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Sample records for ultra-wideband uwb pulse

  1. Ultra Wideband (UWB) communication vulnerability for security applications.

    SciTech Connect

    Cooley, H. Timothy

    2010-07-01

    RF toxicity and Information Warfare (IW) are becoming omnipresent posing threats to the protection of nuclear assets, and within theatres of hostility or combat where tactical operation of wireless communication without detection and interception is important and sometimes critical for survival. As a result, a requirement for deployment of many security systems is a highly secure wireless technology manifesting stealth or covert operation suitable for either permanent or tactical deployment where operation without detection or interruption is important The possible use of ultra wideband (UWB) spectrum technology as an alternative physical medium for wireless network communication offers many advantages over conventional narrowband and spread spectrum wireless communication. UWB also known as fast-frequency chirp is nonsinusoidal and sends information directly by transmitting sub-nanosecond pulses without the use of mixing baseband information upon a sinusoidal carrier. Thus UWB sends information using radar-like impulses by spreading its energy thinly over a vast spectrum and can operate at extremely low-power transmission within the noise floor where other forms of RF find it difficult or impossible to operate. As a result UWB offers low probability of detection (LPD), low probability of interception (LPI) as well as anti-jamming (AJ) properties in signal space. This paper analyzes and compares the vulnerability of UWB to narrowband and spread spectrum wireless network communication.

  2. A Novel Approach to Photonic Generation and Modulation of Ultra-Wideband Pulses

    NASA Astrophysics Data System (ADS)

    Xiang, Peng; Guo, Hao; Chen, Dalei; Zhu, Huatao

    2016-01-01

    A novel approach to photonic generation of ultra-wideband (UWB) signals is proposed in this paper. The proposed signal generator is capable of generating UWB doublet pulses with flexible reconfigurability, and many different pulse modulation formats, including the commonly used pulse-position modulation (PPM) and bi-phase modulation (BPM) can be realized. Moreover, the photonic UWB pulse generator is capable of generating UWB signals with a tunable spectral notch-band, which is desirable to realize the interference avoidance between UWB and other narrow band systems, such as Wi-Fi. A mathematical model describing the proposed system is developed and the generation of UWB signals with different modulation formats is demonstrated via computer simulations.

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

    SciTech Connect

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

    2014-10-07

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

  4. Ultra-wideband pulse generation with flexible pulse shape and polarity control using a Sagnac-interferometer-based intensity modulator.

    PubMed

    Li, Jianqiang; Xu, Kun; Fu, Songnian; Wu, Jian; Lin, Jintong; Tang, Ming; Shum, P

    2007-12-24

    We propose a novel scheme to generate ultra-wideband (UWB) pulse by employing a Sagnac interferometer comprising a phase modulator. This structure performs a dual-input and dual-output intensity modulator (IM), ultimately resulting in the flexibility to select the shape and the polarity of the generated UWB pulse. The experiment results show a good agreement with the theoretical investigation in terms of both pulse profile and spectrum, which conforms to the definition of UWB signals by the U.S. Federal Communications Commission. Furthermore, the proposed scheme is independent of the voltage bias point. PMID:19551113

  5. Emerging Communication Technologies (ECT) Phase 2 Report. Volume 3; Ultra Wideband (UWB) Technology

    NASA Technical Reports Server (NTRS)

    Bastin, Gary L.; Harris, William G.; Chiodini, Robert; Nelson, Richard A.; Huang, PoTien; Kruhm, David A.

    2003-01-01

    The Emerging Communication Technology (ECT) project investigated three First Mile communication technologies in support of NASA s Second Generation Reusable Launch Vehicle (2nd Gen RLV), Orbital Space Plane, Advanced Range Technology Working Group (ARTWG) and the Advanced Spaceport Technology Working Group (ASTWG). These First Mile technologies have the purpose of interconnecting mobile users with existing Range Communication infrastructures. ECT was a continuation of the Range Information System Management (RISM) task started in 2002. RISM identified the three advance communication technologies investigated under ECT. These were Wireless Ethernet (Wi-Fi), Free Space Optics (FSO), and Ultra Wideband (UWB). Due to the report s size, it has been broken into three volumes: 1) Main Report 2) Appendices 3) UWB

  6. Ultra-wideband receiver

    DOEpatents

    McEwan, T.E.

    1996-06-04

    An ultra-wideband (UWB) receiver utilizes a strobed input line with a sampler connected to an amplifier. In a differential configuration, {+-}UWB inputs are connected to separate antennas or to two halves of a dipole antenna. The two input lines include samplers which are commonly strobed by a gating pulse with a very low duty cycle. In a single ended configuration, only a single strobed input line and sampler is utilized. The samplers integrate, or average, up to 10,000 pulses to achieve high sensitivity and good rejection of uncorrelated signals. 21 figs.

  7. Ultra-wideband receiver

    DOEpatents

    McEwan, T.E.

    1994-09-06

    An ultra-wideband (UWB) receiver utilizes a strobed input line with a sampler connected to an amplifier. In a differential configuration, [+-] UWB inputs are connected to separate antennas or to two halves of a dipole antenna. The two input lines include samplers which are commonly strobed by a gating pulse with a very low duty cycle. In a single ended configuration, only a single strobed input line and sampler is utilized. The samplers integrate, or average, up to 10,000 pulses to achieve high sensitivity and good rejection of uncorrelated signals. 16 figs.

  8. Ultra-wideband receiver

    DOEpatents

    McEwan, Thomas E.

    1996-01-01

    An ultra-wideband (UWB) receiver utilizes a strobed input line with a sampler connected to an amplifier. In a differential configuration, .+-.UWB inputs are connected to separate antennas or to two halves of a dipole antenna. The two input lines include samplers which are commonly strobed by a gating pulse with a very low duty cycle. In a single ended configuration, only a single strobed input line and sampler is utilized. The samplers integrate, or average, up to 10,000 pulses to achieve high sensitivity and good rejection of uncorrelated signals.

  9. Ultra-wideband receiver

    DOEpatents

    McEwan, Thomas E.

    1994-01-01

    An ultra-wideband (UWB) receiver utilizes a strobed input line with a sampler connected to an amplifier. In a differential configuration, .+-.UWB inputs are connected to separate antennas or to two halves of a dipole antenna. The two input lines include samplers which are commonly strobed by a gating pulse with a very low duty cycle. In a single ended configuration, only a single strobed input line and sampler is utilized. The samplers integrate, or average, up to 10,000 pulses to achieve high sensitivity and good rejection of uncorrelated signals.

  10. Photonic generation of ultra-wideband pulses using a fiber delay interferometer

    NASA Astrophysics Data System (ADS)

    Wang, Fei; Zhang, Xinliang; Zhang, Yin; Xu, Enming

    2011-11-01

    We demonstrate a novel scheme to generate ultra wideband (UWB) doublet pulses by inputting a dark return-to-zero (RZ) signal into a fiber delay interferometer (FDI). When a dark RZ pulse train with a repetition rate of 0.625 GHz and a pulse width of 120 ps was inputted into a FDI with a free spectrum range (FSR) of 0.16 nm (~20 GHz, according time delay is ~50 ps) and an extinction ratio (ER) of 9 dB, by adjusting the control temperature of the FDI, the phase difference of the input light on the both fiber arms of the FDI is changed and controlled, UWB doublet pulse is directly generated at the output port of the FDI. The system parameters effects on the output signal were also discussed. Moreover, we numerically demonstrated that, by carefully optimizing system parameters, UWB quadruplet pulses also can be generated. This scheme has some distinct advantages including easy integration, convenient tuning, good stability, and so on. Presented method also accords with the general features in future applied UWB system, namely, single optical source input, simple configuration and passive device.

  11. Photonic generation of ultra-wideband pulses using a fiber delay interferometer

    NASA Astrophysics Data System (ADS)

    Wang, Fei; Zhang, Xinliang; Zhang, Yin; Xu, Enming

    2012-02-01

    We demonstrate a novel scheme to generate ultra wideband (UWB) doublet pulses by inputting a dark return-to-zero (RZ) signal into a fiber delay interferometer (FDI). When a dark RZ pulse train with a repetition rate of 0.625 GHz and a pulse width of 120 ps was inputted into a FDI with a free spectrum range (FSR) of 0.16 nm (~20 GHz, according time delay is ~50 ps) and an extinction ratio (ER) of 9 dB, by adjusting the control temperature of the FDI, the phase difference of the input light on the both fiber arms of the FDI is changed and controlled, UWB doublet pulse is directly generated at the output port of the FDI. The system parameters effects on the output signal were also discussed. Moreover, we numerically demonstrated that, by carefully optimizing system parameters, UWB quadruplet pulses also can be generated. This scheme has some distinct advantages including easy integration, convenient tuning, good stability, and so on. Presented method also accords with the general features in future applied UWB system, namely, single optical source input, simple configuration and passive device.

  12. Ultra-wideband Communications

    SciTech Connect

    Waltjen, K; Romero, C; Azevedo, S; Dowla, F; Spiridon, A; Benzel, D; Haugen, P

    2004-02-06

    Many applications in wireless communications often require short-range systems capable of rapidly collecting data and transmitting it reliably. Commercial communication systems operate in fixed frequency bands and are easily detectable and are prone to jamming by the enemy, among other shortcomings. The new ultra-wideband (UWB) communications system in the 3.1 to 10 GHz band is of significant interest to a number of Lawrence Livermore National Laboratory (LLNL) programs including the Nonproliferation, Arms Control, and International Security (NAI) Directorate. Ultra-Wideband (UWB) technology has received a significant degree of attention from communications industry since the Federal Communications Commission (FCC) rulings in February 2002. According to FCC, UWB signals have fractional bandwidth (B{sub f}) of 20% or larger at -10 dB cut-off frequencies, with minimum bandwidth of 500 MHz. Unlike traditional communication systems, UWB systems modulate carrier-less, short-duration (picosec to nanosec) pulses to transmit and receive information. A number of programmatic problems at LLNL, particularly in the NAI and other national security Directorates, require collecting information from multiple sensors distributed over a local area. The information must be collected covertly and by wireless means. The sensors produce data using low power devices and the communication link must operate in severe multipath environments over tens of meters; often the links must be channelized to handle multiple sensors. The communications links between these sensors is a critical issue in the development of LLNL programs to demonstrate distributed sensor network performance in real-time. In summary, such systems must be robust; have a low probability of detection and intercept; employ low-power, small-size hardware; and interface easily with other systems for analysis or to establish long-distance links. The purpose of this work was to develop a new UWB radio-frequency (RF) communications system for the UWB RF band. In this project we addressed the need for robust UWB communication systems with low-power, small-size sensor communication hardware. Our research results have successfully addressed these issues and we developed UWB radios and interfaced these radios with repeater radios for longer distance links. In particular, research and development challenges included signal processing and communication design problems, including developing novel UWB modulation and demodulation schemes, link budget analysis for ultra-wideband signals, multipath mitigation, short-pulse signal synchronization, and building real working radios. We have had a significant degree of success in solving these technical challenges. As a result, several programmatic efforts have spun off from our R&D work in FY04.

  13. Penetration and propagation into biological matter and biological effects of high-power ultra-wideband pulses: a review.

    PubMed

    Schunck, Thérèse; Bieth, François; Pinguet, Sylvain; Delmote, Philippe

    2016-01-01

    Systems emitting ultra-wideband high power microwave (HP/UWB) pulses are developed for military and civilian applications. HP/UWB pulses typically have durations on the order of nanoseconds, rise times of picoseconds and amplitudes around 100 kV m(-1). This article reviews current research on biological effects from HP/UWB exposure. The different references were classified according to endpoints (cardiovascular system, central nervous system, behavior, genotoxicity, teratology …). The article also reviews the aspects of mechanisms of interactions and tissue damage as well as the numerical work that has been done for studying HP/UWB pulse propagation and pulse energy deposition inside biological tissues. The mechanisms proposed are the molecular conformation change, the modification of chemical reaction rates, membrane excitation and breakdown and direct electrical forces on cells or cell constituents, and the energy deposition. As regards the penetration of biological matter and the deposited energy, mainly computations were published. They have shown that the EM field inside the biological matter is strongly modified compared to the incident EM field and that the energy absorption for HP/UWB pulses occurs in the same way as for continuous waves. However, the energy carried by a HP/UWB pulse is very low and the deposited energy is low. The number of published studies dealing with the biological effects is small and only a few pointed out slight effects. It should be further noted that the animal populations used in the studies were not always large, the statistical analyses not always relevant and the teams involved in this research rather limited in number. PMID:25356665

  14. Through-the-wall localization of a moving target by two independent ultra wideband (UWB) radar systems.

    PubMed

    Kocur, Dušan; Svecová, Mária; Rovňáková, Jana

    2013-01-01

    In the case of through-the-wall localization of moving targets by ultra wideband (UWB) radars, there are applications in which handheld sensors equipped only with one transmitting and two receiving antennas are applied. Sometimes, the radar using such a small antenna array is not able to localize the target with the required accuracy. With a view to improve through-the-wall target localization, cooperative positioning based on a fusion of data retrieved from two independent radar systems can be used. In this paper, the novel method of the cooperative localization referred to as joining intersections of the ellipses is introduced. This method is based on a geometrical interpretation of target localization where the target position is estimated using a properly created cluster of the ellipse intersections representing potential positions of the target. The performance of the proposed method is compared with the direct calculation method and two alternative methods of cooperative localization using data obtained by measurements with the M-sequence UWB radars. The direct calculation method is applied for the target localization by particular radar systems. As alternative methods of cooperative localization, the arithmetic average of the target coordinates estimated by two single independent UWB radars and the Taylor series method is considered. PMID:24021968

  15. Through-the-Wall Localization of a Moving Target by Two Independent Ultra Wideband (UWB) Radar Systems

    PubMed Central

    Kocur, Dušan; Švecová, Mária; Rovňáková, Jana

    2013-01-01

    In the case of through-the-wall localization of moving targets by ultra wideband (UWB) radars, there are applications in which handheld sensors equipped only with one transmitting and two receiving antennas are applied. Sometimes, the radar using such a small antenna array is not able to localize the target with the required accuracy. With a view to improve through-the-wall target localization, cooperative positioning based on a fusion of data retrieved from two independent radar systems can be used. In this paper, the novel method of the cooperative localization referred to as joining intersections of the ellipses is introduced. This method is based on a geometrical interpretation of target localization where the target position is estimated using a properly created cluster of the ellipse intersections representing potential positions of the target. The performance of the proposed method is compared with the direct calculation method and two alternative methods of cooperative localization using data obtained by measurements with the M-sequence UWB radars. The direct calculation method is applied for the target localization by particular radar systems. As alternative methods of cooperative localization, the arithmetic average of the target coordinates estimated by two single independent UWB radars and the Taylor series method is considered. PMID:24021968

  16. Millimeter wave band ultra wideband transmitter MMIC

    NASA Astrophysics Data System (ADS)

    Ling, Jin; Rolland, Nathalie

    2015-09-01

    This paper presents a new millimeter-wave (MMW) ultra wideband (UWB) transmitter MMIC which has been developed in an OMMIC 0.1 μm GaAs PHEMT foundry process (ft = 100 GHz) for 22-29 GHz vehicular radar systems. The transmitter is composed of an MMW negative resistance oscillator (NRO), a power amplifier (PA), and two UWB pulse generators (PGs). In order to convert the UWB pulse signal to MMW frequency and reduce the total power consumption, the MMW NRO is driven by one of the UWB pulse generators and the power amplifier is triggered by another UWB pulse generator. The main advantages of this transmitter are: new design, simple architecture, high-precision distance measurements, infinite ON/OFF switch ratio, and low power consumption. The total power consumption of the transmitter MMIC is 218 mW with a peak output power of 5.5 dBm at 27 GHz.

  17. 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.

  18. 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.

  19. 3D SAR image formation for underground targets using ultra-wideband (UWB) radar

    NASA Astrophysics Data System (ADS)

    Nguyen, Lam; Dogaru, Traian; Innocenti, Roberto

    2009-05-01

    This paper analyzes the application of ultra-wideband ground-penetrating radar (GPR) in a down-looking configuration for the detection of buried targets. As compared to previous studies, where target detection algorithms have been developed based on the radar range profiles alone (pre-focus data), we investigate the potential performance improvement by forming synthetic aperture radar (SAR) images of the targets. This becomes important in scenarios with small signal-to-noise or signal-to-clutter ratios. Our three-dimensional (3-D) image formation algorithm is based on the backprojection technique. We apply this method to radar scattering data obtained through computer simulation by the finite-difference time-domain (FDTD) technique. Our analysis demonstrates the advantages of using focused SAR images versus the pre-focus range profiles. We also perform a parametric study of several physical factors that could affect the image quality.

  20. Low data rate ultra wideband ECG monitoring system.

    PubMed

    Keong, Ho Chee; Yuce, Mehmet R

    2008-01-01

    This paper presents a successfully implemented wireless electrocardiograph monitoring using low data rate ultra wideband (UWB) transmission. Low data rate ultra wideband is currently under consideration for the newly formed wireless body area network (WBAN) group (IEEE802.15.6) to develop a standard for wireless vital sign monitoring. Maximizing the transmission power of the transmitter and reducing the stringent requirements and complexity of the receiver have always been the key considerations for an UWB transceiver. Multiple pulses per bit has been sent in our low data rate UWB prototype system to increase the transmitter power, to reduce the complexity of the receiver and to ease the requirement on the receiver's analog to digital converter. Non-coherent technique has been used for the demodulation of UWB signals at the receiver that reduces the receiver complexity further. PMID:19163442

  1. Ultra-wideband directional sampler

    DOEpatents

    McEwan, Thomas E.

    1996-01-01

    The Ultra-Wideband (UWB) Directional Sampler is a four port device that combines the function of a directional coupler with a high speed sampler. Two of the four ports operate at a high sub-nanosecond speed, in "real time", and the other two ports operate at a slow millisecond-speed, in "equivalent time". A signal flowing inbound to either of the high speed ports is sampled and coupled, in equivalent time, to the adjacent equivalent time port while being isolated from the opposite equivalent time port. A primary application is for a time domain reflectometry (TDR) situation where the reflected pulse returns while the outbound pulse is still being transmitted, such as when the reflecting discontinuity is very close to the TDR apparatus.

  2. Ultra-wideband directional sampler

    DOEpatents

    McEwan, T.E.

    1996-05-14

    The Ultra-Wideband (UWB) Directional Sampler is a four port device that combines the function of a directional coupler with a high speed sampler. Two of the four ports operate at a high sub-nanosecond speed, in ``real time``, and the other two ports operate at a slow millisecond-speed, in ``equivalent time``. A signal flowing inbound to either of the high speed ports is sampled and coupled, in equivalent time, to the adjacent equivalent time port while being isolated from the opposite equivalent time port. A primary application is for a time domain reflectometry (TDR) situation where the reflected pulse returns while the outbound pulse is still being transmitted, such as when the reflecting discontinuity is very close to the TDR apparatus. 3 figs.

  3. Self Organization of Wireless Sensor Networks Using Ultra-Wideband Radios

    SciTech Connect

    Nekoogar, F; Dowla, F; Spiridon, A

    2004-07-19

    Ultra-wideband (UWB) technology has proven to be useful in short range, high data rate, robust, and low power communications. These features can make UWB systems ideal candidates for reliable data communications between nodes of a wireless sensor network (WSN). However, the low powered UWB pulses can be significantly degraded by channel noise, inter-node interference, and intentional jamming. In this paper we present a novel interference suppression technique for UWB based WSNs that promises self-organization in terms of power conservation, scalability, and channel estimation for the entire distributed network.

  4. RETRACTED — Photonic generation of UWB pulses with multiple modulation formats

    NASA Astrophysics Data System (ADS)

    Chen, Yang; Wen, Aijun; Shang, Lei; Wang, Yong

    2013-02-01

    A new photonic approach to generate ultra-wideband (UWB) signals with on-off keying, pulse position and shape modulation is proposed and proved by simulation. The proposed system consists of two parallel similar subsystems, which are both made up of an intensity modulator (IM) and a dual-drive Mach-Zehnder modulator (DD-MZM). The optical signal is injected into the two subsystems with equal intensity and phase. The IMs are driven by the data signal, while the DD-MZMs are driven by the Gaussian pulse train. By properly adjusting the bias points of the IMs and DD-MZMs, the amplitudes of the data signals, and the time delays introduced by electrical delay lines, a position-modulated UWB monocycle, a shape-modulated UWB monocycle and doublet, and an on-off keying UWB monocycle can be generated. The fractional bandwidth of the generated UWB monocycle and UWB doublet are 171% and 150%, respectively.

  5. Multi-pulse frequency shifted (MPFS) multiple access modulation for ultra wideband

    SciTech Connect

    Nekoogar, Faranak; Dowla, Farid U.

    2012-01-24

    The multi-pulse frequency shifted technique uses mutually orthogonal short duration pulses o transmit and receive information in a UWB multiuser communication system. The multiuser system uses the same pulse shape with different frequencies for the reference and data for each user. Different users have a different pulse shape (mutually orthogonal to each other) and different transmit and reference frequencies. At the receiver, the reference pulse is frequency shifted to match the data pulse and a correlation scheme followed by a hard decision block detects the data.

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

    NASA Astrophysics Data System (ADS)

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

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

  7. UWB doublet signal generation and modulation based on DFB laser under optical pulses injection

    NASA Astrophysics Data System (ADS)

    Chen, Dalei; Wang, Rong; Xiang, Peng; Pu, Tao; Fang, Tao; Zhou, Hua; Zhao, Jiyong; Huang, Long; Zhu, Huatao; Wang, Peng

    2016-05-01

    In this paper, a novel scheme to generate ultra-wideband (UWB) doublet signals based on the cross-gain modulation (XGM) effect in the DFB lasers is proposed and experimentally demonstrated, the modulation and transmission of the generated UWB doublet signals are also researched. In the proposed system, a gain-switched laser (GSL) is used as a master laser (ML) and the optical pulses from the ML are optically injected into two paralleled DFB lasers, which are used as slave lasers (SL). Then the outputs from the SLs are detected by a balanced photodiode (BPD) to generate the Bi-phased UWB signals. By properly setting the system parameters, UWB signals with various modulation formats such as on-off keying (OOK), pulse amplitude modulation (PAM) as well as the phase-shift keying (PSK) can be generated. In addition, fiber transmission of the modulated UWB signals is also experimentally investigated.

  8. Hemispheric ultra-wideband antenna.

    SciTech Connect

    Brocato, Robert Wesley

    2006-04-01

    This report begins with a review of reduced size ultra-wideband (UWB) antennas and the peculiar problems that arise when building a UWB antenna. It then gives a description of a new type of UWB antenna that resolves these problems. This antenna, dubbed the hemispheric conical antenna, is similar to a conventional conical antenna in that it uses the same inverted conical conductor over a ground plane, but it also uses a hemispheric dielectric fill in between the conductive cone and the ground plane. The dielectric material creates a fundamentally new antenna which is reduced in size and much more rugged than a standard UWB conical antenna. The creation of finite-difference time domain (FDTD) software tools in spherical coordinates, as described in SAND2004-6577, enabled this technological advance.

