Federal Communications Commission (FCC) type accepted general marine radar system for surface navigation...

46 CFR 184.404 - Radars.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 7 2012-10-01 2012-10-01 false Radars. 184.404 Section 184.404 Shipping COAST GUARD... MISCELLANEOUS SYSTEMS AND EQUIPMENT Navigation Equipment § 184.404 Radars. (a) A vessel must be fitted with a Federal Communications Commission (FCC) type accepted general marine radar system for surface navigation...

46 CFR 184.404 - Radars.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 7 2013-10-01 2013-10-01 false Radars. 184.404 Section 184.404 Shipping COAST GUARD... MISCELLANEOUS SYSTEMS AND EQUIPMENT Navigation Equipment § 184.404 Radars. (a) A vessel must be fitted with a Federal Communications Commission (FCC) type accepted general marine radar system for surface navigation...

Advanced Borehole Radar for Hydrogeology

NASA Astrophysics Data System (ADS)

Sato, M.

2014-12-01

Ground Penetrating Radar is a useful tool for monitoring the hydrogeological environment. We have developed GPR systems which can be applied to these purposes, and we will demonstrate examples borehole radar measurements. In order to have longer radar detection range, frequency lower than100MHz has been normally adopted in borehole radar. Typical subsurface fractures of our interests have a few mm aperture and radar resolution is much poorer than a few cm in this frequency range. We are proposing and demonstrating to use radar polarimetry to solve this problem. We have demonstrated that a full-polarimetry borehole radar can be used for characterization of subsurface fractures. Together with signal processing for antenna characteristic compensation to equalize the signal by a dipole antenna and slot antennas, we could demonstrate that polarimetric borehole radar can estimate the surface roughness of subsurface fractures, We believe the surface roughness is closely related to water permeability through the fractures. We then developed a directional borehole radar, which uses optical field sensor. A dipole antenna in a borehole has omni-directional radiation pattern, and we cannot get azimuthal information about the scatterers. We use multiple dipole antennas set around the borehole axis, and from the phase differences, we can estimate the 3-diemnational orientation of subsurface structures. We are using optical electric field sensor for receiver of borehole radar. This is a passive sensor and connected only with optical fibers and does not require any electric power supply to operate the receiver. It has two major advantages; the first one is that the receiver can be electrically isolated from other parts, and wave coupling to a logging cable is avoided. Then, secondary, it can operate for a long time, because it does not require battery installed inside the system. It makes it possible to set sensors in fixed positions to monitor the change of environmental

Radar network communication through sensing of frequency hopping

DOEpatents

Dowla, Farid; Nekoogar, Faranak

2013-05-28

In one embodiment, a radar communication system includes a plurality of radars having a communication range and being capable of operating at a sensing frequency and a reporting frequency, wherein the reporting frequency is different than the sensing frequency, each radar is adapted for operating at the sensing frequency until an event is detected, each radar in the plurality of radars has an identification/location frequency for reporting information different from the sensing frequency, a first radar of the radars which senses the event sends a reporting frequency corresponding to its identification/location frequency when the event is detected, and all other radars in the plurality of radars switch their reporting frequencies to match the reporting frequency of the first radar upon detecting the reporting frequency switch of a radar within the communication range. In another embodiment, a method is presented for communicating information in a radar system.

Sensor management in RADAR/IRST track fusion

NASA Astrophysics Data System (ADS)

Hu, Shi-qiang; Jing, Zhong-liang

2004-07-01

In this paper, a novel radar management strategy technique suitable for RADAR/IRST track fusion, which is based on Fisher Information Matrix (FIM) and fuzzy stochastic decision approach, is put forward. Firstly, optimal radar measurements' scheduling is obtained by the method of maximizing determinant of the Fisher information matrix of radar and IRST measurements, which is managed by the expert system. Then, suggested a "pseudo sensor" to predict the possible target position using the polynomial method based on the radar and IRST measurements, using "pseudo sensor" model to estimate the target position even if the radar is turned off. At last, based on the tracking performance and the state of target maneuver, fuzzy stochastic decision is used to adjust the optimal radar scheduling and retrieve the module parameter of "pseudo sensor". The experiment result indicates that the algorithm can not only limit Radar activity effectively but also keep the tracking accuracy of active/passive system well. And this algorithm eliminates the drawback of traditional Radar management methods that the Radar activity is fixed and not easy to control and protect.

Radar data processing and analysis

NASA Technical Reports Server (NTRS)

Ausherman, D.; Larson, R.; Liskow, C.

1976-01-01

Digitized four-channel radar images corresponding to particular areas from the Phoenix and Huntington test sites were generated in conjunction with prior experiments performed to collect X- and L-band synthetic aperture radar imagery of these two areas. The methods for generating this imagery are documented. A secondary objective was the investigation of digital processing techniques for extraction of information from the multiband radar image data. Following the digitization, the remaining resources permitted a preliminary machine analysis to be performed on portions of the radar image data. The results, although necessarily limited, are reported.

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.

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.

Applications of high-frequency radar

NASA Astrophysics Data System (ADS)

Headrick, J. M.; Thomason, J. F.

1998-07-01

Efforts to extend radar range by an order of magnitude with use of the ionosphere as a virtual mirror started after the end of World War II. A number of HF radar programs were pursued, with long-range nuclear burst and missile launch detection demonstrated by 1956. Successful east coast radar aircraft detect and track tests extending across the Atlantic were conducted by 1961. The major obstacles to success, the large target-to-clutter ratio and low signal-to-noise ratio, were overcome with matched filter Doppler processing. To search the areas that a 2000 nautical mile (3700 km) radar can reach, very complex and high dynamic range processing is required. The spectacular advances in digital processing technology have made truly wide-area surveillance possible. Use of the surface attached wave over the oceans can enable HF radar to obtain modest extension of range beyond the horizon. The decameter wavelengths used by both skywave and surface wave radars require large physical antenna apertures, but they have unique capabilities for air and surface targets, many of which are of resonant scattering dimensions. Resonant scattering from the ocean permits sea state and direction estimation. Military and commercial applications of HF radar are in their infancy.

Forest Biomass Mapping From Lidar and Radar Synergies

NASA Technical Reports Server (NTRS)

Sun, Guoqing; Ranson, K. Jon; Guo, Z.; Zhang, Z.; Montesano, P.; Kimes, D.

2011-01-01

The use of lidar and radar instruments to measure forest structure attributes such as height and biomass at global scales is being considered for a future Earth Observation satellite mission, DESDynI (Deformation, Ecosystem Structure, and Dynamics of Ice). Large footprint lidar makes a direct measurement of the heights of scatterers in the illuminated footprint and can yield accurate information about the vertical profile of the canopy within lidar footprint samples. Synthetic Aperture Radar (SAR) is known to sense the canopy volume, especially at longer wavelengths and provides image data. Methods for biomass mapping by a combination of lidar sampling and radar mapping need to be developed. In this study, several issues in this respect were investigated using aircraft borne lidar and SAR data in Howland, Maine, USA. The stepwise regression selected the height indices rh50 and rh75 of the Laser Vegetation Imaging Sensor (LVIS) data for predicting field measured biomass with a R(exp 2) of 0.71 and RMSE of 31.33 Mg/ha. The above-ground biomass map generated from this regression model was considered to represent the true biomass of the area and used as a reference map since no better biomass map exists for the area. Random samples were taken from the biomass map and the correlation between the sampled biomass and co-located SAR signature was studied. The best models were used to extend the biomass from lidar samples into all forested areas in the study area, which mimics a procedure that could be used for the future DESDYnI Mission. It was found that depending on the data types used (quad-pol or dual-pol) the SAR data can predict the lidar biomass samples with R2 of 0.63-0.71, RMSE of 32.0-28.2 Mg/ha up to biomass levels of 200-250 Mg/ha. The mean biomass of the study area calculated from the biomass maps generated by lidar- SAR synergy 63 was within 10% of the reference biomass map derived from LVIS data. The results from this study are preliminary, but do show the

Validating Cryosat-2 elevation estimates with airborne laser scanner data for the Greenland ice sheet, Austfonna and Devon ice caps

NASA Astrophysics Data System (ADS)

Simonsen, Sebastian B.; Sandberg Sørensen, Louise; Nilsson, Johan; Helm, Veit; Langley, Kirsty A.; Forsberg, Rene; Hvidegaard, Sine M.; Skourup, Henriette

2015-04-01

The ESA CryoSat-2 satellite, launched in late 2010, carries a new type of radar altimeter especially designed for monitoring changes of sea and land ice. The radar signal might penetrate into the snow pack and the depth of the radar reflecting surface depends on the ratio between the surface and the volume backscatter, which is a function of several different properties such as snow density, crystal structure and surface roughness. In case of large volume scatter, the radar waveforms become broad and the determination of the range (surface elevation) becomes more difficult. Different algorithms (retrackers) are used for the range determination, and estimated surface penetration is highly dependent on the applied retracker. As part of the ESA-CryoVEx/CryoVal-Land Ice projects, DTU Space has gathered accurate airborne laser scanner elevation measurements. Sites on the Greenland ice sheet, Austfonna and Devon ice caps, has been surveyed repeatedly, aligned with Cryosat-2 ground tracks and surface experiments. Here, we utilize elevation estimates from available Cryosat-2 retrackers (ESA level-2 retracker, DTU retracker, etc.) and validate the elevation measurements against ESA-CryoVEx campaigns. A difference between laser and radar elevations is expected due to radar penetration issues, however an inter-comparison between retrackers will shed light on individual performances and biases. Additionally, the geo-location of the radar return will also be a determining factor for the precision. Ultimately, the use of multiple retrackers can provide information about subsurface conditions and utilize more of the waveform information than presently used in radar altimetry.

Shuttle Imaging Radar - Geologic applications

NASA Technical Reports Server (NTRS)

Macdonald, H.; Bridges, L.; Waite, W.; Kaupp, V.

1982-01-01

The Space Shuttle, on its second flight (November 12, 1981), carried the first science and applications payload which provided an early demonstration of Shuttle's research capabilities. One of the experiments, the Shuttle Imaging Radar-A (SIR-A), had as a prime objective to evaluate the capability of spaceborne imaging radars as a tool for geologic exploration. The results of the experiment will help determine the value of using the combination of space radar and Landsat imagery for improved geologic analysis and mapping. Preliminary analysis of the Shuttle radar imagery with Seasat and Landsat imagery from similar areas provides evidence that spaceborne radars can significantly complement Landsat interpretation, and vastly improve geologic reconnaissance mapping in those areas of the world that are relatively unmapped because of perpetual cloud cover.

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.

Radar-aeolian roughness project

NASA Technical Reports Server (NTRS)

Greeley, Ronald; Dobrovolskis, A.; Gaddis, L.; Iversen, J. D.; Lancaster, N.; Leach, Rodman N.; Rasnussen, K.; Saunders, S.; Vanzyl, J.; Wall, S.

1991-01-01

The objective is to establish an empirical relationship between measurements of radar, aeolian, and surface roughness on a variety of natural surfaces and to understand the underlying physical causes. This relationship will form the basis for developing a predictive equation to derive aeolian roughness from radar backscatter. Results are given from investigations carried out in 1989 on the principal elements of the project, with separate sections on field studies, radar data analysis, laboratory simulations, and development of theory for planetary applications.

A digital laser slopemeter

NASA Astrophysics Data System (ADS)

Crossingham, Grant James

This thesis is concerned with the design of a new ocean going instrument to measure the local sea surface profile. The motivation behind this project was the need to investigate oceanographic features that have been observed using imaging radar aboard aircraft and satellites. The measurements made with this instrument will further the understanding of the processes involved in radar backscatter from the ocean surface and will enable further analysis of ocean phenomena detected using imaging radars. With an improved understanding of these processes it will be possible to analyse quantitatively satellite images generated from around the globe. This will allow global environmental monitoring which could lead to improved weather forecasting, pollution control such as oil slick monitoring and surface and subsurface operations. It is believed that radar signals having a wavelength of 10 to 300mm are backscattered from waves on the ocean surface of similar length. Earlier attempts to measure waves including those designed to measure millimetric waves are critically reviewed and an account of the evolution of the design of a new instrument to measure these small waves is presented. This new instrument has been tested in the laboratory, which has demonstrated that a repeatable wave slope measurement accuracy of +/-0.56° has been achieved in static tests. Dynamic tests made using a wave tank have generated a wave slope profile, clearly showing 10mm wavelengths present on the surface. The new Digital Slopemeter is designed to measure the small-scale sea surface roughness for wavelengths in the range 10mm to 224mm. This instrument uses two grids of wavelength shifting fibres to digitally record the slope of a refracted laser beam. The laser beam is rapidly scanned over the sea surface to ensure that the profile of the surface is effectively stationary over a length of 224mm. The wave slope is sampled at 3.5mm intervals along each scan, allowing 7mm wavelengths to be resolved

46 CFR 108.717 - Radar.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 4 2011-10-01 2011-10-01 false Radar. 108.717 Section 108.717 Shipping COAST GUARD... Miscellaneous Equipment § 108.717 Radar. Each self-propelled unit of 1,600 gross tons and over in ocean or coastwise service must have— (a) A marine radar system for surface navigation; and (b) Facilities on the...

46 CFR 108.717 - Radar.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 4 2010-10-01 2010-10-01 false Radar. 108.717 Section 108.717 Shipping COAST GUARD... Miscellaneous Equipment § 108.717 Radar. Each self-propelled unit of 1,600 gross tons and over in ocean or coastwise service must have— (a) A marine radar system for surface navigation; and (b) Facilities on the...

46 CFR 108.717 - Radar.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 4 2013-10-01 2013-10-01 false Radar. 108.717 Section 108.717 Shipping COAST GUARD... Miscellaneous Equipment § 108.717 Radar. Each self-propelled unit of 1,600 gross tons and over in ocean or coastwise service must have— (a) A marine radar system for surface navigation; and (b) Facilities on the...

46 CFR 108.717 - Radar.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 4 2012-10-01 2012-10-01 false Radar. 108.717 Section 108.717 Shipping COAST GUARD... Miscellaneous Equipment § 108.717 Radar. Each self-propelled unit of 1,600 gross tons and over in ocean or coastwise service must have— (a) A marine radar system for surface navigation; and (b) Facilities on the...

46 CFR 108.717 - Radar.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 4 2014-10-01 2014-10-01 false Radar. 108.717 Section 108.717 Shipping COAST GUARD... Miscellaneous Equipment § 108.717 Radar. Each self-propelled unit of 1,600 gross tons and over in ocean or coastwise service must have— (a) A marine radar system for surface navigation; and (b) Facilities on the...

Extended target recognition in cognitive radar networks.

PubMed

Wei, Yimin; Meng, Huadong; Liu, Yimin; Wang, Xiqin

2010-01-01

We address the problem of adaptive waveform design for extended target recognition in cognitive radar networks. A closed-loop active target recognition radar system is extended to the case of a centralized cognitive radar network, in which a generalized likelihood ratio (GLR) based sequential hypothesis testing (SHT) framework is employed. Using Doppler velocities measured by multiple radars, the target aspect angle for each radar is calculated. The joint probability of each target hypothesis is then updated using observations from different radar line of sights (LOS). Based on these probabilities, a minimum correlation algorithm is proposed to adaptively design the transmit waveform for each radar in an amplitude fluctuation situation. Simulation results demonstrate performance improvements due to the cognitive radar network and adaptive waveform design. Our minimum correlation algorithm outperforms the eigen-waveform solution and other non-cognitive waveform design approaches.

Laser Calibration Experiment for Small Objects in Space

NASA Technical Reports Server (NTRS)

Campbell, Jonathan; Ayers, K.; Carreras, R.; Carruth, R.; Freestone, T.; Sharp, J.; Rawleigh, A.; Brewer, J.; Schrock, K.; Bell, L.;

Probabilistic discrimination between liquid rainfall events, hailstorms, biomass burning and industrial fires from C-Band Radar Polarimetric Variables

NASA Astrophysics Data System (ADS)

Valencia, J. M.; Sepúlveda, J.; Hoyos, C.; Herrera, L.

2017-12-01

Characterization and identification of fire and hailstorm events using weather radar data in a tropical complex topography region is an important task in risk management and agriculture. Polarimetric variables from a C-Band Dual polarization weather radar have potential uses in particle classification, due to the relationship their sensitivity to shape, spatial orientation, size and fall behavior of particles. In this sense, three forest fires and two chemical fires were identified for the Áburra Valley regions. Measurements were compared between each fire event type and with typical data radar retrievals for liquid precipitation events. Results of this analysis show different probability density functions for each type of event according to the particles present in them. This is very important and useful result for early warning systems to avoid precipitation false alarms during fire events within the study region, as well as for the early detection of fires using radar retrievals in remote cases. The comparative methodology is extended to hailstorm cases. Complementary sensors like laser precipitation sensors (LPM) disdrometers and meteorological stations were used to select dates of solid precipitation occurrence. Then, in this dates weather radar data variables were taken in pixels surrounding the stations and solid precipitation polar values were statistically compared with liquid precipitation values. Spectrum precipitation measured by LPM disdrometer helps to define typical features like particles number, fall velocities and diameters for both precipitation types. In addition, to achieve a complete hailstorm characterization, other meteorological variables were analyzed: wind field from meteorological stations and radar wind profiler, profiling data from Micro Rain Radar (MRR), and thermodynamic data from a microwave radiometer.

Study of atmospheric parameters measurements using MM-wave radar in synergy with LITE-2

NASA Technical Reports Server (NTRS)

Andrawis, Madeleine Y.

1994-01-01

The Lidar In-Space Technology Experiment, (LITE), has been developed, designed, and built by NASA Langley Research Center, to be flown on the space shuttle 'Discovery' on September 9, 1994. Lidar, which stands for light detecting and ranging, is a radar system that uses short pulses of laser light instead of radio waves in the case of the common radar. This space-based lidar offers atmospheric measurements of stratospheric and tropospheric aerosols, the planetary boundary layer, cloud top heights, and atmospheric temperature and density in the 10-40 km altitude range. A study is being done on the use, advantages, and limitations of a millimeterwave radar to be utilized in synergy with the Lidar system, for the LITE-2 experiment to be flown on a future space shuttle mission. The lower atmospheric attenuation, compared to infrared and optical frequencies, permits the millimeter-wave signals to penetrate through the clouds and measure multi-layered clouds, cloud thickness, and cloud-base height. These measurements would provide a useful input to radiation computations used in the operational numerical weather prediction models, and for forecasting. High power levels, optimum modulation, data processing, and high antenna gain are used to increase the operating range, while space environment, radar tradeoffs, and power availability are considered. Preliminary, numerical calculations are made, using the specifications of an experimental system constructed at Georgia Tech. The noncoherent 94 GHz millimeter-wave radar system has a pulsed output with peak value of 1 kW. The backscatter cross section of the particles to be measured, that are present in the volume covered by the beam footprint, is also studied.

Penn State Radar Systems: Implementation and Observations

NASA Astrophysics Data System (ADS)

Urbina, J. V.; Seal, R.; Sorbello, R.; Kuyeng, K.; Dyrud, L. P.

2014-12-01

Software Defined Radio/Radar (SDR) platforms have become increasingly popular as researchers, hobbyists, and military seek more efficient and cost-effective means for radar construction and operation. SDR platforms, by definition, utilize a software-based interface for configuration in contrast to traditional, hard-wired platforms. In an effort to provide new and improved radar sensing capabilities, Penn State has been developing advanced instruments and technologies for future radars, with primary objectives of making such instruments more capable, portable, and more cost effective. This paper will describe the design and implementation of two low-cost radar systems and their deployment in ionospheric research at both low and mid-latitudes. One radar has been installed near Penn State campus, University Park, Pennsylvania (77.97°W, 40.70°N), to make continuous meteor observations and mid-latitude plasma irregularities. The second radar is being installed in Huancayo (12.05°S, -75.33°E), Peru, which is capable of detecting E and F region plasma irregularities as well as meteor reflections. In this paper, we examine and compare the diurnal and seasonal variability of specular, non- specular, and head-echoes collected with these two new radar systems and discuss sampling biases of each meteor observation technique. We report our current efforts to validate and calibrate these radar systems with other VHF radars such as Jicamarca and SOUSY. We also present the general characteristics of continuous measurements of E-region and F-region coherent echoes using these modern radar systems and compare them with coherent radar events observed at other geographic mid-latitude radar stations.

Venus wind-altitude radar

NASA Technical Reports Server (NTRS)

Levanon, N.

1974-01-01

A design study on adding a radar altimeter to the Pioneer Venus small probe is review. Block and timing diagrams are provided. The inherent and interface ambiguities, resolution, and data handling logic for radar altimeters are described.

An operational theory of laser-radar selenodesy

USGS Publications Warehouse

Wildey, R.L.; Schlier, R.E.; Hull, J.A.; Larson, G.

1967-01-01

A theory of the utilization of laser techniques for ranging from the Earth to the Moon for the purpose of providing control points on the lunar surface at which the figure of the Moon is measured to an accuracy at least an order of magnitude better than that of the present astrometric measurements is presented. This, in turn, increases the accuracy of the horizontal selenocentric coordinates of topographical features measured by present astrometric methods. The improvement in the vertical and horizontal coordinates of control points in the Apollo landing zone will aid in the analysis of Unmanned Lunar Orbiter photographs for the selection of Apollo landing sites. The present discussion proposes the means of obtaining the ground control upon which the Orbiter photogrammetry is to be fastened. In addition, a technique of combining Goldstone tracking data to show where the resulting lunar figure is positioned relative to the Moon's center of mass is presented. If corner reflectors are placed on the lunar surface, as suggested by many members of the scientific community, or on a lunar orbiting vehicle, one or more Earth-based laser ranging systems are essential. These reflectors will give enough enhancement in return signal to allow for an additional increase in range accuracy of one to two orders of magnitude. In addition to the primary data on the figure of the Moon, a number of other measurements of scientific importance are then readily obtainable. As far as the measurement of control points is concerned, however, the use of corner reflectors is not essential for the success of this project. Questions regarding the influence on the present shape of the Moon of the frozen tide, isostasy, and past impacts of large asteroids appear in large part answerable through the data which are indicated to be obtainable under the present theory. ?? 1967.

Evaluation of Various Radar Data Quality Control Algorithms Based on Accumulated Radar Rainfall Statistics

NASA Technical Reports Server (NTRS)

Robinson, Michael; Steiner, Matthias; Wolff, David B.; Ferrier, Brad S.; Kessinger, Cathy; Einaudi, Franco (Technical Monitor)

2000-01-01

The primary function of the TRMM Ground Validation (GV) Program is to create GV rainfall products that provide basic validation of satellite-derived precipitation measurements for select primary sites. A fundamental and extremely important step in creating high-quality GV products is radar data quality control. Quality control (QC) processing of TRMM GV radar data is based on some automated procedures, but the current QC algorithm is not fully operational and requires significant human interaction to assure satisfactory results. Moreover, the TRMM GV QC algorithm, even with continuous manual tuning, still can not completely remove all types of spurious echoes. In an attempt to improve the current operational radar data QC procedures of the TRMM GV effort, an intercomparison of several QC algorithms has been conducted. This presentation will demonstrate how various radar data QC algorithms affect accumulated radar rainfall products. In all, six different QC algorithms will be applied to two months of WSR-88D radar data from Melbourne, Florida. Daily, five-day, and monthly accumulated radar rainfall maps will be produced for each quality-controlled data set. The QC algorithms will be evaluated and compared based on their ability to remove spurious echoes without removing significant precipitation. Strengths and weaknesses of each algorithm will be assessed based on, their abilit to mitigate both erroneous additions and reductions in rainfall accumulation from spurious echo contamination and true precipitation removal, respectively. Contamination from individual spurious echo categories will be quantified to further diagnose the abilities of each radar QC algorithm. Finally, a cost-benefit analysis will be conducted to determine if a more automated QC algorithm is a viable alternative to the current, labor-intensive QC algorithm employed by TRMM GV.