  9. Remote Monitoring and Tracking of UF6 Cylinders Using Long-Range Passive Ultra-wideband (UWB) RFID Tags

    SciTech Connect

    Nekoogar, F; Dowla, F

    2007-06-06

    An IAEA Technical Meeting on Techniques for IAEA Verification of Enrichment Activities identified 'smart tags' as a technology that should be assessed for tracking and locating UF6 cylinders. Although there is vast commercial industry working on RFID systems, the vulnerabilities of commercial products are only beginning to emerge. Most of the commercially off-the-shelf (COTS) RFID systems operate in very narrow frequency bands, making them vulnerable to detection, jamming and tampering and also presenting difficulties when used around metals (i.e. UF6 cylinders). Commercial passive RFID tags have short range, while active RFID tags that provide long ranges have limited lifetimes. There are also some concerns with the introduction of strong (narrowband) radio frequency signals around radioactive and nuclear materials. Considering the shortcomings of commercial RFID systems, in their current form, they do not offer a promising solution for continuous monitoring and tracking of UF6 cylinders. In this paper, we identify the key challenges faced by commercial RFID systems for monitoring UF6 cylinders, and introduce an ultra-wideband approach for tag/reader communications that addresses most of the identified challenges for IAEA safeguards applications.

  10. Ultra-Wideband Angle-of-Arrival Tracking Systems

    NASA Technical Reports Server (NTRS)

    Arndt, G. Dickey; Ngo, Phong H.; Phan, Chau T.; Gross, Julia; Ni, Jianjun; Dusl, John

    2010-01-01

    Systems that measure the angles of arrival of ultra-wideband (UWB) radio signals and perform triangulation by use of those angles in order to locate the sources of those signals are undergoing development. These systems were originally intended for use in tracking UWB-transmitter-equipped astronauts and mobile robots on the surfaces of remote planets during early stages of exploration, before satellite-based navigation systems become operational. On Earth, these systems could be adapted to such uses as tracking UWB-transmitter-equipped firefighters inside buildings or in outdoor wildfire areas obscured by smoke. The same characteristics that have made UWB radio advantageous for fine resolution ranging, covert communication, and ground-penetrating radar applications in military and law-enforcement settings also contribute to its attractiveness for the present tracking applications. In particular, the waveform shape and the short duration of UWB pulses make it possible to attain the high temporal resolution (of the order of picoseconds) needed to measure angles of arrival with sufficient precision, and the low power spectral density of UWB pulses enables UWB radio communication systems to operate in proximity to other radio communication systems with little or no perceptible mutual interference.

  11. Photonic ultra-wideband pulse generation, hybrid modulation and dispersion-compensation-free transmission in multi-access communication systems.

    PubMed

    Tan, Kang; Shao, Jing; Sun, Junqiang; Wang, Jian

    2012-01-16

    We propose and demonstrate a scheme for optical ultrawideband (UWB) pulse generation by exploiting a half-carrier-suppressed Mach-Zehnder modulator (MZM) and a delay-interferometer- and wavelength-division-multiplexer-based, reconfigurable and multi-channel differentiator (DWRMD). Multi-wavelength, polarity- and shape-switchable UWB pulses of monocycle, doublet, triplet, and quadruplet are experimentally generated simply by tuning two bias voltages to modify the carrier-suppression ratio of MZM and the differential order of DWRMD respectively. The pulse position modulation, pulse shape modulation, pulse amplitude modulation and binary phase-shift keying modulation of UWB pulses can also be conveniently realized with the same scheme structure, which indicates that the hybrid modulation of those four formats can be achieved. Consequently, the proposed approach has potential applications in multi-shape, multi-modulation and multi-access UWB-over-fiber communication systems. PMID:22274463

  12. UWB transmitter

    SciTech Connect

    Dallum, Gregory E.; Pratt, Garth C.; Haugen, Peter C.; Romero, Carlos E.

    2013-01-15

    An ultra-wideband (UWB) dual impulse transmitter is made up of a trigger edge selection circuit actuated by a single trigger input pulse; a first step recovery diode (SRD) based pulser connected to the trigger edge selection circuit to generate a first impulse output; and a second step recovery diode (SRD) based pulser connected to the trigger edge selection circuit in parallel to the first pulser to generate a second impulse output having a selected delay from the first impulse output.

  13. Optimal waveforms design for ultra-wideband impulse radio sensors.

    PubMed

    Li, Bin; Zhou, Zheng; Zou, Weixia; Li, Dejian; Zhao, Chong

    2010-01-01

    Ultra-wideband impulse radio (UWB-IR) sensors should comply entirely with the regulatory spectral limits for elegant coexistence. Under this premise, it is desirable for UWB pulses to improve frequency utilization to guarantee the transmission reliability. Meanwhile, orthogonal waveform division multiple-access (WDMA) is significant to mitigate mutual interferences in UWB sensor networks. Motivated by the considerations, we suggest in this paper a low complexity pulse forming technique, and its efficient implementation on DSP is investigated. The UWB pulse is derived preliminarily with the objective of minimizing the mean square error (MSE) between designed power spectrum density (PSD) and the emission mask. Subsequently, this pulse is iteratively modified until its PSD completely conforms to spectral constraints. The orthogonal restriction is then analyzed and different algorithms have been presented. Simulation demonstrates that our technique can produce UWB waveforms with frequency utilization far surpassing the other existing signals under arbitrary spectral mask conditions. Compared to other orthogonality design schemes, the designed pulses can maintain mutual orthogonality without any penalty on frequency utilization, and hence, are much superior in a WDMA network, especially with synchronization deviations. PMID:22163511

  14. An EnantioMorphic BLumlein ultra-wideband source

    SciTech Connect

    Rinehart, L.F.; Buttram, M.T.; Crowe, W.R.; Clark, R.S.; Lundstrom, J.M.; Patterson, P.E.

    1992-01-01

    Working designs exist for 1 GW, 1 kHz ultra-wideband (UWB) sources (e. g. SNIPER). As these generators are pressed to higher peak powers and repetition rates, insulation, energy loss due to stray capacitance, and system efficiency (including power supplies and modulators) become critical issues. The EnantioMorphic (mirror image) BLumlein (EMBL) is a new type of vector inversion transmission line pulser which is designed to alleviate some of these problems. The design goals for EMBL are: 10 GW peak power, 700 kV,{approximately}1 kHz rep-rate and <100 ps risetime in a 50 ohm geometry. A gas spark gap peaking switch adds UWB frequency components to the EMBL output pulse.

  15. An EnantioMorphic BLumlein ultra-wideband source

    SciTech Connect

    Rinehart, L.F.; Buttram, M.T.; Crowe, W.R.; Clark, R.S.; Lundstrom, J.M.; Patterson, P.E.

    1992-09-01

    Working designs exist for 1 GW, 1 kHz ultra-wideband (UWB) sources (e. g. SNIPER). As these generators are pressed to higher peak powers and repetition rates, insulation, energy loss due to stray capacitance, and system efficiency (including power supplies and modulators) become critical issues. The EnantioMorphic (mirror image) BLumlein (EMBL) is a new type of vector inversion transmission line pulser which is designed to alleviate some of these problems. The design goals for EMBL are: 10 GW peak power, 700 kV,{approximately}1 kHz rep-rate and <100 ps risetime in a 50 ohm geometry. A gas spark gap peaking switch adds UWB frequency components to the EMBL output pulse.

  16. Pulse Interval Modulation for Ultra-High Speed IR-UWB Communications Systems

    NASA Astrophysics Data System (ADS)

    Herceg, Marijan; Švedek, Tomislav; Matić, Tomislav

    2010-12-01

    This paper analyzes performances of the Pulse Interval Modulation (PIM) scheme for impulse radio ultra-wideband (IR-UWB) communication systems. Due to the PIM anisochronous nature, a tap delay line (TDL) coded division multiple access (CDMA) scheme based on strict optical orthogonal codes (SOOC) is proposed. This scheme is suitable for multiuser high-speed data asynchronous transmission applications because the average symbol length is shorter than in Pulse Position Modulation (PPM) schemes and it needs only chip synchronization. The error probability over the additive white Gaussian noise (AWGN) channel is derived in the single- and multi-user environment and compared with other modulation schemes.

  17. Cyclic Prefix Signaling for Pulse Shape Modulation UWB RAKE Receivers

    NASA Astrophysics Data System (ADS)

    Cartagena Gordillo, Alex; Kohno, Ryuji

    Combining transmission of ultra wideband pulses, organized in blocks, with the inclusion of cyclic prefixing pulses yields a pulsewidth periodic signal at the receiver. Although unknown, this signal fits perfectly the diversity exploitive architecture of a RAKE receiver. Aiming to profit from this signal arrangement, we propose a pulse shape modulation system employing a RAKE receiver that estimates this periodic signal during a training interval and uses the estimated values for detection of data symbols. Our proposal relies on the invariability of the multipath propagation channel during the transmission of a UWB packet, the adequate application of the cyclic prefix, and the fact that different transmitted pulses result in different periodic signals at the receiver. This system is equivalent to transforming the multipath nature of the UWB propagation channel into a multichannel digital communications affected solely by additive noise. Our proposal is important because it ameliorates the performance of a pulse shape modulation RAKE receiver. On the other hand, the cost of our proposed system resides in the inefficiencies product of the cyclic prefix inclusion.

  18. All-optical UWB doublet pulses generation by using a delay interferometer

    NASA Astrophysics Data System (ADS)

    Wang, Fei; Xu, En-Ming

    2013-06-01

    We demonstrated a simple scheme to generate ultra wideband (UWB) doublet pulses by inputting a dark return-to-zero (RZ) signal into a fiber delay interferometer (FDI). An 0.625-Gbit/s dark-RZ pulse train where the pulse width is 120 ps was inputted into a FDI where the free spectral range (FSR) is 0.16 nm (˜20 GHz, according time delay is ˜50 ps) and the extinction ratio (ER) is 9 dB, and the phase difference of the two fiber arms was changed and controlled by adjusting the operation temperature of the FDI, by do so, UWB doublet pulses were directly generated at an output port of the FDI. The system parameter effects on the output UWB pulses were discussed. Moreover, we also numerically demonstrated that the UWB quadruplet pulses can be generated in the same set by optimizing system parameters. This scheme has some distinct advantages including easy integration, convenient tuning, good stability, and so on. Presented method also accords with the general features in future applied UWB-Over-Fiber communication system, such as, single optical source input, simple configuration and passive device.

  19. Safety assessment of ultra-wideband antennas for microwave breast imaging.

    PubMed

    De Santis, Valerio; Sill, Jeff M; Bourqui, Jeremie; Fear, Elise C

    2012-04-01

    This article deals with the safety assessment of several ultra-wideband (UWB) antenna designs for use in prototype microwave breast imaging systems. First, the performances of the antennas are validated by comparison of measured and simulated data collected for a simple test case. An efficient approach to estimating the specific energy absorption (SA) is introduced and validated. Next, SA produced by the UWB antennas inside more realistic breast models is computed. In particular, the power levels and pulse repetition periods adopted for the SA evaluation follow the measurement protocol employed by a tissue sensing adaptive radar (TSAR) prototype system. Results indicate that the SA for the antennas examined is below limits prescribed in standards for exposure of the general population; however, the difficulties inherent in applying such standards to UWB exposures are discussed. The results also suggest that effective tools for the rapid evaluation of new sensors have been developed. PMID:21826686

  20. Spotforming with an Array of Ultra-Wideband Radio Transmitters

    SciTech Connect

    Dowla, F; Spiridon, A

    2003-09-29

    Ultra-wideband (UWB) array signal processing has the distinct advantage in that it is possible to illuminate or focus on ''spots'' at distant points in space, as opposed to just illuminating or steering at certain directions for narrowband array processing. The term ''spotforming'' is used to emphasize the property that point-focusing techniques with UWB waveforms can be viewed as a generalization of the well-known narrowband beamforming techniques. Because methods in spotforming can lead to powerful applications for UWB systems, in this paper we derive, simulate and experimentally verify UWB spot size as a function of frequency, bandwidth and array aperture.

  1. Ultra-wideband communication system prototype using orthogonal frequency coded SAW correlators.

    PubMed

    Gallagher, Daniel R; Kozlovski, Nikolai Y; Malocha, Donald C

    2013-03-01

    This paper presents preliminary ultra-wideband (UWB) communication system results utilizing orthogonal frequency coded SAW correlators. Orthogonal frequency coding (OFC) and pseudo-noise (PN) coding provides a means for spread-spectrum UWB. The use of OFC spectrally spreads a PN sequence beyond that of CDMA; allowing for improved correlation gain. The transceiver approach is still very similar to that of the CDMA approach, but provides greater code diversity. Use of SAW correlators eliminates many of the costly components that are typically needed in the intermediate frequency (IF) section in the transmitter and receiver, and greatly reduces the signal processing requirements. Development and results of an experimental prototype system with center frequency of 250 MHz are presented. The prototype system is configured using modular RF components and benchtop pulse generator and frequency source. The SAW correlation filters used in the test setup were designed using 7 chip frequencies within the transducer. The fractional bandwidth of approximately 29% was implemented to exceed the defined UWB specification. Discussion of the filter design and results are presented and are compared with packaged device measurements. A prototype UWB system using OFC SAW correlators is demonstrated in wired and wireless configurations. OFC-coded SAW filters are used for generation of a transmitted spread-spectrum UWB and matched filter correlated reception. Autocorrelation and cross-correlation system outputs are compared. The results demonstrate the feasibility of UWB SAW correlators for use in UWB communication transceivers. PMID:23475929

  2. Ultra Wideband Electromagnetic Phantoms for Antennas and Propagation Studies

    NASA Astrophysics Data System (ADS)

    Yamamoto, Hironobu; Zhou, Jian; Kobayashi, Takehiko

    Ultra wideband (UWB) technologies are expected to be used in ultra-high-speed wireless personal area networks (WPAN) and wireless body area networks (WBAN). UWB human electromagnetic phantoms are useful for performance evaluation of antennas mounted in the vicinity of a human body and channel assessment when a human body blocks a propagation path. Publications on UWB phantoms, however, have been limited so far. This paper describes the development of liquid UWB phantom material (aqueous solution of sucrose) and UWB arm and torso phantoms. The UWB phantoms are not intended to evaluate a specific absorption rate (SAR) in a human body, because UWB devices are supposed to transmit at very low power and thus should pose no human hazard.

  3. Copper ESEEM and HYSCORE through ultra-wideband chirp EPR spectroscopy.

    PubMed

    Segawa, Takuya F; Doll, Andrin; Pribitzer, Stephan; Jeschke, Gunnar

    2015-07-28

    The main limitation of pulse electron paramagnetic resonance (EPR) spectroscopy is its narrow excitation bandwidth. Ultra-wideband (UWB) excitation with frequency-swept chirp pulses over several hundreds of megahertz overcomes this drawback. This allows to excite electron spin echo envelope modulation (ESEEM) from paramagnetic copper centers in crystals, whereas up to now, only ESEEM of ligand nuclei like protons or nitrogens at lower frequencies could be detected. ESEEM spectra are recorded as two-dimensional correlation experiments, since the full digitization of the electron spin echo provides an additional Fourier transform EPR dimension. Thus, UWB hyperfine-sublevel correlation experiments generate a novel three-dimensional EPR-correlated nuclear modulation spectrum. PMID:26233121

  4. Measurement of the transient shielding effectiveness of enclosures using UWB pulses inside an open TEM waveguide

    NASA Astrophysics Data System (ADS)

    Herlemann, H.; Koch, M.

    2007-06-01

    Recently, new definitions of shielding effectiveness (SE) for high-frequency and transient electromagnetic fields were introduced by Klinkenbusch (2005). Numerical results were shown for closed as well as for non closed cylindrical shields. In the present work, a measurement procedure is introduced using ultra wideband (UWB) electromagnetic field pulses. The procedure provides a quick way to determine the transient shielding effectiveness of an enclosure without performing time consuming frequency domain measurements. For demonstration, a cylindrical enclosure made of conductive textile is examined. The field pulses are generated inside an open TEM-waveguide. From the measurement of the transient electric and magnetic fields with and without the shield in place, the electric and magnetic shielding effectiveness of the shielding material as well as the transient shielding effectiveness of the enclosure are derived.

  5. Ultra-wideband radios for time-of-flight-ranging and network position estimation

    DOEpatents

    Hertzog, Claudia A.; Dowla, Farid U.; Dallum, Gregory E.; Romero, Carlos E.

    2011-06-14

    This invention provides a novel high-accuracy indoor ranging device that uses ultra-wideband (UWB) RF pulsing with low-power and low-cost electronics. A unique of the present invention is that it exploits multiple measurements in time and space for very accurate ranging. The wideband radio signals utilized herein are particularly suited to ranging in harsh RF environments because they allow signal reconstruction in spite of multipath propagation distortion. Furthermore, the ranging and positioning techniques discussed herein directly address many of the known technical challenges encountered in UWB localization regarding synchronization and sampling. In the method developed, noisy, corrupted signals can be recovered by repeating range measurements across a channel, and the distance measurements are combined from many locations surrounding the target in a way that minimizes the range biases associated to indirect flight paths and through-wall propagation delays.

  6. UWB pulse propagation into human tissues

    NASA Astrophysics Data System (ADS)

    Cavagnaro, Marta; Pittella, Erika; Pisa, Stefano

    2013-12-01

    In this paper the propagation of a UWB pulse into a layered model of the human body is studied to characterize absorption and reflection of the UWB signal due to the different body tissues. Several time behaviours for the incident UWB pulse are considered and compared with reference to the feasibility of breath and heartbeat activity monitoring. Results show that if the UWB source is placed far from the human body, the reflection coming from the interface between air and skin can be used to detect the respiratory activity. On the contrary, if the UWB source is placed close to the human body, a small reflection due to the interface between the posterior lung wall and the bone, which is well distanced in time from the reflections due to the first layers of the body model, can be used to detect lung and heart changes associated with the cardio-respiratory activity.

  7. Repetitive, plasma switched, gigawatt, ultra-wideband impulse transmitter development

    SciTech Connect

    Clark, R.S.; Rinehart, L.F.; Buttram, M.T.; Aurand, J.F.; Lundstrom, J.M.; Patterson, P.E.; Roose, L.D.; Crowe, W.

    1992-01-01

    Sandia National Laboratories has developed several repetitive, ultra-wideband (UWB), impulse transmitters to address impulse source, and to support experimental applications. The sources fall into two different classes, pulse peaking and pulse shorting. SNIPER (Sub-Nanosecond ImPulsE Radiator) is a source which uses an oil peaking switch to obtain a fast risetime (250-pS) pulse of 2-nS duration. The output voltage ranges between few tens of kilovolts to 250-kV. EMBL (EnantioMorphic Blumlein) is a similar device (presently under development) which uses a gas switch to short the falling portion of a 2-nS pulse to approximately 100-pS. To date, an output voltage of approximately 600-kV has been obtained (700-kV is the design goal). Depending upon the source, repetitive operation from single shot to 5-kHz (1-kHz nominal) has been obtained with excellent reliability and repeatability. Both sources are plasma switched impulse transmitters using a Hydrogen-thyratron based modulator, an oil-filled Blumlein (of two types), a peaking (or shorting) switch and a wideband TEM horn. Powers exceeding one-gigawatt are routinely generated. This technology appears to be extendable to at least 10-gigawatts. The frequency spectrum of the radiated pulse from these sources include the spectrum of 100-MHz to 3-GHz. The pulse is generated externally and then injected into the antenna. Due to the high powers involved and the need to radiate a broad spectrum of frequencies, Sandia has concentrated on TEM horn antennas. Several TEM horns have been built and used during this program. In those cases where higher gains are desired for the higher frequencies, TEM horn-fed dish antennas have been employed. A detailed overview of the UWB Transmitters along with measured radiated electric field strengths will be presented.

  8. Repetitive, plasma switched, gigawatt, ultra-wideband impulse transmitter development

    SciTech Connect

    Clark, R.S.; Rinehart, L.F.; Buttram, M.T.; Aurand, J.F.; Lundstrom, J.M.; Patterson, P.E.; Roose, L.D.; Crowe, W.

    1992-09-01

    Sandia National Laboratories has developed several repetitive, ultra-wideband (UWB), impulse transmitters to address impulse source, and to support experimental applications. The sources fall into two different classes, pulse peaking and pulse shorting. SNIPER (Sub-Nanosecond ImPulsE Radiator) is a source which uses an oil peaking switch to obtain a fast risetime (250-pS) pulse of 2-nS duration. The output voltage ranges between few tens of kilovolts to 250-kV. EMBL (EnantioMorphic Blumlein) is a similar device (presently under development) which uses a gas switch to short the falling portion of a 2-nS pulse to approximately 100-pS. To date, an output voltage of approximately 600-kV has been obtained (700-kV is the design goal). Depending upon the source, repetitive operation from single shot to 5-kHz (1-kHz nominal) has been obtained with excellent reliability and repeatability. Both sources are plasma switched impulse transmitters using a Hydrogen-thyratron based modulator, an oil-filled Blumlein (of two types), a peaking (or shorting) switch and a wideband TEM horn. Powers exceeding one-gigawatt are routinely generated. This technology appears to be extendable to at least 10-gigawatts. The frequency spectrum of the radiated pulse from these sources include the spectrum of 100-MHz to 3-GHz. The pulse is generated externally and then injected into the antenna. Due to the high powers involved and the need to radiate a broad spectrum of frequencies, Sandia has concentrated on TEM horn antennas. Several TEM horns have been built and used during this program. In those cases where higher gains are desired for the higher frequencies, TEM horn-fed dish antennas have been employed. A detailed overview of the UWB Transmitters along with measured radiated electric field strengths will be presented.

  9. UCom: Ultra-wideband Communications in Harsh Propagation Environments

    SciTech Connect

    Nekoogar, F

    2007-03-14

    LLNL has developed an ultra-wideband (UWB) system that provides unique, through-the-wall wireless communications in heavy metallic and heavy concrete indoor channels. LLNL's UWB system is the only available wireless communications system that performs successfully and reliably in facilities where conventional narrowband communications usually fail due to destructive reflections from multiple surfaces. These environments include: cargo ships and reinforced, heavy concrete buildings. LLNL's revolutionary system has applications for the military, as well as commercial indoor communications in multistory buildings, and cluttered industrial structures.

  10. UWB dual burst transmit driver

    DOEpatents

    Dallum, Gregory E.; Pratt, Garth C.; Haugen, Peter C.; Zumstein, James M.; Vigars, Mark L.; Romero, Carlos E.

    2012-04-17

    A dual burst transmitter for ultra-wideband (UWB) communication systems generates a pair of precisely spaced RF bursts from a single trigger event. An input trigger pulse produces two oscillator trigger pulses, an initial pulse and a delayed pulse, in a dual trigger generator. The two oscillator trigger pulses drive a gated RF burst (power output) oscillator. A bias driver circuit gates the RF output oscillator on and off and sets the RF burst packet width. The bias driver also level shifts the drive signal to the level that is required for the RF output device.

  11. Analysis of a multi-access scheme and asynchronous transmit-only UWB for wireless body area networks.

    PubMed

    Keong, Ho Chee; Yuce, Mehmet R

    2009-01-01

    Ultra Wideband (UWB) has many favorable factors for use in a wireless body area network application. The major drawback is the high power consumption of an UWB receiver. One solution to address this problem is to use a transmit-only UWB sensor node. In this paper, we propose a multi-access scheme that is suitable for asynchronous transmit-only UWB wireless body area networks (UWB-WBAN). Each sensor attached on the patient under monitoring is assigned a unique number of UWB pulses per data bit. The number of UWB pulses assigned to the sensors is optimized to improve the bit error rate and system reliability. Simulation shows that through careful selection of the number of pulses for the sensors, it is possible to maintain almost similar bit error probability, regardless of the distance from the receiver. PMID:19964453

  12. An overview of Sandia National Laboratories' plasma switched, gigawatt, ultra-wideband impulse transmitter program

    SciTech Connect

    Clark, R.S.; Rinehart, L.F.; Buttram, M.T.; Aurand, J.F.

    1992-01-01

    Sandia National Laboratories has developed several repetitive, ultra-wideband (UWB), impulse transmitters to address impulse source technology and to support experimental applications. The sources fall into two different classes, pulse peaking and pulse shorting depending on how the UWB frequency components are generated. ne frequency spectrum of the radiated pulse from these sources include the spectrum of 100-MHz to 3-GHz. Depending upon the source, repetitive operation from single shot to 5-kHz (1-kHz nominal) has been obtained with excellent reliability and repeatability. SNIPER (Sub-Nanosecond impulse Radiator) is a source which uses an oil peaking switch to obtain a fast risetime (250-pS) pulse of 2-nS duration. The output voltage ranges between few tens of kilovolts to 250-kV. EMBL (EnantioMorphic Blumlein) is a similar device (presently under development) which uses a gas switch to sharpen the trailing edge of a 2-nS pulse to approximately 100-pS. To date, an output voltage of approximately 600-kV has been obtained (700- kV is the design goal). Since the frequency spectra are identical between sources with sharpened leading or trailing edges, alternatively, one can use parallel switches to short the pulse at its peak voltage. The pulse is generated externally and then injected into the antenna. Due to the high powers involved and the need to radiate a broad spectrum of frequencies, Sandia has concentrated on TEM horn. antennas with special high voltage feed adapters. Several TEM horns have been built and used during this program. In those cases where higher gains are desired for the higher frequencies, TEM horn-fed, dish antennas have been employed. An overview of the UWB transmitters, including design and operation of the modulators, the PFN'S, the pulse sharpening switches and the antennas will be presented.

  13. An overview of Sandia National Laboratories` plasma switched, gigawatt, ultra-wideband impulse transmitter program

    SciTech Connect

    Clark, R.S.; Rinehart, L.F.; Buttram, M.T.; Aurand, J.F.

    1992-11-01

    Sandia National Laboratories has developed several repetitive, ultra-wideband (UWB), impulse transmitters to address impulse source technology and to support experimental applications. The sources fall into two different classes, pulse peaking and pulse shorting depending on how the UWB frequency components are generated. ne frequency spectrum of the radiated pulse from these sources include the spectrum of 100-MHz to 3-GHz. Depending upon the source, repetitive operation from single shot to 5-kHz (1-kHz nominal) has been obtained with excellent reliability and repeatability. SNIPER (Sub-Nanosecond impulse Radiator) is a source which uses an oil peaking switch to obtain a fast risetime (250-pS) pulse of 2-nS duration. The output voltage ranges between few tens of kilovolts to 250-kV. EMBL (EnantioMorphic Blumlein) is a similar device (presently under development) which uses a gas switch to sharpen the trailing edge of a 2-nS pulse to approximately 100-pS. To date, an output voltage of approximately 600-kV has been obtained (700- kV is the design goal). Since the frequency spectra are identical between sources with sharpened leading or trailing edges, alternatively, one can use parallel switches to short the pulse at its peak voltage. The pulse is generated externally and then injected into the antenna. Due to the high powers involved and the need to radiate a broad spectrum of frequencies, Sandia has concentrated on TEM horn. antennas with special high voltage feed adapters. Several TEM horns have been built and used during this program. In those cases where higher gains are desired for the higher frequencies, TEM horn-fed, dish antennas have been employed. An overview of the UWB transmitters, including design and operation of the modulators, the PFN`S, the pulse sharpening switches and the antennas will be presented.

  14. An overview of Sandia National Laboratories' plasma switched, gigawatt, ultra-wideband impulse transmitter program

    NASA Astrophysics Data System (ADS)

    Clark, R. S.; Rinehart, L. F.; Buttram, M. T.; Aurand, J. F.

    Sandia National Laboratories has developed several repetitive, ultra-wideband (UWB), impulse transmitters to address impulse source technology and to support experimental applications. The sources fall into two different classes, pulse peaking and pulse shorting depending on how the UWB frequency components are generated. The frequency spectrum of the radiated pulse from these sources include the spectrum of 100-MHz to 3-GHz. Depending upon the source, repetitive operation from single shot to 5-kHz (1-kHz nominal) has been obtained with excellent reliability and repeatability. SNIPER (Sub-Nanosecond Impulse Radiator) is a source which uses an oil peaking switch to obtain a fast risetime (250-pS) pulse of 2-nS duration. The output voltage ranges between few tens of kilovolts to 250-kV. EMBL (EnantioMorphic Blumlein) is a similar device (presently under development) which uses a gas switch to sharpen the trailing edge of a 2-nS pulse to approximately 100-pS. To date, an output voltage of approximately 600-kV has been obtained (700-kV is the design goal). Since the frequency spectra are identical between sources with sharpened leading or trailing edges, alternatively, one can use parallel switches to short the pulse at its peak voltage. The pulse is generated externally and then injected into the antenna. Due to the high powers involved and the need to radiate a broad spectrum of frequencies, Sandia has concentrated on TEM horn antennas with special high voltage feed adapters. Several TEM horns have been built and used during this program. In those cases where higher gains are desired for the higher frequencies, TEM horn-fed, dish antennas have been employed. An overview of the UWB transmitters, including design and operation of the modulators, the PFN'S, the pulse sharpening switches and the antennas will be presented.

  15. Three-dimensional confocal imaging for breast cancer detection using CMOS Gaussian monocycle pulse transmitter and 4 × 4 ultra wideband antenna array with impedance matching layer

    NASA Astrophysics Data System (ADS)

    Sugitani, Takumi; Kubota, Shinichi; Hafiz, Mohiuddin; Xiao, Xia; Kikkawa, Takamaro

    2014-01-01

    A time-domain reflectometry breast cancer detection system was developed, which was composed of a Gaussian monocycle pulse (GMP) transmitter circuit fabricated by complementary metal oxide semiconductor (CMOS) 65 nm technology and an ultra wide-band (UWB) planar slot antenna array. The center frequency and bandwidth of the antenna were 6 and 9.2 GHz, respectively. The GMP train having the pulse width of 160 ps was generated by the 65 nm CMOS logic circuit with a core area of 0.0017 mm2 and was emitted by the 4 × 4 planar slot antenna array. The fabricated planar 4 × 4 antenna array with the matching layer could resolve the two separate 5 × 5 × 5 mm3 breast tumor phantoms, which were located at the depth of 22 mm with the spacing of 8 mm.

  16. Ultra-Wideband Tracking System Design for Relative Navigation

    NASA Technical Reports Server (NTRS)

    Ni, Jianjun David; Arndt, Dickey; Bgo, Phong; Dekome, Kent; Dusl, John

    2011-01-01

    This presentation briefly discusses a design effort for a prototype ultra-wideband (UWB) time-difference-of-arrival (TDOA) tracking system that is currently under development at NASA Johnson Space Center (JSC). The system is being designed for use in localization and navigation of a rover in a GPS deprived environment for surface missions. In one application enabled by the UWB tracking, a robotic vehicle carrying equipments can autonomously follow a crewed rover from work site to work site such that resources can be carried from one landing mission to the next thereby saving up-mass. The UWB Systems Group at JSC has developed a UWB TDOA High Resolution Proximity Tracking System which can achieve sub-inch tracking accuracy of a target within the radius of the tracking baseline [1]. By extending the tracking capability beyond the radius of the tracking baseline, a tracking system is being designed to enable relative navigation between two vehicles for surface missions. A prototype UWB TDOA tracking system has been designed, implemented, tested, and proven feasible for relative navigation of robotic vehicles. Future work includes testing the system with the application code to increase the tracking update rate and evaluating the linear tracking baseline to improve the flexibility of antenna mounting on the following vehicle.

  17. Orthogonal frequency coded filters for use in ultra-wideband communication systems.

    PubMed

    Gallagher, Daniel R; Malocha, Donald C; Puccio, Derek; Saldanha, Nancy

    2008-03-01

    The use of ultra-short pulses, producing very wide bandwidths and low spectral power density, are the widely accepted approach for ultra-wideband (UWB) communication systems. This approach is simple and can be implemented with current digital signal processing technologies. However, surface acoustic wave (SAW) devices have the capability of producing complex signals with wide bandwidths and relatively high frequency operation. This approach, using SAW based correlators, eliminates many of the costly components that are needed in the IF block in the transmitter and receiver, and reduces many of the signal processing requirements. This work presents the development of SAW correlators using orthogonal frequency coding (OFC) for use in UWB spread spectrum communication systems. OFC and pseudonoise (PN) coding provide a means for UWB spreading of data. The use of OFC spectrally spreads a PN sequence beyond that of code division multiple access (CDMA) because of the increased bandwidth providing an improvement in processing gain. The transceiver approach is still very similar to that of a CDMA but provides greater code diversity. Experimental results of a SAW filter designed with OFC transducers are presented. The SAW correlation filter was designed using seven contiguous chip frequencies within the transducer. SAW correlators with a 29% fractional bandwidth were fabricated on lithium niobate (LiNbO3) having a center frequency of 250 MHz. A coupling-of-modes (COM) model is used to predict the SAW filter response experimentally and is compared to the measured data. Good correlation between the predicted COM responses and the measured device data is obtained. Discussion of the design, analysis, and measurements are presented. The experimental matched filter results are shown for the OFC device and are compared to the ideal correlation. The results demonstrate the OFC SAW device concept for UWB communication transceivers. PMID:18407859

  18. 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.

  19. Background-free millimeter-wave ultra-wideband signal generation based on a dual-parallel Mach-Zehnder modulator.

    PubMed

    Zhang, Fangzheng; Pan, Shilong

    2013-11-01

    A novel scheme for photonic generation of a millimeter-wave ultra-wideband (MMW-UWB) signal is proposed and experimentally demonstrated based on a dual-parallel Mach-Zehnder modulator (DPMZM). In the proposed scheme, a single-frequency radio frequency (RF) signal is applied to one sub-MZM of the DPMZM to achieve optical suppressed-carrier modulation, and an electrical control pulse train is applied to the other sub-MZM biased at the minimum transmission point, to get an on/off switchable optical carrier. By filtering out the optical carrier with one of the first-order sidebands, and properly setting the amplitude of the control pulse, an MMW-UWB pulse train without the residual local oscillation is generated after photo-detection. The generated MMW-UWB signal is background-free, because the low-frequency components in the electrical spectrum are effectively suppressed. In the experiment, an MMW-UWB pulse train centered at 25 GHz with a 10-dB bandwidth of 5.5 GHz is successfully generated. The low frequency components are suppressed by 22 dB. PMID:24216925

  20. Optically addressed ultra-wideband phased antenna array

    NASA Astrophysics Data System (ADS)

    Bai, Jian

    Demands for high data rate and multifunctional apertures from both civilian and military users have motivated development of ultra-wideband (UWB) electrically steered phased arrays. Meanwhile, the need for large contiguous frequency is pushing operation of radio systems into the millimeter-wave (mm-wave) range. Therefore, modern radio systems require UWB performance from VHF to mm-wave. However, traditional electronic systems suffer many challenges that make achieving these requirements difficult. Several examples includes: voltage controlled oscillators (VCO) cannot provide a tunable range of several octaves, distribution of wideband local oscillator signals undergo high loss and dispersion through RF transmission lines, and antennas have very limited bandwidth or bulky sizes. Recently, RF photonics technology has drawn considerable attention because of its advantages over traditional systems, with the capability of offering extreme power efficiency, information capacity, frequency agility, and spatial beam diversity. A hybrid RF photonic communication system utilizing optical links and an RF transducer at the antenna potentially provides ultra-wideband data transmission, i.e., over 100 GHz. A successful implementation of such an optically addressed phased array requires addressing several key challenges. Photonic generation of an RF source with over a seven-octave bandwidth has been demonstrated in the last few years. However, one challenge which still remains is how to convey phased optical signals to downconversion modules and antennas. Therefore, a feed network with phase sweeping capability and low excessive phase noise needs to be developed. Another key challenge is to develop an ultra-wideband array antenna. Modern frontends require antennas to be compact, planar, and low-profile in addition to possessing broad bandwidth, conforming to stringent space, weight, cost, and power constraints. To address these issues, I will study broadband and miniaturization techniques for both single and array antennas. In addition, a prototype transmitting phased array system is developed and shown to demonstrate large bandwidth as well as a beam steering capability. The architecture of this system can be further developed to a large-scale array at higher frequencies such as mm-wave. This solution serves as a candidate for UWB multifunctional frontends.

  1. Ultra-wideband impedance sensor

    DOEpatents

    McEwan, T.E.

    1999-03-16

    The ultra-wideband impedance sensor (UWBZ sensor, or Z-sensor) is implemented in differential and single-ended configurations. The differential UWBZ sensor employs a sub-nanosecond impulse to determine the balance of an impedance bridge. The bridge is configured as a differential sample-and-hold circuit that has a reference impedance side and an unknown impedance side. The unknown impedance side includes a short transmission line whose impedance is a function of the near proximity of objects. The single-ended UWBZ sensor eliminates the reference side of the bridge and is formed of a sample and hold circuit having a transmission line whose impedance is a function of the near proximity of objects. The sensing range of the transmission line is bounded by the two-way travel time of the impulse, thereby eliminating spurious Doppler modes from large distant objects that would occur in a microwave CW impedance bridge. Thus, the UWBZ sensor is a range-gated proximity sensor. The Z-sensor senses the near proximity of various materials such as metal, plastic, wood, petroleum products, and living tissue. It is much like a capacitance sensor, yet it is impervious to moisture. One broad application area is the general replacement of magnetic sensors, particularly where nonferrous materials need to be sensed. Another broad application area is sensing full/empty levels in tanks, vats and silos, e.g., a full/empty switch in water or petroleum tanks. 2 figs.

  2. Ultra-wideband impedance sensor

    DOEpatents

    McEwan, Thomas E.

    1999-01-01

    The ultra-wideband impedance sensor (UWBZ sensor, or Z-sensor) is implemented in differential and single-ended configurations. The differential UWBZ sensor employs a sub-nanosecond impulse to determine the balance of an impedance bridge. The bridge is configured as a differential sample-and-hold circuit that has a reference impedance side and an unknown impedance side. The unknown impedance side includes a short transmission line whose impedance is a function of the near proximity of objects. The single-ended UWBZ sensor eliminates the reference side of the bridge and is formed of a sample and hold circuit having a transmission line whose impedance is a function of the near proximity of objects. The sensing range of the transmission line is bounded by the two-way travel time of the impulse, thereby eliminating spurious Doppler modes from large distant objects that would occur in a microwave CW impedance bridge. Thus, the UWBZ sensor is a range-gated proximity sensor. The Z-sensor senses the near proximity of various materials such as metal, plastic, wood, petroleum products, and living tissue. It is much like a capacitance sensor, yet it is impervious to moisture. One broad application area is the general replacement of magnetic sensors, particularly where nonferrous materials need to be sensed. Another broad application area is sensing full/empty levels in tanks, vats and silos, e.g., a full/empty switch in water or petroleum tanks.

  3. Compact electromagnetic bandgap structures for notch band in ultra-wideband applications.

    PubMed

    Rotaru, Mihai; Sykulski, Jan

    2010-01-01

    This paper introduces a novel approach to create notch band filters in the front-end of ultra-wideband (UWB) communication systems based on electromagnetic bandgap (EBG) structures. The concept presented here can be implemented in any structure that has a microstrip in its configuration. The EBG structure is first analyzed using a full wave electromagnetic solver and then optimized to work at WLAN band (5.15-5.825 GHz). Two UWB passband filters are used to demonstrate the applicability and effectiveness of the novel EBG notch band feature. Simulation results are provided for two cases studied. PMID:22163430

  4. Compact Electromagnetic Bandgap Structures for Notch Band in Ultra-Wideband Applications

    PubMed Central

    Rotaru, Mihai; Sykulski, Jan

    2010-01-01

    This paper introduces a novel approach to create notch band filters in the front-end of ultra-wideband (UWB) communication systems based on electromagnetic bandgap (EBG) structures. The concept presented here can be implemented in any structure that has a microstrip in its configuration. The EBG structure is first analyzed using a full wave electromagnetic solver and then optimized to work at WLAN band (5.15–5.825 GHz). Two UWB passband filters are used to demonstrate the applicability and effectiveness of the novel EBG notch band feature. Simulation results are provided for two cases studied. PMID:22163430

  5. Method of remote powering and detecting multiple UWB passive tags in an RFID system

    DOEpatents

    Dowla, Farid U.; Nekoogar, Faranak; Benzel, David M.; Dallum, Gregory E.; Spiridon, Alex

    2012-05-29

    A new Radio Frequency Identification (RFID), tracking, powering apparatus/system and method using coded Ultra-wideband (UWB) signaling is introduced. The proposed hardware and techniques disclosed herein utilize a plurality of passive UWB transponders in a field of an RFID-radar system. The radar system itself enables multiple passive tags to be remotely powered (activated) at about the same time frame via predetermined frequency UWB pulsed formats. Once such tags are in an activated state, an UWB radar transmits specific "interrogating codes" to put predetermined tags in an awakened status. Such predetermined tags can then communicate by a unique "response code" so as to be detected by an UWB system using radar methods.

  6. Augmented reality using ultra-wideband radar imagery

    NASA Astrophysics Data System (ADS)

    Nguyen, Lam; Koenig, Francois; Sherbondy, Kelly

    2011-06-01

    The U.S. Army Research Laboratory (ARL) has been investigating the utility of ultra-wideband (UWB) synthetic aperture radar (SAR) technology for detecting concealed targets in various applications. We have designed and built a vehicle-based, low-frequency UWB SAR radar for proof-of-concept demonstration in detecting obstacles for autonomous navigation, detecting concealed targets (mines, etc.), and mapping internal building structures to locate enemy activity. Although the low-frequency UWB radar technology offers valuable information to complement other technologies due to its penetration capability, it is very difficult to comprehend the radar imagery and correlate the detection list from the radar with the objects in the real world. Using augmented reality (AR) technology, we can superimpose the information from the radar onto the video image of the real world in real-time. Using this, Soldiers would view the environment and the superimposed graphics (SAR imagery, detection locations, digital map, etc.) via a standard display or a head-mounted display. The superimposed information would be constantly changed and adjusted for every perspective and movement of the user. ARL has been collaborating with ITT Industries to implement an AR system that integrates the video data captured from the real world and the information from the UWB radar. ARL conducted an experiment and demonstrated the real-time geo-registration of the two independent data streams. The integration of the AR sub-system into the radar system is underway. This paper presents the integration of the AR and SAR systems. It shows results that include the real-time embedding of the SAR imagery and other information into the video data stream.

  7. Software-Defined Ultra-wideband Radio Communications: A New RF Technology for Emergency Response Applications

    SciTech Connect

    Nekoogar, F; Dowla, F

    2009-10-19

    Reliable wireless communication links for local-area (short-range) and regional (long-range) reach capabilities are crucial for emergency response to disasters. Lack of a dependable communication system can result in disruptions in the situational awareness between the local responders in the field and the emergency command and control centers. To date, all wireless communications systems such as cell phones and walkie-talkies use narrowband radio frequency (RF) signaling for data communication. However, the hostile radio propagation environment caused by collapsed structures and rubble in various disaster sites results in significant degradation and attenuation of narrowband RF signals, which ends up in frequent communication breakdowns. To address the challenges of reliable radio communication in disaster fields, we propose an approach to use ultra-wideband (UWB) or wideband RF waveforms for implementation on Software Defined Radio (SDR) platforms. Ultra-wideband communications has been proven by many research groups to be effective in addressing many of the limitations faced by conventional narrowband radio technologies. In addition, LLNL's radio and wireless team have shown significant success in field deployment of various UWB communications system for harsh environments based on LLNL's patented UWB modulation and equalization techniques. Furthermore, using software defined radio platform for UWB communications offers a great deal of flexibility in operational parameters and helps the radio system to dynamically adapt itself to its environment for optimal performance.

  8. Ultra-wideband radar sensors and networks

    DOEpatents

    Leach, Jr., Richard R; Nekoogar, Faranak; Haugen, Peter C

    2013-08-06

    Ultra wideband radar motion sensors strategically placed in an area of interest communicate with a wireless ad hoc network to provide remote area surveillance. Swept range impulse radar and a heart and respiration monitor combined with the motion sensor further improves discrimination.

  9. Narrowband Registration of Ultra-Wideband Signal

    NASA Astrophysics Data System (ADS)

    Kamenev, A. V.; Satarov, R. N.; Yakubov, V. P.; Shipilov, S. E.

    2016-01-01

    The research of various parameters influence on the Fresnel reflector focusing properties in particular spatial sizes, the focal point position, etc. is conducted. The version of using a flat Fresnel reflector for receiving ultra-wideband signals with the use of Wiener filtering is suggested.

  10. UWB delay and multiply receiver

    DOEpatents

    Dallum, Gregory E.; Pratt, Garth C.; Haugen, Peter C.; Romero, Carlos E.

    2013-09-10

    An ultra-wideband (UWB) delay and multiply receiver is formed of a receive antenna; a variable gain attenuator connected to the receive antenna; a signal splitter connected to the variable gain attenuator; a multiplier having one input connected to an undelayed signal from the signal splitter and another input connected to a delayed signal from the signal splitter, the delay between the splitter signals being equal to the spacing between pulses from a transmitter whose pulses are being received by the receive antenna; a peak detection circuit connected to the output of the multiplier and connected to the variable gain attenuator to control the variable gain attenuator to maintain a constant amplitude output from the multiplier; and a digital output circuit connected to the output of the multiplier.