Three-dimensional radar imaging of structures and craters in the Martian polar caps.

PubMed

Putzig, Nathaniel E; Smith, Isaac B; Perry, Matthew R; Foss, Frederick J; Campbell, Bruce A; Phillips, Roger J; Seu, Roberto

2018-07-01

Over the last decade, observations acquired by the Shallow Radar (SHARAD) sounder on individual passes of the Mars Reconnaissance Orbiter have revealed the internal structure of the Martian polar caps and provided new insights into the formation of the icy layers within and their relationship to climate. However, a complete picture of the cap interiors has been hampered by interfering reflections from off-nadir surface features and signal losses associated with sloping structures and scattering. Foss et al. (2017) addressed these limitations by assembling three-dimensional data volumes of SHARAD observations from thousands of orbital passes over each polar region and applying geometric corrections simultaneously. The radar volumes provide unprecedented views of subsurface features, readily imaging structures previously inferred from time-intensive manual analysis of single-orbit data (e.g., trough-bounding surfaces, a buried chasma, and a basal unit in the north, massive carbon-dioxide ice deposits and discontinuous layered sequences in the south). Our new mapping of the carbon-dioxide deposits yields a volume of 16,500 km 3 , 11% larger than the prior estimate. In addition, the radar volumes newly reveal other structures, including what appear to be buried impact craters with no surface expression. Our first assessment of 21 apparent craters at the base of the north polar layered deposits suggests a Hesperian age for the substrate, consistent with that of the surrounding plains as determined from statistics of surface cratering rates. Planned mapping of similar features throughout both polar volumes may provide new constraints on the age of the icy layered deposits. The radar volumes also provide new topographic data between the highest latitudes observed by the Mars Orbiter Laser Altimeter and those observed by SHARAD. In general, mapping of features in these radar volumes is placing new constraints on the nature and evolution of the polar deposits and associated

Mapping Ross Ice Shelf with ROSETTA-Ice airborne laser altimetry

NASA Astrophysics Data System (ADS)

Becker, M. K.; Fricker, H. A.; Padman, L.; Bell, R. E.; Siegfried, M. R.; Dieck, C. C. M.

2017-12-01

The Ross Ocean and ice Shelf Environment and Tectonic setting Through Aerogeophysical surveys and modeling (ROSETTA-Ice) project combines airborne glaciological, geological, and oceanographic observations to enhance our understanding of the history and dynamics of the large ( 500,000 square km) Ross Ice Shelf (RIS). Here, we focus on the Light Detection And Ranging (LiDAR) data collected in 2015 and 2016. This data set represents a significant advance in resolution: Whereas the last attempt to systematically map RIS (the surface-based RIGGS program in the 1970s) was at 55 km grid spacing, the ROSETTA-Ice grid has 10-20 km line spacing and much higher along-track resolution. We discuss two different strategies for processing the raw LiDAR data: one that requires proprietary software (Riegl's RiPROCESS package), and one that employs open-source programs and libraries. With the processed elevation data, we are able to resolve fine-scale ice-shelf features such as the "rampart-moat" ice-front morphology, which has previously been observed on and modeled for icebergs. This feature is also visible in the ROSETTA-Ice shallow-ice radar data; comparing the laser data with radargrams provides insight into the processes leading to their formation. Near-surface firn state and total firn air content can also be investigated through combined analysis of laser altimetry and radar data. By performing similar analyses with data from the radar altimeter aboard CryoSat-2, we demonstrate the utility of the ROSETTA-Ice LiDAR data set in satellite validation efforts. The incorporation of the LiDAR data from the third and final field season (December 2017) will allow us to construct a DEM and an ice thickness map of RIS for the austral summers of 2015-2017. These products will be used to validate and extend observations of height changes from satellite radar and laser altimetry, as well as to update regional models of ocean circulation and ice dynamics.

SMAP RADAR Calibration and Validation

NASA Astrophysics Data System (ADS)

West, R. D.; Jaruwatanadilok, S.; Chaubel, M. J.; Spencer, M.; Chan, S. F.; Chen, C. W.; Fore, A.

2015-12-01

The Soil Moisture Active Passive (SMAP) mission launched on Jan 31, 2015. The mission employs L-band radar and radiometer measurements to estimate soil moisture with 4% volumetric accuracy at a resolution of 10 km, and freeze-thaw state at a resolution of 1-3 km. Immediately following launch, there was a three month instrument checkout period, followed by six months of level 1 (L1) calibration and validation. In this presentation, we will discuss the calibration and validation activities and results for the L1 radar data. Early SMAP radar data were used to check commanded timing parameters, and to work out issues in the low- and high-resolution radar processors. From April 3-13 the radar collected receive only mode data to conduct a survey of RFI sources. Analysis of the RFI environment led to a preferred operating frequency. The RFI survey data were also used to validate noise subtraction and scaling operations in the radar processors. Normal radar operations resumed on April 13. All radar data were examined closely for image quality and calibration issues which led to improvements in the radar data products for the beta release at the end of July. Radar data were used to determine and correct for small biases in the reported spacecraft attitude. Geo-location was validated against coastline positions and the known positions of corner reflectors. Residual errors at the time of the beta release are about 350 m. Intra-swath biases in the high-resolution backscatter images are reduced to less than 0.3 dB for all polarizations. Radiometric cross-calibration with Aquarius was performed using areas of the Amazon rain forest. Cross-calibration was also examined using ocean data from the low-resolution processor and comparing with the Aquarius wind model function. Using all a-priori calibration constants provided good results with co-polarized measurements matching to better than 1 dB, and cross-polarized measurements matching to about 1 dB in the beta release. During the

Borehole radar interferometry revisited

USGS Publications Warehouse

Liu, Lanbo; Ma, Chunguang; Lane, John W.; Joesten, Peter K.

2014-01-01

Single-hole, multi-offset borehole-radar reflection (SHMOR) is an effective technique for fracture detection. However, commercial radar system limitations hinder the acquisition of multi-offset reflection data in a single borehole. Transforming cross-hole transmission mode radar data to virtual single-hole, multi-offset reflection data using a wave interferometric virtual source (WIVS) approach has been proposed but not fully demonstrated. In this study, we compare WIVS-derived virtual single-hole, multi-offset reflection data to real SHMOR radar reflection profiles using cross-hole and single-hole radar data acquired in two boreholes located at the University of Connecticut (Storrs, CT USA). The field data results are similar to full-waveform numerical simulations developed for a two-borehole model. The reflection from the adjacent borehole is clearly imaged by both the real and WIVS-derived virtual reflection profiles. Reflector travel-time changes induced by deviation of the two boreholes from the vertical can also be observed on the real and virtual reflection profiles. The results of this study demonstrate the potential of the WIVS approach to improve bedrock fracture imaging for hydrogeological and petroleum reservoir development applications.

Solid-state radar switchboard

NASA Astrophysics Data System (ADS)

Thiebaud, P.; Cross, D. C.

1980-07-01

A new solid-state radar switchboard equipped with 16 input ports which will output data to 16 displays is presented. Each of the ports will handle a single two-dimensional radar input, or three ports will accommodate a three-dimensional radar input. A video switch card of the switchboard is used to switch all signals, with the exception of the IFF-mode-control lines. Each card accepts inputs from up to 16 sources and can pass a signal with bandwidth greater than 20 MHz to the display assigned to that card. The synchro amplifier of current systems has been eliminated and in the new design each PPI receives radar data via a single coaxial cable. This significant reduction in cabling is achieved by adding a serial-to-parallel interface and a digital-to-synchro converter located at the PPI.

Interpreting Radar View near Mars' North Pole, Orbit 1512

NASA Technical Reports Server (NTRS)

2006-01-01

A radargram from the Shallow Subsurface Radar instrument (SHARAD) on NASA's Mars Reconnaissance Orbiter is shown in the upper-right panel and reveals detailed structure in the polar layered deposits of the north pole of Mars (with blowups shown in the upper-left panels). The sounding radar collected the data presented here during orbit 1512 of the mission, on Nov. 22, 2006.

The horizontal scale in the radargram is distance along the ground track. It can be referenced to the ground track map shown in the lower right. The radar traversed from about 83.5 degrees to 80.5 degrees north latitude, or about 180 kilometers (110 miles). The ground track map shows elevation measured by the Mars Orbiter Laser Altimeter on NASA's Mars Global Surveyor orbiter. Green indicates low elevation; reddish-white indicates higher elevation. The traverse is from the high elevation of the plateau formed by the layers to the lowlands below.

The vertical scale on the radargram is time delay of the radar signals reflected back to Mars Reconnaissance Orbiter from the surface and subsurface. For reference, using an assumed velocity of the radar waves in the subsurface, time is converted to depth below the surface in two places: about 600 meters (2,000 feet) to the lowest of an upper series of bright reflectors and about 2,000 meters (6,500 feet) to the base of the polar layered deposits. The color scale of the radargram varies from black for weak reflections to bright yellow for strong reflections.

The lower-left panel is a image from the Mars Orbiter Camera on Mars Global Surveyor showing exposed polar layering in the walls of a canyon near the north pole. The layering is divided into a finely structured upper unit (labeled 'Upper PLD') and less-well-defined stratigraphy in the lower unit (labeled 'Lower PLD'). The radargram clearly reveals the complexity of the layering in the upper unit, additional reflections from the lower unit, and the base of the entire stack of

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.

Rapid decrease of radar cross section of meteor head echo observed by the MU radar

NASA Astrophysics Data System (ADS)

Nakamura, T.; Nishio, M.; Sato, T.; Tsutsumi, S.; Tsuda, T.; Fushimi, K.

The meteor head echo observation using the MU (Middle and Upper atmosphere) radar (46.5M Hz, 1MW), Shigaraki, Japan, was carried out simultaneously with a high sensitive ICCD (Image-intensified CCD) camera observation in November 2001. The time records were synchronized using GPS satellite signals, in order to compare instantaneous radar and optical meteor magnitudes. 26 faint meteors were successfully observed simultaneously by both equipments. Detailed comparison of the time variation of radar echo intensity and absolute optical magnitude showed that the radar scattering cross section is likely to decrease rapidly by 5 - 20 dB without no corresponding magnitude variation in the optical data. From a simple modeling, we concluded that such decrease of RCS (radar cross section ) is probably due to the transition from overdense head echo to underd ense head echo.

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.

Eyeballing oscillators for pulsed Doppler radar

NASA Astrophysics Data System (ADS)

Goldman, S.

1985-03-01

The visibility of small targets to a Doppler radar system in the presence of large targets is limited by phase noise. Such limitations occur when an airborne radar searches the ground for a mobile vehicle. Under these conditions, the performance of the Doppler radar depends greatly on the specifications of its phased-locked oscillator. Goldman (1984) has discussed the steps required to evaluate the noise resulting from a pulsed Doppler radar system. In the present investigation, these techniques are applied in reverse to determine system specifications for oscillator noise. A 95-GHz pulsed Doppler radar system is used as an example of specifying system phase noise.

Coded continuous wave meteor radar

NASA Astrophysics Data System (ADS)

Chau, J. L.; Vierinen, J.; Pfeffer, N.; Clahsen, M.; Stober, G.

2016-12-01

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, such as wind fields. This type of a radar would also be useful for over-the-horizon radar, ionosondes, and observations of field-aligned-irregularities.

Space Radar Image of Weddell Sea

NASA Image and Video Library

1999-04-15

Two radar images are shown in this composite to compare the size of a standard spaceborne radar image small inset to the image that is created when the radar instrument is used in the ScanSAR mode large image.

Shuttle orbiter radar cross-sectional analysis

NASA Technical Reports Server (NTRS)

Cooper, D. W.; James, R.

1979-01-01

Theoretical and model simulation studies on signal to noise levels and shuttle radar cross section are described. Pre-mission system calibrations, system configuration, and postmission system calibration of the tracking radars are described. Conversion of target range, azimuth, and elevation into radar centered east north vertical position coordinates are evaluated. The location of the impinging rf energy with respect to the target vehicles body axis triad is calculated. Cross section correlation between the two radars is presented.

Iterative Self-Dual Reconstruction on Radar Image Recovery

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martins, Charles; Medeiros, Fatima; Ushizima, Daniela

2010-05-21

Imaging systems as ultrasound, sonar, laser and synthetic aperture radar (SAR) are subjected to speckle noise during image acquisition. Before analyzing these images, it is often necessary to remove the speckle noise using filters. We combine properties of two mathematical morphology filters with speckle statistics to propose a signal-dependent noise filter to multiplicative noise. We describe a multiscale scheme that preserves sharp edges while it smooths homogeneous areas, by combining local statistics with two mathematical morphology filters: the alternating sequential and the self-dual reconstruction algorithms. The experimental results show that the proposed approach is less sensitive to varying window sizesmore » when applied to simulated and real SAR images in comparison with standard filters.« less

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.

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.

Simulation Studies of Forest Structure using 3D Lidar and Radar Models

NASA Technical Reports Server (NTRS)

Sun, Guoqing; Ranson, K. Jon; Koetz, Benjamin; Liu, Dawei

2007-01-01

The use of lidars and radars to measure forest structure attributes such as height and biomass are being considered for future Earth Observation missions. Large footprint lidar makes a direct measurement of the heights of scatterers in the illuminated footprint and can yield information about the vertical profile of the canopy. Synthetic Aperture Radar (SAR) is known to sense the canopy volume, especially at longer wavelengths and is useful for estimating biomass. Interferometric SAR (InSAR) has been shown to yield forest canopy height information. For example, the height of scattering phase retrieved from InSAR data is considered to be correlated with the three height and the spatial structure of the forest stand. There is much interest in exploiting these technologies separately and together to get important information for carbon cycle and ecosystem science. More detailed information of the electromagnetic radiation interactions within forest canopies is needed. And backscattering models can be of much utility here. As part of a NASA funded project to explore data fusion, a three-dimensional (3D) coherent radar backscattering model and a 3D lidar backscatter models were used to investigate the use of large footprint lidar, SAR and InSAR for characterizing realistic forest scenes. For this paper, we use stem maps and other forest measurements to develop a realistic spatial structure of a spruce-hemlock forest canopy found in Maine, USA. The radar and lidar models used measurements of the 3D forest scene as input and simulated the coherent radar backscattering signature and 1064nm energy backscatter, respectively. The relationships of backscatter derived forest structure were compared with field measurements. In addition, we also had detailed airborne lidar (Laser Imaging Vegetation Sensor, LVIS) data available over the stem map sites that was used to study the accuracies of tree height derived from modeled SAR backscatter and the scattering phase center retrieved

Bistatic and Multistatic Radar: Surveillance, Countermeasures, and Radar Cross Sections. (Latest citations from the Aerospace Database)

NASA Technical Reports Server (NTRS)

1998-01-01

The bibliography contains citations concerning the design, development, testing, and evaluation of bistatic and multistatic radar used in surveillance and countermeasure technology. Citations discuss radar cross sections, target recognition and characteristics, ghost recognition, motion image compensation, and wavelet analysis. Stealth aircraft design, stealth target tracking, synthetic aperture radar, and space applications are examined.

Bistatic and Multistatic Radar: Surveillance, Countermeasures, and Radar Cross Sections. (Latest Citations from the Aerospace Database)

NASA Technical Reports Server (NTRS)

1997-01-01

The bibliography contains citations concerning the design, development, testing, and evaluation of bistatic and multistatic radar used in surveillance and countermeasure technology. Citations discuss radar cross sections, target recognition and characteristics, ghost recognition, motion image compensation, and wavelet analysis. Stealth aircraft design, stealth target tracking, synthetic aperture radar, and space applications are examined.

HF Radar Sea-echo from Shallow Water.

PubMed

Lipa, Belinda; Nyden, Bruce; Barrick, Don; Kohut, Josh

2008-08-06

HF radar systems are widely and routinely used for the measurement of ocean surface currents and waves. Analysis methods presently in use are based on the assumption of infinite water depth, and may therefore be inadequate close to shore where the radar echo is strongest. In this paper, we treat the situation when the radar echo is returned from ocean waves that interact with the ocean floor. Simulations are described which demonstrate the effect of shallow water on radar sea-echo. These are used to investigate limits on the existing theory and to define water depths at which shallow-water effects become significant. The second-order spectral energy increases relative to the first-order as the water depth decreases, resulting in spectral saturation when the waveheight exceeds a limit defined by the radar transmit frequency. This effect is particularly marked for lower radar transmit frequencies. The saturation limit on waveheight is less for shallow water. Shallow water affects second-order spectra (which gives wave information) far more than first-order (which gives information on current velocities), the latter being significantly affected only for the lowest radar transmit frequencies for extremely shallow water. We describe analysis of radar echo from shallow water measured by a Rutgers University HF radar system to give ocean wave spectral estimates. Radar-derived wave height, period and direction are compared with simultaneous shallow-water in-situ measurements.

Mathematical analysis study for radar data processing and enhancement. Part 1: Radar data analysis

NASA Technical Reports Server (NTRS)

James, R.; Brownlow, J. D.

1985-01-01

A study is performed under NASA contract to evaluate data from an AN/FPS-16 radar installed for support of flight programs at Dryden Flight Research Facility of NASA Ames Research Center. The purpose of this study is to provide information necessary for improving post-flight data reduction and knowledge of accuracy of derived radar quantities. Tracking data from six flights are analyzed. Noise and bias errors in raw tracking data are determined for each of the flights. A discussion of an altiude bias error during all of the tracking missions is included. This bias error is defined by utilizing pressure altitude measurements made during survey flights. Four separate filtering methods, representative of the most widely used optimal estimation techniques for enhancement of radar tracking data, are analyzed for suitability in processing both real-time and post-mission data. Additional information regarding the radar and its measurements, including typical noise and bias errors in the range and angle measurements, is also presented. This is in two parts. This is part 1, an analysis of radar data.

Tracking radar studies of bird migration

NASA Technical Reports Server (NTRS)

Williams, T. C.; Williams, J. M.; Teal, J. M.; Kanwisher, J. W.

1972-01-01

The application of tracking radar for determining the flight paths of migratory birds is discussed. The effects produced by various meteorological parameters are described. Samples of radar scope presentations obtained during tracking studies are presented. The characteristics of the radars and their limitations are examined.

High voltage switch triggered by a laser-photocathode subsystem

DOEpatents

Chen, Ping; Lundquist, Martin L.; Yu, David U. L.

2013-01-08

A spark gap switch for controlling the output of a high voltage pulse from a high voltage source, for example, a capacitor bank or a pulse forming network, to an external load such as a high gradient electron gun, laser, pulsed power accelerator or wide band radar. The combination of a UV laser and a high vacuum quartz cell, in which a photocathode and an anode are installed, is utilized as triggering devices to switch the spark gap from a non-conducting state to a conducting state with low delay and low jitter.

Metamaterial for Radar Frequencies

DTIC Science & Technology

2012-09-01

Circuit Board RAM Radar Absorbing Material RCS Radar Cross Section SNR Signal-to-Noise Ratio SNG Single-Negative SRR Split Ring Resonator...although some can be single-negative ( SNG ). DNG refers to material with simultaneous negative real parts of the permittivity r  and permeability

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.

Radar investigation of asteroids

NASA Astrophysics Data System (ADS)

Ostro, S. J.

1984-07-01

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.

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.

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.

Investigations on the sensitivity of a stepped-frequency radar utilizing a vector network analyzer for Ground Penetrating Radar

NASA Astrophysics Data System (ADS)

Seyfried, Daniel; Schubert, Karsten; Schoebel, Joerg

2014-12-01

Employing a continuous-wave radar system, with the stepped-frequency radar being one type of this class, all reflections from the environment are present continuously and simultaneously at the receiver. Utilizing such a radar system for Ground Penetrating Radar purposes, antenna cross-talk and ground bounce reflection form an overall dominant signal contribution while reflections from objects buried in the ground are of quite weak amplitude due to attenuation in the ground. This requires a large dynamic range of the receiver which in turn requires high sensitivity of the radar system. In this paper we analyze the sensitivity of our vector network analyzer utilized as stepped-frequency radar system for GPR pipe detection. We furthermore investigate the performance of increasing the sensitivity of the radar by means of appropriate averaging and low-noise pre-amplification of the received signal. It turns out that the improvement in sensitivity actually achievable may differ significantly from theoretical expectations. In addition, we give a descriptive explanation why our appropriate experiments demonstrate that the sensitivity of the receiver is independent of the distance between the target object and the source of dominant signal contribution. Finally, our investigations presented in this paper lead to a preferred setting of operation for our vector network analyzer in order to achieve best detection capability for weak reflection amplitudes, hence making the radar system applicable for Ground Penetrating Radar purposes.

Multimission airborne radar for the 1990s

NASA Astrophysics Data System (ADS)

Robinson, Thomas H.

1986-07-01

The continuing trend towards the development and production of aircraft capable of multiple missions indicates that future airborne radars must provide a broad spectrum of air-to-air and air-to-ground modes. This paper investigates the modal and functional requirements of a multimode radar projected for the mid-1990s period. The paper is divided into two sections. In the first, the multimission capabilities of current radars are presented to establish trends and capabilities. In the second, the requirements of the next generation system are established. Current multimode radars lay the basis for future systems. The experience gained on the APG-65 and APG-63/70 radars is presented and conclusions are drawn regarding their impact on future system requirements. Not only are modes and performance reviewed for these radars but also their system architecture. The discussion starts with the APG-65 radar which is the first true multimission radar with programmable signal and data processing. Following this, the evolution of the APG-63 radar, culminating with the most recent upgrading resulting in redesignation of APG-70, is presented. The incorporation of air-to-ground capabilities in the APG-70, resulting from the Dual Role Fighter program, is reviewed. Results from the Advanced Fighter Capabilities Demonstration program are presented showing how high resolution SAR was incorporated into a full weapon delivery solution. The specific radar requirements for the next decade radar system are developed. This development is done in two parts. First, mode requirements are synthesized for air superiority, navigation and strike/interdiction operation. This includes low altitude penetration requirements and a review of radar timeline constraints which arise. Second, the fundamental functional requirements needed to implement the mode requirements are explored. Architectural issues and their impact on reliability and sustainability are also considered.

Radar/radiometer facilities for precipitation measurements

NASA Technical Reports Server (NTRS)

Hodge, D. B.; Taylor, R. C.

1973-01-01

The OSU ElectroScience Laboratory Radar/Radiometer Facilities are described. This instrumentation includes a high-resolution radar/radiometer system, a fully automated low-resolution radar system, and a small surveillance radar system. The high-resolution radar/radiometer system operates at 3, 9, and 15 GHz using two 9.1 m and one 4.6 m parabolic antennas, respectively. The low-resolution and surveillance radars operate at 9 and 15 GHz, respectively. Both the high- and low-resolution systems are interfaced to real-time digital processing and recording systems. This capability was developed for the measurement of the temporal and spatial characteristics of precipitation in conjunction with millimeter wavelength propagation studies utilizing the Advanced Technology Satellites. Precipitation characteristics derived from these measurements could also be of direct benefit in such diverse areas as: the atmospheric sciences, meteorology, water resources, flood control and warning, severe storm warning, agricultural crop studies, and urban and regional planning.