  11. UTag: Long-range Ultra-wideband Passive Radio Frequency Tags

    SciTech Connect

    Dowla, F

    2007-03-14

    Long-range, ultra-wideband (UWB), passive radio frequency (RF) tags are key components in Radio Frequency IDentification (RFID) system that will revolutionize inventory control and tracking applications. Unlike conventional, battery-operated (active) RFID tags, LLNL's small UWB tags, called 'UTag', operate at long range (up to 20 meters) in harsh, cluttered environments. Because they are battery-less (that is, passive), they have practically infinite lifetimes without human intervention, and they are lower in cost to manufacture and maintain than active RFID tags. These robust, energy-efficient passive tags are remotely powered by UWB radio signals, which are much more difficult to detect, intercept, and jam than conventional narrowband frequencies. The features of long range, battery-less, and low cost give UTag significant advantage over other existing RFID tags.

  12. Joint Time/Frequency Analysis and Design of Spiral Antennas and Arrays for Ultra-Wideband Applications

    NASA Astrophysics Data System (ADS)

    Elmansouri, Mohamed Ali

    Ultra-wideband (UWB) systems transmit and receive extremely short pulses, permitting the corresponding antennas to distort their shape. Thus the design of an antenna for a UWB system plays an important role for the reliability and quality of communication. A UWB antenna design coalesces both the determination of conventional frequency domain parameters and the analysis of time domain response into a single overarching system requirement. While the former is needed to ensure system's sensitivity, the later is critical to minimize pulse distortion. Well-designed spiral antennas are known for their almost frequency independent characteristics; thus they are viable candidates for UWB systems from the frequency-domain side. However, due to their fundamental principles of operation, they are dispersive and arguments were made they should not be used for pulsed UWB applications (time-domain side). The presented research unequivocally proves that spiral antennas and various derivatives thereof, including arrays, can be excellent candidates for multi-functional time/frequency domain systems. A complete framework for joint frequency and time domain characterization of planar spiral antennas in UWB communication systems is developed first. By utilizing theory, simulations, and experiments, all essential to the analysis frameworks, the various hypotheses are comprehensively treated and relevant conclusions are established. The dispersion and pulse distortion of the conventional spiral antennas are characterized in the radiation and system modes and conclusions regarding the effects of geometrical parameters such as number of arms, mode of operations, etc., on time- and frequency-domain performance are derived for the first time. A method based on controlling the spiral's growth rate and input pulse shape is demonstrated as an effective approach to reduce the pulse distortion. Theoretical pre-distortion compensation method based on a frequency-dependent delay removal technique is employed and performance enhancement of spiral antennas as pulse radiators is successfully demonstrated. A novel spiral antenna topology, named combined power spiral, is derived from first principles to have simultaneously excellent time- and frequency-domain performances without any auxiliary hardware and/or pre-distortion compensation. The role of the reflective cavity backing on the performance of spiral antennas in time and frequency domains is investigated in order to achieve an efficient unidirectional UWB radiation. Resistively-loaded cavity-backed spirals are designed as a compromise for achieving simultaneously good time and frequency domain performances while maintaining high efficiency over the most of operating bandwidth. The lens loading approach is used as a way to further improve the spiral's gain and reduce the amplitude distortion associated with a typical communication channel. UWB spiral arrays based on the derived good time/frequency two- and four-arm spiral antennas are developed and analyzed in time and frequency domains. Multi-mode capabilities of four-arm spirals are used to engineer a dual-circularly polarized array embodiment. To make these arrays practically more desirable, novel feeding scheme which significantly reduces the beamformer complexity is proposed. Time and frequency scanning capabilities and the advantages of the proposed arrays for UWB communications are also discussed. The results of this thesis can pave the way for the use of spiral antennas in many non-traditional, for spiral antennas, applications across commercial and military sectors.

  13. Performance of Ultra Wideband On-Body Communication Based on Statistical Channel Model

    NASA Astrophysics Data System (ADS)

    Wang, Qiong; Wang, Jianqing

    Ultra wideband (UWB) on-body communication is attracting much attention in biomedical applications. In this paper, the performance of UWB on-body communication is investigated based on a statistically extracted on-body channel model, which provides detailed characteristics of the multi-path-affected channel with an emphasis on various body postures or body movement. The possible data rate, the possible communication distance, as well as the bit error rate (BER) performance are clarified via computer simulation. It is found that the conventional correlation receiver is incompetent in the multi-path-affected on-body channel, while the RAKE receiver outperforms the conventional correlation receiver at a cost of structure complexity. Different RAKE receiver structures are compared to show the improvement of the BER performance.

  14. Suppression of radio frequency inteference (RFI) for synchronous impulse reconstruction ultra-wideband radar

    NASA Astrophysics Data System (ADS)

    Nguyen, Lam; Soumekh, Mehrdad

    2005-05-01

    This paper is concerned with the issues associated with the suppression of radio frequency interference (RFI) for a synchronous impulse reconstruction (SIRE) ultra-wideband (UWB) synthetic aperture radar (SAR) that is currently being designed and built at the Army Research Laboratory. In this effort, we are developing the next version of the UWB radar that can employ inexpensive A/D converters to digitize wideband signals using the equivalent time sampling technique. In this presentation, we provide an analytical model for the signature of the RFI sources that are measured via an equivalent time sampling scheme. This formulation reveals spectral as well as temporal properties of the measured RFI signals that would aid a user in developing sniff (passive) data collection strategies for constructing adaptive digital signal processing methods for suppressing RFI sources.

  15. Ultra-wideband horn antenna with abrupt radiator

    DOEpatents

    McEwan, Thomas E.

    1998-01-01

    An ultra-wideband horn antenna transmits and receives impulse waveforms for short-range radars and impulse time-of flight systems. The antenna reduces or eliminates various sources of close-in radar clutter, including pulse dispersion and ringing, sidelobe clutter, and feedline coupling into the antenna. Dispersion is minimized with an abrupt launch point radiator element; sidelobe and feedline coupling are minimized by recessing the radiator into a metallic horn. Low frequency cut-off associated with a horn is extended by configuring the radiator drive impedance to approach a short circuit at low frequencies. A tapered feed plate connects at one end to a feedline, and at the other end to a launcher plate which is mounted to an inside wall of the horn. The launcher plate and feed plate join at an abrupt edge which forms the single launch point of the antenna.

  16. Ultra-wideband horn antenna with abrupt radiator

    DOEpatents

    McEwan, T.E.

    1998-05-19

    An ultra-wideband horn antenna transmits and receives impulse waveforms for short-range radars and impulse time-of flight systems. The antenna reduces or eliminates various sources of close-in radar clutter, including pulse dispersion and ringing, sidelobe clutter, and feedline coupling into the antenna. Dispersion is minimized with an abrupt launch point radiator element; sidelobe and feedline coupling are minimized by recessing the radiator into a metallic horn. Low frequency cut-off associated with a horn is extended by configuring the radiator drive impedance to approach a short circuit at low frequencies. A tapered feed plate connects at one end to a feedline, and at the other end to a launcher plate which is mounted to an inside wall of the horn. The launcher plate and feed plate join at an abrupt edge which forms the single launch point of the antenna. 8 figs.

  17. Ultra-wideband Propagation Loss Around a Human Body in Various Surrounding Environments

    NASA Astrophysics Data System (ADS)

    Yamamoto, H.; Kobayashi, T.

    Ultra-wideband (UWB) technologies have been anticipated for use in wireless body area networks (WBAN) because of their low power consumption and anti-multipath capabilities. This chapter presents the UWB (3.1-10.6 GHz) propagation loss in WBAN scenarios between on-body antennas in three different surrounding environments. The measurements were performed in a 3-m radio anechoic chamber, a classroom, and a small room. The propagation paths were roughly divided into line-of-sight (LOS) and non-LOS (NLOS) ones. Small rooms, particularly NLOS, yielded higher reception power than larger rooms. This was attributed to the ample multipath from the nearby floor, walls, and ceiling. The UWB maximum propagation losses in three surrounding environments were smaller than ones of CW (6.85 GHz). This is because nulls caused by interference were cancelled out by the ultra-wide bandwidth. The propagation losses of low-band (3.4-4.8 GHz) and high-band (7.25-10.25 GHz) UWB were also evaluated. In WBAN scenarios, the low-band yielded lower propagation loss than the high-band and approximately the same loss as the full-band UWB (3.1-10.6 GHz).

  18. Ultra-Wideband Time-Difference-of-Arrival High Resolution 3D Proximity Tracking System

    NASA Technical Reports Server (NTRS)

    Ni, Jianjun; Arndt, Dickey; Ngo, Phong; Phan, Chau; Dekome, Kent; Dusl, John

    2010-01-01

    This paper describes a research and development effort for a prototype ultra-wideband (UWB) tracking system that is currently under development at NASA Johnson Space Center (JSC). The system is being studied for use in tracking of lunar./Mars rovers and astronauts during early exploration missions when satellite navigation systems are not available. U IATB impulse radio (UWB-IR) technology is exploited in the design and implementation of the prototype location and tracking system. A three-dimensional (3D) proximity tracking prototype design using commercially available UWB products is proposed to implement the Time-Difference- Of-Arrival (TDOA) tracking methodology in this research effort. The TDOA tracking algorithm is utilized for location estimation in the prototype system, not only to exploit the precise time resolution possible with UWB signals, but also to eliminate the need for synchronization between the transmitter and the receiver. Simulations show that the TDOA algorithm can achieve the fine tracking resolution with low noise TDOA estimates for close-in tracking. Field tests demonstrated that this prototype UWB TDOA High Resolution 3D Proximity Tracking System is feasible for providing positioning-awareness information in a 3D space to a robotic control system. This 3D tracking system is developed for a robotic control system in a facility called "Moonyard" at Honeywell Defense & System in Arizona under a Space Act Agreement.

  19. 47 CFR 15.521 - Technical requirements applicable to all UWB devices.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 1 2011-10-01 2011-10-01 false Technical requirements applicable to all UWB devices. 15.521 Section 15.521 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL RADIO FREQUENCY DEVICES Ultra-Wideband Operation § 15.521 Technical requirements applicable to all UWB devices. (a) UWB devices may not be employed for...

  20. 47 CFR 15.521 - Technical requirements applicable to all UWB devices.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 1 2012-10-01 2012-10-01 false Technical requirements applicable to all UWB devices. 15.521 Section 15.521 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL RADIO FREQUENCY DEVICES Ultra-Wideband Operation § 15.521 Technical requirements applicable to all UWB devices. (a) UWB devices may not be employed for...

  1. 47 CFR 15.517 - Technical requirements for indoor UWB systems.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 1 2014-10-01 2014-10-01 false Technical requirements for indoor UWB systems... DEVICES Ultra-Wideband Operation 15.517 Technical requirements for indoor UWB systems. (a) Operation under the provisions of this section is limited to UWB transmitters employed solely for indoor...

  2. 47 CFR 15.517 - Technical requirements for indoor UWB systems.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 1 2013-10-01 2013-10-01 false Technical requirements for indoor UWB systems... DEVICES Ultra-Wideband Operation 15.517 Technical requirements for indoor UWB systems. (a) Operation under the provisions of this section is limited to UWB transmitters employed solely for indoor...

  3. 47 CFR 15.517 - Technical requirements for indoor UWB systems.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 1 2012-10-01 2012-10-01 false Technical requirements for indoor UWB systems... DEVICES Ultra-Wideband Operation 15.517 Technical requirements for indoor UWB systems. (a) Operation under the provisions of this section is limited to UWB transmitters employed solely for indoor...

  4. 47 CFR 15.517 - Technical requirements for indoor UWB systems.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 1 2011-10-01 2011-10-01 false Technical requirements for indoor UWB systems... DEVICES Ultra-Wideband Operation 15.517 Technical requirements for indoor UWB systems. (a) Operation under the provisions of this section is limited to UWB transmitters employed solely for indoor...

  5. 47 CFR 15.519 - Technical requirements for hand held UWB systems.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false Technical requirements for hand held UWB... DEVICES Ultra-Wideband Operation § 15.519 Technical requirements for hand held UWB systems. (a) UWB devices operating under the provisions of this section must be hand held, i.e., they are relatively...

  6. 47 CFR 15.519 - Technical requirements for hand held UWB systems.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 1 2011-10-01 2011-10-01 false Technical requirements for hand held UWB... DEVICES Ultra-Wideband Operation § 15.519 Technical requirements for hand held UWB systems. (a) UWB devices operating under the provisions of this section must be hand held, i.e., they are relatively...

  7. Waveform Analysis of UWB GPR Antennas

    PubMed Central

    Rial, Fernando I.; Lorenzo, Henrique; Pereira, Manuel; Armesto, Julia

    2009-01-01

    Ground Penetrating Radar (GPR) systems fall into the category of ultra-wideband (UWB) devices. Most GPR equipment covers a frequency range between an octave and a decade by using short-time pulses. Each signal recorded by a GPR gathers a temporal log of attenuated and distorted versions of these pulses (due to the effect of the propagation medium) plus possible electromagnetic interferences and noise. In order to make a good interpretation of this data and extract the most possible information during processing, a deep knowledge of the wavelet emitted by the antennas is essential. Moreover, some advanced processing techniques require specific knowledge of this signal to obtain satisfactory results. In this work, we carried out a series of tests in order to determine the source wavelet emitted by a ground-coupled antenna with a 500 MHz central frequency. PMID:22573965

  8. Waveform Analysis of UWB GPR Antennas.

    PubMed

    Rial, Fernando I; Lorenzo, Henrique; Pereira, Manuel; Armesto, Julia

    2009-01-01

    Ground Penetrating Radar (GPR) systems fall into the category of ultra-wideband (UWB) devices. Most GPR equipment covers a frequency range between an octave and a decade by using short-time pulses. Each signal recorded by a GPR gathers a temporal log of attenuated and distorted versions of these pulses (due to the effect of the propagation medium) plus possible electromagnetic interferences and noise. In order to make a good interpretation of this data and extract the most possible information during processing, a deep knowledge of the wavelet emitted by the antennas is essential. Moreover, some advanced processing techniques require specific knowledge of this signal to obtain satisfactory results. In this work, we carried out a series of tests in order to determine the source wavelet emitted by a ground-coupled antenna with a 500 MHz central frequency. PMID:22573965

  9. Multi-pulse multi-delay (MPMD) multiple access modulation for UWB

    SciTech Connect

    Dowla, Farid U.; Nekoogar, Faranak

    2007-03-20

    A new modulation scheme in UWB communications is introduced. This modulation technique utilizes multiple orthogonal transmitted-reference pulses for UWB channelization. The proposed UWB receiver samples the second order statistical function at both zero and non-zero lags and matches the samples to stored second order statistical functions, thus sampling and matching the shape of second order statistical functions rather than just the shape of the received pulses.

  10. 3D positioning scheme exploiting nano-scale IR-UWB orthogonal pulses.

    PubMed

    Kim, Nammoon; Kim, Youngok

    2011-01-01

    In these days, the development of positioning technology for realizing ubiquitous environments has become one of the most important issues. The Global Positioning System (GPS) is a well-known positioning scheme, but it is not suitable for positioning in in-door/building environments because it is difficult to maintain line-of-sight condition between satellites and a GPS receiver. To such problem, various positioning methods such as RFID, WLAN, ZigBee, and Bluetooth have been developed for indoor positioning scheme. However, the majority of positioning schemes are focused on the two-dimension positioning even though three-dimension (3D) positioning information is more useful especially in indoor applications, such as smart space, U-health service, context aware service, etc. In this paper, a 3D positioning system based on mutually orthogonal nano-scale impulse radio ultra-wideband (IR-UWB) signals and cross array antenna is proposed. The proposed scheme uses nano-scale IR-UWB signals providing fine time resolution and high-resolution multiple signal specification algorithm for the time-of-arrival and the angle-of-arrival estimation. The performance is evaluated over various IEEE 802.15.4a channel models, and simulation results show the effectiveness of proposed scheme. PMID:21970578

  11. The Parkes Ultra-Wideband Receiver

    NASA Astrophysics Data System (ADS)

    Manchester, Richard N.

    2015-08-01

    An ultra-wideband receiver system for the Parkes 64-m radio telescope covering the frequency range 0.7 - 4.0 GHz is currently under construction. Its main applications will be to pulsar studies, but it will also be used for spectral-line and continuum background polarisation studies and VLBI. A new feed design with remarkably constant beam properties across the band and excellent polarisation performance will be used. We plan to directly digitise the RF signals in the focus cabin and transmit the digital data via optical fibre to a versatile signal processing system using FPGA processors and a GPU cluster located in the telescope tower. With the relatively low radio frequency and very wide band, dealing with radio frequency interference is a critical issue. We have undertaken surveys of the RFI environment at Parkes and are developing several complementary techniques for mitigating the effects on data quality of both broad-band transients and quasi-stationary narrow-band signals.

  12. Ultra-wideband electronics, design methods, algorithms, and systems for dielectric spectroscopy of isolated B16 tumor cells in liquid medium

    NASA Astrophysics Data System (ADS)

    Maxwell, Erick N.

    Quantifying and characterizing isolated tumor cells (ITCs) is of interest in surgical pathology and cytology for its potential to provide data for cancer staging, classification, and treatment. Although the independent prognostic significance of circulating ITCs has not been proven, their presence is gaining clinical relevance as an indicator. However, researchers have not established an optimal method for detecting ITCs. Consequently, this Ph.D. dissertation is concerned with the development and evaluation of dielectric spectroscopy as a low-cost method for cell characterization and quantification. In support of this goal, ultra-wideband (UWB), microwave pulse generator circuits, coaxial transmission line fixtures, permittivity extraction algorithms, and dielectric spectroscopy measurement systems were developed for evaluating the capacity to quantify B16-F10 tumor cells in suspension. First, this research addressed challenges in developing tunable UWB circuits for pulse generation. In time-domain dielectric spectroscopy, a tunable UWB pulse generator facilitates exploration of microscopic dielectric mechanisms, which contribute to dispersion characteristics. Conventional approaches to tunable pulse generator design have resulted in complex circuit topologies and unsymmetrical waveform morphologies. In this research, a new design approach for low-complexity, tunable, sub-nanosecond and UWB pulse generator was developed. This approach was applied to the development of a novel generator that produces symmetrical waveforms (patent pending 60/597,746). Next, this research addressed problems with transmission-reflection (T/R) measurement of cell suspensions. In T/R measurement, coaxial transmission line fixtures have historically required an elaborate sample holder for containing liquids, resulting in high cost and complexity. Furthermore, the algorithms used to extract T/R dielectric properties have suffered from myriad problems including local minima and halfwavelength resonance. In this dissertation, a simple coaxial transmission line fixture for holding liquids by dispensing with the air-core assumption inherent in previous designs was developed (patent pending 60/916,042). In addition, a genetic algorithm was applied towards extracting dielectric properties from measurement data to circumvent problems of local minima and half wavelength resonance. Finally, in this research the capacity for using dielectric properties to quantify isolated B16-F10 tumor cells in McCoy's liquid medium was investigated. In so doing, the utility of the Maxwell-Wagner mixture formula for cell quantification was demonstrated by measuring distinct dielectric properties for differing volumes of cell suspensions using frequency- and time-domain dielectric spectroscopy.

  13. Technical note: a novel approach to the detection of estrus in dairy cows using ultra-wideband technology.

    PubMed

    Homer, E M; Gao, Y; Meng, X; Dodson, A; Webb, R; Garnsworthy, P C

    2013-10-01

    Detection of estrus is a key determinant of profitability of dairy herds, but estrus is increasingly difficult to observe in the modern dairy cow with shorter duration and less-intense estrus. Concurrent with the unfavorable correlation between milk yield and fertility, estrus-detection rates have declined to less than 50%. We tested ultra-wideband (UWB) radio technology (Thales Research & Technology Ltd., Reading, UK) for proof of concept that estrus could be detected in dairy cows (two 1-wk-long trials; n=16 cows, 8 in each test). The 3-dimensional positions of 12 cows with synchronized estrous cycles and 4 pregnant control cows were monitored continuously using UWB mobile units operating within a network of 8 base units for a period of 7d. In the study, 10 cows exhibited estrus as confirmed by visual observation, activity monitoring, and milk progesterone concentrations. Automated software was developed for analysis of UWB data to detect cows in estrus and report the onset of estrus in real time. The UWB technology accurately detected 9 out of 10 cows in estrus. In addition, UWB technology accurately confirmed all 6 cows not in estrus. In conclusion, UWB technology can accurately detect estrus and hence we have demonstrated proof of concept for a novel technology that has significant potential to improve estrus-detection rates. PMID:23910546

  14. UWB Wind Turbine Blade Deflection Sensing for Wind Energy Cost Reduction.

    PubMed

    Zhang, Shuai; Jensen, Tobias Lindstrøm; Franek, Ondrej; Eggers, Patrick C F; Olesen, Kim; Byskov, Claus; Pedersen, Gert Frølund

    2015-01-01

    A new application of utilizing ultra-wideband (UWB) technology to sense wind turbine blade deflections is introduced in this paper for wind energy cost reduction. The lower UWB band of 3.1-5.3 GHz is applied. On each blade, there will be one UWB blade deflection sensing system, which consists of two UWB antennas at the blade root and one UWB antenna at the blade tip. The detailed topology and challenges of this deflection sensing system are addressed. Due to the complexity of the problem, this paper will first realize the on-blade UWB radio link in the simplest case, where the tip antenna is situated outside (and on the surface of) a blade tip. To investigate this case, full-blade time-domain measurements are designed and conducted under different deflections. The detailed measurement setups and results are provided. If the root and tip antenna locations are properly selected, the first pulse is always of sufficient quality for accurate estimations under different deflections. The measured results reveal that the blade tip-root distance and blade deflection can be accurately estimated in the complicated and lossy wireless channels around a wind turbine blade. Some future research topics on this application are listed finally. PMID:26274964

  15. UWB Wind Turbine Blade Deflection Sensing for Wind Energy Cost Reduction

    PubMed Central

    Zhang, Shuai; Jensen, Tobias Lindstrøm; Franek, Ondrej; Eggers, Patrick C. F.; Olesen, Kim; Byskov, Claus; Pedersen, Gert Frølund

    2015-01-01

    A new application of utilizing ultra-wideband (UWB) technology to sense wind turbine blade deflections is introduced in this paper for wind energy cost reduction. The lower UWB band of 3.1–5.3 GHz is applied. On each blade, there will be one UWB blade deflection sensing system, which consists of two UWB antennas at the blade root and one UWB antenna at the blade tip. The detailed topology and challenges of this deflection sensing system are addressed. Due to the complexity of the problem, this paper will first realize the on-blade UWB radio link in the simplest case, where the tip antenna is situated outside (and on the surface of) a blade tip. To investigate this case, full-blade time-domain measurements are designed and conducted under different deflections. The detailed measurement setups and results are provided. If the root and tip antenna locations are properly selected, the first pulse is always of sufficient quality for accurate estimations under different deflections. The measured results reveal that the blade tip-root distance and blade deflection can be accurately estimated in the complicated and lossy wireless channels around a wind turbine blade. Some future research topics on this application are listed finally. PMID:26274964

  16. Ultra wideband ground penetrating radar imaging of heterogeneous solids

    DOEpatents

    Warhus, John P.; Mast, Jeffrey E.

    1998-01-01

    A non-invasive imaging system for analyzing engineered structures comprises pairs of ultra wideband radar transmitters and receivers in a linear array that are connected to a timing mechanism that allows a radar echo sample to be taken at a variety of delay times for each radar pulse transmission. The radar transmitters and receivers are coupled to a position determining system that provides the x,y position on a surface for each group of samples measured for a volume from the surface. The radar transmitter and receivers are moved about the surface, e.g., attached to the bumper of a truck, to collect such groups of measurements from a variety of x,y positions. Return signal amplitudes represent the relative reflectivity of objects within the volume and the delay in receiving each signal echo represents the depth at which the object lays in the volume and the propagation speeds of the intervening material layers. Successively deeper z-planes are backward propagated from one layer to the next with an adjustment for variations in the expected propagation velocities of the material layers that lie between adjacent z-planes.

  17. Ultra wideband ground penetrating radar imaging of heterogeneous solids

    DOEpatents

    Warhus, J.P.; Mast, J.E.

    1998-11-10

    A non-invasive imaging system for analyzing engineered structures comprises pairs of ultra wideband radar transmitters and receivers in a linear array that are connected to a timing mechanism that allows a radar echo sample to be taken at a variety of delay times for each radar pulse transmission. The radar transmitters and receivers are coupled to a position determining system that provides the x,y position on a surface for each group of samples measured for a volume from the surface. The radar transmitter and receivers are moved about the surface, e.g., attached to the bumper of a truck, to collect such groups of measurements from a variety of x,y positions. Return signal amplitudes represent the relative reflectivity of objects within the volume and the delay in receiving each signal echo represents the depth at which the object lays in the volume and the propagation speeds of the intervening material layers. Successively deeper z-planes are backward propagated from one layer to the next with an adjustment for variations in the expected propagation velocities of the material layers that lie between adjacent z-planes. 11 figs.

  18. Matching layer for path loss reduction in ultra wideband implant communications.

    PubMed

    Chavez-Santiago, Raul; Khaleghi, Ali; Balasingham, Ilangko

    2014-01-01

    Real-time monitoring of various physiological signals is of utmost importance for the treatment of chronic conditions. Radio technology can enable real-time sensing and collection of physiological data to facilitate timely medication and early pre-hospital management of patients. This can be realized with the aid of implantable biomedical sensors with the capability to transmit wirelessly the collected information to an external unit for display and analysis. Currently, commercial wireless medical implantable sensors operate in frequencies below 1 GHz with narrowband signals. Recently, it has been demonstrated that ultra wideband (UWB) signals could be also used for the radio interface of these devices. However, establishing an implant communication link in the allocated UWB spectrum of 3.1-10.6 GHz is challenging. The attenuation of UWB signals propagating through biological tissues at these frequencies is high. Part of these path losses are caused by the impedance mismatch between the two propagation environments (i.e., air and biological tissues) that constitute an implant communication link. This mismatch results in inefficient power transmission of the radio waves. In this paper we propose the use of a layer of dielectric material that can be applied on the patient's skin. The permittivity value of this matching layer has to be chosen such that wave coupling is maximized. Through numerical simulations we determined the appropriate permittivity value of a matching layer for UWB implant communication links in the human thorax for 1-6 GHz. Path loss reduction of up to 10 dB can be obtained in this frequency band. These results can help improve the use of UWB signals for other in-body biomedical devices like the wireless capsule endoscope (WCE). PMID:25571604

  19. Switchable UWB pulse generation using a polarization maintaining fiber Bragg grating as frequency discriminator.

    PubMed

    Feng, Xinhuan; Li, Zhaohui; Guan, Bai-Ou; Lu, C; Tam, H Y; Wai, P K A

    2010-02-15

    We propose and successfully demonstrate a novel approach to optically generate ultrawideband (UWB) pulse with switchable shape and polarity by using a polarization-maintaining fiber Bragg grating (PM-FBG) as frequency discriminator. Depending on the shape of the reflective spectrum of the PM-FBG, the system can function as a first- or second-order differentiator for the generation of Gaussian UWB monocycle or doublet pulses. Consequently, the shape and the polarity of the generated UWB pulse can be switched by simple adjustment of a polarization controller (PC). Gaussian monocycle and doublet pulses were successfully obtained with fractional bandwidths of about 188% and 152%, respectively. Higher-order UWB pulses with spectrum covering from 2.9 GHz to 9.8 GHz have also been obtained through adjustment of the PC. PMID:20389374

  20. Photonic generation of millimeter-wave ultra-wideband signal using phase modulation to intensity modulation conversion and frequency up-conversion

    NASA Astrophysics Data System (ADS)

    Yu, Yuan; Dong, Jianji; Li, Xiang; Zhang, Xinliang

    2012-04-01

    We propose and experimentally demonstrate the generation of a pair of polarity-reversed 24 GHz millimeter-wave (MMW) ultra-wideband (UWB) monocycles. The scheme is realized by using delay interferometer (DI) based phase modulation to intensity modulation (PM-IM) conversion and carrier suppression modulation (CSM) based frequency up-conversion. The phase modulation is realized by using either electro-optic phase modulator (EOPM) or cross phase modulation (XPM) in semiconductor optical amplifier (SOA), which is an all-optical approach to obtaining baseband UWB signals, respectively. After frequency up-converted by using CSM in a Mach-Zehnder modulator (MZM), a pair of polarity-reversed 24 GHz MMW-UWB signals complying with the Federal Communication Committee (FCC) requirements is generated. The bi-phase modulation (BPM) of 24 GHz MMW-UWB signals can also be realized by electrically switching the bias voltage of delay interferometer.

  1. Principle and experimental results of ultra-wideband noise radar imaging of a cylindrical conducting object using diffraction tomography

    NASA Astrophysics Data System (ADS)

    Shin, Hee Jung; Asmuth, Mark A.; Narayanan, Ram M.; Rangaswamy, Muralidhar

    2015-05-01

    In this paper, the principle, simulation, and experiment results of tomographic imaging of a cylindrical conducting object using random noise waveforms are presented. Theoretical analysis of scattering and the image reconstruction technique are developed based on physical optics approximation and Fourier diffraction tomography, respectively. The bistatic radar system is designed to transmit band-limited ultra-wideband (UWB) random noise waveforms at a fixed position, and a linear scanner allows a single receiving antenna to move along a horizontal axis for backward scattering measurement in the frequency range from 3-5 GHz. The reconstructed tomographic image of the rotating cylindrical conducting object based on experimental results are seen to be in good agreement with the simulation results, which demonstrates the capability of UWB noise radar for complete two-dimensional tomographic image reconstruction of a cylindrical conducting object.

  2. Ultra-wideband transparent 90° polarization conversion metasurfaces

    NASA Astrophysics Data System (ADS)

    Chen, Hongya; Ma, Hua; Wang, Jiafu; Qu, Shaobo; Pang, Yongqiang; Yan, Mingbao; Li, Yongfeng

    2016-04-01

    We propose to realize ultra-wideband transparent 90° polarization conversion metasurfaces by combining multiple plasmon resonances and Fabry-Perot-like resonances. An ultra-wideband polarization conversion metasurface is designed using a double-head arrow structure and metal gratings. It has been demonstrated that the bandwidth can be broadened greatly based on multiple plasmon resonances, while the efficiency can be enhanced strongly based on Fabry-Perot-like resonances. The both simulated and measured results show that the bandwidth of cross-polarized transmission is very wide, with a 1:6 3 dB bandwidth. The experimental results agree well with simulation ones.

  3. A Novel Picosecond Pulse Generation Circuit Based on SRD and NLTL

    PubMed Central

    Zhou, Jianming; Lu, Qiuyuan; Liu, Fan; Li, Yinqiao

    2016-01-01

    Because of the importance of ultra-wideband (UWB) radar in various applications, short pulse generation in UWB systems has attracted a lot of attention in recent years. In order to shorten the pulse, nonlinear transmission line (NLTL) is imported, which expands the application of step recovery diode (SRD) for pulse generation. Detailed analysis and equations for this SRD and NLTL-based pulse generation are provided and verified by simulation and experimental results. Factors that could cause pulse waveform distortions are also analyzed. The generator circuit presented in this paper generates 130ps and 3.3V pulse, which can be used in UWB radar systems that require sub-nanosecond pulses. PMID:26919290

  4. A Novel Picosecond Pulse Generation Circuit Based on SRD and NLTL.

    PubMed

    Zhou, Jianming; Lu, Qiuyuan; Liu, Fan; Li, Yinqiao

    2016-01-01

    Because of the importance of ultra-wideband (UWB) radar in various applications, short pulse generation in UWB systems has attracted a lot of attention in recent years. In order to shorten the pulse, nonlinear transmission line (NLTL) is imported, which expands the application of step recovery diode (SRD) for pulse generation. Detailed analysis and equations for this SRD and NLTL-based pulse generation are provided and verified by simulation and experimental results. Factors that could cause pulse waveform distortions are also analyzed. The generator circuit presented in this paper generates 130ps and 3.3V pulse, which can be used in UWB radar systems that require sub-nanosecond pulses. PMID:26919290

  5. Measurement of Ultra Wideband Radar Cross Sections of an Automobile at Ka Band Using Circular Polarizations

    NASA Astrophysics Data System (ADS)

    Osaki, Hideyuki; Nishide, Takehiko; Kobayashi, Takehiko

    Ultra wideband (UWB) radar cross sections (RCSs) of several targets have been measured using various combinations of transmitting and receiving linear polarizations (V-V, H-H, and +45°--45°) with a view to obtaining information on the design of vehicular short-range radars. This paper reports the UWB RCSs (σLR and σLL) of a typical passenger automobile using two circular polarization combinations (L and R denote left and right circular polarizations). The wideband measurements were carried out with use of a vector network analyzer by sweeping the frequency from 24.5 to 28.8GHz in a radio anechoic chamber. The UWB RCSs were derived by integrating the received power in the frequency domain. Similar to the linear polarization results, fluctuations of the RCSs were smaller in the UWB than in narrowband for both L-R and L-L, because the ultra-wide bandwidth cancels out RCS plunges caused by narrowband interference among reflected waves from various facets of the target. The median of (σLR-σLL) was 2dB, while the median of (σHH-σ+45°--45°) or (σVV-σ+45°--45°) was 6dB. This is because the body of the automobile comprises a number of smaller scattering objects yielding σLL, either similar to the corner reflectors or asymmetrical to the radar boresight. Frequency-domain responses showed a number of notches caused by the interference between numerous reflecting waves having power levels of a similar order and different round-trip path lengths. Some representative reflective parts of the automobile were identified through analyses of time-domain responses.

  6. Small Patch Antennas for UWB Wireless Body Area Network

    NASA Astrophysics Data System (ADS)

    Klemm, M.; Trster, G.

    This paper presents the transient characteristics of an aperture-stacked patch antenna (ASPA) and its miniaturized version. These antennas were designed for ultra-wideband (UWB) body area network (BAN) applications, to operate within the 3 to 6 GHz frequency band. The APSA with large ground plane size has a planar dimensions 70 70 mm2, the smaller version has dimensions 32 26 mm2. The latest yields 85% reduction of the antenna surface. Time- and frequency-domain characteristics of these antennas were calculated in a transmission mode (Tx) and also in a complete, two-antenna (Tx-Rx) system. We have used 3 different waveforms to drive the antenna: gaussian pulse (duration-250 ps), monocycle pulse (duration-300 ps) and defined wavelet (duration-650 ps). The received pulses have very similar shapes (fidelity >90%), but they differ in the voltage amplitudes. Results show that the highest received voltage (best transmission efficiency) is achieved for the pulse with the closest spectrum to the antenna's transfer function characteristic. In order to disclose the effects of the human body proximity, two body models were built and full-wave FDTD method was employed to carry out the simulations. Significant changes of the UWB antenna performance when close to the body were identified. The most important effects are the seriously decreased radiation efficiency (16 to 34%) and different (from that in a free space) shape of the antenna transfer function. The first one can have the impact on low power implementations of UWB wearable radios; the second one discloses possible influence on the UWB systems design (especially for template receivers). The impact of the human body on antenna characteristics was identified to be a key factor in UWB body-worn antenna design.

  7. Design and investigation of planar technology based ultra-wideband antenna with directional radiation patterns

    NASA Astrophysics Data System (ADS)

    Meena, M. L.; Parmar, Girish; Kumar, Mithilesh

    2016-03-01

    A novel design technique based on planar technology for ultra-wideband (UWB) antennas with different ground shape having directional radiation pattern is being presented here. Firstly, the L-shape corner reflector ground plane antenna is designed with microstrip feed line in order to achieve large bandwidth and directivity. Thereafter, for the further improvement in the directivity as well as for better impedance matching the parabolic-shape ground plane has been introduced. The coaxial feed line is given for the proposed directional antenna in order to achieve better impedance matching with 50 ohm transmission line. The simulation analysis of the antenna is done on CST Microwave Studio software using FR-4 substrate having thickness of 1.6 mm and dielectric constant of 4.4. The simulated result shows a good return loss (S11) with respect to -10 dB. The radiation pattern characteristic, angular width, directivity and bandwidth performance of the antenna have also been compared at different resonant frequencies. The designed antennas exhibit low cost, low reflection coefficient and better directivity in the UWB frequency band.

  8. Ultra-Wideband Sensors for Improved Magnetic Resonance Imaging, Cardiovascular Monitoring and Tumour Diagnostics

    PubMed Central

    Thiel, Florian; Kosch, Olaf; Seifert, Frank

    2010-01-01

    The specific advantages of ultra-wideband electromagnetic remote sensing (UWB radar) make it a particularly attractive technique for biomedical applications. We partially review our activities in utilizing this novel approach for the benefit of high and ultra-high field magnetic resonance imaging (MRI) and other applications, e.g., for intensive care medicine and biomedical research. We could show that our approach is beneficial for applications like motion tracking for high resolution brain imaging due to the non-contact acquisition of involuntary head motions with high spatial resolution, navigation for cardiac MRI due to our interpretation of the detected physiological mechanical contraction of the heart muscle and for MR safety, since we have investigated the influence of high static magnetic fields on myocardial mechanics. From our findings we could conclude, that UWB radar can serve as a navigator technique for high and ultra-high field magnetic resonance imaging and can be beneficial preserving the high resolution capability of this imaging modality. Furthermore it can potentially be used to support standard ECG analysis by complementary information where sole ECG analysis fails. Further analytical investigations have proven the feasibility of this method for intracranial displacements detection and the rendition of a tumour’s contrast agent based perfusion dynamic. Beside these analytical approaches we have carried out FDTD simulations of a complex arrangement mimicking the illumination of a human torso model incorporating the geometry of the antennas applied. PMID:22163498

  9. Full-duplex multiband orthogonal frequency division multiplexing ultra-wideband over fiber system

    NASA Astrophysics Data System (ADS)

    He, Jing; Wen, Xuejie; Chen, Ming; Chen, Lin; Su, Jinshu

    2015-01-01

    A full-duplex multiband orthogonal frequency division multiplexing (MB-OFDM) ultra-wideband over fiber (UWBoF) system is proposed, and bidirectional transmission of a 1.28-Gbps MB-OFDM UWB signal over 50-km standard single-mode fiber (SSMF) is demonstrated. An optical remote heterodyning mixing scheme is employed to generate a 60-GHz optical millimeter wave. Meanwhile, an optical carrier without modulation data is extracted by using a fiber Bragg grating for the uplink MB-OFDM UWB signal transmission. After 50-km SSMF transmission at a bit error rate of 1×10-4, the power penalties are 0.7 dB for a 4 quadrature amplitude modulation (QAM)-uplink and 1.0 dB for a 16QAM-uplink, respectively. The proposed scheme would greatly reduce the cost and significantly improve the spectrum utilization efficiency in the full-duplex MB-OFDM UWBoF systems.

  10. Performance Evaluation of a UWB-RFID System for Potential Space Applications

    NASA Technical Reports Server (NTRS)

    Phan, Chan T.; Arndt, D.; Ngo, P.; Gross, J.; Ni, Jianjun; Rafford, Melinda

    2006-01-01

    This talk presents a brief overview of the ultra-wideband (UWB) RFID system with emphasis on the performance evaluation of a commercially available UWB-RFID system. There are many RFID systems available today, but many provide just basic identification for auditing and inventory tracking. For applications that require high precision real time tracking, UWB technology has been shown to be a viable solution. The use of extremely short bursts of RF pulses offers high immunity to interference from other RF systems, precise tracking due to sub-nanosecond time resolution, and robust performance in multipath environments. The UWB-RFID system Sapphire DART (Digital Active RFID & Tracking) will be introduced in this talk. Laboratory testing using Sapphire DART is performed to evaluate its capability such as coverage area, accuracy, ease of operation, and robustness. Performance evaluation of this system in an operational environment (a receiving warehouse) for inventory tracking is also conducted. Concepts of using the UWB-RFID technology to track astronauts and assets are being proposed for space exploration.

  11. Matched filter design optimisation for UWB receiver for sensor network application

    NASA Astrophysics Data System (ADS)

    Naik, Rohit; Singh, Jugdutt; Veljanovski, Ronny

    2005-12-01

    Ultra Wideband (UWB) communications is one of the possible solutions for future wireless personal area network (WPAN) applications. The Federal Communications Commission (FCC), in the USA, allocated 7.5 GHz of unlicensed frequency bandwidth from 3.1 GHz to 10.6 GHz for UWB communication. It is an available spectrum which can be utilised for data communication using different technologies complying with FCC regulations. This paper presents a brief overview of the world wide regulations and Institute of Electrical and Electronic Engineers (IEEE) standardisation updates for UWB. It also focuses on the wireless sensor network application and the use of UWB communications in biomedical sensor networks. The paper aims at the design and implementation of an optimised pulsed matched filter (OPMF) used in the digital backend of a UWB radio. The optimisations are performed at the architectural and circuit level in order to reduce hardware complexity and reduced power. The OPMF is successfully implemented using the application specific integrated circuit (ASIC) design methodology and the results are compared with those obtained in previous implementation. The OPMF implementation presented in this paper yields improved characteristics such as reduction in area, almost 25% power reduction and better timing.

  12. Impulse radio ultra wideband wireless transmission of dopamine concentration levels recorded by fast-scan cyclic voltammetry.

    PubMed

    Ebrazeh, Ali; Bozorgzadeh, Bardia; Mohseni, Pedram

    2015-08-01

    This paper demonstrates the feasibility of utilizing impulse radio ultra wideband (IR-UWB) signaling technique for reliable, wireless transmission of dopamine concentration levels recorded by fast-scan cyclic voltammetry (FSCV) at a carbon-fiber microelectrode (CFM) to address the problem of elevated data rates in high-channel-count neurochemical monitoring. Utilizing an FSCV-sensing chip fabricated in AMS 0.35μm 2P/4M CMOS, a 3-5-GHz, IR-UWB transceiver (TRX) chip fabricated in TSMC 90nm 1P/9M RF CMOS, and two off-chip, miniature, UWB antennae, wireless transfer of pseudo-random binary sequence (PRBS) data at 50Mbps over a distance of <;1m is first shown with bit-error rates (BER) <; 10(-3). Further, IR-UWB wireless transmission of dopamine concentration levels prerecorded with FSCV at a CFM during flow injection analysis (FIA) is also demonstrated with transmitter (TX) power dissipation of only ~4.4μW from 1.2V, representing two orders of magnitude reduction in TX power consumption compared to that of a conventional frequency-shift-keyed (FSK) link operating at ~433MHz. PMID:26737929

  13. An Ultra-Wideband Millimeter-Wave Phased Array

    NASA Technical Reports Server (NTRS)

    Novak, Markus H.; Miranda, Felix A.; Volakis, John L.

    2016-01-01

    Wideband millimeter-wave arrays are of increasing importance due to their growing use in high data rate systems, including 5G communication networks. In this paper, we present a new class of ultra-wideband millimeter wave arrays that operate from nearly 20 GHz to 90 GHz. The array is based on tightly coupled dipoles. Feeding designs and fabrication challenges are presented, and a method for suppressing feed resonances is provided.

  14. Ultra-wideband Active Receiving Array Antenna with Dual Polarization

    NASA Astrophysics Data System (ADS)

    Koshelev, V. I.; Balzovsky, E. V.; Buyanov, Yu. I.

    This chapter presents results of the investigations directed to creation of large ultra-wideband active receiving array antennas with dual polarization. The array element is made on the basis of two crossed electric dipoles. Each arm of the dipoles is loaded to the single-stage FET amplifier. Four such elements form a 2 2 module being a component of a multielement array antenna.

  15. Liquid and moisture sensing by ultra-wideband pseudo-noise sequence signals

    NASA Astrophysics Data System (ADS)

    Sachs, J.; Peyerl, P.; Wöckel, S.; Kmec, M.; Herrmann, R.; Zetik, R.

    2007-04-01

    The use of ultra-wideband signals for moisture sensing by electromagnetic wave interaction provides more information on the material under test compared to single tone or narrowband approaches, regarding spatial and frequency dependent phenomena. Current activities to regulate the emission of electromagnetic waves in the spectral band up to 10 GHz for sensor applications open new perspectives for microwave moisture sensing. Therefore, improved and cost effective ultra-wideband measurement principles will become more and more interesting. The use of short pulses or swept sine waves are classic approaches to cover a large spectral band. However, this paper deals with some variants of an alternative method, which applies pseudo-random codes, namely M-sequences, to stimulate the test objects. The method permits monolithic integration of the RF-electronics in SiGe technology. The signal generation and data capturing are referred to a common stable single tone clock and they are controlled by steep trigger signals. This provides for very stable operation, which allows for measurements in both time and frequency domain. Two versions of an M-sequence approach will be considered and their functioning will be demonstrated by means of simple measurement examples.