Radar Reflectivity in Wingtip-Generated Wake Vortices

NASA Technical Reports Server (NTRS)

Marshall, Robert E.; Mudukutore, Ashok; Wissel, Vicki

1997-01-01

This report documents new predictive models of radar reflectivity, with meter-scale resolution, for aircraft wakes in clear air and fog. The models result from a radar design program to locate and quantify wake vortices from commercial aircraft in support of the NASA Aircraft Vortex Spacing System (AVOSS). The radar reflectivity model for clear air assumes: 1) turbulent eddies in the wake produce small discontinuities in radar refractive index; and 2) these turbulent eddies are in the 'inertial subrange' of turbulence. From these assumptions, the maximum radar frequency for detecting a particular aircraft wake, as well as the refractive index structure constant and radar volume reflectivity in the wake can be obtained from the NASA Terminal Area Simulation System (TASS) output. For fog conditions, an empirical relationship is used to calculate radar reflectivity factor from TASS output of bulk liquid water. Currently, two models exist: 1) Atlas-based on observations of liquid water and radar reflectivity factor in clouds; and 2) de Wolf- specifically tailored to a specific measured dataset (1992 Vandenberg Air Force Base).

An analytical investigation of acquisition techniques and system integration studies for a radar aircraft guidance research facility, phase 2

NASA Technical Reports Server (NTRS)

Thompson, W. S.; Ruedger, W. H.

1973-01-01

A review of user requirements and updated instrumentation plans are presented for the aircraft tracking and guidance facility at NASA Wallops Station. User demand has increased as a result of new flight research programs; however, basic requirements remain the same as originally reported. Instrumentation plans remain essentially the same but with plans for up- and down-link telemetry more firm. With slippages in the laser acquisition schedule, added importance is placed on the FPS-16 radar as the primary tracking device until the laser is available. Limited simulation studies of a particular Kalman-type filter are also presented. These studies simulated the use of the filter in a helicopter guidance loop in a real-time mode. Disadvantages and limitations of this mode of operation are pointed out. Laser eyesafety calculations show that laser tracking of aircraft is readily feasible from the eyesafety viewpoint.

Airborne Visible Laser Optical Communications (AVLOC) experiment

NASA Technical Reports Server (NTRS)

1974-01-01

A series of optical communication experiments between a high altitude aircraft at 18.3 km (60,000 ft) and a ground station were conducted by NASA from summer 1972 through winter 1973. The basic system was an optical tracker and transmitter located in each terminal. The aircraft transceiver consisted of a 5-mW HeNe laser transmitter with a 30-megabit modulator. The ground station beacon was an argon laser operating at 488 nm. A separate pulsed laser radar was used for initial acquisition. The objective of the experiment was to obtain engineering data on the precision tracking and communication system performance at both terminals. Atmospheric effects on the system performance was also an experiment objective. The system description, engineering analysis, testing, and flight results are discussed.

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.

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.

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.

Radar, Insect Population Ecology, and Pest Management

NASA Technical Reports Server (NTRS)

Vaughn, C. R. (Editor); Wolf, W. (Editor); Klassen, W. (Editor)

1979-01-01

Discussions included: (1) the potential role of radar in insect ecology studies and pest management; (2) the potential role of radar in correlating atmospheric phenomena with insect movement; (3) the present and future radar systems; (4) program objectives required to adapt radar to insect ecology studies and pest management; and (5) the specific action items to achieve the objectives.

Shallow Water Laser Bathymetry: Accomplishments and Applications

DTIC Science & Technology

2016-05-12

developed specifically to detect underwater mines , such as the Airborne Laser Radar Mine Sensor (ALARMS) built by Optech for the U.S. Defense...borne mine detection based upon an earlier proven ALB receiver configuration, was developed from urgent requirements related to the Persian Gulf War...resolution depiction of a large area which had recently been mined for a neighboring beach restoration project, it highlighted the capability for

High-Resolution Radar Imagery of Mars

NASA Astrophysics Data System (ADS)

Harmon, John K.; Nolan, M. C.

2009-09-01

We present high-resolution radar images of Mars obtained during the 2005 and 2007 oppositions. The images were constructed from long-code delay-Doppler observations made with the Arecibo S-band (13-cm) radar. The average image resolution of 3 km represented a better than order-of-magnitude improvement over pre-upgrade Arecibo imagery of the planet. Images of depolarized reflectivity (an indicator primarily of wavelength-scale surface roughness) show the same bright volcanic flow features seen in earlier imagery, but with much finer detail. A new image of the Elysium region shows fine detail in the radar-bright channels of Athabasca Vallis, Marte Vallis, and Grjota Vallis. The new images of Tharsis and Olympus Mons also show a complex array of radar-bright and radar-dark features. Southern Amazonis exhibits some of the most complex and puzzling radar-bright structure on the planet. Another curiosity is the Chryse/Xanthe/Channels region, where we find some radar-bright features in or adjacent to fluvial chaos structures. Chryse/Xanthe is also the only region of Mars showing radar-bright craters (which are rare on Mars but common on the Moon and Mercury). We also obtained the first delay-Doppler image showing the enhanced backscatter from the residual south polar ice cap. In addition to the depolarized imagery, we were able to make the first delay-Doppler images of the circular polarization ratio (an important diagnostic for surface roughness texture). We find that vast areas of the radar-bright volcanic regions have polarization ratios close to unity. Such high ratios are rare for terrestrial lava flows and only seen for extremely blocky surfaces giving high levels of multiple scattering.

Laser and optics activities at CREOL

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stickley, C.M.

1995-06-01

CREOL is an interdisciplinary institute with a mission to foster and support research and education in the optical and laser sciences and engineering. CREOL`s principal members are its 21-strong faculty. The faculty are encouraged and supported in developing, maintaining, and expanding innovative and sponsored research programs, especially ones that are coupled to industry`s needs. The CREOL Director and Assistant Director, through empowerment by the CREOL faculty, coordinate and oversee the interactive, interdisciplinary projects of the faculty, the 85 graduate students and the 39 research staff. CREOL integrates these research efforts with the general educational mission and goals of the university,more » develops comprehensive course work in the optical and laser sciences and engineering, provides guidance and instruction to graduate students, administers MS and PhD programs, and provides facilities, funds, and administrative support to assist the faculty in carrying out CREOL`s mission and obtaining financial support for the research projects. CREOL`s specific areas of research activity include the following: IR systems; nonlinear optics; crystal growth; nonlinear integrated optics; new solid-state lasers; tunable far-infrared lasers; thin-film optics; theory; semiconductor lasers; x-ray/optical scattering; laser-induced damage; free-electron lasers; solid-state spectroscopy; x-ray sources and applications; laser propagation; laser processing of materials; optical design; optical limiting/sensor protection; diffractive optics; quantum well optoelectronics; dense plasmas/high-field physics; laser radar and remote sensing; diode-based lasers; and glass science.« less

HF Radar Sea-echo from Shallow Water

PubMed Central

Lipa, Belinda; Nyden, Bruce; Barrick, Don; Kohut, Josh

2008-01-01

HF radar systems are widely and routinely used for the measurement of ocean surface currents and waves. Analysis methods presently in use are based on the assumption of infinite water depth, and may therefore be inadequate close to shore where the radar echo is strongest. In this paper, we treat the situation when the radar echo is returned from ocean waves that interact with the ocean floor. Simulations are described which demonstrate the effect of shallow water on radar sea-echo. These are used to investigate limits on the existing theory and to define water depths at which shallow-water effects become significant. The second-order spectral energy increases relative to the first-order as the water depth decreases, resulting in spectral saturation when the waveheight exceeds a limit defined by the radar transmit frequency. This effect is particularly marked for lower radar transmit frequencies. The saturation limit on waveheight is less for shallow water. Shallow water affects second-order spectra (which gives wave information) far more than first-order (which gives information on current velocities), the latter being significantly affected only for the lowest radar transmit frequencies for extremely shallow water. We describe analysis of radar echo from shallow water measured by a Rutgers University HF radar system to give ocean wave spectral estimates. Radar-derived wave height, period and direction are compared with simultaneous shallow-water in-situ measurements. PMID:27873776

Unified anomaly suppression and boundary extraction in laser radar range imagery based on a joint curve-evolution and expectation-maximization algorithm.

PubMed

Feng, Haihua; Karl, William Clem; Castañon, David A

2008-05-01

In this paper, we develop a new unified approach for laser radar range anomaly suppression, range profiling, and segmentation. This approach combines an object-based hybrid scene model for representing the range distribution of the field and a statistical mixture model for the range data measurement noise. The image segmentation problem is formulated as a minimization problem which jointly estimates the target boundary together with the target region range variation and background range variation directly from the noisy and anomaly-filled range data. This formulation allows direct incorporation of prior information concerning the target boundary, target ranges, and background ranges into an optimal reconstruction process. Curve evolution techniques and a generalized expectation-maximization algorithm are jointly employed as an efficient solver for minimizing the objective energy, resulting in a coupled pair of object and intensity optimization tasks. The method directly and optimally extracts the target boundary, avoiding a suboptimal two-step process involving image smoothing followed by boundary extraction. Experiments are presented demonstrating that the proposed approach is robust to anomalous pixels (missing data) and capable of producing accurate estimation of the target boundary and range values from noisy data.

Satellite Laser Ranging operations

NASA Technical Reports Server (NTRS)

Pearlman, Michael R.

1994-01-01

Satellite Laser Ranging (SLR) is currently providing precision orbit determination for measurements of: 1) Ocean surface topography from satellite borne radar altimetry, 2) Spatial and temporal variations of the gravity field, 3) Earth and ocean tides, 4) Plate tectonic and regional deformation, 5) Post-glacial uplift and subsidence, 6) Variations in the Earth's center-of-mass, and 7) Variations in Earth rotation. SLR also supports specialized programs in time transfer and classical geodetic positioning, and will soon provide precision ranging to support experiments in relativity.

46 CFR 169.726 - Radar reflector.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 7 2011-10-01 2011-10-01 false Radar reflector. 169.726 Section 169.726 Shipping COAST... Control, Miscellaneous Systems, and Equipment § 169.726 Radar reflector. Each nonmetallic vessel less than 90 feet in length must exhibit a radar reflector of suitable size and design while underway. Markings ...

46 CFR 169.726 - Radar reflector.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 7 2010-10-01 2010-10-01 false Radar reflector. 169.726 Section 169.726 Shipping COAST... Control, Miscellaneous Systems, and Equipment § 169.726 Radar reflector. Each nonmetallic vessel less than 90 feet in length must exhibit a radar reflector of suitable size and design while underway. Markings ...

46 CFR 169.726 - Radar reflector.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 7 2012-10-01 2012-10-01 false Radar reflector. 169.726 Section 169.726 Shipping COAST... Control, Miscellaneous Systems, and Equipment § 169.726 Radar reflector. Each nonmetallic vessel less than 90 feet in length must exhibit a radar reflector of suitable size and design while underway. Markings ...

46 CFR 169.726 - Radar reflector.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 7 2014-10-01 2014-10-01 false Radar reflector. 169.726 Section 169.726 Shipping COAST... Control, Miscellaneous Systems, and Equipment § 169.726 Radar reflector. Each nonmetallic vessel less than 90 feet in length must exhibit a radar reflector of suitable size and design while underway. Markings ...

46 CFR 169.726 - Radar reflector.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 7 2013-10-01 2013-10-01 false Radar reflector. 169.726 Section 169.726 Shipping COAST... Control, Miscellaneous Systems, and Equipment § 169.726 Radar reflector. Each nonmetallic vessel less than 90 feet in length must exhibit a radar reflector of suitable size and design while underway. Markings ...

Survey of Radar Refraction Error Corrections

DTIC Science & Technology

2016-11-01

ELECTRONIC TRAJECTORY MEASUREMENTS GROUP RCC 266-16 SURVEY OF RADAR REFRACTION ERROR CORRECTIONS DISTRIBUTION A: Approved for...DOCUMENT 266-16 SURVEY OF RADAR REFRACTION ERROR CORRECTIONS November 2016 Prepared by Electronic...This page intentionally left blank. Survey of Radar Refraction Error Corrections, RCC 266-16 iii Table of Contents Preface

Research relative to weather radar measurement techniques

NASA Technical Reports Server (NTRS)

Smith, Paul L.

1992-01-01

Research relative to weather radar measurement techniques, which involves some investigations related to measurement techniques applicable to meteorological radar systems in Thailand, is reported. A major part of the activity was devoted to instruction and discussion with Thai radar engineers, technicians, and meteorologists concerning the basic principles of radar meteorology and applications to specific problems, including measurement of rainfall and detection of wind shear/microburst hazards. Weather radar calibration techniques were also considered during this project. Most of the activity took place during two visits to Thailand, in December 1990 and February 1992.

Advanced Architectures for Modern Weather/Multifunction Radars

DTIC Science & Technology

2017-03-01

Advanced Architectures for Modern Weather /Multifunction Radars Caleb Fulton The University of Oklahoma Advanced Radar Research Center Norman...and all of them are addressing the need to lower cost while improving beamforming flexibility in future weather radar systems that will be tasked...with multiple non- weather functions. Keywords: Phased arrays, digital beamforming, multifunction radar. Introduction and Overview As the performance

Radar cross section lectures

NASA Astrophysics Data System (ADS)

Fuhs, A. E.

A comprehensive account is given of the principles that can be applied in military aircraft configuration studies to minimize the radar cross section (RCS) that will be presented by the resulting design to advanced radars under various mission circumstances. It is noted that, while certain ECM techniques can be nullified by improved enemy electronics in a very short time, RCS reductions may require as much as a decade of radar development before prior levels of detectability can be reestablished by enemy defenses. Attention is given to RCS magnitude determinants, inverse scattering, the polarization and scattering matrix, the RCSs of flat plates and conducting cylinders, and antenna geometry and beam patterns.

Radar studies of bird migration

NASA Technical Reports Server (NTRS)

Williams, T. C.; Williams, J. M.

1974-01-01

Observations of bird migration with NASA radars were made at Wallops Island, Va. Simultaneous observations were made at a number of radar sites in the North Atlantic Ocean in an effort to discover what happened to those birds that were observed leaving the coast of North America headed toward Bermuda, the Caribbean and South America. Transatlantic migration, utilizing observations from a large number of radars is discussed. Detailed studies of bird movements at Wallops Island are presented.

46 CFR 11.480 - Radar observer.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 1 2014-10-01 2014-10-01 false Radar observer. 11.480 Section 11.480 Shipping COAST... ENDORSEMENTS Professional Requirements for National Deck Officer Endorsements § 11.480 Radar observer. (a) This section contains the requirements that an applicant must meet to qualify as a radar observer. (b) If an...

Weather Radar Studies

DTIC Science & Technology

1988-03-31

radar operation and data - collection activities, a large data -analysis effort has been under way in support of automatic wind-shear detection algorithm ...REDUCTION AND ALGORITHM DEVELOPMENT 49 A. General-Purpose Software 49 B. Concurrent Computer Systems 49 C. Sun Workstations 51 D. Radar Data Analysis 52...1. Algorithm Verification 52 2. Other Studies 53 3. Translations 54 4. Outside Distributions 55 E. Mesonet/LLWAS Data Analysis 55 1. 1985 Data 55 2

Hydrologic applications of weather radar

NASA Astrophysics Data System (ADS)

Seo, Dong-Jun; Habib, Emad; Andrieu, Hervé; Morin, Efrat

2015-12-01

By providing high-resolution quantitative precipitation information (QPI), weather radars have revolutionized hydrology in the last two decades. With the aid of GIS technology, radar-based quantitative precipitation estimates (QPE) have enabled routine high-resolution hydrologic modeling in many parts of the world. Given the ever-increasing need for higher-resolution hydrologic and water resources information for a wide range of applications, one may expect that the use of weather radar will only grow. Despite the tremendous progress, a number of significant scientific, technological and engineering challenges remain to realize its potential. New challenges are also emerging as new areas of applications are discovered, explored and pursued. The purpose of this special issue is to provide the readership with some of the latest advances, lessons learned, experiences gained, and science issues and challenges related to hydrologic applications of weather radar. The special issue features 20 contributions on various topics which reflect the increasing diversity as well as the areas of focus in radar hydrology today. The contributions may be grouped as follows:

Kharkiv Meteor Radar System (the XX Age)

NASA Astrophysics Data System (ADS)

Kolomiyets, S. V.

2012-09-01

Kharkiv meteor radar research are of historic value (Kolomiyets and Sidorov 2007). Kharkiv radar observations of meteors proved internationally as the best in the world, it was noted at the IAU General Assembly in 1958. In the 1970s Kharkiv meteor automated radar system (MARS) was recommended at the international level as a successful prototype for wide distribution. Until now, this radar system is one of the most sensitive instruments of meteor radars in the world for astronomical observations. In 2004 Kharkiv meteor radar system is included in the list of objects which compose the national property of Ukraine. Kharkiv meteor radar system has acquired the status of the important historical astronomical instrument in world history. Meteor Centre for researching meteors in Kharkiv is a analogue of the observatory and performs the same functions of a generator and a battery of special knowledge and skills (the world-famous studio). Kharkiv and the location of the instrument were brand points on the globe, as the place where the world-class meteor radar studies were carried out. They are inscribed in the history of meteor astronomy, in large letters and should be immortalized on a world-wide level.

Radar research on thunderstorms and lightning

NASA Technical Reports Server (NTRS)

Rust, W. D.; Doviak, R. J.

1982-01-01

Applications of Doppler radar to detection of storm hazards are reviewed. Normal radar sweeps reveal data on reflectivity fields of rain drops, ionized lightning paths, and irregularities in humidity and temperature. Doppler radar permits identification of the targets' speed toward or away from the transmitter through interpretation of the shifts in the microwave frequency. Wind velocity fields can be characterized in three dimensions by the use of two radar units, with a Nyquist limit on the highest wind speeds that may be recorded. Comparisons with models numerically derived from Doppler radar data show substantial agreement in storm formation predictions based on information gathered before the storm. Examples are provided of tornado observations with expanded Nyquist limits, gust fronts, turbulence, lightning and storm structures. Obtaining vertical velocities from reflectivity spectra is discussed.

MST radar data-base management

NASA Technical Reports Server (NTRS)

Wickwar, V. B.

1983-01-01

Data management for Mesospheric-Stratospheric-Tropospheric, (MST) radars is addressed. An incoherent-scatter radar data base is discussed in terms of purpose, centralization, scope, and nature of the data base management system.

Study on feasibility of laser reflective tomography with satellite-accompany

NASA Astrophysics Data System (ADS)

Gu, Yu; Hu, Yi-hua; Hao, Shi-qi; Gu, You-lin; Zhao, Nan-xiang; Wang, Yang-yang

2015-10-01

Laser reflective tomography is a long-range, high-resolution active detection technology, whose advantage is that the spatial resolution is unrelated with the imaging distance. Accompany satellite is a specific satellite around the target spacecraft with encircling movement. When using the accompany satellite to detect the target aircraft, multi-angle echo data can be obtained with the application of reflective tomography imaging. The feasibility of such detection working mode was studied in this article. Accompany orbit model was established with horizontal circular fleet and the parameters of accompany flight was defined. The simulation of satellite-to-satellite reflective tomography imaging with satellite-accompany was carried out. The operating mode of reflective tomographic data acquisition from monostatic laser radar was discussed and designed. The flight period, which equals to the all direction received data consuming time, is one of the important accompany flight parameters. The azimuth angle determines the plane of image formation while the elevation angle determines the projection direction. Both of the azimuth and elevation angles guide the satellite attitude stability controller in order to point the laser radar spot on the target. The influences of distance between accompany satellite and target satellite on tomographic imaging consuming time was analyzed. The influences of flight period, azimuth angle and elevation angle on tomographic imaging were analyzed as well. Simulation results showed that the satellite-accompany laser reflective tomography is a feasible and effective method to the satellite-to-satellite detection.

46 CFR 15.815 - Radar observers.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 1 2011-10-01 2011-10-01 false Radar observers. 15.815 Section 15.815 Shipping COAST... Computations § 15.815 Radar observers. (a) Each person in the required complement of deck officers, including the master, on inspected vessels of 300 gross tons or over which are radar equipped, shall hold an...

46 CFR 11.480 - Radar observer.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 1 2011-10-01 2011-10-01 false Radar observer. 11.480 Section 11.480 Shipping COAST... ENDORSEMENTS Professional Requirements for Deck Officers § 11.480 Radar observer. (a) This section contains the requirements that an applicant must meet to qualify as a radar observer. (Part 15 of this chapter specifies who...

46 CFR 11.480 - Radar observer.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 1 2010-10-01 2010-10-01 false Radar observer. 11.480 Section 11.480 Shipping COAST... ENDORSEMENTS Professional Requirements for Deck Officers § 11.480 Radar observer. (a) This section contains the requirements that an applicant must meet to qualify as a radar observer. (Part 15 of this chapter specifies who...

46 CFR 11.480 - Radar observer.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 1 2012-10-01 2012-10-01 false Radar observer. 11.480 Section 11.480 Shipping COAST... ENDORSEMENTS Professional Requirements for Deck Officers § 11.480 Radar observer. (a) This section contains the requirements that an applicant must meet to qualify as a radar observer. (Part 15 of this chapter specifies who...

46 CFR 11.480 - Radar observer.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 1 2013-10-01 2013-10-01 false Radar observer. 11.480 Section 11.480 Shipping COAST... ENDORSEMENTS Professional Requirements for Deck Officers § 11.480 Radar observer. (a) This section contains the requirements that an applicant must meet to qualify as a radar observer. (Part 15 of this chapter specifies who...

Airborne Radar Interferometric Repeat-Pass Processing

NASA Technical Reports Server (NTRS)

Hensley, Scott; Michel, Thierry R.; Jones, Cathleen E.; Muellerschoen, Ronald J.; Chapman, Bruce D.; Fore, Alexander; Simard, Marc; Zebker, Howard A.

2011-01-01

Earth science research often requires crustal deformation measurements at a variety of time scales, from seconds to decades. Although satellites have been used for repeat-track interferometric (RTI) synthetic-aperture-radar (SAR) mapping for close to 20 years, RTI is much more difficult to implement from an airborne platform owing to the irregular trajectory of the aircraft compared with microwave imaging radar wavelengths. Two basic requirements for robust airborne repeat-pass radar interferometry include the ability to fly the platform to a desired trajectory within a narrow tube and the ability to have the radar beam pointed in a desired direction to a fraction of a beam width. Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) is equipped with a precision auto pilot developed by NASA Dryden that allows the platform, a Gulfstream III, to nominally fly within a 5 m diameter tube and with an electronically scanned antenna to position the radar beam to a fraction of a beam width based on INU (inertial navigation unit) attitude angle measurements.

Mars Radar Opens a Planet's Third Dimension

NASA Technical Reports Server (NTRS)

2008-01-01

Radar sounder instruments orbiting Mars have looked beneath the Martian surface and opened up the third dimension for planetary exploration. The technique's success is prompting scientists to think of all the other places in the Solar System where they would like to use radar sounders.

The first radar sounder at Mars was the Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) on the European Space Agency's Mars Express Orbiter. It has been joined by the complementary Shallow Subsurface Radar (SHARAD), operating at a different wavelength aboard NASA's Mars Reconnaissance Orbiter. The data in this animation are from SHARAD.

Simultaneous dual-band radar development

NASA Technical Reports Server (NTRS)

Liskow, C. L.

1974-01-01

Efforts to design and construct an airborne imaging radar operating simultaneously at L band and X band with an all-inertial navigation system in order to form a dual-band radar system are described. The areas of development include duplex transmitters, receivers, and recorders, a control module, motion compensation for both bands, and adaptation of a commercial inertial navigation system. Installation of the system in the aircraft and flight tests are described. Circuit diagrams, performance figures, and some radar images are presented.

46 CFR 167.40-40 - Radar.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 7 2010-10-01 2010-10-01 false Radar. 167.40-40 Section 167.40-40 Shipping COAST GUARD... Requirements § 167.40-40 Radar. All mechanically propelled vessels of 1,600 gross tons and over in ocean or coastwise service must be fitted with a marine radar system for surface navigation. Facilities for plotting...

46 CFR 167.40-40 - Radar.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 7 2011-10-01 2011-10-01 false Radar. 167.40-40 Section 167.40-40 Shipping COAST GUARD... Requirements § 167.40-40 Radar. All mechanically propelled vessels of 1,600 gross tons and over in ocean or coastwise service must be fitted with a marine radar system for surface navigation. Facilities for plotting...

46 CFR 167.40-40 - Radar.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 7 2012-10-01 2012-10-01 false Radar. 167.40-40 Section 167.40-40 Shipping COAST GUARD... Requirements § 167.40-40 Radar. All mechanically propelled vessels of 1,600 gross tons and over in ocean or coastwise service must be fitted with a marine radar system for surface navigation. Facilities for plotting...

46 CFR 167.40-40 - Radar.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 7 2013-10-01 2013-10-01 false Radar. 167.40-40 Section 167.40-40 Shipping COAST GUARD... Requirements § 167.40-40 Radar. All mechanically propelled vessels of 1,600 gross tons and over in ocean or coastwise service must be fitted with a marine radar system for surface navigation. Facilities for plotting...

46 CFR 167.40-40 - Radar.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 7 2014-10-01 2014-10-01 false Radar. 167.40-40 Section 167.40-40 Shipping COAST GUARD... Requirements § 167.40-40 Radar. All mechanically propelled vessels of 1,600 gross tons and over in ocean or coastwise service must be fitted with a marine radar system for surface navigation. Facilities for plotting...

Mutual information-based LPI optimisation for radar network

NASA Astrophysics Data System (ADS)

Shi, Chenguang; Zhou, Jianjiang; Wang, Fei; Chen, Jun

2015-07-01

Radar network can offer significant performance improvement for target detection and information extraction employing spatial diversity. For a fixed number of radars, the achievable mutual information (MI) for estimating the target parameters may extend beyond a predefined threshold with full power transmission. In this paper, an effective low probability of intercept (LPI) optimisation algorithm is presented to improve LPI performance for radar network. Based on radar network system model, we first provide Schleher intercept factor for radar network as an optimisation metric for LPI performance. Then, a novel LPI optimisation algorithm is presented, where for a predefined MI threshold, Schleher intercept factor for radar network is minimised by optimising the transmission power allocation among radars in the network such that the enhanced LPI performance for radar network can be achieved. The genetic algorithm based on nonlinear programming (GA-NP) is employed to solve the resulting nonconvex and nonlinear optimisation problem. Some simulations demonstrate that the proposed algorithm is valuable and effective to improve the LPI performance for radar network.

Radar research at University of Oklahoma (Conference Presentation)

NASA Astrophysics Data System (ADS)

Zhang, Yan R.; Weber, Mark E.

2017-05-01

This abstract is for the academic institution profiles session This presentation will focus on radar research programs at the University of Oklahoma, the radar research in OU has more than 50 years history of collaboration with NOAA, and has been through tremendous growth since early 2000. Before 2010, the focus was weather radar and weather surveillance, and since the Defense, Security and Intelligence (DSI) initiative in 2011, there have many new efforts on the defense and military radar applications. This presentation will focus on the following information: (1) The history, facilities and instrumentations of Advanced Radar Research Center, (2) Focus area of polarimetric phased array systems, (3) Focus area of airborne and spaceborne radars, (4) Intelligent radar information processing, (5) Innovative antenna and components.

Weather Radars and Lidar for Observing the Atmosphere

NASA Astrophysics Data System (ADS)

(Vivek) Vivekanandan, J.

2010-05-01

The Earth Observing Laboratory (EOL) at the National Center for Atmospheric Research (NCAR) in Boulder, Colorado develops and deploys state-of-the-art ground-based radar, airborne radar and lidar instruments to advance scientific understanding of the earth system. The ground-based radar (S-Pol) is equipped with dual-wavelength capability (S-band and Ka-band). S-Pol is the only transportable radar in the world. In order to capture faster moving weather events such as tornadoes and record observations of clouds over rugged mountainous terrain and ocean, an airborne radar (ELDORA) is used. It is the only airborne Doppler meteorological radar that is able to detect motions in the clear air. The EOL is in the process of building the first phase of a three phase dual wavelength W/Ka-band airborne cloud radar to be called the HIAPER Cloud Radar (HCR). This phase is a pod based W-band radar system with scanning capability. The second phase will add pulse compression and polarimetric capability to the W-band system, while the third phase will add complementary Ka-band radar. The pod-based radar is primarily designed to fly on the Gulfstream V (GV) and C-130 aircraft. The envisioned capability of a millimeter wave radar system on GV is enhanced by coordination with microwave radiometer, in situ probes, and especially by the NCAR GV High-Spectral Resolution Lidar (HSRL) which is also under construction. The presentation will describe the capabilities of current instruments and also planned instrumentation development.

Academician Basov, high-power lasers, and the antimissile defense problem

NASA Astrophysics Data System (ADS)

Zarubin, Peter Vasilievich

2013-02-01

A review of the extensive program of the pioneering research and development of high-power lasers and laser radar undertaken in the USSR during the years 1964 to 1978 under the scientific supervision of N.G. Basov is presented. In the course of this program, many high-energy lasers with unique properties were created, new big research and design teams were formed, and the laser production and testing facilities were extended and developed. The program was fulfilled at many leading research institutions and design bureaus of the USSR Academy of Sciences and defense industry.

Passive bistatic radar analysis

NASA Astrophysics Data System (ADS)

O'Hagan, Daniel W.; Kuschel, H.; Schiller, Joachim

2009-06-01

Passive Bistatic Radar (PBR) research is at its zenith with several notable PBR systems currently operational, or available for deployment. Such PBRs include the Manastash Ridge Radar (MRR) developed for and by academia; Silent Sentry developed as a commercial concern by Lockheed Martin; and Homeland Alerter (HA100) also a commercial system developed by Thales. However at present, despite the existence of numerous PBR prototypes, take up of commercial passive radar technology remains slow. This is due in part to technology immaturity, in part to politics, and particularly due to the fact that monostatic radars perform so well. If PBRs are to enjoy longevity as a viable technology then it is imperative that they address certain niche application areas, with the aforementioned MRR being one prime example of this. The focus of this paper will be an analysis of a PBR system that utilised FM radio signals of opportunity to detect aircraft targets with an RCS generally not lower than 20 m2. The paper will demonstrate the theoretical detection coverage of an FM based PBR operating in a severe interference environment.

Optimal frequency range for medical radar measurements of human heartbeats using body-contact radar.

PubMed

Brovoll, Sverre; Aardal, Øyvind; Paichard, Yoann; Berger, Tor; Lande, Tor Sverre; Hamran, Svein-Erik

2013-01-01

In this paper the optimal frequency range for heartbeat measurements using body-contact radar is experimentally evaluated. A Body-contact radar senses electromagnetic waves that have penetrated the human body, but the range of frequencies that can be used are limited by the electric properties of the human tissue. The optimal frequency range is an important property needed for the design of body-contact radar systems for heartbeat measurements. In this study heartbeats are measured using three different antennas at discrete frequencies from 0.1 - 10 GHz, and the strength of the received heartbeat signal is calculated. To characterize the antennas, when in contact with the body, two port S-parameters(†) are measured for the antennas using a pork rib as a phantom for the human body. The results shows that frequencies up to 2.5 GHz can be used for heartbeat measurements with body-contact radar.

Pedestrian recognition using automotive radar sensors

NASA Astrophysics Data System (ADS)

Bartsch, A.; Fitzek, F.; Rasshofer, R. H.

2012-09-01

The application of modern series production automotive radar sensors to pedestrian recognition is an important topic in research on future driver assistance systems. The aim of this paper is to understand the potential and limits of such sensors in pedestrian recognition. This knowledge could be used to develop next generation radar sensors with improved pedestrian recognition capabilities. A new raw radar data signal processing algorithm is proposed that allows deep insights into the object classification process. The impact of raw radar data properties can be directly observed in every layer of the classification system by avoiding machine learning and tracking. This gives information on the limiting factors of raw radar data in terms of classification decision making. To accomplish the very challenging distinction between pedestrians and static objects, five significant and stable object features from the spatial distribution and Doppler information are found. Experimental results with data from a 77 GHz automotive radar sensor show that over 95% of pedestrians can be classified correctly under optimal conditions, which is compareable to modern machine learning systems. The impact of the pedestrian's direction of movement, occlusion, antenna beam elevation angle, linear vehicle movement, and other factors are investigated and discussed. The results show that under real life conditions, radar only based pedestrian recognition is limited due to insufficient Doppler frequency and spatial resolution as well as antenna side lobe effects.

Using phase for radar scatterer classification

NASA Astrophysics Data System (ADS)

Moore, Linda J.; Rigling, Brian D.; Penno, Robert P.; Zelnio, Edmund G.

2017-04-01

Traditional synthetic aperture radar (SAR) systems tend to discard phase information of formed complex radar imagery prior to automatic target recognition (ATR). This practice has historically been driven by available hardware storage, processing capabilities, and data link capacity. Recent advances in high performance computing (HPC) have enabled extremely dense storage and processing solutions. Therefore, previous motives for discarding radar phase information in ATR applications have been mitigated. First, we characterize the value of phase in one-dimensional (1-D) radar range profiles with respect to the ability to correctly estimate target features, which are currently employed in ATR algorithms for target discrimination. These features correspond to physical characteristics of targets through radio frequency (RF) scattering phenomenology. Physics-based electromagnetic scattering models developed from the geometrical theory of diffraction are utilized for the information analysis presented here. Information is quantified by the error of target parameter estimates from noisy radar signals when phase is either retained or discarded. Operating conditions (OCs) of signal-tonoise ratio (SNR) and bandwidth are considered. Second, we investigate the value of phase in 1-D radar returns with respect to the ability to correctly classify canonical targets. Classification performance is evaluated via logistic regression for three targets (sphere, plate, tophat). Phase information is demonstrated to improve radar target classification rates, particularly at low SNRs and low bandwidths.

Radar Control Optimal Resource Allocation

DTIC Science & Technology

2015-07-13

other tunable parameters of radars [17, 18]. Such radar resource scheduling usually demands massive computation. Even myopic 14 Distribution A: Approved...reduced validity of the optimal choice of radar resource. In the non- myopic context, the computational problem becomes exponentially more difficult...computed as t? = ασ2 q + σ r √ α q (σ + r + α q) α q2 r − 1ασ q2 + q r2 . (19) We are only interested in t? > 1 and solving the inequality we obtain the

Target scattering characteristics for OAM-based radar

NASA Astrophysics Data System (ADS)

Liu, Kang; Gao, Yue; Li, Xiang; Cheng, Yongqiang

2018-02-01

The target scattering characteristics are crucial for radar systems. However, there is very little study conducted for the recently developed orbital angular momentum (OAM) based radar system. To illustrate the role of OAM-based radar cross section (ORCS), conventional radar equation is modified by taking characteristics of the OAM waves into account. Subsequently, the ORCS is defined in analogy to classical radar cross section (RCS). The unique features of the incident OAM-carrying field are analyzed. The scattered field is derived, and the analytical expressions of ORCSs for metal plate and cylinder targets are obtained. Furthermore, the ORCS and RCS are compared to illustrate the influences of OAM mode number, target size and signal frequency on the ORCS. Analytical studies demonstrate that the mirror-reflection phenomenon disappears and peak values of ORCS are in the non-specular direction. Finally, the ORCS features are summarized to show its advantages in radar target detection. This work can provide theoretical guidance to the design of OAM-based radar as well as the target detection and identification applications.

Basic Radar Altimetry Toolbox: Tools to Use Radar Altimetry for Geodesy

NASA Astrophysics Data System (ADS)

Rosmorduc, V.; Benveniste, J. J.; Bronner, E.; Niejmeier, S.

2010-12-01

Radar altimetry is very much a technique expanding its applications and uses. If quite a lot of efforts have been made for oceanography users (including easy-to-use data), the use of those data for geodesy, especially combined witht ESA GOCE mission data is still somehow hard. ESA and CNES thus had the Basic Radar Altimetry Toolbox developed (as well as, on ESA side, the GOCE User Toolbox, both being linked). The Basic Radar Altimetry Toolbox is an "all-altimeter" collection of tools, tutorials and documents designed to facilitate the use of radar altimetry data. The software is able: - to read most distributed radar altimetry data, from ERS-1 & 2, Topex/Poseidon, Geosat Follow-on, Jason-1, Envisat, Jason- 2, CryoSat and the future Saral missions, - to perform some processing, data editing and statistic, - and to visualize the results. It can be used at several levels/several ways: - as a data reading tool, with APIs for C, Fortran, Matlab and IDL - as processing/extraction routines, through the on-line command mode - as an educational and a quick-look tool, with the graphical user interface As part of the Toolbox, a Radar Altimetry Tutorial gives general information about altimetry, the technique involved and its applications, as well as an overview of past, present and future missions, including information on how to access data and additional software and documentation. It also presents a series of data use cases, covering all uses of altimetry over ocean, cryosphere and land, showing the basic methods for some of the most frequent manners of using altimetry data. It is an opportunity to teach remote sensing with practical training. It has been available from April 2007, and had been demonstrated during training courses and scientific meetings. About 1200 people downloaded it (Summer 2010), with many "newcomers" to altimetry among them. Users' feedbacks, developments in altimetry, and practice, showed that new interesting features could be added. Some have been

Radar, target and ranging

NASA Astrophysics Data System (ADS)

1984-09-01

This Test Operations Procedure (TOP) provides conventional test methods employing conventional test instrumentation for testing conventional radars. Single tests and subtests designed to test radar components, transmitters, receivers, antennas, etc., and system performance are conducted with single item instruments such as meters, generators, attenuators, counters, oscillators, plotters, etc., and with adequate land areas for conducting field tests.

Radar Imaging with a Network of Digital Noise Radar Systems

DTIC Science & Technology

2009-03-01

This chapter develops the theoretical foundations of noise radar technology. Comprehensive theoretical models are developed for UWB noise radar, digital...Power to the Antenna +23 dBm Polarization HH Antenna Gain 6 dB ADC 8 Bits Sampling Rate 1.5 GHz/per channel Dynamic Range (0.8 Pd, 0.2 Pf ) 20 dB Range...from Eq. 3.25, can be found by solving Eq. 3.23 for E[XY ]. µrXY = E[XY ] = 〈xy〉 = ρσ2 (3.26) σrXY , from Eq. 3.25 can be derived through the

Simulation of Space-borne Radar Observation from High Resolution Cloud Model - for GPM Dual frequency Precipitation Radar -

NASA Astrophysics Data System (ADS)

Kim, H.; Meneghini, R.; Jones, J.; Liao, L.

2011-12-01

A comprehensive space-borne radar simulator has been developed to support active microwave sensor satellite missions. The two major objectives of this study are: 1) to develop a radar simulator optimized for the Dual-frequency Precipitation Radar (KuPR and KaPR) on the Global Precipitation Measurement Mission satellite (GPM-DPR) and 2) to generate the synthetic test datasets for DPR algorithm development. This simulator consists of two modules: a DPR scanning configuration module and a forward module that generates atmospheric and surface radar observations. To generate realistic DPR test data, the scanning configuration module specifies the technical characteristics of DPR sensor and emulates the scanning geometry of the DPR with a inner swath of about 120 km, which contains matched-beam data from both frequencies, and an outer swath from 120 to 245 km over which only Ku-band data will be acquired. The second module is a forward model used to compute radar observables (reflectivity, attenuation and polarimetric variables) from input model variables including temperature, pressure and water content (rain water, cloud water, cloud ice, snow, graupel and water vapor) over the radar resolution volume. Presently, the input data to the simulator come from the Goddard Cumulus Ensemble (GCE) and Weather Research and Forecast (WRF) models where a constant mass density is assumed for each species with a particle size distribution given by an exponential distribution with fixed intercept parameter (N0) and a slope parameter (Λ) determined from the equivalent water content. Although the model data do not presently contain mixed phase hydrometeors, the Yokoyama-Tanaka melting model is used along with the Bruggeman effective dielectric constant to replace rain and snow particles, where both are present, with mixed phase particles while preserving the snow/water fraction. For testing one of the DPR retrieval algorithms, the Surface Reference Technique (SRT), the simulator uses

SAR Ambiguity Study for the Cassini Radar

NASA Technical Reports Server (NTRS)

Hensley, Scott; Im, Eastwood; Johnson, William T. K.

1993-01-01

The Cassini Radar's synthetic aperture radar (SAR) ambiguity analysis is unique with respect to other spaceborne SAR ambiguity analyses owing to the non-orbiting spacecraft trajectory, asymmetric antenna pattern, and burst mode of data collection. By properly varying the pointing, burst mode timing, and radar parameters along the trajectory this study shows that the signal-to-ambiguity ratio of better than 15 dB can be achieved for all images obtained by the Cassini Radar.

Design of an infrared camera based aircraft detection system for laser guide star installations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Friedman, H.; Macintosh, B.

1996-03-05

There have been incidents in which the irradiance resulting from laser guide stars have temporarily blinded pilots or passengers of aircraft. An aircraft detection system based on passive near infrared cameras (instead of active radar) is described in this report.

Laser Doppler systems in pollution monitoring

NASA Technical Reports Server (NTRS)

Miller, C. R.; Sonnenschein, C. M.; Herget, W. F.; Huffaker, R. M.

1976-01-01

The paper reports on a program undertaken to determine the feasibility of using a laser Doppler velocimeter (LDV) to measure smoke-stack gas exit velocity, particulate concentration, and mass flow. Measurements made with a CO2 laser Doppler radar system at a coal-burning power plant are compared with in-stack measurements made by a pitot tube. The operational principles of a LDV are briefly described along with the system employed in the present study. Data discussed include typical Doppler spectra from smoke-stack effluents at various laser elevation angles, the measured velocity profile across the stack exit, and the LDV-measured exit velocity as a function of the exit velocity measured by the in-stack instrument. The in-stack velocity is found to be about 14% higher than the LDV velocity, but this discrepancy is regarded as a systematic error. In general, linear relationships are observed between the laser data, the exit velocity, and the particulate concentration. It is concluded that an LDV has the capability of determining both the mass concentration and the mass flow from a power-plant smoke stack.

Research on Radar Importance with Decision Matrix

NASA Astrophysics Data System (ADS)

Meng, Lingjie; Du, Yu; Wang, Liuheng

2017-12-01

Considering the characteristic of radar, constructed the evaluation index system of radar importance, established the comprehensive evaluation model based on decision matrix. Finally, by means of an example, the methods of this evaluation on radar importance was right and feasibility.

Radar Polarimetry: Theory, Analysis, and Applications

NASA Astrophysics Data System (ADS)

Hubbert, John Clark

The fields of radar polarimetry and optical polarimetry are compared. The mathematics of optic polarimetry are formulated such that a local right handed coordinate system is always used to describe the polarization states. This is not done in radar polarimetry. Radar optimum polarization theory is redeveloped within the framework of optical polarimetry. The radar optimum polarizations and optic eigenvalues of common scatterers are compared. In addition a novel definition of an eigenpolarization state is given and the accompanying mathematics is developed. The polarization response calculated using optic, radar and novel definitions is presented for a variety of scatterers. Polarimetric transformation provides a means to characterize scatters in more than one polarization basis. Polarimetric transformation for an ensemble of scatters is obtained via two methods: (1) the covariance method and (2) the instantaneous scattering matrix (ISM) method. The covariance method is used to relate the mean radar parameters of a +/-45^circ linear polarization basis to those of a horizontal and vertical polarization basis. In contrast the ISM method transforms the individual time samples. Algorithms are developed for transforming the time series from fully polarimetric radars that switch between orthogonal states. The transformed time series are then used to calculate the mean radar parameters of interest. It is also shown that propagation effects do not need to be removed from the ISM's before transformation. The techniques are demonstrated using data collected by POLDIRAD, the German Aerospace Research Establishment's fully polarimetric C-band radar. The differential phase observed between two copolar states, Psi_{CO}, is composed of two phases: (1) differential propagation phase, phi_{DP}, and (2) differential backscatter phase, delta. The slope of phi_{DP } with range is an estimate of the specific differential phase, K_{DP}. The process of estimating K_{DP} is complicated when

Reflectivity retrieval in a networked radar environment

NASA Astrophysics Data System (ADS)

Lim, Sanghun

Monitoring of precipitation using a high-frequency radar system such as X-band is becoming increasingly popular due to its lower cost compared to its counterpart at S-band. Networks of meteorological radar systems at higher frequencies are being pursued for targeted applications such as coverage over a city or a small basin. However, at higher frequencies, the impact of attenuation due to precipitation needs to be resolved for successful implementation. In this research, new attenuation correction algorithms are introduced to compensate the attenuation impact due to rain medium. In order to design X-band radar systems as well as evaluate algorithm development, it is useful to have simultaneous X-band observation with and without the impact of path attenuation. One way to obtain that data set is through theoretical models. Methodologies for generating realistic range profiles of radar variables at attenuating frequencies such as X-band for rain medium are presented here. Fundamental microphysical properties of precipitation, namely size and shape distribution information, are used to generate realistic profiles of X-band starting with S-band observations. Conditioning the simulation from S-band radar measurements maintains the natural distribution of microphysical parameters associated with rainfall. In this research, data taken by the CSU-CHILL radar and the National Center for Atmospheric Research S-POL radar are used to simulate X-band radar variables. Three procedures to simulate the radar variables at X-band and sample applications are presented. A new attenuation correction algorithm based on profiles of reflectivity, differential reflectivity, and differential propagation phase shift is presented. A solution for specific attenuation retrieval in rain medium is proposed that solves the integral equations for reflectivity and differential reflectivity with cumulative differential propagation phase shift constraint. The conventional rain profiling algorithms

Cross-evaluation of reflectivity from the space-borne precipitation radar and multi-type ground-based weather radar network in China

NASA Astrophysics Data System (ADS)

Zhong, Lingzhi; Yang, Rongfang; Wen, Yixin; Chen, Lin; Gou, Yabin; Li, Ruiyi; Zhou, Qing; Hong, Yang

2017-11-01

China operational weather radar network consists of more than 200 ground-based radars (GR(s)). The lack of unified calibrators often result in poor mosaic products as well as its limitation in radar data assimilation in numerical models. In this study, radar reflectivity and precipitation vertical structures observed from space-borne TRMM (Tropical Rainfall Measurement Mission) PR (precipitation radar) and GRs are volumetrically matched and cross-evaluated. It is found that observation of GRs is basically consistent with that of PR. For their overlapping scanning regions, the GRs are often affected by the beam blockage for complex terrain. The statistics show the better agreement among S band A type (SA) radars, S band B type (SB) radars and PR, as well as poor performance of S band C type (SC) radars. The reflectivity offsets between GRs and PR depend on the reflectivity magnitudes: They are positive for weak precipitation and negative for middle and heavy precipitation, respectively. Although the GRs are quite consistent with PR for large sample, an individual GR has its own fluctuated biases monthly. When the sample number is small, the bias statistics may be determined by a single bad GR in a group. Results from this study shed lights that the space-borne precipitation radars could be used to quantitatively calibrate systematic bias existing in different GRs in order to improve the consistency of ground-based weather radar network across China, and also bears the promise to provide a robust reference even form a space and ground constellation network for the dual-frequency precipitation radars onboard the satellites anticipated in the near future.