  16. Amplify-and-Forward Cooperative Diversity for Green UWB-Based WBSNs

    PubMed Central

    2013-01-01

    This paper proposes a novel green cooperative diversity technique based on suboptimal template-based ultra-wideband (UWB) wireless body sensor networks (WBSNs) using amplify-and-forward (AF) relays. In addition, it analyzes the bit-error-rate (BER) performance of the proposed nodes. The analysis is based on the moment-generating function (MGF) of the total signal-to-noise ratio (SNR) at the destination. It also provides an approximate value for the total SNR. The analysis studies the performance of equally correlated binary pulse position modulation (EC-BPPM) assuming the sinusoidal and square suboptimal template pulses. Numerical results are provided for the performance evaluation of optimal and suboptimal template-based nodes with and without relay cooperation. Results show that one relay node provides ~23 dB performance enhancement at 1e − 3 BER, which mitigates the effect of the nondesirable non-line-of-sight (NLOS) links in WBSNs. PMID:24307880

  17. Design and Performance Evaluation on Ultra-Wideband Time-Of-Arrival 3D Tracking System

    NASA Technical Reports Server (NTRS)

    Ni, Jianjun; Arndt, Dickey; Ngo, Phong; Dusl, John

    2012-01-01

    A three-dimensional (3D) Ultra-Wideband (UWB) Time--of-Arrival (TOA) tracking system has been studied at NASA Johnson Space Center (JSC) to provide the tracking capability inside the International Space Station (ISS) modules for various applications. One of applications is to locate and report the location where crew experienced possible high level of carbon-dioxide and felt upset. In order to accurately locate those places in a multipath intensive environment like ISS modules, it requires a robust real-time location system (RTLS) which can provide the required accuracy and update rate. A 3D UWB TOA tracking system with two-way ranging has been proposed and studied. The designed system will be tested in the Wireless Habitat Testbed which simulates the ISS module environment. In this presentation, we discuss the 3D TOA tracking algorithm and the performance evaluation based on different tracking baseline configurations. The simulation results show that two configurations of the tracking baseline are feasible. With 100 picoseconds standard deviation (STD) of TOA estimates, the average tracking error 0.2392 feet (about 7 centimeters) can be achieved for configuration Twisted Rectangle while the average tracking error 0.9183 feet (about 28 centimeters) can be achieved for configuration Slightly-Twisted Top Rectangle . The tracking accuracy can be further improved with the improvement of the STD of TOA estimates. With 10 picoseconds STD of TOA estimates, the average tracking error 0.0239 feet (less than 1 centimeter) can be achieved for configuration "Twisted Rectangle".

  18. UWB Tracking Software Development

    NASA Technical Reports Server (NTRS)

    Gross, Julia; Arndt, Dickey; Ngo, Phong; Phan, Chau; Dusl, John; Ni, Jianjun; Rafford, Melinda

    2006-01-01

    An Ultra-Wideband (UWB) two-cluster Angle of Arrival (AOA) tracking prototype system is currently being developed and tested at NASA Johnson Space Center for space exploration applications. This talk discusses the software development efforts for this UWB two-cluster AOA tracking system. The role the software plays in this system is to take waveform data from two UWB radio receivers as an input, feed this input into an AOA tracking algorithm, and generate the target position as an output. The architecture of the software (Input/Output Interface and Algorithm Core) will be introduced in this talk. The development of this software has three phases. In Phase I, the software is mostly Matlab driven and calls C++ socket functions to provide the communication links to the radios. This is beneficial in the early stage when it is necessary to frequently test changes in the algorithm. Phase II of the development is to have the software mostly C++ driven and call a Matlab function for the AOA tracking algorithm. This is beneficial in order to send the tracking results to other systems and also to improve the tracking update rate of the system. The third phase is part of future work and is to have the software completely C++ driven with a graphics user interface. This software design enables the fine resolution tracking of the UWB two-cluster AOA tracking system.

  19. Radiated Emission of Breath Monitoring System Based on UWB Pulses in Spacecraft Modules

    NASA Astrophysics Data System (ADS)

    Russo, P.; Mariani Primiani, V.; De Leo, A.; Cerri, G.

    2012-05-01

    The paper describes some EMC aspects related to a UWB radar for monitoring astronauts breathing activity. Compliance to EMC space standards forces some design aspects, in particular the peak voltage and the pulse waveform. Moreover some simulations were carried out to consider realistic operating condition. In the first case the interference towards a victim wifi circuit was analyzed, in the second case the effect of the environment on the radiated pulse was studied.

  20. Response to FCC 98-208 notice of inquiry in the matter of revision of part 15 of the commission's rules regarding ultra-wideband transmission systems

    SciTech Connect

    Morey, R M

    1998-12-08

    In general, Micropower Impulse Radar (MIR) depends on Ultra-Wideband (UWB) transmission systems. UWB technology can supply innovative new systems and products that have an obvious value for radar and communications uses. Important applications include bridge-deck inspection systems, ground penetrating radar, mine detection, and precise distance resolution for such things as liquid level measurement. Most of these UWB inspection and measurement methods have some unique qualities, which need to be pursued. Therefore, in considering changes to Part 15 the FCC needs to take into account the unique features of UWB technology. MIR is applicable to two general types of UWB systems: radar systems and communications systems. Currently LLNL and its licensees are focusing on radar or radar type systems. LLNL is evaluating MIR for specialized communication systems. MIR is a relatively low power technology. Therefore, MIR systems seem to have a low potential for causing harmful interference to other users of the spectrum since the transmitted signal is spread over a wide bandwidth, which results in a relatively low spectral power density.

  1. All optical ultra-wideband signal generation and transmission using mode-locked laser incorporated with add-drop microring resonator

    NASA Astrophysics Data System (ADS)

    Soltanian, M. R. K.; Amiri, I. S.; Alavi, S. E.; Ahmad, H.

    2015-06-01

    The novel technique for generating the robust, ultra-wideband (UWB) signal in the optical domain using a mode-locked laser incorporated with an add-drop microring resonator filter is presented. In order to enable the down conversion of the UWB signal to the RF domain, two wavelength ranges 1553.72 and 1553.92 nm, which are 24.65 GHz apart from each other, are used. These wavelengths were generated based on a single longitudinal mode (SLM) dual-wavelength fiber laser in a laser ring cavity. The upper wavelength of the generated dual-wavelength laser is modulated with the UWB spectrum using an optical carrier suppression (OCS) scheme and the lower wavelength is kept unmodulated. After beating the modulated and unmodulated wavelength by launching into the photodiode, the 24 GHz UWB signal can be generated to be applied to UWB over fiber (UWBoF) technology. The error vector magnitude (EVM) for the signal transmission was calculated and the EVM below 10% is achieved for 25 Km optical and 20 m wireless links.

  2. Three-Dimensional Planetary Surface Tracking Based on a Simple Ultra-Wideband Impulse-Radio Infrastructure

    NASA Technical Reports Server (NTRS)

    Barton, Richard J.; Ni, David; Ngo, Phong

    2010-01-01

    Several prototype ultra-wideband (UWB) impulse-radio (IR) tracking systems are currently under development at NASA Johnson Space Center (JSC). These systems are being studied for use in tracking of Lunar/Mars rovers and astronauts during early exploration missions when satellite navigation systems (such as GPS) are not available. To date, the systems that have been designed and tested are intended only for two-dimensional location and tracking, but these designs can all be extended to three-dimensional tracking with only minor modifications and increases in complexity. In this presentation, we will briefly review the design and performance of two of the current 2-D systems: one designed specifically for short-range, extremely high-precision tracking (approximately 1-2 cm resolution) and the other designed specifically for much longer range tracking with less stringent precision requirements (1-2 m resolution). We will then discuss a new multi-purpose system design based on a simple UWB-IR architecture that can be deployed easily on a planetary surface to support arbitrary three-dimensional localization and tracking applications. We will discuss utilization of this system as an infrastructure to provide both short-range and long-range tracking and analyze the localization performance of the system in several different configurations. We will give theoretical performance bounds for some canonical system configurations and compare these performance bounds with both numerical simulations of the system as well as actual experimental system performance evaluations.

  3. Remote Respiration Monitoring Using Ultra-wideband Microwave Sensor

    NASA Astrophysics Data System (ADS)

    Higashikatsuragi, Kenji; Nakahata, Youichiro; Matsunami, Isamu; Kajiwara, Akihiro

    Impulse based ultra-wideband radio has lately attracted considerable attention as medical monitoring sensor since it is expected to measure bio-signals of a patient on a bed such as respiration rate and heartbeat with a remote non-contact approach. It is also friendly to the environment including the human body due to the very low electromagnetic energy emission. Using conventional ranging scheme, however, high speed A/D device should be required in order to detect the small respiratory displacement. This paper suggests a respiratory monitoring scheme where the respiration rate is measured by observing the variation of the path strength from the patient. Therefore, it does not require high speed A/D. It also makes possible to design the simultaneous monitoring of multiple patients in hospital beds, for example. In this paper the measurements were conducted for various scenarios and the feasibility is discussed.

  4. On UWB beamforming

    NASA Astrophysics Data System (ADS)

    Kaiser, T.

    2004-05-01

    Ultra-Wideband (UWB) communication systems and Multi-Input-Multi-Output (MIMO) techniques rank among the few emerging key technologies in wireless communications. For that reason the marriage of these two complementary approaches should deserve attention. Apparently, the extremely large ultra-wide bandwidth creates rich multipath diversity which calls, at a first glance, additional antenna elements into question. However, another point of view is as follows. The attenuation by solid materials usually increases with increasing frequency; e.g. frequencies above, say, 10 GHz are considered to be blocked by walls etc. Since UWB can occupy more than 7 GHz of bandwidth (according to FCC regularisation) the performance of a communication link can be physically extended only by adding spatial information, i.e. multiple antennas, even if such extension may play a minor role. From this point of view UWB& MIMO presents an upper physical bound for indoor communications and is therefore at least worth to be investigated. In order to see the forest for the trees, we will focus in this limited contribution on beamforming among all alternative MIMO techniques (like space time coding or spatial multiplexing).

  5. Ultra-wideband radar methods and techniques of medical sensing and imaging

    NASA Astrophysics Data System (ADS)

    Paulson, Christine N.; Chang, John T.; Romero, Carlos E.; Watson, Joseph; Pearce, Fred J.; Levin, Nathan

    2005-11-01

    Ultra-wideband radar holds great promise for a variety of medical applications. We have demonstrated the feasibility of using ultra-wideband sensors for detection of internal injuries, monitoring of respiratory and cardiac functions, and continuous non-contact imaging of the human body. Sensors are low-power, portable, and do not require physical contact with the patient. They are ideal for use by emergency responders to make rapid diagnosis and triage decisions. In the hospital, vital signs monitoring and imaging application could improve patient outcomes. In this paper we present an overview of ultra-wideband radar technology, discuss key design tradeoffs, and give examples of ongoing research in applying ultra-wideband technology to the medical field.

  6. Studies of scattering, reflectivity, and transmitivity in WBAN channel: feasibility of using UWB.

    PubMed

    Kabir, Md Humaun; Ashrafuzzaman, Kazi; Chowdhury, M Sanaullah; Kwak, Kyung Sup

    2010-01-01

    The Wireless Personal Area Network (WPAN) is one of the fledging paradigms that the next generation of wireless systems is sprouting towards. Among them, a more specific category is the Wireless Body Area Network (WBAN) used for health monitoring. On the other hand, Ultra-Wideband (UWB) comes with a number of desirable features at the physical layer for wireless communications. One big challenge in adoption of UWB in WBAN is the fact that signals get attenuated exponentially. Due to the intrinsic structural complexity in human body, electromagnetic waves show a profound variation during propagation through it. The reflection and transmission coefficients of human body are highly dependent upon the dielectric constants as well as upon the frequency. The difference in structural materials such as fat, muscles and blood essentially makes electromagnetic wave attenuation to be different along the way. Thus, a complete characterization of body channel is a challenging task. The connection between attenuation and frequency of the signal makes the investigation of UWB in WBAN an interesting proposition. In this paper, we study analytically the impact of body channels on electromagnetic signal propagation with reference to UWB. In the process, scattering, reflectivity and transmitivity have been addressed with analysis of approximate layer-wise modeling, and with numerical depictions. Pulses with Gaussian profile have been employed in our analysis. It shows that, under reasonable practical approximations, the human body channel can be modeled in layers so as to have the effects of total reflections or total transmissions in certain frequency bands. This could help decide such design issues as antenna characteristics of implant devices for WBAN employing UWB. PMID:22219673

  7. UWB Tracking System Design for Free-Flyers

    NASA Technical Reports Server (NTRS)

    Ni, Jianjun; Arndt, Dickey; Phan, Chan; Ngo, Phong; Gross, Julia; Dusl, John

    2004-01-01

    This paper discusses an ultra-wideband (UWB) tracking system design effort for Mini-AERCam (Autonomous Extra-vehicular Robotic Camera), a free-flying video camera system under development at NASA Johnson Space Center for aid in surveillance around the International Space Station (ISS). UWB technology is exploited to implement the tracking system due to its properties, such as high data rate, fine time resolution, and low power spectral density. A system design using commercially available UWB products is proposed. A tracking algorithm TDOA (Time Difference of Arrival) that operates cooperatively with the UWB system is developed in this research effort. Matlab simulations show that the tracking algorithm can achieve fine tracking resolution with low noise TDOA data. Lab experiments demonstrate the UWB tracking capability with fine resolution.

  8. The GIMLI: A Compact High-Power UWB Radiation Source

    NASA Astrophysics Data System (ADS)

    Delmote, P.; Martin, B.

    This chapter presents the design and performances of a compact, general-purpose, high-power ultra-wideband (UWB) source named GIMLI. The system was designed for dual use, homeland security and military applications. It is powered by a compact, coaxial 12-stage Marx generator with a rise time lower than 25 ns and an operating voltage up to 360 kV. A fast monocycle pulse is sharpened using a pulse former (MPF). The shaper stage comprises a switching module including a peaking and a grounding multi-channel spark gap under a N2 pressure of 6 MPa. The module is followed by a monopulse-to-monocycle converter based on a coaxial Blumlein pulse forming line. The bipolar signal measured at the output of the MPF has a duration shorter than 2 ns with a rise time of 250 ps. The peak-to-peak output voltage is 250 kV on a 50 Ω resistive load. Repetitive operation of the MPF has been experienced with a 200 Hz Tesla transformer developed by the CEA (Commissariat à l'Energie Atomique). Electromagnetic energy is focused by a dedicated antenna. The designed antenna is a TEM half-horn with two ridges which improve the low-frequency focusing. High-power radiation tests show that the field measured at a distance of 9 m from the TEM Horn-antenna is higher than 120 kV/m.

  9. UWB Technology and Applications on Space Exploration

    NASA Technical Reports Server (NTRS)

    Ngo, Phong; Phan, Chau; Gross, Julia; Dusl, John; Ni, Jianjun; Rafford, Melinda

    2006-01-01

    Ultra-wideband (UWB), also known as impulse or carrier-free radio technology, is one promising new technology. In February 2002, the Federal Communications Commission (FCC) approved the deployment of this technology. It is increasingly recognized that UWB technology holds great potential to provide significant benefits in many terrestrial and space applications such as precise positioning/tracking and high data rate mobile wireless communications. This talk presents an introduction to UWB technology and some applications on space exploration. UWB is characterized by several uniquely attractive features, such as low impact on other RF systems due to its extremely low power spectral densities, immunity to interference from narrow band RF systems due to its ultra-wide bandwidth, multipath immunity to fading due to ample multipath diversity, capable of precise positioning due to fine time resolution, capable of high data rate multi-channel performance. The related FCC regulations, IEEE standardization efforts and industry activities also will be addressed in this talk. For space applications, some projects currently under development at NASA Johnson Space Center will be introduced. These include the UWB integrated communication and tracking system for Lunar/Mars rover and astronauts, UWB-RFID ISS inventory tracking, and UWB-TDOA close-in high resolution tracking for potential applications on robonaut.

  10. Ultra Wideband Indoor Positioning Technologies: Analysis and Recent Advances.

    PubMed

    Alarifi, Abdulrahman; Al-Salman, AbdulMalik; Alsaleh, Mansour; Alnafessah, Ahmad; Al-Hadhrami, Suheer; Al-Ammar, Mai A; Al-Khalifa, Hend S

    2016-01-01

    In recent years, indoor positioning has emerged as a critical function in many end-user applications; including military, civilian, disaster relief and peacekeeping missions. In comparison with outdoor environments, sensing location information in indoor environments requires a higher precision and is a more challenging task in part because various objects reflect and disperse signals. Ultra WideBand (UWB) is an emerging technology in the field of indoor positioning that has shown better performance compared to others. In order to set the stage for this work, we provide a survey of the state-of-the-art technologies in indoor positioning, followed by a detailed comparative analysis of UWB positioning technologies. We also provide an analysis of strengths, weaknesses, opportunities, and threats (SWOT) to analyze the present state of UWB positioning technologies. While SWOT is not a quantitative approach, it helps in assessing the real status and in revealing the potential of UWB positioning to effectively address the indoor positioning problem. Unlike previous studies, this paper presents new taxonomies, reviews some major recent advances, and argues for further exploration by the research community of this challenging problem space. PMID:27196906

  11. Ultra Wideband Indoor Positioning Technologies: Analysis and Recent Advances †

    PubMed Central

    Alarifi, Abdulrahman; Al-Salman, AbdulMalik; Alsaleh, Mansour; Alnafessah, Ahmad; Al-Hadhrami, Suheer; Al-Ammar, Mai A.; Al-Khalifa, Hend S.

    2016-01-01

    In recent years, indoor positioning has emerged as a critical function in many end-user applications; including military, civilian, disaster relief and peacekeeping missions. In comparison with outdoor environments, sensing location information in indoor environments requires a higher precision and is a more challenging task in part because various objects reflect and disperse signals. Ultra WideBand (UWB) is an emerging technology in the field of indoor positioning that has shown better performance compared to others. In order to set the stage for this work, we provide a survey of the state-of-the-art technologies in indoor positioning, followed by a detailed comparative analysis of UWB positioning technologies. We also provide an analysis of strengths, weaknesses, opportunities, and threats (SWOT) to analyze the present state of UWB positioning technologies. While SWOT is not a quantitative approach, it helps in assessing the real status and in revealing the potential of UWB positioning to effectively address the indoor positioning problem. Unlike previous studies, this paper presents new taxonomies, reviews some major recent advances, and argues for further exploration by the research community of this challenging problem space. PMID:27196906

  12. Ultra-Wideband Optical Modulation Spectrometer (OMS) Development

    NASA Technical Reports Server (NTRS)

    Gardner, Jonathan (Technical Monitor); Tolls, Volker

    2004-01-01

    The optical modulation spectrometer (OMS) is a novel, highly efficient, low mass backend for heterodyne receiver systems. Current and future heterodyne receiver systems operating at frequencies up to a few THz require broadband spectrometer backends to achieve spectral resolutions of R approximately 10(exp 5) to 10(exp 6) to carry out many important astronomical investigations. Among these are observations of broad emission and absorption lines from extra-galactic objects at high redshifts, spectral line surveys, and observations of planetary atmospheres. Many of these lines are pressure or velocity broadened with either large half-widths or line wings extending over several GHz. Current backend systems can cover the needed bandwidth only by combining the output of several spectrometers, each with typically up to 1 GHz bandwidth, or by combining several frequency-shifted spectra taken with a single spectrometer. An ultra-wideband optical modulation spectrometer with 10 - 40 GHz bandwidth will enable broadband ob- servations without the limitations and disadvantages of hybrid spectrometers. Spectrometers like the OMS will be important for both ground-based observatories and future space missions like the Single Aperture Far-Infrared Telescope (SAFIR) which might carry IR/submm array heterodyne receiver systems requiring a spectrometer for each array pixel. Small size, low mass and small power consumption are extremely important for space missions. This report summarizes the specifications developed for the OMS and lists already identified commercial parts. The report starts with a review of the principle of operation, then describes the most important components and their specifications which were derived from theory, and finishes with a conclusion and outlook.

  13. UWB multi-burst transmit driver for averaging receivers

    DOEpatents

    Dallum, Gregory E

    2012-11-20

    A multi-burst transmitter for ultra-wideband (UWB) communication systems generates a sequence of precisely spaced RF bursts from a single trigger event. There are two oscillators in the transmitter circuit, a gated burst rate oscillator and a gated RF burst or RF power output oscillator. The burst rate oscillator produces a relatively low frequency, i.e., MHz, square wave output for a selected transmit cycle, and drives the RF burst oscillator, which produces RF bursts of much higher frequency, i.e., GHz, during the transmit cycle. The frequency of the burst rate oscillator sets the spacing of the RF burst packets. The first oscillator output passes through a bias driver to the second oscillator. The bias driver conditions, e.g., level shifts, the signal from the first oscillator for input into the second oscillator, and also controls the length of each RF burst. A trigger pulse actuates a timing circuit, formed of a flip-flop and associated reset time delay circuit, that controls the operation of the first oscillator, i.e., how long it oscillates (which defines the transmit cycle).

  14. Performance evaluation of photonic UWB generation based on silicon MZM.

    PubMed

    Shao, Haifeng; Chen, Weiwei; Zhao, Yong; Chi, Hao; Yang, Jianyi; Jiang, Xiaoqing

    2012-03-26

    Silicon photonics has emerged as the premier candidate for the photonic systems-on-chip (SoC). The scheme based on the silicon Mach-Zehnder modulator (MZM) to generate photonic ultra-wideband (UWB) signals is helpful to the integration of the UWB system with other optical networks on a single silicon-based chip. In this paper, according to the influence of the nonlinear free carrier dispersion (FCD) effect and the free carrier absorption (FCA) effect, the performance of two typical UWB generation schemes is numerically analyzed. The double side-band UWB (DSB-UWB) generation scheme needs the DC reverse bias which increases the complexity of the modulator and there is a residual chirp resulting from the FCD effect even the push-pull operation is adopted. The quasi single-sideband UWB (QSSB-UWB) generation scheme doesn't have these problems. However there is the asymmetric amplitude peak in the generated UWB signal. The property of the large singal modulation is also investigated to improve the signal-to-noise ratio (SNR). PMID:22453419

  15. Principles and Limitations of Ultra-Wideband FM Communications Systems

    NASA Astrophysics Data System (ADS)

    Gerrits, John F. M.; Kouwenhoven, Michiel H. L.; van der Meer, Paul R.; Farserotu, John R.; Long, John R.

    2005-12-01

    This paper presents a novel UWB communications system using double FM: a low-modulation index digital FSK followed by a high-modulation index analog FM to create a constant-envelope UWB signal. FDMA techniques at the subcarrier level are exploited to accommodate multiple users. The system is intended for low (1-10 kbps) and medium (100-1000 kbps) bit rate, and short-range WPAN systems. A wideband delay-line FM demodulator that is not preceded by any limiting amplifier constitutes the key component of the UWBFM receiver. This unusual approach permits multiple users to share the same RF bandwidth. Multipath, however, may limit the useful subcarrier bandwidth to one octave. This paper addresses the performance with AWGN and multipath, the resistance to narrowband interference, as well as the simultaneous detection of multiple FM signals at the same carrier frequency. SPICE and Matlab simulation results illustrate the principles and limitations of this new technology. A hardware demonstrator has been realized and has allowed the confirmation of theory with practical results.

  16. Accurate TOA-Based UWB Localization System in Coal Mine Based on WSN

    NASA Astrophysics Data System (ADS)

    Cheng, Guangliang

    Over the last years, there has been a great deal of interest in Ultra Wideband (UWB) wireless communication and Wireless Sensor Networks(WSN), especially following the proposing of the internet of things by the MIT (Massachusetts Institute of Technology) in 1999, hich is also result in an increasing research on UWB and WSN applications. This article mainly introduced the accurate UWB Localization System based on WSN in coal mine. Firstly, we briefly introduced UWB and WSN Localization technology. Secondly, the advantages and disadvantages of the previous personnel localization technology in coal mine was analyzed and contrasted, and then the suitable personnel localization system in coal mine based on UWB signal and TOA estimate positioning scheme are presented. At last the rationality and feasibility of this scheme was proved through the simulation results.

  17. UWB Tracking Algorithms: AOA and TDOA

    NASA Technical Reports Server (NTRS)

    Ni, Jianjun David; Arndt, D.; Ngo, P.; Gross, J.; Refford, Melinda

    2006-01-01

    Ultra-Wideband (UWB) tracking prototype systems are currently under development at NASA Johnson Space Center for various applications on space exploration. For long range applications, a two-cluster Angle of Arrival (AOA) tracking method is employed for implementation of the tracking system; for close-in applications, a Time Difference of Arrival (TDOA) positioning methodology is exploited. Both AOA and TDOA are chosen to utilize the achievable fine time resolution of UWB signals. This talk presents a brief introduction to AOA and TDOA methodologies. The theoretical analysis of these two algorithms reveal the affecting parameters impact on the tracking resolution. For the AOA algorithm, simulations show that a tracking resolution less than 0.5% of the range can be achieved with the current achievable time resolution of UWB signals. For the TDOA algorithm used in close-in applications, simulations show that the (sub-inch) high tracking resolution is achieved with a chosen tracking baseline configuration. The analytical and simulated results provide insightful guidance for the UWB tracking system design.

  18. Ultra-Wideband Vivaldi Antenna Array for High Resolution Subsurface Imaging

    NASA Astrophysics Data System (ADS)

    Yedlin, M. J.; Cresp, A.; Pichot, C.; Aliferis, I.; Dauvignac, J.; Fortino, N.; Gaffet, S.

    2008-05-01

    Use of ultra-wideband electromagnetic waves to image the subsurface yields enhanced resolution, provided sources, antennas and recording equipment can be developed and calibrated over the complete bandwidth of interest. We present a demonstration of the latest microwave transmission and recording technology to obtain high-resolution images. Our transmitter and receiver electronics are embodied in the vector network analyzer (PNA series) from Agilent, an eight-port vector network analyzer that records amplitude and phase. The analyzer is connected through a microwave multiplexer and microwave switch to an 8 element, balanced, antipodal Vivaldi antenna array, which can transmit or receive data over a bandwidth from 1.3 to 20 GHz. The bandwidth of the integrated system is determined by the bandwidth of the microwave switch, from DC to 18GHz, which interfaces the multiplexer to the PNA. The capabilities of a microwave multiplexer are employed to collect multi-channel data, by using one channel for transmission and reception on all 8 channels. The demonstration of this integrated system will be focussed on scattering from a single conducting cylinder as well as two cylinders, a dielectric and conducting cylinder, spaced at different intervals. The increased bandwidth, over that obtained in conventional GPR recording will result in pulses that have little ringing, allowing the detection of deeper reflections and eliminating any post-processing distortions that arise from deconvolving the traditional oscillatory waveform. Although the demonstration will be presented in the GHz bandwidth, suitable for imaging over a length scale to 1m, this integrated system will scale to lower bandwidths and can operate from 100 MHz to 3 GHz, with a resultant penetration depth of 10 to 20 m depending on the subsurface properties. Given the electronic constraints of the switch and the PNA, this scaling is simply achieved by enlarging the Vivaldi antenna dimensions. The advantage of using the PNA is the complete programmability, with a typical average noise level of -147 dBc and a dynamic range of 128 dB at the test-set ports. Scattering data obtained in this configuration will be imaged using time reversal techniques and an animation of a data set obtained using a previous generation of vector network analyzers will be presented. A minimum entropy stopping condition will be employed.

  19. Photonic generation of UWB impulses by using a Fabry-Pérot semiconductor optical amplifier

    NASA Astrophysics Data System (ADS)

    Yu, Yuan; Dong, Jianji; Jiang, Fan; Luo, Bowen; Zhang, Xinliang

    2014-03-01

    A novel approach to generating ultra-wideband (UWB) impulses based on a Mach-Zehnder modulator (MZM) and a Fabry-Pérot semiconductor optical amplifier (FP-SOA) is proposed and demonstrated. Both the carrier dynamic behavior of SOA and the feedback of FP cavity are exploited to generate a pair of polarity-reversed doublet-like impulses. Simulations and experiments are carried out to verify the UWB generation. In the experiment, the fractional bandwidths of the negative-doublet-like and the positive-doublet-like impulses are 100% and 108%, respectively. The bit error rate (BER) performance of the UWB before and after a span of 19-km standard single mode fiber (SSMF) transmission is also investigated and error-free performance can be achieved for each condition. Finally the UWB wireless transmission over a span of 10 cm is investigated.

  20. 79 GHz UWB automotive short range radar - Spectrum allocation and technology trends

    NASA Astrophysics Data System (ADS)

    Bloecher, H.-L.; Sailer, A.; Rollmann, G.; Dickmann, J.

    2009-05-01

    Automotive UWB (Ultra-Wideband) short range radar (SSR) is on the market as a key technology for novel comfort and safety systems. SiGe based 79 GHz UWB SRR will be a definite candidate for the long term substitution of the 24 GHz UWB SRR. This paper will give an overview of the finished BMBF joint project KOKON and the recently started successing project RoCC, which concentrate on the development of this technology and sensor demonstrators. In both projects, the responsibilities of Daimler AG deal with application based sensor specification, test and evaluation of realized sensor demonstrators. Recent UWB SRR frequency regulation approaches and activitites will be introduced. Furthermore, some first results of Daimler activities within RoCC will be presented, dealing with the packaging and operation of these sensors within the complex car environment.

  1. Performance comparison between UWB-IR and MB-OFDM with transmit diversity in implant communications.

    PubMed

    Shimizu, Yuto; Furukawa, Tomofumi; Anzai, Daisuke; Jianqing Wang

    2015-08-01

    An ultra wideband (UWB) technology is a potential candidate for implant body area networks (BANs), where wireless communications are established between inside and outside of a human body. The UWB can accomplish higher data rate than the other frequency band for the implant communication. However, due to its high frequencies, the UWB signals suffer from quite large attenuation in the implant communication link, which makes it difficult to achieve reliable communications. For achieving reliable communication, it is well known that a spatial diversity technique is efficient without any frequency extension. In our previous works, we developed a transmit polarization diversity antenna for the UWB implant communication. However, optimal UWB modulation scheme for transmit diversity were rarely discussed. In this paper, in order to investigate the optimal UWB modulation schemes for implant communication with transmit diversity, we compare the communication performances of UWB-impulse radio (UWB-IR) and multiband-orthogonal frequency division multiplexing (MB-OFDM). For this purpose, we first analyze the propagation characteristics in the implant UWB channel, which ranges from 3.4 GHz to 4.8 GHz, using a finite difference time domain (FDTD) numerical analysis technique. Then, we evaluate and discuss the communication performances of both modulation schemes for the transmit polarization diversity from the viewpoint of the BER and the required transmit power. PMID:26737529

  2. A novel ultra-wideband 80 GHz FMCW radar system for contactless monitoring of vital signs.

    PubMed

    Siying Wang; Pohl, Antje; Jaeschke, Timo; Czaplik, Michael; Kony, Marcus; Leonhardt, Steffen; Pohl, Nils

    2015-08-01

    In this paper an ultra-wideband 80 GHz FMCW-radar system for contactless monitoring of respiration and heart rate is investigated and compared to a standard monitoring system with ECG and CO(2) measurements as reference. The novel FMCW-radar enables the detection of the physiological displacement of the skin surface with submillimeter accuracy. This high accuracy is achieved with a large bandwidth of 10 GHz and the combination of intermediate frequency and phase evaluation. This concept is validated with a radar system simulation and experimental measurements are performed with different radar sensor positions and orientations. PMID:26737409

  3. Fuzzy neighborhood filters for UWB range radios in multipath environments

    NASA Astrophysics Data System (ADS)

    Cheok, Ka C.; Hudas, Gregory R.; Overholt, James L.

    2008-04-01

    An ultra-wideband (UWB) inter-radio ranging technology with measurement resolution of +/-0.5 ft and range up to 0.5 kilometer under certain FCC regulation was recently introduced. However, measurement data are extremely erroneous due to stochastic variables in the device and multipath radio wave reflections. This paper presents fuzzy logic tuned double tracking filters as a solution to remove misinformation in the data. The 1st tracker locates the overall center of the data in the presence of the large sporadic noise. A fuzzy logic admits only neighborhood data to a 2nd tracker which takes care of smaller deviation noise. The fuzzy neighborhood filter approach has been successfully applied to clean up the UWB radio ranges. Experimental results are shown.

  4. UWB Tracking System Design with TDOA Algorithm

    NASA Technical Reports Server (NTRS)

    Ni, Jianjun; Arndt, Dickey; Ngo, Phong; Phan, Chau; Gross, Julia; Dusl, John; Schwing, Alan

    2006-01-01

    This presentation discusses an ultra-wideband (UWB) tracking system design effort using a tracking algorithm TDOA (Time Difference of Arrival). UWB technology is exploited to implement the tracking system due to its properties, such as high data rate, fine time resolution, and low power spectral density. A system design using commercially available UWB products is proposed. A two-stage weighted least square method is chosen to solve the TDOA non-linear equations. Matlab simulations in both two-dimensional space and three-dimensional space show that the tracking algorithm can achieve fine tracking resolution with low noise TDOA data. The error analysis reveals various ways to improve the tracking resolution. Lab experiments demonstrate the UWBTDOA tracking capability with fine resolution. This research effort is motivated by a prototype development project Mini-AERCam (Autonomous Extra-vehicular Robotic Camera), a free-flying video camera system under development at NASA Johnson Space Center for aid in surveillance around the International Space Station (ISS).

  5. Ultra-Wideband GPR Imaging of the Vaucluse Karst Aquifer

    NASA Astrophysics Data System (ADS)

    Dauvignac, J.; Fortino, N.; Snchal, G.; Cresp, A.; Yedlin, M.; Gaffet, S.; Rousset, D.; Pichot, C.

    2008-12-01

    In this paper, we present the validation of an Ultra Wide band measurement system which is the first experimental step of the French MAXWELL Research Project devoted to the survey of the karst aquifer located in the Vaucluse in Provence. This radar system employs Exponentially Tapered Slot Antennas (ETSA), with a usable bandwidth from 100 MHz to 2.5 GHz. The antenna is driven by a .01- 26.5 GHz Agilent vector network analyzer (VNA), with a noise floor of -120dB under test conditions and a noise floor of -100 dB in a field setting. A synthetic pulse is applied to the antenna by using a classical step frequency sweeping. The recorded amplitudes and phases of the reflection coefficient (S11 parameter) are filtered and inverse Fourier transformed to obtain the time-domain data. In principal, due to the flat radiation characteristic of the frequency generator, appropriate synthetic pulses can be generated for analysis. The advantages of this approach are mainly, 1) a large depth resolution due to increased bandwidth, 2) a wider dynamic range for detection of weak late underground echoes, 3) a low signal distortion due to absence of pulse deconvolution post-processing. The foregoing system was deployed inside a tunnel in the Low-Noise Underground Laboratory (LSBB) located in Rustrel (France) which allows the use of low power radiation. Minimization of noise interference was accomplished by : 1) using low noise and low-loss cables, 2) using a PVC structure covered with absorbers to shield the ETSA from unwanted tunnel wall reflections and from radiation from the vector network analyzer, 3) an effective calibration of long cables to the antenna connector with careful cable unwinding to reduce phase errors, 4) a power level fixed at 8 dBm in the frequency band of interest to avoid distortion in the mixer of the VNA. Monostatic or multistatic data, were collected by moving manually the antennas along the PVC frame, in 5 cm increments over a length of 6 m. Both parallel and perpendicular polarizations were recorded. Data were obtained from 150 MHz to 2 GHz to reduce any reflections from the connection to the analyzer. Time sections were then processed after an inverse Fourier transform. To validate our results (from a geophysics point of view), reference data were also collected using 100, 250 and 500 MHz RAMAC GPR systems. Results are very promising especially regarding the resolution of the images, depth penetration and low emitting power. In future experiments, our approach could be still improved by using shorter cables, high directive antennas and absorbers to reduce coupling in multistatic configurations.

  6. 30 pJ/b, 67 Mbps, Centimeter-to-Meter Range Data Telemetry With an IR-UWB Wireless Link.

    PubMed

    Ebrazeh, Ali; Mohseni, Pedram

    2015-06-01

    This paper reports an energy-efficient, impulse radio ultra wideband (IR-UWB) wireless link operating in 3-5 GHz for data telemetry over centimeter-to-meter range distances at rates extended to tens of Mbps. The link comprises an all-digital, integrated transmitter (TX) fabricated in 90 nm 1P/9M CMOS that incorporates a waveform-synthesis pulse generator and a timing generator for on-off-keying (OOK) pulse modulation and phase scrambling. The link also incorporates an energy-detection receiver (RX) realized with commercial off-the-shelf (COTS) components that performs radio-frequency (RF) filtering, amplification, logarithmic power detection for data demodulation and automatic level control for robust operation in the presence of distance variations. Employing a miniaturized, UWB, chip antenna for the TX and RX, wireless transmission of pseudo-random binary sequence (PRBS) data at rates up to 50 Mbps over 10 cm-1 m is shown. Further, employing a high-gain horn antenna for the RX, wireless transmission of PRBS data at rates up to 67 Mbps over 50 cm-4 m is shown with a TX energy consumption of 30 pJ/b (i.e., power consumption of 2 mW) from 1.2 V. The measured bit error rate (BER) in both cases is < 10(-7) . Results from wireless recording of the background current of a carbon-fiber microelectrode (CFM) in one fast-scan cyclic voltammetry (FSCV) scan using the IR-UWB link are also included, exhibiting excellent match with those obtained from a conventional frequency-shift-keyed (FSK) link at ~433 MHz. PMID:25134088

  7. Ultra-wideband radar target detection for sloped and diffuse scattering environments

    NASA Astrophysics Data System (ADS)

    Mitra, Atindra K.; Lewis, Thomas L.; LaRue, James P.; Shaw, Arnab K.

    2004-09-01

    This paper extends simulation and target detection results from an investigation entitled "Self-Training Algorithms for Ultra-wideband SAR Target Detection" that was conducted last year and presented at the 2003 SPIE Aerosense Conference on "Algorithms for Synthetic Aperture Radar Imagery." Under this approach, simulated SAR impulse clutter data was generated by modulating a tophat model for the SAR video phase history with K-distributed data models. Targets were synthesized and "instanced" within the SAR image via the application of a dihedral model to represent broadside targets. For this paper, these models are extended and generalized by developing a set of models that approximate major scattering mechanisms due to terrain relief and approximate major scattering mechanisms due to scattering from off-angle targets. Off-angle targets are difficult to detect at typical ultra-wideband radar frequencies and are denoted as "diffuse scatterers." Potential approaches for detecting synthetic off-angle targets that demonstrate this type of "diffuse scattering" are developed and described in the algorithms and results section of the paper. A preliminary set of analysis outputs are presented with synthetic data from the resulting simulation testbed.

  8. Induced Mitogenic Activity in AML-12 Mouse Hepatocytes Exposed to Low-dose Ultra-Wideband Electromagnetic Radiation

    PubMed Central

    Dorsey, W. C.; Ford, B. D.; Roane, L.; Haynie, D. T.; Tchounwou, P. B.

    2005-01-01

    Ultra–wideband (UWB) technology has increased with the use of various civilian and military applications. In the present study, we hypothesized that low-dose UWB electromagnetic radiation (UWBR) could elicit a mitogenic effect in AML-12 mouse hepatocytes, in vitro. To test this hypothesis, we exposed AML-12 mouse hepatocytes, to UWBR in a specially constructed gigahertz transverse electromagnetic mode (GTEM) cell. Cells were exposed to UWBR for 2 h at a temperature of 23°C, a pulse width of 10 ns, a repetition rate of 1 kHz, and field strength of 5–20 kV/m. UWB pulses were triggered by an external pulse generator for UWBR exposure but were not triggered for the sham exposure. We performed an MTT Assay to assess cell viability for UWBR-treated and sham-exposed hepatocytes. Data from viability studies indicated a time-related increase in hepatocytes at time intervals from 8–24 h post exposure. UWBR exerted a statistically significant (p < 0.05) dose-dependent response in cell viability in both serum-treated and serum free medium (SFM) -treated hepatocytes. Western blot analysis of hepatocyte lysates demonstrated that cyclin A protein was induced in hepatocytes, suggesting that increased MTT activity after UWBR exposure was due to cell proliferation. This study indicates that UWBR has a mitogenic effect on AML-12 mouse hepatocytes and implicates a possible role for UWBR in hepatocarcinoma. PMID:16705798

  9. Effect of the antenna-body distance on the on-ext and on-on channel link path gain in UWB WBAN applications.

    PubMed

    Tuovinen, T; Kumpuniemi, T; Hamalainen, M; Yekeh Yazdandoost, K; Iinatti, J

    2013-01-01

    This paper investigates the effect of the operation distance (i.e., practical use) between an antenna and a human body on wireless body area network (WBAN) channel path gain. Different use cases in WBAN on-external (ext) and on-on links with different antenna-body distances for ultra wideband (UWB) technology are considered. These studies are carried out with two types of planar UWB antennas in the vicinity of a real human body. Corresponding scenarios are repeated by computer simulations, and differences between these environs (i.e., challenges in the modelling of the measurement situation) are analysed and discussed. PMID:24109919

  10. UWB communication receiver feedback loop

    DOEpatents

    Spiridon, Alex; Benzel, Dave; Dowla, Farid U.; Nekoogar, Faranak; Rosenbury, Erwin T.

    2007-12-04

    A novel technique and structure that maximizes the extraction of information from reference pulses for UWB-TR receivers is introduced. The scheme efficiently processes an incoming signal to suppress different types of UWB as well as non-UWB interference prior to signal detection. Such a method and system adds a feedback loop mechanism to enhance the signal-to-noise ratio of reference pulses in a conventional TR receiver. Moreover, sampling the second order statistical function such as, for example, the autocorrelation function (ACF) of the received signal and matching it to the ACF samples of the original pulses for each transmitted bit provides a more robust UWB communications method and system in the presence of channel distortions.

  11. UWB Tracking System Design for Lunar/Mars Exploration

    NASA Technical Reports Server (NTRS)

    Ni, Jianjun; Arndt, Dickey; Ngo, Phong; Phan, Chau; Gross, Julia

    2006-01-01

    This paper describes a design effort for a prototype ultra-wideband (UWB) tracking system that is currently under development at NASA Johnson Space Center (JSC). The system is being studied for use in tracking of lunar/Mars rovers during early exploration missions when satellite navigation systems are not available. The UWB technology is exploited to implement the tracking system due to its properties such as high data rate, fine time resolution, low power spectral density, and multipath immunity. A two-cluster prototype design using commercially available UWB products is proposed to implement the Angle Of Arrival (AOA) tracking methodology in this research effort. An AOA technique using the Time Difference Of Arrival (TDOA) information is utilized for location estimation in the prototype system, not only to exploit the precise time resolution possible with UWB signals, but also to eliminate the need for synchronization between the transmitter and the receiver. After the UWB radio at each cluster is used to obtain the TDOA estimates from the UWB signal sent from the target, the TDOA data is converted to AOA data to find the angle of arrival, assuming this is a far field application. Since the distance between two clusters is known, the target position is computed by a simple triangulation. Simulations show that the average tracking error at a range of 610 meters is 2.7595 meters, less than 0.5% of the tracking range. Outdoor tests to track the SCOUT vehicle (The Science Crew Operations and Utility Testbed) near the Meteor Crater, Flagstaff, Arizona were performed on September 12-13, 2005. The tracking performance was obtained with less than 1% tracking error at ranges up to 2000 feet. No RF interference with on-board GPS, video, voice and telemetry systems was detected. Outdoor tests demonstrated the UWB tracking capability.

  12. An Ultra-wideband and Polarization-independent Metasurface for RCS Reduction

    NASA Astrophysics Data System (ADS)

    Su, Pei; Zhao, Yongjiu; Jia, Shengli; Shi, Wenwen; Wang, Hongli

    2016-02-01

    In this paper, an ultra-wideband and polarization-independent metasurface for radar cross section (RCS) reduction is proposed. The unit cell of the metasurface operates in a linear cross-polarization scheme in a broad band. The phase and amplitude of cross-polarized reflection can be separately controlled by its geometry and rotation angle. Based on the diffuse reflection theory, a 3-bit coding metasurface is designed to reduce the RCS in an ultra-wide band. The wideband property of the metasurface benefits from the wideband cross polarization conversion and flexible phase modulation. In addition, the polarization-independent feature of the metasurface is achieved by tailoring the rotation angle of each element. Both the simulated and measured results demonstrate that the proposed metasurface can reduce the RCS significantly in an ultra-wide frequency band for both normal and oblique incidences, which makes it promising in the applications such as electromagnetic cloaking.

  13. An Ultra-wideband and Polarization-independent Metasurface for RCS Reduction

    PubMed Central

    Su, Pei; Zhao, Yongjiu; Jia, Shengli; Shi, Wenwen; Wang, Hongli

    2016-01-01

    In this paper, an ultra-wideband and polarization-independent metasurface for radar cross section (RCS) reduction is proposed. The unit cell of the metasurface operates in a linear cross-polarization scheme in a broad band. The phase and amplitude of cross-polarized reflection can be separately controlled by its geometry and rotation angle. Based on the diffuse reflection theory, a 3-bit coding metasurface is designed to reduce the RCS in an ultra-wide band. The wideband property of the metasurface benefits from the wideband cross polarization conversion and flexible phase modulation. In addition, the polarization-independent feature of the metasurface is achieved by tailoring the rotation angle of each element. Both the simulated and measured results demonstrate that the proposed metasurface can reduce the RCS significantly in an ultra-wide frequency band for both normal and oblique incidences, which makes it promising in the applications such as electromagnetic cloaking. PMID:26864084

  14. An ultra-wideband dielectric material characterization method using grounded coplanar waveguide and genetic algorithm optimization

    NASA Astrophysics Data System (ADS)

    Hadjloum, Massinissa; El Gibari, Mohammed; Li, Hongwu; Daryoush, Afshin S.