UAV-based Radar Sounding of Antarctic Ice

NASA Astrophysics Data System (ADS)

Leuschen, Carl; Yan, Jie-Bang; Mahmood, Ali; Rodriguez-Morales, Fernando; Hale, Rick; Camps-Raga, Bruno; Metz, Lynsey; Wang, Zongbo; Paden, John; Bowman, Alec; Keshmiri, Shahriar; Gogineni, Sivaprasad

2014-05-01

We developed a compact radar for use on a small UAV to conduct measurements over the ice sheets in Greenland and Antarctica. It operates at center frequencies of 14 and 35 MHz with bandwidths of 1 MHz and 4 MHz, respectively. The radar weighs about 2 kgs and is housed in a box with dimensions of 20.3 cm x 15.2 cm x 13.2 cm. It transmits a signal power of 100 W at a pulse repletion frequency of 10 kHz and requires average power of about 20 W. The antennas for operating the radar are integrated into the wings and airframe of a small UAV with a wingspan of 5.3 m. We selected the frequencies of 14 and 35 MHz based on previous successful soundings of temperate ice in Alaska with a 12.5 MHz impulse radar [Arcone, 2002] and temperate glaciers in Patagonia with a 30 MHz monocycle radar [Blindow et al., 2012]. We developed the radar-equipped UAV to perform surveys over a 2-D grid, which allows us to synthesize a large two-dimensional aperture and obtain fine resolution in both the along- and cross-track directions. Low-frequency, high-sensitivity radars with 2-D aperture synthesis capability are needed to overcome the surface and volume scatter that masks weak echoes from the ice-bed interface of fast-flowing glaciers. We collected data with the radar-equipped UAV on sub-glacial ice near Lake Whillans at both 14 and 35 MHz. We acquired data to evaluate the concept of 2-D aperture synthesis and successfully demonstrated the first successful sounding of ice with a radar on an UAV. We are planning to build multiple radar-equipped UAVs for collecting fine-resolution data near the grounding lines of fast-flowing glaciers. In this presentation we will provide a brief overview of the radar and UAV, as well as present results obtained at both 14 and 35 MHz. Arcone, S. 2002. Airborne-radar stratigraphy and electrical structure of temperate firn: Bagley Ice Field, Alaska, U.S.A. Journal of Glaciology, 48, 317-334. Blindow, N., C. Salat, and G. Casassa. 2012. Airborne GPR sounding of

Three-dimensional radar imaging of structures and craters in the Martian polar caps

NASA Astrophysics Data System (ADS)

Putzig, Nathaniel E.; Smith, Isaac B.; Perry, Matthew R.; Foss, Frederick J.; Campbell, Bruce A.; Phillips, Roger J.; Seu, Roberto

2018-07-01

Over the last decade, observations acquired by the Shallow Radar (SHARAD) sounder on individual passes of the Mars Reconnaissance Orbiter have revealed the internal structure of the Martian polar caps and provided new insights into the formation of the icy layers within and their relationship to climate. However, a complete picture of the cap interiors has been hampered by interfering reflections from off-nadir surface features and signal losses associated with sloping structures and scattering. Foss et al. (The Leading Edge 36, 43-57, 2017, https://doi.org/10.1190/tle36010043.1) addressed these limitations by assembling three-dimensional data volumes of SHARAD observations from thousands of orbital passes over each polar region and applying geometric corrections simultaneously. The radar volumes provide unprecedented views of subsurface features, readily imaging structures previously inferred from time-intensive manual analysis of single-orbit data (e.g., trough-bounding surfaces, a buried chasma, and a basal unit in the north, massive carbon-dioxide ice deposits and discontinuous layered sequences in the south). Our new mapping of the carbon-dioxide deposits yields a volume of 16,500 km3, 11% larger than the prior estimate. In addition, the radar volumes newly reveal other structures, including what appear to be buried impact craters with no surface expression. Our first assessment of 21 apparent craters at the base of the north polar layered deposits suggests a Hesperian age for the substrate, consistent with that of the surrounding plains as determined from statistics of surface cratering rates. Planned mapping of similar features throughout both polar volumes may provide new constraints on the age of the icy layered deposits. The radar volumes also provide new topographic data between the highest latitudes observed by the Mars Orbiter Laser Altimeter and those observed by SHARAD. In general, mapping of features in these radar volumes is placing new constraints

Theoretical analyses of an injection-locked diode-pumped rubidium vapor laser.

PubMed

Cai, He; Gao, Chunqing; Liu, Xiaoxu; Wang, Shunyan; Yu, Hang; Rong, Kepeng; An, Guofei; Han, Juhong; Zhang, Wei; Wang, Hongyuan; Wang, You

2018-04-02

Diode-pumped alkali lasers (DPALs) have drawn much attention since they were proposed in 2001. The narrow-linewidth DPAL can be potentially applied in the fields of coherent communication, laser radar, and atomic spectroscopy. In this study, we propose a novel protocol to narrow the width of one kind of DPAL, diode-pumped rubidium vapor laser (DPRVL), by use of an injection locking technique. A kinetic model is first set up for an injection-locked DPRVL with the end-pumped configuration. The laser tunable duration is also analyzed for a continuous wave (CW) injection-locked DPRVL system. Then, the influences of the pump power, power of a master laser, and reflectance of an output coupler on the output performance are theoretically analyzed. The study should be useful for design of a narrow-linewidth DPAL with the relatively high output.

Radar observations of asteroids and comets

NASA Technical Reports Server (NTRS)

Ostro, S. J.

1985-01-01

Radar techniques for the observation of asteroids and comets are reviewed, emphasizing the logical basis for inferring physical properties from radar measurements. Results to date are reviewed, focusing on some recent highlights of the research to demonstrate the synergism between radar and other ground-based techniques. Particular attention is given to the asteroids 2 Pallas, 16 Psyche, 2101 Adonis, and the comet IRAS-Araki-Alcock.

Ground and Space Radar Volume Matching and Comparison Software

NASA Technical Reports Server (NTRS)

Morris, Kenneth; Schwaller, Mathew

2010-01-01

This software enables easy comparison of ground- and space-based radar observations. The software was initially designed to compare ground radar reflectivity from operational, ground based Sand C-band meteorological radars with comparable measurements from the Tropical Rainfall Measuring Mission (TRMM) satellite s Precipitation Radar (PR) instrument. The software is also applicable to other ground-based and space-based radars. The ground and space radar volume matching and comparison software was developed in response to requirements defined by the Ground Validation System (GVS) of Goddard s Global Precipitation Mission (GPM) project. This software innovation is specifically concerned with simplifying the comparison of ground- and spacebased radar measurements for the purpose of GPM algorithm and data product validation. This software is unique in that it provides an operational environment to routinely create comparison products, and uses a direct geometric approach to derive common volumes of space- and ground-based radar data. In this approach, spatially coincident volumes are defined by the intersection of individual space-based Precipitation Radar rays with the each of the conical elevation sweeps of the ground radar. Thus, the resampled volume elements of the space and ground radar reflectivity can be directly compared to one another.

Developing tools for digital radar image data evaluation

NASA Technical Reports Server (NTRS)

Domik, G.; Leberl, F.; Raggam, J.

1986-01-01

The refinement of radar image analysis methods has led to a need for a systems approach to radar image processing software. Developments stimulated through satellite radar are combined with standard image processing techniques to create a user environment to manipulate and analyze airborne and satellite radar images. One aim is to create radar products for the user from the original data to enhance the ease of understanding the contents. The results are called secondary image products and derive from the original digital images. Another aim is to support interactive SAR image analysis. Software methods permit use of a digital height model to create ortho images, synthetic images, stereo-ortho images, radar maps or color combinations of different component products. Efforts are ongoing to integrate individual tools into a combined hardware/software environment for interactive radar image analysis.

Characterising soil surface roughness with a frequency modulated polarimetric radar

NASA Astrophysics Data System (ADS)

Seeger, Manuel; Gronz, Oliver; Beiske, Joshua; Klein, Tobias

2014-05-01

Soil surface roughness is considered crucial for soil erosion as it determines the effective surface exposed to the raindrop impact. It regulates surface runoff velocity and it causes runoff concentration. But a comprehensive characterisation of the shape of the soils' surface is still difficult to achieve. Photographic systems and terrestrial laser-scanning are nowadays able to generate high resolution DEMs, but the derivation of roughness parameters is still not clear. Spaceborne radar systems are used for about 3 decades for earth survey. Spatial soil moisture distribution, ice sheet monitoring and earth-wide topographic survey are the main objectives of these radar systems, working generally with frequencies <10 GHz. Contrasting with this, technologies emitting frequencies up to 77 GHz are generally used for object tracking purposes. But it is known, that the reflection characteristics, such as intensity and polarisation, strongly depend on the properties of the target object. A new design of a frequency modulated continuous wave radar, emitting a right hand shaped circular polarization and receiving both polarization directions, right and left-hand shaped, is tested here for its ability to detect and quantify different surface roughness. The reflection characteristics of 4 different materials 1) steel, 2) sand (0,5-1 mm), 3) fine (2-4 mm) and 4) coarse (15-30 mm) rock-fragments and different roughness as well as moisture content are analysed. In addition, the signals are taken at 2 different angles to the soil's surface (90° and 70°). For quantification of the roughness, a photographic method (Structure-from-Motion) is applied to generate a detailed DEM and random roughness (RR) is calculated. To characterise the radar signal, different ratios of the reflected channels and polarisations are calculated. The signals show differences for all substrates, also clearly visible between sand and fine rock fragments, despite a wavelength of 1 cm of the

Structural geologic interpretations from radar imagery

USGS Publications Warehouse

Reeves, Robert G.

1969-01-01

Certain structural geologic features may be more readily recognized on sidelooking airborne radar (SLAR) images than on conventional aerial photographs, other remote sensor imagery, or by ground observations. SLAR systems look obliquely to one or both sides and their images resemble aerial photographs taken at low sun angle with the sun directly behind the camera. They differ from air photos in geometry, resolution, and information content. Radar operates at much lower frequencies than the human eye, camera, or infrared sensors, and thus "sees" differently. The lower frequency enables it to penetrate most clouds and some precipitation, haze, dust, and some vegetation. Radar provides its own illumination, which can be closely controlled in intensity and frequency. It is narrow band, or essentially monochromatic. Low relief and subdued features are accentuated when viewed from the proper direction. Runs over the same area in significantly different directions (more than 45° from each other), show that images taken in one direction may emphasize features that are not emphasized on those taken in the other direction; optimum direction is determined by those features which need to be emphasized for study purposes. Lineaments interpreted as faults stand out on radar imagery of central and western Nevada; folded sedimentary rocks cut by faults can be clearly seen on radar imagery of northern Alabama. In these areas, certain structural and stratigraphic features are more pronounced on radar images than on conventional photographs; thus radar imagery materially aids structural interpretation.

Space Radar Image of Munich, Germany

NASA Technical Reports Server (NTRS)

1994-01-01

This spaceborne radar image of Munich, Germany illustrates the capability of a multi-frequency radar system to highlight different land use patterns in the area surrounding Bavaria's largest city. Central Munich is the white area at the middle of the image, on the banks of the Isar River. Pink areas are forested, while green areas indicate clear-cut and agricultural terrain. The Munich region served as a primary 'supersite' for studies in ecology, hydrology and radar calibration during the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) missions. Scientists were able to use these data to map patterns of forest damage from storms and areas affected by bark beetle infestation. The image was acquired by SIR-C/X-SAR onboard the space shuttle Endeavour on April 18, 1994. The image is 37 kilometers by 32 kilometers (23 miles by 20 miles) and is centered at 48.2 degrees North latitude, 11.5 degrees East longitude. North is toward the upper right. The colors are assigned to different radar frequencies and polarizations of the radar as follows: red is L-band, vertically transmitted and horizontally received; green is C-band, vertically transmitted and horizontally received; and blue is C-band vertically transmitted and received. SIR-C/X-SAR, a joint mission of the German, Italian, and United States space agencies, is part of NASA's Mission to Planet Earth.

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.

Laser space rendezvous and docking tradeoff

NASA Technical Reports Server (NTRS)

Adelman, S.; Levinson, S.; Raber, P.; Weindling, F.

1974-01-01

A spaceborne laser radar (LADAR) was configured to meet the requirements for rendezvous and docking with a cooperative object in synchronous orbit. The LADAR, configurated using existing pulsed CO2 laser technology and a 1980 system technology baseline, is well suited for the envisioned space tug missions. The performance of a family of candidate LADARS was analyzed. Tradeoff studies as a function of size, weight, and power consumption were carried out for maximum ranges of 50, 100, 200, and 300 nautical miles. The investigation supports the original contention that a rendezvous and docking LADAR can be constructed to offer a cost effective and reliable solution to the envisioned space missions. In fact, the CO2 ladar system offers distinct advantages over other candidate systems.

Laboratory Measurements of Radar Transmission Through Dust with Implications for Radar Imaging on Mars

NASA Technical Reports Server (NTRS)

Williams, K. K.; Greeley, R.

2001-01-01

Measurements of radar transmission through a Mars analog dust are used to calculate values of signal attenuation over a frequency range of 0.5-12 GHz. These values are discussed in the context of a Mars radar imaging mission. Additional information is contained in the original extended abstract.

A 100 GHz Polarimetric Compact Radar Range for Scale-Model Radar Cross Section Measurements

DTIC Science & Technology

2013-10-01

common radar bands. ACKNOWLEDGEMENTS The authors wish to thank David Jillson (UML STL – Electrical Engineer) for efforts involved in RF and DC wiring...Waldman J., Fetterman H.R., Duffy P.E., Bryant T.G., Tannenwald P.E., “Submillimeter Model Measurements and Their Applications to Millimeter Radar

Arecibo Radar Observation of Near-Earth Asteroids: Expanded Sample Size, Determination of Radar Albedos, and Measurements of Polarization Ratios

NASA Astrophysics Data System (ADS)

Lejoly, Cassandra; Howell, Ellen S.; Taylor, Patrick A.; Springmann, Alessondra; Virkki, Anne; Nolan, Michael C.; Rivera-Valentin, Edgard G.; Benner, Lance A. M.; Brozovic, Marina; Giorgini, Jon D.

2017-10-01

The Near-Earth Asteroid (NEA) population ranges in size from a few meters to more than 10 kilometers. NEAs have a wide variety of taxonomic classes, surface features, and shapes, including spheroids, binary objects, contact binaries, elongated, as well as irregular bodies. Using the Arecibo Observatory planetary radar system, we have measured apparent rotation rate, radar reflectivity, apparent diameter, and radar albedos for over 350 NEAs. The radar albedo is defined as the radar cross-section divided by the geometric cross-section. If a shape model is available, the actual cross-section is known at the time of the observation. Otherwise we derive a geometric cross-section from a measured diameter. When radar imaging is available, the diameter was measured from the apparent range depth. However, when radar imaging was not available, we used the continuous wave (CW) bandwidth radar measurements in conjunction with the period of the object. The CW bandwidth provides apparent rotation rate, which, given an independent rotation measurement, such as from lightcurves, constrains the size of the object. We assumed an equatorial view unless we knew the pole orientation, which gives a lower limit on the diameter. The CW also provides the polarization ratio, which is the ratio of the SC and OC cross-sections.We confirm the trend found by Benner et al. (2008) that taxonomic types E and V have very high polarization ratios. We have obtained a larger sample and can analyze additional trends with spin, size, rotation rate, taxonomic class, polarization ratio, and radar albedo to interpret the origin of the NEAs and their dynamical processes. The distribution of radar albedo and polarization ratio at the smallest diameters (≤50 m) differs from the distribution of larger objects (>50 m), although the sample size is limited. Additionally, we find more moderate radar albedos for the smallest NEAs when compared to those with diameters 50-150 m. We will present additional trends we

Applications review for a Space Program Imaging Radar (SPIR)

NASA Technical Reports Server (NTRS)

Simonett, D. S.

1976-01-01

The needs, applications, user support, research, and theoretical studies of imaging radar are reviewed. The applications of radar in water resources, minerals and petroleum exploration, vegetation resources, ocean radar imaging, and cartography are discussed. The advantages of space imaging radar are presented, and it is recommended that imaging radar be placed on the space shuttle.

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.

Radar sensors for intersection collision avoidance

NASA Astrophysics Data System (ADS)

Jocoy, Edward H.; Phoel, Wayne G.

1997-02-01

On-vehicle sensors for collision avoidance and intelligent cruise control are receiving considerably attention as part of Intelligent Transportation Systems. Most of these sensors are radars and `look' in the direction of the vehicle's headway, that is, in the direction ahead of the vehicle. Calspan SRL Corporation is investigating the use of on- vehicle radar for Intersection Collision Avoidance (ICA). Four crash scenarios are considered and the goal is to design, develop and install a collision warning system in a test vehicle, and conduct both test track and in-traffic experiments. Current efforts include simulations to examine ICA geometry-dependent design parameters and the design of an on-vehicle radar and tracker for threat detection. This paper discusses some of the simulation and radar design efforts. In addition, an available headway radar was modified to scan the wide angles (+/- 90 degree(s)) associated with ICA scenarios. Preliminary proof-of-principal tests are underway as a risk reduction effort. Some initial target detection results are presented.

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.

Research relative to weather radar measurement techniques

NASA Technical Reports Server (NTRS)

Smith, Paul L.

1992-01-01

This grant provides for some investigations related to weather radar measurement techniques applicable to meteorological radar systems in Thailand. Quality data are needed from those systems to support TRMM and other scientific investigations. Activities carried out during a trip to the radar facilities at Phuket are described.

FMCW Radar Jamming Techniques and Analysis

DTIC Science & Technology

2013-09-01

an education system that is compacted with various radar capabilities, the circuitry does not provide the full functionality of each type of radar as...example of a typical FMCW architecture. The hardware components and their functionalities are explained individually in the order of the signal processing...drawn. Chapter IV presents a MATLAB model that emulates the functionality of the homodyne FMCW radar discussed in Chapter II. The model design and

A new system model for radar polarimeters

NASA Technical Reports Server (NTRS)

Freeman, Anthony

1991-01-01

The validity of the 2 x 2 receive R and transmit T model for radar polarimeter systems, first proposed by Zebker et al. (1987), is questioned. The model is found to be invalid for many practical realizations of radar polarimeters, which can lead to significant errors in the calibration of polarimetric radar images. A more general model is put forward, which addresses the system defects which cause the 2 x 2 model to break down. By measuring one simple parameter from a polarimetric active radar calibration (PARC), it is possible to transform the scattering matrix measurements made by a radar polarimeter to a format compatible with a 2 x 2 R and T matrix model. Alternatively, the PARC can be used to verify the validity of the 2 x 2 model for any polarimetric radar system. Recommendations for the use of PARCs in polarimetric calibration and to measure the orientation angle of the horizontal (H) and vertical (V) coordinate system are also presented.

A new system model for radar polarimeters

NASA Astrophysics Data System (ADS)

Freeman, Anthony

1991-09-01

The validity of the 2 x 2 receive R and transmit T model for radar polarimeter systems, first proposed by Zebker et al. (1987), is questioned. The model is found to be invalid for many practical realizations of radar polarimeters, which can lead to significant errors in the calibration of polarimetric radar images. A more general model is put forward, which addresses the system defects which cause the 2 x 2 model to break down. By measuring one simple parameter from a polarimetric active radar calibration (PARC), it is possible to transform the scattering matrix measurements made by a radar polarimeter to a format compatible with a 2 x 2 R and T matrix model. Alternatively, the PARC can be used to verify the validity of the 2 x 2 model for any polarimetric radar system. Recommendations for the use of PARCs in polarimetric calibration and to measure the orientation angle of the horizontal (H) and vertical (V) coordinate system are also presented.

Cassini's Final Titan Radar Swath

NASA Image and Video Library

2017-08-11

During its final targeted flyby of Titan on April 22, 2017, Cassini's radar mapper got the mission's last close look at the moon's surface. On this 127th targeted pass by Titan (unintuitively named "T-126"), the radar was used to take two images of the surface, shown at left and right. Both images are about 200 miles (300 kilometers) in width, from top to bottom. Objects appear bright when they are tilted toward the spacecraft or have rough surfaces; smooth areas appear dark. At left are the same bright, hilly terrains and darker plains that Cassini imaged during its first radar pass of Titan, in 2004. Scientists do not see obvious evidence of changes in this terrain over the 13 years since the original observation. At right, the radar looked once more for Titan's mysterious "magic island" (PIA20021) in a portion of one of the large hydrocarbon seas, Ligeia Mare. No "island" feature was observed during this pass. Scientists continue to work on what the transient feature might have been, with waves and bubbles being two possibilities. In between the two parts of its imaging observation, the radar instrument switched to altimetry mode, in order to make a first-ever (and last-ever) measurement of the depths of some of the lakes that dot the north polar region. For the measurements, the spacecraft pointed its antenna straight down at the surface and the radar measured the time delay between echoes from the lakes' surface and bottom. A graph is available at https://photojournal.jpl.nasa.gov/catalog/PIA21626

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.

An X-Band Radar Terrain Feature Detection Method for Low-Altitude SVS Operations and Calibration Using LiDAR

NASA Technical Reports Server (NTRS)

Young, Steve; UijtdeHaag, Maarten; Campbell, Jacob

2004-01-01

To enable safe use of Synthetic Vision Systems at low altitudes, real-time range-to-terrain measurements may be required to ensure the integrity of terrain models stored in the system. This paper reviews and extends previous work describing the application of x-band radar to terrain model integrity monitoring. A method of terrain feature extraction and a transformation of the features to a common reference domain are proposed. Expected error distributions for the extracted features are required to establish appropriate thresholds whereby a consistency-checking function can trigger an alert. A calibration-based approach is presented that can be used to obtain these distributions. To verify the approach, NASA's DC-8 airborne science platform was used to collect data from two mapping sensors. An Airborne Laser Terrain Mapping (ALTM) sensor was installed in the cargo bay of the DC-8. After processing, the ALTM produced a reference terrain model with a vertical accuracy of less than one meter. Also installed was a commercial-off-the-shelf x-band radar in the nose radome of the DC-8. Although primarily designed to measure precipitation, the radar also provides estimates of terrain reflectivity at low altitudes. Using the ALTM data as the reference, errors in features extracted from the radar are estimated. A method to estimate errors in features extracted from the terrain model is also presented.

Efficient Ways to Learn Weather Radar Polarimetry

ERIC Educational Resources Information Center

Cao, Qing; Yeary, M. B.; Zhang, Guifu

2012-01-01

The U.S. weather radar network is currently being upgraded with dual-polarization capability. Weather radar polarimetry is an interdisciplinary area of engineering and meteorology. This paper presents efficient ways to learn weather radar polarimetry through several basic and practical topics. These topics include: 1) hydrometeor scattering model…

CBSIT 2009: Airborne Validation of Envisat Radar Altimetry and In Situ Ice Camp Measurements Over Arctic Sea Ice

NASA Technical Reports Server (NTRS)

Connor, Laurence; Farrell, Sinead; McAdoo, David; Krabill, William; Laxon, Seymour; Richter-Menge, Jacqueline; Markus, Thorsten

2010-01-01

The past few years have seen the emergence of satellite altimetry as valuable tool for taking quantitative sea ice monitoring beyond the traditional surface extent measurements and into estimates of sea ice thickness and volume, parameters that arc fundamental to improved understanding of polar dynamics and climate modeling. Several studies have now demonstrated the use of both microwave (ERS, Envisat/RA-2) and laser (ICESat/GLAS) satellite altimeters for determining sea ice thickness. The complexity of polar environments, however, continues to make sea ice thickness determination a complicated remote sensing task and validation studies remain essential for successful monitoring of sea ice hy satellites. One such validation effort, the Arctic Aircraft Altimeter (AAA) campaign of2006. included underflights of Envisat and ICESat north of the Canadian Archipelago using NASA's P-3 aircraft. This campaign compared Envisat and ICESat sea ice elevation measurements with high-resolution airborne elevation measurements, revealing the impact of refrozen leads on radar altimetry and ice drift on laser altimetry. Continuing this research and validation effort, the Canada Basin Sea Ice Thickness (CBSIT) experiment was completed in April 2009. CBSIT was conducted by NOAA. and NASA as part of NASA's Operation Ice Bridge, a gap-filling mission intended to supplement sea and land ice monitoring until the launch of NASA's ICESat-2 mission. CBIST was flown on the NASA P-3, which was equipped with a scanning laser altimeter, a Ku-band snow radar, and un updated nadir looking photo-imaging system. The CB5IT campaign consisted of two flights: an under flight of Envisat along a 1000 km track similar to that flown in 2006, and a flight through the Nares Strait up to the Lincoln Sea that included an overflight of the Danish GreenArc Ice Camp off the coast of northern Greenland. We present an examination of data collected during this campaign, comparing airborne laser altimeter measurements

The Clementine Bistatic Radar Experiment

NASA Technical Reports Server (NTRS)

Nozette, S.; Lichtenberg, C. L.; Spudis, P.; Bonner, R.; Ort, W.; Malaret, E.; Robinson, M.; Shoemaker, E. M.

1996-01-01

During the Clementine 1 mission, a bistatic radar experiment measured the magnitude and polarization of the radar echo versus bistatic angle, beta, for selected lunar areas. Observations of the lunar south pole yield a same-sense polarization enhancement around beta = 0. Analysis shows that the observed enhancement is localized to the permanently shadowed regions of the lunar south pole. Radar observations of periodically solar-illuminated lunar surfaces, including the north pole, yielded no such enhancement. A probable explanation for these differences is the presence of low-loss volume scatterers, such as water ice, in the permanently shadowed region at the south pole.

Investment Criteria for Airport Surveillance Radar, Air Traffic Control Radar Beacon System, and Automated Radar Terminal System (ASR/ATCRBS/ARTS)

DTIC Science & Technology

1983-05-01

15 FIQGX 4 Tine Saved By ASR: 3 Mile vs. 7.5 Mile Separation 40 3 4 S10" 6 ;9 q4, ItI I ILI 10! i~o 2 _ _P𔃻_ _ P_ _ IFR HUM 16 :,.4eS _OE_ AT_...8217 16 . Abstract ""This report develops revised investment criteria for Airport Survoiillance Radar, Air Traffic Control Radar Beacon System, and...12 A. Introduction. .................... 1. 32 B. IFR Delay Reduction Benefits ...... ............. 13 C. Safety Benefits

Radar ornithology and the conservation of migratory birds

Treesearch

Sidney A. Gauthreaux; Carroll G. Belser

2005-01-01

It is possible to study with surveillance radar the movements of migrating birds in the atmosphere at different spatial scales. At a spatial scale within a range of 6 kilometers, high-resolution, 3-centimeter wavelength surveillance radar (e.g. BIRDRAD) can detect the departure of migrants from different types of habitat within a few kilometers of the radar. The radar...

Quantification of Reflection Patterns in Ground-Penetrating Radar Data

NASA Astrophysics Data System (ADS)

Moysey, S.; Knight, R. J.; Jol, H. M.; Allen-King, R. M.; Gaylord, D. R.

2005-12-01

Radar facies analysis provides a way of interpreting the large-scale structure of the subsurface from ground-penetrating radar (GPR) data. Radar facies are often distinguished from each other by the presence of patterns, such as flat-lying, dipping, or chaotic reflections, in different regions of a radar image. When these patterns can be associated with radar facies in a repeated and predictable manner we refer to them as `radar textures'. While it is often possible to qualitatively differentiate between radar textures visually, pattern recognition tools, like neural networks, require a quantitative measure to discriminate between them. We investigate whether currently available tools, such as instantaneous attributes or metrics adapted from standard texture analysis techniques, can be used to improve the classification of radar facies. To this end, we use a neural network to perform cross-validation tests that assess the efficacy of different textural measures for classifying radar facies in GPR data collected from the William River delta, Saskatchewan, Canada. We found that the highest classification accuracies (>93%) were obtained for measures of texture that preserve information about the spatial arrangement of reflections in the radar image, e.g., spatial covariance. Lower accuracy (87%) was obtained for classifications based directly on windows of amplitude data extracted from the radar image. Measures that did not account for the spatial arrangement of reflections in the image, e.g., instantaneous attributes and amplitude variance, yielded classification accuracies of less than 65%. Optimal classifications were obtained for textural measures that extracted sufficient information from the radar data to discriminate between radar facies but were insensitive to other facies specific characteristics. For example, the rotationally invariant Fourier-Mellin transform delivered better classification results than the spatial covariance because dip angle of the

Radar systems for the water resources mission, volume 1

NASA Technical Reports Server (NTRS)

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

1976-01-01

The state of the art determination was made for radar measurement of: soil moisture, snow, standing and flowing water, lake and river ice, determination of required spacecraft radar parameters, study of synthetic-aperture radar systems to meet these parametric requirements, and study of techniques for on-board processing of the radar data. Significant new concepts developed include the following: scanning synthetic-aperture radar to achieve wide-swath coverage; single-sideband radar; and comb-filter range-sequential, range-offset SAR processing. The state of the art in radar measurement of water resources parameters is outlined. The feasibility for immediate development of a spacecraft water resources SAR was established. Numerous candidates for the on-board processor were examined.

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.

Airborne radar radiometer measurements of tropical storms

NASA Technical Reports Server (NTRS)

Kumagai, H.; Meneghini, R.; Kozu, T.; Okamoto, K.

1992-01-01

The results from an airborne radar radiometer experiment of rainfall measurement in tropical storms are presented. The experiment was conducted in the Western Pacific in September 1990 with the NASA/DC-8 aircraft which was equipped with a nadir-loking dual-frequency rain radar operating at X band and Ka band, and several channels of microwave radiometers. The X-band radar has a capability of dual-polarization reception which enables the measurements of Linear Depolarization Ratio (LDR). The data of the microwave radiometers are compared with the radar data.

Shuttle Radar Topography Mission (SRTM)

USGS Publications Warehouse

,

2003-01-01

Under an agreement with the National Aeronautics and Space Administration (NASA) and the Department of Defense's National Imagery and Mapping Agency (NIMA), the U.S. Geological Survey (USGS) is now distributing elevation data from the Shuttle Radar Topography Mission (SRTM). The SRTM is a joint project between NASA and NIMA to map the Earth's land surface in three dimensions at a level of detail unprecedented for such a large area. Flown aboard the NASA Space Shuttle Endeavour February 11-22, 2000, the SRTM successfully collected data over 80 percent of the Earth's land surface, for most of the area between 60? N. and 56? S. latitude. The SRTM hardware included the Spaceborne Imaging Radar-C (SIR-C) and X-band Synthetic Aperture Radar (X-SAR) systems that had flown twice previously on other space shuttle missions. The SRTM data were collected specifically with a technique known as interferometry that allows image data from dual radar antennas to be processed for the extraction of ground heights.

Shuttle Radar Topography Mission (SRTM)

USGS Publications Warehouse

,

2009-01-01

Under an agreement with the National Aeronautics and Space Administration (NASA) and the Department of Defense's National Geospatial-Intelligence Agency (NGA), the U.S. Geological Survey (USGS) is distributing elevation data from the Shuttle Radar Topography Mission (SRTM). The SRTM is a joint project of NASA and NGA to map the Earth's land surface in three dimensions at an unprecedented level of detail. As part of space shuttle Endeavour's flight during February 11-22, 2000, the SRTM successfully collected data over 80 percent of the Earth's land surface for most of the area between latitudes 60 degrees north and 56 degrees south. The SRTM hardware included the Spaceborne Imaging Radar-C (SIR-C) and X-band Synthetic Aperture Radar (X-SAR) systems that had flown twice previously on other space shuttle missions. The SRTM data were collected with a technique known as interferometry that allows image data from dual radar antennas to be processed for the extraction of ground heights.

Chaos Through-Wall Imaging Radar

NASA Astrophysics Data System (ADS)

Xu, Hang; Wang, Bingjie; Zhang, Jianguo; Liu, Li; Li, Ying; Wang, Yuncai; Wang, Anbang

2017-12-01

We experimentally demonstrate a chaos through-wall imaging radar using ultra-wideband chaotic-pulse-position modulation (CPPM) microwave signal. The CPPM signal based on logistic map with 1-ns pulse width and 1-GHz bandwidth is implemented by a field programmable gate array (FPGA) and then up-converted as the radar transmitting signal. Two-dimensional image of human objects behind obstacles is obtained by correlation method and back projection algorithm. Our experiments successfully perform through-wall imaging for single and multiple human objects through 20-cm thick wall. The down-range resolution of the proposed radar is 15 cm. Furthermore, the anti-jamming properties of the proposed radar in CPPM jamming, linear frequency-modulated jamming, and Gaussian noise jamming environments are demonstrated by electromagnetic simulations using the finite-difference time-domain. The simulation results show the CPPM microwave signal possesses excellent jamming immunity to the noise and radio frequency interference, which makes it perform superbly in multiradar environments.

Radar monitoring of oil pollution

NASA Technical Reports Server (NTRS)

Guinard, N. W.

1970-01-01

Radar is currently used for detecting and monitoring oil slicks on the sea surface. The four-frequency radar system is used to acquire synthetic aperature imagery of the sea surface on which the oil slicks appear as a nonreflecting area on the surface surrounded by the usual sea return. The value of this technique was demonstrated, when the four-frequency radar system was used to image the oil spill of tanker which has wrecked. Imagery was acquired on both linear polarization (horizontal, vertical) for frequencies of 428, 1228, and 8910 megahertz. Vertical returns strongly indicated the presence of oil while horizontal returns failed to detect the slicks. Such a result is characteristic of the return from the sea and cannot presently be interpreted as characteristics of oil spills. Because an airborne imaging radar is capable of providing a wide-swath coverage under almost all weather conditions, it offers promise in the development of a pollution-monitoring system that can provide a coastal watch for oil slicks.

Observation of snowfall with a low-power FM-CW K-band radar (Micro Rain Radar)

NASA Astrophysics Data System (ADS)

Kneifel, Stefan; Maahn, Maximilian; Peters, Gerhard; Simmer, Clemens

2011-06-01

Quantifying snowfall intensity especially under arctic conditions is a challenge because wind and snow drift deteriorate estimates obtained from both ground-based gauges and disdrometers. Ground-based remote sensing with active instruments might be a solution because they can measure well above drifting snow and do not suffer from flow distortions by the instrument. Clear disadvantages are, however, the dependency of e.g. radar returns on snow habit which might lead to similar large uncertainties. Moreover, high sensitivity radars are still far too costly to operate in a network and under harsh conditions. In this paper we compare returns from a low-cost, low-power vertically pointing FM-CW radar (Micro Rain Radar, MRR) operating at 24.1 GHz with returns from a 35.5 GHz cloud radar (MIRA36) for dry snowfall during a 6-month observation period at an Alpine station (Environmental Research Station Schneefernerhaus, UFS) at 2,650 m height above sea level. The goal was to quantify the potential and limitations of the MRR in relation to what is achievable by a cloud radar. The operational MRR procedures to derive standard radar variables like effective reflectivity factor ( Z e) or the mean Doppler velocity ( W) had to be modified for snowfall since the MRR was originally designed for rain observations. Since the radar returns from snowfall are weaker than from comparable rainfall, the behavior of the MRR close to its detection threshold has been analyzed and a method is proposed to quantify the noise level of the MRR based on clear sky observations. By converting the resulting MRR- Z e into 35.5 GHz equivalent Z e values, a remaining difference below 1 dBz with slightly higher values close to the noise threshold could be obtained. Due to the much higher sensitivity of MIRA36, the transition of the MRR from the true signal to noise can be observed, which agrees well with the independent clear sky noise estimate. The mean Doppler velocity differences between both radars

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.

Probabilistic forecasts based on radar rainfall uncertainty

NASA Astrophysics Data System (ADS)

Liguori, S.; Rico-Ramirez, M. A.

2012-04-01

The potential advantages resulting from integrating weather radar rainfall estimates in hydro-meteorological forecasting systems is limited by the inherent uncertainty affecting radar rainfall measurements, which is due to various sources of error [1-3]. The improvement of quality control and correction techniques is recognized to play a role for the future improvement of radar-based flow predictions. However, the knowledge of the uncertainty affecting radar rainfall data can also be effectively used to build a hydro-meteorological forecasting system in a probabilistic framework. This work discusses the results of the implementation of a novel probabilistic forecasting system developed to improve ensemble predictions over a small urban area located in the North of England. An ensemble of radar rainfall fields can be determined as the sum of a deterministic component and a perturbation field, the latter being informed by the knowledge of the spatial-temporal characteristics of the radar error assessed with reference to rain-gauges measurements. This approach is similar to the REAL system [4] developed for use in the Southern-Alps. The radar uncertainty estimate can then be propagated with a nowcasting model, used to extrapolate an ensemble of radar rainfall forecasts, which can ultimately drive hydrological ensemble predictions. A radar ensemble generator has been calibrated using radar rainfall data made available from the UK Met Office after applying post-processing and corrections algorithms [5-6]. One hour rainfall accumulations from 235 rain gauges recorded for the year 2007 have provided the reference to determine the radar error. Statistics describing the spatial characteristics of the error (i.e. mean and covariance) have been computed off-line at gauges location, along with the parameters describing the error temporal correlation. A system has then been set up to impose the space-time error properties to stochastic perturbations, generated in real-time at

Development and Testing of the VAHIRR Radar Product

NASA Technical Reports Server (NTRS)

Barrett, Joe III; Miller, Juli; Charnasky, Debbie; Gillen, Robert; Lafosse, Richard; Hoeth, Brian; Hood, Doris; McNamara, Todd

2008-01-01

Lightning Launch Commit Criteria (LLCC) and Flight Rules (FR) are used for launches and landings at government and commercial spaceports. They are designed to avoid natural and triggered lightning strikes to space vehicles, which can endanger the vehicle, payload, and general public. The previous LLCC and FR were shown to be overly restrictive, potentially leading to costly launch delays and scrubs. A radar algorithm called Volume Averaged Height Integrated Radar Reflectivity (VAHIRR), along with new LLCC and FR for anvil clouds, were developed using data collected by the Airborne Field Mill II research program. VAHIRR is calculated at every horizontal position in the coverage area of the radar and can be displayed similar to a two-dimensional derived reflectivity product, such as composite reflectivity or echo tops. It is the arithmetic product of two quantities not currently generated by the Weather Surveillance Radar 1988 Doppler (WSR-88D): a volume average of the reflectivity measured in dBZ and the average cloud thickness based on the average echo top height and base height. This presentation will describe the VAHIRR algorithm, and then explain how the VAHIRR radar product was implemented and tested on a clone of the National Weather Service's (NWS) Open Radar Product Generator (ORPG-clone). The VAHIRR radar product was then incorporated into the Advanced Weather Interactive Processing System (AWIPS), to make it more convenient for weather forecasters to utilize. Finally, the reliability of the VAHIRR radar product was tested with real-time level II radar data from the WSR-88D NWS Melbourne radar.

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.

Remotely sensing wheat maturation with radar

NASA Technical Reports Server (NTRS)

Bush, T. F.; Ulaby, F. T.

1975-01-01

The scattering properties of wheat were studied in the 8-18 GHz band as a function of frequency, polarization, incidence angle, and crop maturity. Supporting ground truth was collected at the time of measurement. The data indicate that the radar backscattering coefficient is sensitive to both radar system parameters and crop characteristics particularly at incidence angles near nadir. Linear regression analyses of the radar backscattering coefficient on both time and plant moisture content result in rather good correlation. Furthermore, by calculating the average time rate of change of the radar backscattering coefficient it is found that it undergoes rapid variations shortly before and after the wheat is harvested. Both of these analyses suggest methods for estimating wheat maturity and for monitoring the progress of harvest.

Investigating nearby exoplanets via interstellar radar

NASA Astrophysics Data System (ADS)

Scheffer, Louis K.

2014-01-01

Interstellar radar is a potential intermediate step between passive observation of exoplanets and interstellar exploratory missions. Compared with passive observation, it has the traditional advantages of radar astronomy. It can measure surface characteristics, determine spin rates and axes, provide extremely accurate ranges, construct maps of planets, distinguish liquid from solid surfaces, find rings and moons, and penetrate clouds. It can do this even for planets close to the parent star. Compared with interstellar travel or probes, it also offers significant advantages. The technology required to build such a radar already exists, radar can return results within a human lifetime, and a single facility can investigate thousands of planetary systems. The cost, although too high for current implementation, is within the reach of Earth's economy.

Optically Pumped Far Infrared Molecular Lasers.

DTIC Science & Technology

1980-04-01

and 4 were reported by Fetterman , et al. and Gullberg, et al.3 An additional FIR transition (i.e., G:sR(5,4) has been reported,5 but is not shown in...attempt has been made to frequency stabilize the experiment. Recently, Fetterman , et al. 11 performed "real-ti adctral analysis for FIR laser pulses...wave device known 4 as a Reflective Array Compressor (RAC) was developed for just this sort of problem in the radar community. Recently, Fetterman , et al

Tangential velocity measurement using interferometric MTI radar

DOEpatents

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.

Radar Image Interpretability Analysis.

DTIC Science & Technology

1981-01-01

the measured image properties with respect to image utility changed with image application. This study has provided useful information as to how...Eneea.d) ABSTRACT The utility of radar images with respect to trained image inter - preter ability to identify, classify and detect specific terrain... changed with image applica- tion. This study has provided useful information as to how certain image characteristics relate to radar image utility as

Agricultural and hydrological applications of radar

NASA Technical Reports Server (NTRS)

Ulaby, F. T.

1976-01-01

Program objectives, covering a wide range of disciplines and activities in radar remote sensing, include radar systems development and analysis, data processing and display, and data interpretation in geology, geography and oceanography. Research was focused on the evaluation of radar remote sensing applications in hydrology and agriculture based on data acquired with the Microwave Active Spectrometer (MAS) system. The title, author(s) and abstract of each of the 62 technical reports generated under this contract are appended.

Radar image of Rio Sao Francisco, Brazil

NASA Technical Reports Server (NTRS)

2000-01-01

This radar image acquired by SRTM shows an area south of the Sao Francisco River in Brazil. The area is predominantly scrub forest. Areas such as these are difficult to map by traditional methods because of frequent cloud cover and local inaccessibility. Image brightness differences in this image are caused by differences in vegetation type and density. Tributaries of the Sao Francisco are visible in the upper right. The Sao Francisco River is a major source of water for irrigation and hydroelectric power. Mapping such regions will allow scientists to better understand the relationships between flooding cycles, forestation and human influences on ecosystems.

This radar image was obtained by the Shuttle Radar Topography Mission as part of its mission to map the Earth's topography. The image was acquired by just one of SRTM's two antennas, and consequently does not show topographic data but only the strength of the radar signal reflected from the ground. This signal, known as radar backscatter, provides insight into the nature of the surface, including its roughness, vegetation cover, and urbanization.

The Shuttle Radar Topography Mission (SRTM), launched on February 11, 2000, uses the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. The mission is designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, an additional C-band imaging antenna and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Imagery and Mapping Agency (NIMA) and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Earth Science Enterprise, Washington, DC.

Compact pulsed high-energy Er:glass laser

NASA Astrophysics Data System (ADS)

Wan, Peng; Liu, Jian

2012-03-01

Bulk Erbium-doped lasers are widely used for long-distance telemetry and ranging. In some applications such as coherent Doppler radars, laser outputs with a relatively long pulse width, good beam profile and pulse shape are required. High energy Q-switched Er:glass lasers were demonstrated by use of electro-optic (E/O) Q-switching or frustrated total internal reflection (FTIR) Q-switching. However, the output pulse durations in these lasers were fixed to relatively small values and extremely hard to tune. We report here on developing a novel and compact Q-switched Er:Yb co-doped phosphate glass laser at an eye-safe wavelength of 1.5 μm. A rotating mirror was used as a Q-switch. Co-linear pump scheme was used to maintain a good output beam profile. Near-perfect Gaussian temporal shape was obtained in our experiment. By changing motor rotation speed, pulse duration was tunable and up to 240 ns was achieved. In our preliminary experiment, output pulse energies of 44 mJ and 4.5 mJ were obtained in free-running and Q-switched operation modes respectively.

An overview of DREV's activities on pulsed CO2 laser transmitters: Frequency stability and lifetime aspects

NASA Technical Reports Server (NTRS)

Cruickshank, James; Pace, Paul; Mathieu, Pierre

1987-01-01

After introducing the desired features in a transmitter for laser radar applications, the output characteristics of several configurations of frequency-stable TEA-CO2 lasers are reviewed. Based on work carried out at the Defence Research Establishment Valcartier (DREV), output pulses are examined from short cavity lasers, CW-TEA hybrid lasers, and amplifiers for low power pulses. It is concluded that the technique of injecting a low-power laser beam into a TEA laser resonator with Gaussian reflectivity mirrors should be investigated because it appears well adapted to producing high energy, single mode, low chirp pulses. Finally, a brief report on tests carried out on catalysts composed of stannic oxide and noble metals demonstrates the potential of these catalysts, operating at close to room temperature, to provide complete closed-cycle laser operation.

47 CFR 80.104 - Identification of radar transmissions not authorized.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 47 Telecommunication 5 2011-10-01 2011-10-01 false Identification of radar transmissions not... Procedures-General § 80.104 Identification of radar transmissions not authorized. This section applies to all maritime radar transmitters except radar beacon stations. (a) Radar transmitters must not transmit station...

47 CFR 80.104 - Identification of radar transmissions not authorized.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 47 Telecommunication 5 2010-10-01 2010-10-01 false Identification of radar transmissions not... Procedures-General § 80.104 Identification of radar transmissions not authorized. This section applies to all maritime radar transmitters except radar beacon stations. (a) Radar transmitters must not transmit station...

47 CFR 80.104 - Identification of radar transmissions not authorized.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 47 Telecommunication 5 2012-10-01 2012-10-01 false Identification of radar transmissions not... Procedures-General § 80.104 Identification of radar transmissions not authorized. This section applies to all maritime radar transmitters except radar beacon stations. (a) Radar transmitters must not transmit station...

47 CFR 80.104 - Identification of radar transmissions not authorized.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 47 Telecommunication 5 2014-10-01 2014-10-01 false Identification of radar transmissions not... Procedures-General § 80.104 Identification of radar transmissions not authorized. This section applies to all maritime radar transmitters except radar beacon stations. (a) Radar transmitters must not transmit station...

47 CFR 80.104 - Identification of radar transmissions not authorized.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 47 Telecommunication 5 2013-10-01 2013-10-01 false Identification of radar transmissions not... Procedures-General § 80.104 Identification of radar transmissions not authorized. This section applies to all maritime radar transmitters except radar beacon stations. (a) Radar transmitters must not transmit station...

Effects of respiration depth on human body radar cross section Using 2.4GHz continuous wave radar.

PubMed

Lee, Alexander; Xiaomeng Gao; Jia Xu; Boric-Lubecke, Olga

2017-07-01

In this study, it was tested whether deep and shallow breathing has an effect on the cardiopulmonary radar cross-section (RCS). Continuous wave radar with quadrature architecture at 2.4GHz was used to test 2 human subjects breathing deep and shallow for 30 seconds each while seated 2 meters away from the radar. A retro-reflective marker was placed on the sternum of each subject and measured by infrared motion capture cameras to accurately track displacement of the chest. The quadrature radar outputs were processed to find the radius of the arc on the IQ plot using a circle-fitting algorithm. Results showed that the effective RCS ratio of deep to shallow breathing for subjects 1 and 2 was 6.99 and 2.24 respectively.

Radar attenuation and temperature within the Greenland Ice Sheet

USGS Publications Warehouse

MacGregor, Joseph A; Li, Jilu; Paden, John D; Catania, Ginny A; Clow, Gary D.; Fahnestock, Mark A; Gogineni, Prasad S.; Grimm, Robert E.; Morlighem, Mathieu; Nandi, Soumyaroop; Seroussi, Helene; Stillman, David E

2015-01-01

The flow of ice is temperature-dependent, but direct measurements of englacial temperature are sparse. The dielectric attenuation of radio waves through ice is also temperature-dependent, and radar sounding of ice sheets is sensitive to this attenuation. Here we estimate depth-averaged radar-attenuation rates within the Greenland Ice Sheet from airborne radar-sounding data and its associated radiostratigraphy. Using existing empirical relationships between temperature, chemistry, and radar attenuation, we then infer the depth-averaged englacial temperature. The dated radiostratigraphy permits a correction for the confounding effect of spatially varying ice chemistry. Where radar transects intersect boreholes, radar-inferred temperature is consistently higher than that measured directly. We attribute this discrepancy to the poorly recognized frequency dependence of the radar-attenuation rate and correct for this effect empirically, resulting in a robust relationship between radar-inferred and borehole-measured depth-averaged temperature. Radar-inferred englacial temperature is often lower than modern surface temperature and that of a steady state ice-sheet model, particularly in southern Greenland. This pattern suggests that past changes in surface boundary conditions (temperature and accumulation rate) affect the ice sheet's present temperature structure over a much larger area than previously recognized. This radar-inferred temperature structure provides a new constraint for thermomechanical models of the Greenland Ice Sheet.

Ultra Low-Cost Radar

NASA Astrophysics Data System (ADS)

Davies, P.; da Silva Curiel, A.; Eves, S.; Sweeting, M.; Thompson, A.; Hall, D.

From early 2003, Surrey Satellite Technology Limited (SSTL), together with its partners from Algeria, Nigeria and Turkey, has operated the Disaster Monitoring Constellation (DMC). During this period we have demonstrated the utility of a low-cost satellite system that uses optical sensors and is capable of providing daily imaging globally. For example, DMC data has been used operationally in the relief work in Darfur and following the Asian Tsunami. In addition to the use of the DMC to support disasters, the DMC has also been extensively used by the consortium members in support of national imaging needs and some residual system capacity has been provided to commercial customers. In the same timeframe, EADS Astrium Ltd has developed the technologies needed to implement the low-cost radar satellites of the MicroSAR range of synthetic aperture radar (SAR) satellites. EADS Astrium Ltd and SSTL are now looking to combine their expertises in low cost space technology and extend the capability of the DMC constellation by including a complementary small satellite radar sensor. The product of this activity is a satellite design that strikes an appropriate balance between revisit frequency and resolution. Hence, by comparison with other small satellite SAR concepts, the satellite described in this paper will provide broader area coverage at spatial resolutions in the region of 10 - 15m. Most significantly, perhaps, as a result of the specific cost targets imposed at the beginning of the design process, the satellite can provide this level of performance at a lower cost than other comparable space-based radar systems and significantly lower than larger, more performant, space-based radar systems.

Radar geomorphology of coastal and wetland environments

NASA Technical Reports Server (NTRS)

Lewis, A. J.; Macdonald, H. C.

1973-01-01

Details regarding the collection of radar imagery over the past ten years are considered together with the geomorphic, geologic, and hydrologic data which have been extracted from radar imagery. Recent investigations were conducted of the Louisiana swamp marsh and the Oregon coast. It was found that radar imagery is a useful tool to the scientist involved in wetland research.

Recent advances in radar applications to agriculture

NASA Technical Reports Server (NTRS)

Morain, S. A.

1970-01-01

A series of remote radar sensing studies are summarized. These efforts comprise geoscience interpretations of such complex phenomena as those manifested in agricultural patterns. Considered are basic remote sensing needs in agriculture and the design and implementation of radar keys in the active microwave region as well as fine resolution radar imagery techniques for agriculture determinations and soil mapping.

space Radar Image of Long Valley, California

NASA Image and Video Library

1999-05-01

An area near Long Valley, California, was mapped by the Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar aboard the space shuttle Endeavor on April 13, 1994, during the first flight of the radar instrument, and on October 4, 1994, during the second flight of the radar instrument. The orbital configurations of the two data sets were ideal for interferometric combination -- that is overlaying the data from one image onto a second image of the same area to create an elevation map and obtain estimates of topography. Once the topography is known, any radar-induced distortions can be removed and the radar data can be geometrically projected directly onto a standard map grid for use in a geographical information system. The 50 kilometer by 50 kilometer (31 miles by 31 miles) map shown here is entirely derived from SIR-C L-band radar (horizontally transmitted and received) results. The color shown in this image is produced from the interferometrically determined elevations, while the brightness is determined by the radar backscatter. The map is in Universal Transverse Mercator (UTM) coordinates. Elevation contour lines are shown every 50 meters (164 feet). Crowley Lake is the dark feature near the south edge of the map. The Adobe Valley in the north and the Long Valley in the south are separated by the Glass Mountain Ridge, which runs through the center of the image. The height accuracy of the interferometrically derived digital elevation model is estimated to be 20 meters (66 feet) in this image. http://photojournal.jpl.nasa.gov/catalog/PIA01749

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.

Comparison of High Resolution Quantitative Extreme Precipitation Estimation from GPM Dual-frequency Radar and S-band Radar Observation over Southern China

NASA Astrophysics Data System (ADS)

Zhang, A.; Chen, S.; Fan, S.; Min, C.

2017-12-01

Precipitation is one of the basic elements of regional and global climate change. Not only does the precipitation have a great impact on the earth's hydrosphere, but also plays a crucial role in the global energy balance. S-band ground-based dual-polarization radar has the excellent performance of identifying the different phase states of precipitation, which can dramatically improve the accuracy of hail identification and quantitative precipitation estimation (QPE). However, the ground-based radar cannot measure the precipitation in mountains, sparsely populated plateau, desert and ocean because of the ground-based radar void. The Unites States National Aeronautics and Space Administration (NASA) and Japan Aerospace Exploration Agency (JAXA) have launched the Global Precipitation Measurement (GPM) for almost three years. GPM is equipped with a GPM Microwave Imager (GMI) and a Dual-frequency (Ku- and Ka-band) Precipitation Radar (DPR) that covers the globe between 65°S and 65°N. The main parameters and the detection method of DPR are different from those of ground-based radars, thus, the DPR's reliability and capability need to be investigated and evaluated by the ground-based radar. This study compares precipitation derived from the ground-based radar measurement to that derived from the DPR's observations. The ground-based radar is a S-band dual-polarization radar deployed near an airport in the west of Zhuhai city. The ground-based quantitative precipitation estimates are with a high resolution of 1km×1km×6min. It shows that this radar covers the whole Pearl River Delta of China, including Hong Kong and Macao. In order to quantify the DPR precipitation quantification capabilities relative to the S-band radar, statistical metrics used in this study are as follows: the difference (Dif) between DPR and the S-band radar observation, root-mean-squared error (RMSE) and correlation coefficient (CC). Additionally, Probability of Detection (POD) and False Alarm Ratio

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.

Textural features for radar image analysis

NASA Technical Reports Server (NTRS)

Shanmugan, K. S.; Narayanan, V.; Frost, V. S.; Stiles, J. A.; Holtzman, J. C.

1981-01-01

Texture is seen as an important spatial feature useful for identifying objects or regions of interest in an image. While textural features have been widely used in analyzing a variety of photographic images, they have not been used in processing radar images. A procedure for extracting a set of textural features for characterizing small areas in radar images is presented, and it is shown that these features can be used in classifying segments of radar images corresponding to different geological formations.

Workshop on Radar Investigations of Planetary and Terrestrial Environments

NASA Technical Reports Server (NTRS)

2005-01-01

Contents include the following: Salt Kinematics and InSAR. SAR Interferometry as a Tool for Monitoring Coastal Changes in the Nile River Delta of Egypt. Modem Radar Techniques for Geophysical Applications: Two Examples. WISDOM Experiment on the EXOMARS ESA Mission. An Ice Thickness Study Utilizing Ground Penetrating Radar on the Lower Jamapa. Probing the Martian Subsurface with Synthetic Aperture Radar. Planetary Surface Properties from Radar Polarimetric Observations. Imaging the Sub-surface Reflectors : Results From the RANETA/NETLANDER Field Test on the Antarctic Ice Shelf. Strategy for Selection of Mars Geophysical Analogue Sites. Observations of Low Frequency Low Altitude Plasma Oscillations at Mars and Implications for Electromagnetic Sounding of the Subsurface. Ionospheric Transmission Losses Associated with Mars-orbiting Radar. A Polarimetric Scattering Model for the 2-Layer Problem. Radars for Imaging and Sounding of Polar Ice Sheets. Strata: Ground Penetrating Radar for Mars Rovers. Scattering Limits to Depth of Radar Investigation: Lessons from the Bishop Tuff.

Design of a Forward Looking Synthetic Aperture Radar for an Autonomous Cryobot for Subsurface Exploration of Europa and Enceladus

NASA Astrophysics Data System (ADS)

Pradhan, O.; Gasiewski, A. J.; Stone, W.

2017-12-01

We present the design, analyses and field testing of a forward-looking endfire synthetic aperture radar (SAR) for the `Very deep Autonomous Laser-powered Kilowatt-class Yo-yoing Robotic Ice explorer' (VALKYRIE) ice-penetrating cryobot. This design demonstrates critical technologies that will support an eventual landing and ice penetrating mission to Jupiter's icy moon, Europa. The project consists of (1) design of an array of four conformal cavity-backed log-periodic folded slot dipole array (LPFSA) antennas that form the radiating elements, (2) design of a radar system that includes RF signal generation, 4x4 transmit-receive antenna switching and isolation and digital SAR data processing and (3) field testing of the SAR system. The antennas were designed, fabricated, and lab tested at the Center for Environmental Technology (CET) at CU-Boulder. The radar analog and digital system were also designed and integrated at CET utilizing rugged RF components and FPGA based digital waveform generation. Field testing was performed in conjunction with VALKYRIE tests by Stone Aerospace in June, 2015 on Matanuska Glacier, Alaska. In this presentation we will describe in detail the following aspects pertaining to the design, analysis and testing of the endfire SAR system; (1) Waveform generation capability of the radar as well as transmit and receive channel calibration (2) Theoretical analysis of the radial resolution improvement made possible by using the radar in an endfire SAR mode along with the free space radar tests performed to validate the proposed endfire SAR system (3) A method for azimuth ambiguity resolution by operating the endfire SAR in a bistatic mode (4) Modal analysis of the layered cylindrical LPFSA antenna structure and a forward model of the wave propagation path through planar layered ice medium and (5) Analysis and interpretation of the in-situ measurements of the antennas and endfire SAR operation on the Matanuska glacier.

Application of Interferometric Radars to Planetary Geologic Studies

NASA Technical Reports Server (NTRS)

Mouginis-Mark, P. J.; Rosen, P.; Freeman, A.

2005-01-01

Radar interferometry is rapidly becoming one of the major applications of radar systems in Earth orbit. So far the 2000 flight of the Shuttle Radar Topographic Mission (SRTM) is the only dedicated U.S. radar to be flown for the collection of interferometric data, but enough has been learned from this mission and from the use of foreign partner radars (ERS-1/2, Radarsat, ENIVISAT and JERS-1) for the potential planetary applications of this technique to be identified. A recent workshop was organized by the Jet Propulsion Laboratory and the Southern California Earthquake Center (SCEC), and was held at Oxnard, CA, from October 20th - 22nd, 2004. At this meeting, the major interest was in terrestrial radar systems, but approx. 20 or the approx. 250 attendees also discussed potential applications of interferometric radar for the terrestrial planets. The primary foci were for the detection of planetary water, the search for active tectonism and volcanism and the improved topographic mapping. This abstract provides a summary of these planetary discussions at the Oxnard meeting.

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

Simulation of effect of anti-radar stealth principle

NASA Astrophysics Data System (ADS)

Zhao, Borao; Xing, Shuchen; Li, Chunyi

1988-02-01

The paper presents simulation methods and results of the anti-radar stealth principle, proving that anti-radar stealth aircraft can drastically reduce the combat efficiency of an air defense radar system. In particular, when anti-radar stealth aircraft are coordinated with jamming as a self-defense soft weapon, the discovery probability, response time and hit rate of the air defense radar system are much lower, with extensive reduction in jamming power and maximum exposure distance of self-defense and long-range support. The paper describes an assumed combat situation and construction of a calculation model for the aircraft survival rate, as well as simulation results and analysis. Four figures show an enemy bomber attacking an airfield, as well as the effects of the radar effective reflecting surface on discovery probability, guidance radius, aircraft survival and exposure distance (for long-range support and jamming).

Physical working principles of medical radar.

PubMed

Aardal, Øyvind; Paichard, Yoann; Brovoll, Sverre; Berger, Tor; Lande, Tor Sverre; Hamran, Svein-Erik

2013-04-01

There has been research interest in using radar for contactless measurements of the human heartbeat for several years. While many systems have been demonstrated, not much attention have been given to the actual physical causes of why this work. The consensus seems to be that the radar senses small body movements correlated with heartbeats, but whether only the movements of the body surface or reflections from internal organs are also monitored have not been answered definitely. There has recently been proposed another theory that blood perfusion in the skin could be the main reason radars are able to detect heartbeats. In this paper, an experimental approach is given to determine the physical causes. The measurement results show that it is the body surface reflections that dominate radar measurements of human heartbeats.

Closed-Cycle, Frequency-Stable CO2 Laser Technology

NASA Technical Reports Server (NTRS)

Batten, Carmen E. (Editor); Miller, Irvin M. (Editor); Wood, George M., Jr. (Editor); Willetts, David V. (Editor)

1987-01-01

These proceedings contain a collection of papers and comments presented at a workshop on technology associated with long-duration closed-cycle operation of frequency-stable, pulsed carbon dioxide lasers. This workshop was held at the NASA Langley Research Center June 10 to 12, 1986. The workshop, jointly sponsored by the National Aeronautics and Space Administration (NASA) and the Royal Signals and Radar Establishment (RSRE), was attended by 63 engineers and scientists from the United States and the United Kingdom. During the 2 1/2 days of the workshop, a number of issues relating to obtaining frequency-stable operation and to the catalytic control of laser gas chemistry were discussed, and specific recommendations concerning future activities were drafted.

Comparison of Ground- and Space-based Radar Observations with Disdrometer Measurements During the PECAN Field Campaign

NASA Astrophysics Data System (ADS)

Torres, A. D.; Rasmussen, K. L.; Bodine, D. J.; Dougherty, E.

2015-12-01

Plains Elevated Convection At Night (PECAN) was a large field campaign that studied nocturnal mesoscale convective systems (MCSs), convective initiation, bores, and low-level jets across the central plains in the United States. MCSs are responsible for over half of the warm-season precipitation across the central U.S. plains. The rainfall from deep convection of these systems over land have been observed to be underestimated by satellite radar rainfall-retrieval algorithms by as much as 40 percent. These algorithms have a strong dependence on the generally unmeasured rain drop-size distribution (DSD). During the campaign, our group measured rainfall DSDs, precipitation fall velocities, and total precipitation in the convective and stratiform regions of MCSs using Ott Parsivel optical laser disdrometers. The disdrometers were co-located with mobile pod units that measured temperature, wind, and relative humidity for quality control purposes. Data from the operational NEXRAD radar in LaCrosse, Wisconsin and space-based radar measurements from a Global Precipitation Measurement satellite overpass on July 13, 2015 were used for the analysis. The focus of this study is to compare DSD measurements from the disdrometers to radars in an effort to reduce errors in existing rainfall-retrieval algorithms. The error analysis consists of substituting measured DSDs into existing quantitative precipitation estimation techniques (e.g. Z-R relationships and dual-polarization rain estimates) and comparing these estimates to ground measurements of total precipitation. The results from this study will improve climatological estimates of total precipitation in continental convection that are used in hydrological studies, climate models, and other applications.

Radar Testing for Mars Science Labotatory

NASA Image and Video Library

2010-04-13

This image, taken April 9, 2010, shows the test radar affixed to a gimbal mounting at the front of a helicopter, carrying an engineering test model of the landing radar for NASA Mars Science Laboratory.

To See the Unseen: A History of Planetary Radar Astronomy

NASA Technical Reports Server (NTRS)

Butrica, Andrew J.

1996-01-01

This book relates the history of planetary radar astronomy from its origins in radar to the present day and secondarily to bring to light that history as a case of 'Big Equipment but not Big Science'. Chapter One sketches the emergence of radar astronomy as an ongoing scientific activity at Jodrell Bank, where radar research revealed that meteors were part of the solar system. The chief Big Science driving early radar astronomy experiments was ionospheric research. Chapter Two links the Cold War and the Space Race to the first radar experiments attempted on planetary targets, while recounting the initial achievements of planetary radar, namely, the refinement of the astronomical unit and the rotational rate and direction of Venus. Chapter Three discusses early attempts to organize radar astronomy and the efforts at MIT's Lincoln Laboratory, in conjunction with Harvard radio astronomers, to acquire antenna time unfettered by military priorities. Here, the chief Big Science influencing the development of planetary radar astronomy was radio astronomy. Chapter Four spotlights the evolution of planetary radar astronomy at the Jet Propulsion Laboratory, a NASA facility, at Cornell University's Arecibo Observatory, and at Jodrell Bank. A congeries of funding from the military, the National Science Foundation, and finally NASA marked that evolution, which culminated in planetary radar astronomy finding a single Big Science patron, NASA. Chapter Five analyzes planetary radar astronomy as a science using the theoretical framework provided by philosopher of science Thomas Kuhn. Chapter Six explores the shift in planetary radar astronomy beginning in the 1970s that resulted from its financial and institutional relationship with NASA Big Science. Chapter Seven addresses the Magellan mission and its relation to the evolution of planetary radar astronomy from a ground-based to a space-based activity. Chapters Eight and Nine discuss the research carried out at ground

High-energy laser activities at MBDA Germany

NASA Astrophysics Data System (ADS)

Mohring, Bernd; Dietrich, Stephan; Tassini, Leonardo; Protz, Rudolf; Geidek, Franz; Zoz, Jürgen

2013-05-01

At MBDA Germany a concept for a high-energy laser weapon system is investigated, which is based on existing industrial laser sources. Due to the enormous progress in the field of high-power fiber lasers, commercial industrial fiber lasers are now available delivering a nearly-diffraction limited beam quality with power levels of up to 10 kW. By using a geometric beam coupling scheme, a number of individual high-power fiber laser beams are combined together using one common beam director telescope. A total laser beam power of more than 100 kW can be achieved, which is sufficient for an operational laser weapon system. The individual beams from the different lasers are steered by servo-loops using fast tip-tilt mirrors. This principle enables the concentration of the total laser beam power at one common focal point on a distant target, also allowing fine tracking of target movements and first-order compensation of turbulence effects on laser beam propagation. The proposed beam combination concept was demonstrated by using different experimental set-ups. A number of experiments were performed successfully to investigate laser beam target interaction and target fine tracking, also at large distances and at moving targets. Content and results of these investigations are reported, which demonstrate the complete engagement sequence for a C-RAM scenario. This includes subsequent steps of target acquisition by radar and IR optics, followed by large angle coarse tracking, active fine tracking and destruction of the target by the laser system. This successful implementation of geometric beam combining is an important step for the realization of a laser weapon system in the near future.

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.

Research on Debonding Defects in Thermal Barrier Coatings Structure by Thermal-Wave Radar Imaging (TWRI)

NASA Astrophysics Data System (ADS)

Wang, Fei; Liu, Junyan; Mohummad, Oliullah; Wang, Yang

2018-06-01

In this paper, thermal-wave radar imaging (TWRI) is introduced to detect debonding defects in SiC-coated Ni-based superalloy plates. Linear frequency modulation signal (chirp) is used as the excitation signal which has a large time-bandwidth product. Artificial debonding defects in SiC coating are excited by the laser beam with the light intensity modulated by a chirp signal. Cross-correlation algorithm and chirp lock-in algorithm are introduced to extract the thermal-wave signal characteristic. The comparative experiment between TWRI reflection mode and transmission mode was carried out. Experiments are conducted to investigate the influence of laser power density, chirp period, and excitation frequency. Experimental results illustrate that chirp lock-in phase has a better detection capability than other characteristic parameters. TWRI can effectively detect simulated debonding defects of SiC-coated Ni-based superalloy plates.

47 CFR 80.273 - Technical requirements for radar equipment.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 47 Telecommunication 5 2011-10-01 2011-10-01 false Technical requirements for radar equipment. 80... Technical requirements for radar equipment. (a) Radar installations on board ships that are required by the Safety Convention or the U.S. Coast Guard to be equipped with radar must comply with the documents...

47 CFR 80.273 - Technical requirements for radar equipment.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 47 Telecommunication 5 2010-10-01 2010-10-01 false Technical requirements for radar equipment. 80... Technical requirements for radar equipment. (a) Radar installations on board ships that are required by the Safety Convention or the U.S. Coast Guard to be equipped with radar must comply with the documents...

Space Radar Image of Maui, Hawaii

NASA Image and Video Library

1999-04-15

This spaceborne radar image shows the Valley Island of Maui, Hawaii. The cloud-penetrating capabilities of radar provide a rare view of many parts of the island, since the higher elevations are frequently shrouded in clouds.

Detection of Marine Radar Targets

NASA Astrophysics Data System (ADS)

Briggs, John N.

A radar must detect targets before it can display them. Yet manufacturers' data sheets rarely tell us what the products will detect at what range. Many of the bigger radars are Type Approved so we consult the relevant IMO performance standard A 477 (XII). Paraphrasing Section 3.1 of the draft forthcoming revision (NAV 41/6): under normal propagation conditions with the scanner at height of 15 m, in the absence of clutter, the radar is required to give clear indication of an object such as a navigational buoy having a radar cross section area (RCS) of 10 m2 at 2 n.m. and, as examples, coastlines whose ground rises to 60/6 m at ranges of 20/7 n.m., a ship of 5000 tons at any aspect at 7 n.m. and a small vessel 10 m long at 3 n.m.This helps, but suppose we must pick up a 5 m2 buoy at g km? What happens in clutter? Should we prefer S- or X-band? To answer such questions we use equations which define the performance of surveillance radars, but the textbooks and specialist papers containing them often generalize with aeronautical and defence topics, making life difficult for the nonspecialist.This paper attempts a concise and self-contained engineering account of all main factors affecting detection of passive and active targets on civil marine and vessel traffic service (VTS) radars. We develop a set of equations for X- and S-band (3 and 10 cm, centred on 9400 and 3000 MHz respectively), suited for spreadsheet calculation.Sufficient theory is sketched in to indicate where results should be valid. Some simplifications of conventional treatments have been identified.

Microwave emissions from police radar.

PubMed

Fink, J M; Wagner, J P; Congleton, J J; Rock, J C

1999-01-01

This study evaluated police officers' exposures to microwaves emitted by traffic radar units. Exposure measurements were taken at approximated ocular and testicular levels of officers seated in patrol vehicles. Comparisons were made of the radar manufacturers' published maximum power density specifications and actual measured power densities taken at the antenna faces of those units. Four speed-enforcement agencies and one transportation research institute provided 54 radar units for evaluation; 17 different models, encompassing 4 frequency bands and 3 antenna configurations, were included. Four of the 986 measurements taken exceeded the 5 mW/cm2 limit accepted by the International Radiation Protection Association and the National Council on Radiation Protection and Measurement, though none exceeded the American Conference of Governmental Industrial Hygienists, American National Standards Institute, Institute of Electrical and Electronic Engineers, or Occupational Safety and Health Administration standard of 10 mW/cm2. The four high measurements were maximum power density readings taken directly in front of the radar. Of the 812 measurements taken at the officers' seated ocular and testicular positions, none exceeded 0.04 mW/cm2; the highest of these (0.034 mW/cm2) was less than 1% of the most conservative current safety standards. High exposures in the limited region directly in front of the radar aperture are easily avoided with proper training. Results of this study indicate that police officer exposure to microwave radiation is apparently minimal. However, because of uncertainty in the medical and scientific communities concerning nonionizing radiation, it is recommended that law enforcement agencies implement a policy of prudent avoidance, including purchasing units with the lowest published maximum power densities, purchasing dash/rear deck-mounted units with antennae mounted outside the patrol vehicle, and training police officers to use the "stand-by" mode

National Radar Conference, Los Angeles, CA, March 12, 13, 1986, Proceedings

NASA Astrophysics Data System (ADS)

The topics discussed include radar systems, radar subsystems, and radar signal processing. Papers are presented on millimeter wave radar for proximity fuzing of smart munitions, a solid state low pulse power ground surveillance radar, and the Radarsat prototype synthetic-aperture radar signal processor. Consideration is also given to automatic track quality assessment in ADT radar systems instrumentation of RCS measurements of modulation spectra of aircraft blades.

Radar Versus Stealth: Passive Radar and the Future of U.S. Military Power

DTIC Science & Technology

2009-01-01

minimizing, if not nul- lifying , the advantages of the defensive.”3 Douhet did not envision the many sur- face-to-air threats that would evolve over the...is emerging, enabled by advances in networked computing and passive radar technology. Because of their potential to counter stealth-based airpower...waveforms include FM and AM radio, television, digital audio/video broadcast, and cellular phone networks .38 Today, passive radar is often configured as a

Close-range radar rainfall estimation and error analysis

NASA Astrophysics Data System (ADS)

van de Beek, C. Z.; Leijnse, H.; Hazenberg, P.; Uijlenhoet, R.

2016-08-01

Quantitative precipitation estimation (QPE) using ground-based weather radar is affected by many sources of error. The most important of these are (1) radar calibration, (2) ground clutter, (3) wet-radome attenuation, (4) rain-induced attenuation, (5) vertical variability in rain drop size distribution (DSD), (6) non-uniform beam filling and (7) variations in DSD. This study presents an attempt to separate and quantify these sources of error in flat terrain very close to the radar (1-2 km), where (4), (5) and (6) only play a minor role. Other important errors exist, like beam blockage, WLAN interferences and hail contamination and are briefly mentioned, but not considered in the analysis. A 3-day rainfall event (25-27 August 2010) that produced more than 50 mm of precipitation in De Bilt, the Netherlands, is analyzed using radar, rain gauge and disdrometer data. Without any correction, it is found that the radar severely underestimates the total rain amount (by more than 50 %). The calibration of the radar receiver is operationally monitored by analyzing the received power from the sun. This turns out to cause a 1 dB underestimation. The operational clutter filter applied by KNMI is found to incorrectly identify precipitation as clutter, especially at near-zero Doppler velocities. An alternative simple clutter removal scheme using a clear sky clutter map improves the rainfall estimation slightly. To investigate the effect of wet-radome attenuation, stable returns from buildings close to the radar are analyzed. It is shown that this may have caused an underestimation of up to 4 dB. Finally, a disdrometer is used to derive event and intra-event specific Z-R relations due to variations in the observed DSDs. Such variations may result in errors when applying the operational Marshall-Palmer Z-R relation. Correcting for all of these effects has a large positive impact on the radar-derived precipitation estimates and yields a good match between radar QPE and gauge

Levee Monitoring with Radar Remote Sensing

NASA Technical Reports Server (NTRS)

Jones, Cathleen E.

2012-01-01

Topics in this presentation are: 1. Overview of radar remote sensing 2. Surface change detection with Differential Interferometric Radar Processing 3. Study of the Sacramento - San Joaquin levees 4. Mississippi River Levees during the Spring 2011 floods.

Phased Array Radar Network Experiment for Severe Weather

NASA Astrophysics Data System (ADS)

Ushio, T.; Kikuchi, H.; Mega, T.; Yoshikawa, E.; Mizutani, F.; Takahashi, N.

2017-12-01

Phased Array Weather Radar (PAWR) was firstly developed in 2012 by Osaka University and Toshiba under a grant of NICT using the Digital Beamforming Technique, and showed a impressive thunderstorm behavior with 30 second resolution. After that development, second PAWR was installed in Kobe city about 60 km away from the first PAWR site, and Tokyo Metropolitan University, Osaka Univeristy, Toshiba and the Osaka Local Government started a new project to develop the Osaka Urban Demonstration Network. The main sensor of the Osaka Network is a 2-node Phased Array Radar Network and lightning location system. Data products that are created both in local high performance computer and Toshiba Computer Cloud, include single and multi-radar data, vector wind, quantitative precipitation estimation, VIL, nowcasting, lightning location and analysis. Each radar node is calibarated by the baloon measurement and through the comparison with the GPM (Global Precipitation Measurement)/ DPR (Dual Frequency Space borne Radar) within 1 dB. The attenuated radar reflectivities obtained by the Phased Array Radar Network at X band are corrected based on the bayesian scheme proposed in Shimamura et al. [2016]. The obtained high resolution (every 30 seconds/ 100 elevation angles) 3D reflectivity and rain rate fields are used to nowcast the surface rain rate up to 30 minutes ahead. These new products are transferred to Osaka Local Government in operational mode and evaluated by several section in Osaka Prefecture. Furthermore, a new Phased Array Radar with polarimetric function has been developed in 2017, and will be operated in the fiscal year of 2017. In this presentation, Phased Array Radar, network architecuture, processing algorithm, evalution of the social experiment and first Multi-Prameter Phased Array Radar experiment are presented.

Mapping Wintering Waterfowl Distributions Using Weather Surveillance Radar

PubMed Central

Buler, Jeffrey J.; Randall, Lori A.; Fleskes, Joseph P.; Barrow, Wylie C.; Bogart, Tianna; Kluver, Daria

2012-01-01

The current network of weather surveillance radars within the United States readily detects flying birds and has proven to be a useful remote-sensing tool for ornithological study. Radar reflectivity measures serve as an index to bird density and have been used to quantitatively map landbird distributions during migratory stopover by sampling birds aloft at the onset of nocturnal migratory flights. Our objective was to further develop and validate a similar approach for mapping wintering waterfowl distributions using weather surveillance radar observations at the onset of evening flights. We evaluated data from the Sacramento, CA radar (KDAX) during winters 1998–1999 and 1999–2000. We determined an optimal sampling time by evaluating the accuracy and precision of radar observations at different times during the onset of evening flight relative to observed diurnal distributions of radio-marked birds on the ground. The mean time of evening flight initiation occurred 23 min after sunset with the strongest correlations between reflectivity and waterfowl density on the ground occurring almost immediately after flight initiation. Radar measures became more spatially homogeneous as evening flight progressed because birds dispersed from their departure locations. Radars effectively detected birds to a mean maximum range of 83 km during the first 20 min of evening flight. Using a sun elevation angle of −5° (28 min after sunset) as our optimal sampling time, we validated our approach using KDAX data and additional data from the Beale Air Force Base, CA (KBBX) radar during winter 1998–1999. Bias-adjusted radar reflectivity of waterfowl aloft was positively related to the observed diurnal density of radio-marked waterfowl locations on the ground. Thus, weather radars provide accurate measures of relative wintering waterfowl density that can be used to comprehensively map their distributions over large spatial extents. PMID:22911816

Mapping wintering waterfowl distributions using weather surveillance radar.

PubMed

Buler, Jeffrey J; Randall, Lori A; Fleskes, Joseph P; Barrow, Wylie C; Bogart, Tianna; Kluver, Daria

2012-01-01

The current network of weather surveillance radars within the United States readily detects flying birds and has proven to be a useful remote-sensing tool for ornithological study. Radar reflectivity measures serve as an index to bird density and have been used to quantitatively map landbird distributions during migratory stopover by sampling birds aloft at the onset of nocturnal migratory flights. Our objective was to further develop and validate a similar approach for mapping wintering waterfowl distributions using weather surveillance radar observations at the onset of evening flights. We evaluated data from the Sacramento, CA radar (KDAX) during winters 1998-1999 and 1999-2000. We determined an optimal sampling time by evaluating the accuracy and precision of radar observations at different times during the onset of evening flight relative to observed diurnal distributions of radio-marked birds on the ground. The mean time of evening flight initiation occurred 23 min after sunset with the strongest correlations between reflectivity and waterfowl density on the ground occurring almost immediately after flight initiation. Radar measures became more spatially homogeneous as evening flight progressed because birds dispersed from their departure locations. Radars effectively detected birds to a mean maximum range of 83 km during the first 20 min of evening flight. Using a sun elevation angle of -5° (28 min after sunset) as our optimal sampling time, we validated our approach using KDAX data and additional data from the Beale Air Force Base, CA (KBBX) radar during winter 1998-1999. Bias-adjusted radar reflectivity of waterfowl aloft was positively related to the observed diurnal density of radio-marked waterfowl locations on the ground. Thus, weather radars provide accurate measures of relative wintering waterfowl density that can be used to comprehensively map their distributions over large spatial extents.

Space Radar Image of Dublin, Ireland

NASA Image and Video Library

1999-04-15

This radar image of Dublin, Ireland, shows how the radar distinguishes between densely populated urban areas and nearby areas that are relatively unsettled. In the center of the image is the city natural harbor along the Irish Sea.

KU-Band rendezvous radar performance computer simulation model

NASA Technical Reports Server (NTRS)

Griffin, J. W.

1980-01-01

The preparation of a real time computer simulation model of the KU band rendezvous radar to be integrated into the shuttle mission simulator (SMS), the shuttle engineering simulator (SES), and the shuttle avionics integration laboratory (SAIL) simulator is described. To meet crew training requirements a radar tracking performance model, and a target modeling method were developed. The parent simulation/radar simulation interface requirements, and the method selected to model target scattering properties, including an application of this method to the SPAS spacecraft are described. The radar search and acquisition mode performance model and the radar track mode signal processor model are examined and analyzed. The angle, angle rate, range, and range rate tracking loops are also discussed.

Flyby Comet Imaged By Radar

NASA Image and Video Library

2016-03-24

Radar data of comet P/2016 BA14 taken over three days (March 21-23, 2016), when the comet was between 2.5 million miles and 2.2 million miles (4.1 million kilometers and 3.6 million kilometers) from Earth. Radar images from the flyby indicated that the comet is about 3,000 feet (1 kilometer) in diameter.

Monitoring by holographic radar systems

NASA Astrophysics Data System (ADS)

Catapano, Ilaria; Crocco, Lorenzo; Affinito, Antonio; Gennarelli, Gianluca; Soldovieri, Francesco

2013-04-01

Nowadays, radar technology represents a significant opportunity to collect useful information for the monitoring and conservation of critical infrastructures. Radar systems exploit the non-invasive interaction between the matter and the electromagnetic waves at microwave frequencies. Such an interaction allows obtaining images of the region under test from which one can infer the presence of potential anomalies such as deformations, cracks, water infiltrations, etc. This information turns out to be of primary importance in practical scenarios where the probed structure is in a poor state of preservation and renovation works must be planned. In this framework, the aim of this contribution is to describe the potentialities of the holographic radar Rascan 4/4000, a holographic radar developed by Remote Sensing Laboratory of Bauman Moscow State Technical University, as a non-destructive diagnostic tool capable to provide, in real-time, high resolution subsurface images of the sounded structure [1]. This radar provides holograms of hidden anomalies from the amplitude of the interference signal arising between the backscattered signal and a reference signal. The performance of the holographic radar is appraised by means of several experiments. Preliminary tests concerning the imaging below the floor and inside wood structures are carried out in controlled conditions at the Electromagnetic Diagnostic Laboratory of IREA-CNR. After, with reference to bridge monitoring for security aim, the results of a measurement campaign performed on the Musmeci bridge are presented [2]. Acknowledgments This research has been performed in the framework of the "Active and Passive Microwaves for Security and Subsurface imaging (AMISS)" EU 7th Framework Marie Curie Actions IRSES project (PIRSES-GA-2010-269157). REFERENCES [1] S. Ivashov, V. Razevig, I. Vasilyev, A. Zhuravlev, T. Bechtel, L. Capineri, The holographic principle in subsurface radar technology, International Symposium to

Capabilities of radar as they might relate to entomological studies

NASA Technical Reports Server (NTRS)

Skolnik, M. I.

1979-01-01

A tutoral background of radar capabilities and its potential for insect research is provided. The basic principles and concepts of radar were reviewed. Information on current radar equipment was examined. Specific issues related to insect research included; target cross-section, radar frequency, tracking target recognition and false alarms, clutter reduction, radar transmitter power, and ascertained atmospheric processes.

Imaging Radar Applications in the Death Valley Region

NASA Technical Reports Server (NTRS)

Farr, Tom G.

1996-01-01

Death Valley has had a long history as a testbed for remote sensing techniques (Gillespie, this conference). Along with visible-near infrared and thermal IR sensors, imaging radars have flown and orbited over the valley since the 1970's, yielding new insights into the geologic applications of that technology. More recently, radar interferometry has been used to derive digital topographic maps of the area, supplementing the USGS 7.5' digital quadrangles currently available for nearly the entire area. As for their shorter-wavelength brethren, imaging radars were tested early in their civilian history in Death Valley because it has a variety of surface types in a small area without the confounding effects of vegetation. In one of the classic references of these early radar studies, in a semi-quantitative way the response of an imaging radar to surface roughness near the radar wavelength, which typically ranges from about 1 cm to 1 m was explained. This laid the groundwork for applications of airborne and spaceborne radars to geologic problems in and regions. Radar's main advantages over other sensors stems from its active nature- supplying its own illumination makes it independent of solar illumination and it can also control the imaging geometry more accurately. Finally, its long wavelength allows it to peer through clouds, eliminating some of the problems of optical sensors, especially in perennially cloudy and polar areas.

VHF radar measurements during MAP/WINE

NASA Technical Reports Server (NTRS)

Czechowsky, P.; Klostermeyer, J.; Ruster, R.; Schmidt, G.; Rottger, J.

1983-01-01

Sensitive Doppler radars which operate in the very high frequency (VHF) band, usually near 50 MHz can measure profiles of background winds, tides, atmospheric gravity waves and turbulence at tropospheric, stratospheric and mesospheric heights. Their ability to observe simultaneously large and small-scale processes makes them unique instruments for studying not only each process separately but also their nonlinear interactions. The mobile VHF radar to be used during the MAP/WINE campaign on Andoya is a modified version of the SOUSY VHF radar being in operation for six years in the Harz Mountains.

Laser backscattered from partially convex targets of large sizes in random media for E-wave polarization.

PubMed

El-Ocla, Hosam

2006-08-01

The characteristics of a radar cross section (RCS) of partially convex targets with large sizes up to five wavelengths in free space and random media are studied. The nature of the incident wave is an important factor in remote sensing and radar detection applications. I investigate the effects of beam wave incidence on the performance of RCS, drawing on the method I used in a previous study on plane-wave incidence. A beam wave can be considered a plane wave if the target size is smaller than the beam width. Therefore, to have a beam wave with a limited spot on the target, the target size should be larger than the beam width (assuming E-wave incidence wave polarization. The effects of the target configuration, random medium parameters, and the beam width on the laser RCS and the enhancement in the radar cross section are numerically analyzed, resulting in the possibility of having some sort of control over radar detection using beam wave incidence.

Radar characteristics of small craters - Implications for Venus

NASA Technical Reports Server (NTRS)

Greeley, Ronald; Christensen, Philip R.; Mchone, John F.

1987-01-01

Shuttle radar images (SIR-A) of volcanic and impact craters were examined to assess their appearance on radar images. Radar characteristics were determined for (1) nine maarlikie craters in the Pinacate volcanic field, Sonora, Mexico; (2) the caldera of Cerro Volcan Quemado, in the Bolivian Andes; (3) Talemzane impact crater, Algeria; and (4) Al Umchaimin, a possible impact structure in Iraq. SIR-A images were compared with conventional photographs and with results from field studies. Consideration was then given to radar images available for Venus, or anticipated from the Magellan mission. Of the criteria ordinarily used to identify impact craters, some can be assessed with radar images and others cannot be used; planimetric form, expressed as circularity, and ejecta-block distribution can be assessed on radar images, but rim and floor elevations relative to the surrounding plain and disposition of rim strata are difficult or impossible to determine. It is concluded that it will be difficult to separate small impact craters from small volcanic craters on Venus using radar images and is suggested that it will be necessary to understand the geological setting of the areas containing the craters in order to determine their origin.

Rain volume estimation over areas using satellite and radar data

NASA Technical Reports Server (NTRS)

Doneaud, A. A.; Vonderhaar, T. H.

1985-01-01

An investigation of the feasibility of rain volume estimation using satellite data following a technique recently developed with radar data called the Arera Time Integral was undertaken. Case studies were selected on the basis of existing radar and satellite data sets which match in space and time. Four multicell clusters were analyzed. Routines for navigation remapping amd smoothing of satellite images were performed. Visible counts were normalized for solar zenith angle. A radar sector of interest was defined to delineate specific radar echo clusters for each radar time throughout the radar echo cluster lifetime. A satellite sector of interest was defined by applying small adjustments to the radar sector using a manual processing technique. The radar echo area, the IR maximum counts and the IR counts matching radar echo areas were found to evolve similarly, except for the decaying phase of the cluster where the cirrus debris keeps the IR counts high.

46 CFR 28.400 - Radar and depth sounding devices.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 1 2011-10-01 2011-10-01 false Radar and depth sounding devices. 28.400 Section 28.400... Operate With More Than 16 Individuals on Board § 28.400 Radar and depth sounding devices. (a) Each vessel must be fitted with a general marine radar system for surface navigation with a radar screen mounted at...

46 CFR 28.400 - Radar and depth sounding devices.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 1 2010-10-01 2010-10-01 false Radar and depth sounding devices. 28.400 Section 28.400... Operate With More Than 16 Individuals on Board § 28.400 Radar and depth sounding devices. (a) Each vessel must be fitted with a general marine radar system for surface navigation with a radar screen mounted at...

46 CFR 28.400 - Radar and depth sounding devices.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 1 2012-10-01 2012-10-01 false Radar and depth sounding devices. 28.400 Section 28.400... Operate With More Than 16 Individuals on Board § 28.400 Radar and depth sounding devices. (a) Each vessel must be fitted with a general marine radar system for surface navigation with a radar screen mounted at...

46 CFR 28.400 - Radar and depth sounding devices.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 1 2014-10-01 2014-10-01 false Radar and depth sounding devices. 28.400 Section 28.400... Operate With More Than 16 Individuals on Board § 28.400 Radar and depth sounding devices. (a) Each vessel must be fitted with a general marine radar system for surface navigation with a radar screen mounted at...

46 CFR 28.400 - Radar and depth sounding devices.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 1 2013-10-01 2013-10-01 false Radar and depth sounding devices. 28.400 Section 28.400... Operate With More Than 16 Individuals on Board § 28.400 Radar and depth sounding devices. (a) Each vessel must be fitted with a general marine radar system for surface navigation with a radar screen mounted at...

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.

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

Radar investigation of asteroids

NASA Technical Reports Server (NTRS)

Ostro, S. J.

1986-01-01

The number of radar detected asteroids has climbed from 6 to 40 (27 mainbelt plus 13 near-Earth). The dual-circular-polarization radar sample now comprises more than 1% of the numbered asteroids. Radar results for mainbelt asteroids furnish the first available information on the nature of these objects at macroscopic scales. At least one object (2 Pallas) and probably many others are extraordinarily smooth at centimeter-to-meter scales but are extremely rough at some scale between several meters and many kilometers. Pallas has essentially no small-scale structure within the uppermost several meters of the regolith, but the rms slope of this regolith exceeds 20 deg., much larger than typical lunar values (approx. 7 deg.). The origin of these slopes could be the hypervelocity impact cratering process, whose manifestations are likely to be different on low-gravity, low-radius-of-curvature objects from those on the terrestrial planets. The range of mainbelt asteroid radar albedoes is very broad and implies big variations in regolith porosity or metal concentration, or both. The highest albedo estimate, for 16 Psyche, is consistent with a surface having porosities typical of lunar soil and a composition nearly completely metallic. Therefore, Psyche might be the collisionally stripped core of a differentiated small plant, and might resemble mineralogically the parent bodies of iron meteorites.

Observation of the Earth by radar

NASA Technical Reports Server (NTRS)

Elachi, C.

1982-01-01

Techniques and applications of radar observation from Earth satellites are discussed. Images processing and analysis of these images are discussed. Also discussed is radar imaging from aircraft. Uses of this data include ocean wave analysis, surface water evaluation, and topographic analysis.

Space Radar Image of Manaus, Brazil

NASA Image and Video Library