    2015-10-01

    An ultra-wideband complex permittivity extraction method is reported here using numerical fitting of scattering parameters to measured results. A grounded coplanar waveguide transmission line is realized on an unknown dielectric material, whose dielectric constant and loss tangent are extracted by the best fitting of the simulated magnitude, |S21|, and phase, ϕ21, of forward scattering parameter using an electromagnetic full-wave simulator (high frequency structure simulator) to the measured results. The genetic algorithm is employed for optimum rapid extraction, where errors between the numerically simulated and measured S21 (|S21| and ϕ21) are minimized in an iterative manner. As long as the convergence criterion is not satisfied, modifications to dielectric properties are made with this genetic algorithm implemented in Matlab. Feasibility of this extraction technique is validated on benzocyclobutane polymer from 10 MHz to 40 GHz.

  15. Signal processing and image formation using low-frequency ultra-wideband radar data

    NASA Astrophysics Data System (ADS)

    Nguyen, Lam H.; Ressler, Marc; Soumekh, Mehrdad

    2004-09-01

    In support of the U.S. Army Night Vision And Electronic Sensors Directorate (NVESD), the U.S. Army Research Laboratory (ARL) has developed infrastructures, tools, and algorithms to evaluate the data set. This paper focuses on the signal processing and image formation using data from a low-frequency ultra-wideband sensor. We examine various issues that are associated with this class of SAR databases such as radio frequency interference (RFI), the effects of spectral notches, and errors in motion measurement to image quality. We show the pre-processing steps such as frequency and phase calibration, radio frequency interference extraction. We also show the application of digital spotlight technique to correct motion errors introduced by the measurement system. Finally, we show the resulting SAR imagery of various minefields.

  16. An Ultra-wideband and Polarization-independent Metasurface for RCS Reduction.

    PubMed

    Su, Pei; Zhao, Yongjiu; Jia, Shengli; Shi, Wenwen; Wang, Hongli

    2016-01-01

    In this paper, an ultra-wideband and polarization-independent metasurface for radar cross section (RCS) reduction is proposed. The unit cell of the metasurface operates in a linear cross-polarization scheme in a broad band. The phase and amplitude of cross-polarized reflection can be separately controlled by its geometry and rotation angle. Based on the diffuse reflection theory, a 3-bit coding metasurface is designed to reduce the RCS in an ultra-wide band. The wideband property of the metasurface benefits from the wideband cross polarization conversion and flexible phase modulation. In addition, the polarization-independent feature of the metasurface is achieved by tailoring the rotation angle of each element. Both the simulated and measured results demonstrate that the proposed metasurface can reduce the RCS significantly in an ultra-wide frequency band for both normal and oblique incidences, which makes it promising in the applications such as electromagnetic cloaking. PMID:26864084

  17. Design and performance of an ultra-wideband stepped-frequency radar with precise frequency control for landmine and IED detection

    NASA Astrophysics Data System (ADS)

    Phelan, Brian R.; Sherbondy, Kelly D.; Ranney, Kenneth I.; Narayanan, Ram M.

    2014-05-01

    The Army Research Laboratory (ARL) has developed an impulse-based vehicle-mounted forward-looking ultra- wideband (UWB) radar for imaging buried landmines and improvised explosive devices (IEDs). However, there is no control of the radiated spectrum in this system. As part of ARL's Partnerships in Research Transition (PIRT) program, the above deficiency is addressed by the design of a Stepped-Frequency Radar (SFR) which allows for precise control over the radiated spectrum, while still maintaining an effective ultra-wide bandwidth. The SFR utilizes a frequency synthesizer which can be configured to excise prohibited and interfering frequency bands and also implement frequency-hopping capabilities. The SFR is designed to be a forward-looking ground- penetrating (FLGPR) Radar utilizing a uniform linear array of sixteen (16) Vivaldi notch receive antennas and two (2) Quad-ridge horn transmit antennas. While a preliminary SFR consisting of four (4) receive channels has been designed, this paper describes major improvements to the system, and an analysis of expected system performance. The 4-channel system will be used to validate the SFR design which will eventually be augmented in to the full 16-channel system. The SFR has an operating frequency band which ranges from 300 - 2000 MHz, and a minimum frequency step-size of 1 MHz. The radar system is capable of illuminating range swaths that have maximum extents of 30 to 150 meters (programmable). The transmitter has the ability to produce approximately -2 dBm/MHz average power over the entire operating frequency range. The SFR will be used to determine the practicality of detecting and classifying buried and concealed landmines and IEDs from safe stand-off distances.

  18. UWB Two-Cluster AOA Tracking Prototype System Design

    NASA Technical Reports Server (NTRS)

    Ngo, Phong H.; Arndt, D.; Phan, C.; Gross, J.; Jianjun; Rafford, Melinda

    2006-01-01

    This presentation discusses a design effort for a prototype ultra-wideband (UWB) tracking system that is currently under development at NASA Johnson Space Center (JSC). The system is being studied for use in tracking of lunar/Mars rovers during early exploration missions when satellite navigation systems are not available. The UWB technology is exploited to implement the tracking system due to its properties such as fine time resolution, low power spectral density and multipath immunity. A two cluster prototype design using commercially available UWB radios is employed to implement the Angle of Arrival (AOA) tracking methodology in this design effort. In order to increase the tracking range, low noise amplifiers (LNA) and high gain horns are used at the receiving sides. Field tests were conducted jointly with the Science and Crew Operation Utility Testbed (SCOUT) vehicle near the Meteor Crater in Arizona to test the tracking capability for a moving target in an operational environment. These tests demonstrate that the UWB tracking system can co-exist with other on-board radio frequency (RF) communication systems (such as Global Positioning System (GPS), video, voice and telemetry systems), and that a tracking resolution less than 1% of the range can be achieved.

  19. Body Area Networks performance analysis using UWB.

    PubMed

    Fatehy, Mohammed; Kohno, Ryuji

    2013-01-01

    The successful realization of a Wireless Body Area Network (WBAN) using Ultra Wideband (UWB) technology supports different medical and consumer electronics (CE) applications but stand in a need for an innovative solution to meet the different requirements of these applications. Previously, we proposed to use adaptive processing gain (PG) to fulfill the different QoS requirements of these WBAN applications. In this paper, interference occurred between two different BANs in a UWB-based system has been analyzed in terms of acceptable ratio of overlapping between these BANs' PG providing the required QoS for each BAN. The first BAN employed for a healthcare device (e.g. EEG, ECG, etc.) with a relatively longer spreading sequence is used and the second customized for entertainment application (e.g. wireless headset, wireless game pad, etc.) where a shorter spreading code is assigned. Considering bandwidth utilization and difference in the employed spreading sequence, the acceptable ratio of overlapping between these BANs should fall between 0.05 and 0.5 in order to optimize the used spreading sequence and in the meantime satisfying the required QoS for these applications. PMID:24109913

  20. Self organization of wireless sensor networks using ultra-wideband radios

    SciTech Connect

    Dowla, Farid U.; Nekoogar, Franak; Spiridon, Alex

    2009-06-16

    A novel UWB communications method and system that provides self-organization for wireless sensor networks is introduced. The self-organization is in terms of scalability, power conservation, channel estimation, and node synchronization in wireless sensor networks. The UWB receiver in the present invention adds two new tasks to conventional TR receivers. The two additional units are SNR enhancing unit and timing acquisition and tracking unit.

  1. Single-element based ultra-wideband antenna array concepts for wireless high-precision 2-D local positioning

    NASA Astrophysics Data System (ADS)

    Gardill, M.; Fischer, G.; Weigel, R.; Koelpin, A.

    2013-07-01

    We generally categorize the approaches for ultra-wideband antenna array design, and consequently propose simplified concepts for antenna arrays for a high-precision, ultra-wideband FMCW radar 2-D local positioning system to obtain robustness against multi path interference, perform angle of arrival analysis, as well as instantaneous heading estimation. We focus on low-cost and mechanical robust, industrial-application ready antennas. The antenna arrays are optimized for operation in the 5 GHz to 8 GHz frequency range and are designed towards supporting full omnidirectional 360 as well as partial half-plane direction of arrival estimation. Two different concepts for vehicle- as well as wall-mounted antenna array systems are proposed and discussed. We propose a wideband unidirectional bow-tie antenna array element having 97% impedance and 37% pattern bandwidth and a robust vehicle mounted omnidirectional antenna element having more than 85% impedance and pattern bandwidth.

  2. Transmission over UWB channels with OFDM system using LDPC coding

    NASA Astrophysics Data System (ADS)

    Dziwoki, Grzegorz; Kucharczyk, Marcin; Sulek, Wojciech

    2009-06-01

    Hostile wireless environment requires use of sophisticated signal processing methods. The paper concerns on Ultra Wideband (UWB) transmission over Personal Area Networks (PAN) including MB-OFDM specification of physical layer. In presented work the transmission system with OFDM modulation was connected with LDPC encoder/decoder. Additionally the frame and bit error rate (FER and BER) of the system was decreased using results from the LDPC decoder in a kind of turbo equalization algorithm for better channel estimation. Computational block using evolutionary strategy, from genetic algorithms family, was also used in presented system. It was placed after SPA (Sum-Product Algorithm) decoder and is conditionally turned on in the decoding process. The result is increased effectiveness of the whole system, especially lower FER. The system was tested with two types of LDPC codes, depending on type of parity check matrices: randomly generated and constructed deterministically, optimized for practical decoder architecture implemented in the FPGA device.

  3. A Novel Triangular Shaped UWB Fractal Antenna Using Circular Slot

    NASA Astrophysics Data System (ADS)

    Shahu, Babu Lal; Pal, Srikanta; Chattoraj, Neela

    2016-03-01

    The article presents the design of triangular shaped fractal based antenna with circular slot for ultra wideband (UWB) application. The antenna is fed using microstrip line and has overall dimension of 24×24×1.6 mm3. The proposed antenna is covering the wide frequency bandwidth of 2.99-11.16 GHz and is achieved using simple fractal based triangular-circular geometries and asymmetrical ground plane. The antenna is designed and parametrical studies are performed using method of moment (MOM) based Full Wave Electromagnetic (EM) software Simulator Zeland IE3D. The prototype of proposed antenna is fabricated and tested to compare the simulated and measured results of various antenna parameters. The antenna has good impedance bandwidth, nearly constant gain and stable radiation pattern. Measured return loss shows fair agreement with simulated one. Also measured group delay variation obtained is less than 1.0 ns, which proves good time domain behavior of the proposed antenna.

  4. Conformal and Spectrally Agile Ultra Wideband Phased Array Antenna for Communication and Sensing

    NASA Technical Reports Server (NTRS)

    Novak, M.; Alwan, Elias; Miranda, Felix; Volakis, John

    2015-01-01

    There is a continuing need for reducing size and weight of satellite systems, and is also strong interest to increase the functional role of small- and nano-satellites (for instance SmallSats and CubeSats). To this end, a family of arrays is presented, demonstrating ultra-wideband operation across the numerous satellite communications and sensing frequencies up to the Ku-, Ka-, and Millimeter-Wave bands. An example design is demonstrated to operate from 3.5-18.5 GHz with VSWR2 at broadside, and validated through fabrication of an 8 x 8 prototype. This design is optimized for low cost, using Printed Circuit Board (PCB) fabrication. With the same fabrication technology, scaling is shown to be feasible up to a 9-49 GHz band. Further designs are discussed, which extend this wideband operation beyond the Ka-band, for instance from 20-80 GHz. Finally we will discuss recent efforts in the direct integration of such arrays with digital beamforming back-ends. It will be shown that using a novel on-site coding architecture, orders of magnitude reduction in hardware size, power, and cost is accomplished in this transceiver.

  5. Lensless, ultra-wideband fiber optic rotary joint for biomedical applications.

    PubMed

    Kim, Wihan; Chen, Xi; Jo, Javier A; Applegate, Brian E

    2016-05-01

    The demands of optical fiber-based biomedical applications can, in many cases, outstrip the capabilities of lens-based commercially available fiber optic rotary joints. In some circumstances, it is necessary to use very broad spectral bandwidths (near UV to short-wave IR) and specialized optical fibers, such as double-clad fiber, and have the capacity to accommodate high rotational velocities. The broad spectrum, stretching down into the UV, presents two problems: (1) adequate chromatic correction in the lenses across the entire bandwidth and (2) strong UV absorption by the fluids used to lubricate the rotary joint. To accommodate these types of applications, we have developed an ultra-wideband lensless fiber optic rotary joint based on the principle that when two optical fibers are coaligned and placed in contact (or very close), the optical losses at the junction are very low. The advances demonstrated here enable excellent performance (<0.2  dB insertion loss), even down into the UV and spanning a wavelength range of at least 355-1360 nm with single-mode, multimode, and double-clad fibers. We also demonstrate excellent performance, ∼0.38  dB insertion loss, at rotational velocities up to 8800 rpm (146 Hz). To the best of our knowledge, this is the first demonstration of this type of rotary joint capable of such a wide bandwidth and high rotational velocities. PMID:27128052

  6. Accurate Permittivity Measurements for Microwave Imaging via Ultra-Wideband Removal of Spurious Reflectors

    PubMed Central

    Pelletier, Mathew G.; Viera, Joseph A.; Wanjura, John; Holt, Greg

    2010-01-01

    The use of microwave imaging is becoming more prevalent for detection of interior hidden defects in manufactured and packaged materials. In applications for detection of hidden moisture, microwave tomography can be used to image the material and then perform an inverse calculation to derive an estimate of the variability of the hidden material, such internal moisture, thereby alerting personnel to damaging levels of the hidden moisture before material degradation occurs. One impediment to this type of imaging occurs with nearby objects create strong reflections that create destructive and constructive interference, at the receiver, as the material is conveyed past the imaging antenna array. In an effort to remove the influence of the reflectors, such as metal bale ties, research was conducted to develop an algorithm for removal of the influence of the local proximity reflectors from the microwave images. This research effort produced a technique, based upon the use of ultra-wideband signals, for the removal of spurious reflections created by local proximity reflectors. This improvement enables accurate microwave measurements of moisture in such products as cotton bales, as well as other physical properties such as density or material composition. The proposed algorithm was shown to reduce errors by a 4:1 ratio and is an enabling technology for imaging applications in the presence of metal bale ties. PMID:22163668

  7. Novel Dual-band Slot Antenna Design for Bluetooth and UWB Applications

    NASA Astrophysics Data System (ADS)

    Huang, Hai-Yan; Shao, Wei; Wang, Bing-Zhong; Ma, Xiao-Liang

    2014-05-01

    A novel technique to introduce an additional low frequency band to compact ultra wideband (UWB) slot antennas is proposed in this paper. To get an additional Bluetooth band, a parasitic strip is mounted on the back side of the slot edge. Because of the interaction of the strip and the slot edge, the Bluetooth band can be obtained while a notch band between the Bluetooth band and UWB band also appears. Two types of feeding, coplanar waveguide and microstrip line, are investigated. The proposed antennas are both fabricated on a low-cost FR4 substrate and have compact size (24 mm × 28 mm × 1 mm). The good agreement between measured and simulated results verifies our design.

  8. Ultra-Wideband Time-Difference-of-Arrival Two-Point-Tracking System

    NASA Technical Reports Server (NTRS)

    Ni, Jianjun David; Arndt, Dickey; Ngo, Phong; Phan, Chau; Dekome, Kent; Dusl, John

    2009-01-01

    A UWB TDOA Two-Point-Tracking System has been conceived and developed at JSC. This system can provide sub-inch tracking capability of two points on one target. This capability can be applied to guide a docking process in a 2D space. Lab tests demonstrate the feasibility of this technology.

  9. Improved Resolution and Reduced Clutter in Ultra-Wideband Microwave Imaging Using Cross-Correlated Back Projection: Experimental and Numerical Results

    PubMed Central

    Jacobsen, S.; Birkelund, Y.

    2010-01-01

    Microwave breast cancer detection is based on the dielectric contrast between healthy and malignant tissue. This radar-based imaging method involves illumination of the breast with an ultra-wideband pulse. Detection of tumors within the breast is achieved by some selected focusing technique. Image formation algorithms are tailored to enhance tumor responses and reduce early-time and late-time clutter associated with skin reflections and heterogeneity of breast tissue. In this contribution, we evaluate the performance of the so-called cross-correlated back projection imaging scheme by using a scanning system in phantom experiments. Supplementary numerical modeling based on commercial software is also presented. The phantom is synthetically scanned with a broadband elliptical antenna in a mono-static configuration. The respective signals are pre-processed by a data-adaptive RLS algorithm in order to remove artifacts caused by antenna reverberations and signal clutter. Successful detection of a 7 mm diameter cylindrical tumor immersed in a low permittivity medium was achieved in all cases. Selecting the widely used delay-and-sum (DAS) beamforming algorithm as a benchmark, we show that correlation based imaging methods improve the signal-to-clutter ratio by at least 10 dB and improves spatial resolution through a reduction of the imaged peak full-width half maximum (FWHM) of about 40–50%. PMID:21331362

  10. Improved resolution and reduced clutter in ultra-wideband microwave imaging using cross-correlated back projection: experimental and numerical results.

    PubMed

    Jacobsen, S; Birkelund, Y

    2010-01-01

    Microwave breast cancer detection is based on the dielectric contrast between healthy and malignant tissue. This radar-based imaging method involves illumination of the breast with an ultra-wideband pulse. Detection of tumors within the breast is achieved by some selected focusing technique. Image formation algorithms are tailored to enhance tumor responses and reduce early-time and late-time clutter associated with skin reflections and heterogeneity of breast tissue. In this contribution, we evaluate the performance of the so-called cross-correlated back projection imaging scheme by using a scanning system in phantom experiments. Supplementary numerical modeling based on commercial software is also presented. The phantom is synthetically scanned with a broadband elliptical antenna in a mono-static configuration. The respective signals are pre-processed by a data-adaptive RLS algorithm in order to remove artifacts caused by antenna reverberations and signal clutter. Successful detection of a 7 mm diameter cylindrical tumor immersed in a low permittivity medium was achieved in all cases. Selecting the widely used delay-and-sum (DAS) beamforming algorithm as a benchmark, we show that correlation based imaging methods improve the signal-to-clutter ratio by at least 10 dB and improves spatial resolution through a reduction of the imaged peak full-width half maximum (FWHM) of about 40-50%. PMID:21331362

  11. A Framework for UWB-Based Communication and Location Tracking Systems for Wireless Sensor Networks

    PubMed Central

    Chóliz, Juan; Hernández, Ángela; Valdovinos, Antonio

    2011-01-01

    Ultra wideband (UWB) radio technology is nowadays one of the most promising technologies for medium-short range communications. It has a wide range of applications including Wireless Sensor Networks (WSN) with simultaneous data transmission and location tracking. The combination of location and data transmission is important in order to increase flexibility and reduce the cost and complexity of the system deployment. In this scenario, accuracy is not the only evaluation criteria, but also the amount of resources associated to the location service, as it has an impact not only on the location capacity of the system but also on the sensor data transmission capacity. Although several studies can be found in the literature addressing UWB-based localization, these studies mainly focus on distance estimation and position calculation algorithms. Practical aspects such as the design of the functional architecture, the procedure for the transmission of the associated information between the different elements of the system, and the need of tracking multiple terminals simultaneously in various application scenarios, are generally omitted. This paper provides a complete system level evaluation of a UWB-based communication and location system for Wireless Sensor Networks, including aspects such as UWB-based ranging, tracking algorithms, latency, target mobility and MAC layer design. With this purpose, a custom simulator has been developed, and results with real UWB equipment are presented too. PMID:22164120

  12. Ultra-wideband coaxial hybrid coupler for load resilient ion cyclotron range of frequency heating at fusion plasmas

    NASA Astrophysics Data System (ADS)

    Kim, H. J.; Bae, Y. S.; Yang, H. L.; Kwak, J.-G.; Wang, S. J.; Kim, B. K.; Choi, J. J.

    2012-06-01

    We designed a high power and ultra-wideband two-section 3 dB coaxial hybrid coupler for load resilient ion cyclotron range of frequency heating by configuring asymmetric impedance matching using a three-dimensional simulation code, hfss. By adjusting the characteristic impedances of main and coupled lines of the hybrid coupler, we realized that the bandwidth of the proposed circuit is not only wider than that of a conventional three-section coupler, but also that the bandwidth is almost twice as wide compared to the conventional two-section hybrid coupler while maintaining the identical overall size.

  13. Design of a Tunable All-Digital UWB Pulse Generator CMOS Chip for Wireless Endoscope.

    PubMed

    Chul Kim; Nooshabadi, S

    2010-04-01

    A novel tunable all-digital, ultrawideband pulse generator (PG) has been implemented in a standard 0.18-¿ m complementary metal-oxide semiconductor (CMOS) process for implantable medical applications. The chip shows that an ultra-low dynamic energy consumption of 27 pJ per pulse without static current flow at a 200-MHz pulse repetition frequency (PRF) with a 1.8-V power supply and low area of 90 × 50 ¿m(2). The PG generates tunable pulsewidth, amplitude, and transmit (Tx) power by using simple circuitry, through precise timing control of the H-bridge output stage. The all-digital architecture allows easy integration into a standard CMOS process, thus making it the most suitable candidate for in-vivo biotelemetry applications. PMID:23853319

  14. A hybrid TOA-fingerprinting based localization of mobile nodes using UWB signaling for Non-line-of-sight conditions.

    PubMed

    Kabir, Md Humayun; Kohno, Ryuji

    2012-01-01

    Recently, Impulse Radio Ultra Wideband (IR-UWB) signaling has become popular for providing precise location accuracy for mobile and wireless sensor node localization in the indoor environment due to its large bandwidth and high time resolution while providing ultra-high transmission capacity. However, the Non-line-of-sight (NLOS) error mitigation has considerable importance in localization of wireless nodes. In order to mitigate NLOS errors in indoor localization this paper proposes and investigates a novel approach which creates a hybrid combination of channel impulse response (CIR)-based fingerprinting (FP) positioning and an iterative Time of Arrival (TOA) real time positioning method using Ultra Wideband (UWB) signaling. Besides, to reduce the calculation complexities in FP method, this paper also introduces a unique idea for the arrangement of reference nodes (or tags) to create a fingerprinting database. The simulation results confirm that the proposed hybrid method yields better positioning accuracies and is much more robust in NLOS error mitigation than TOA only and FP only and a conventional iterative positioning method. PMID:23112651

  15. On IEEE 802.15.6 IR-UWB receivers - simulations for DBPSK modulation.

    PubMed

    Niemelä, Ville; Hämäläinen, Matti; Iinatti, Jari

    2013-01-01

    In 2002, Federal Communications Commission (FCC) was the first in defining regulations for ultra wideband (UWB) communications followed by Europe and Japan some years later. Focusing on impulse radio (IR) UWB, in 2007 was the time for the first published standard targeting in personal area networks, released by the IEEE. The second IEEE released standard including UWB definitions is targeted for wireless body area networks (WBAN) and was published in 2012. As the wireless communications has been and will be passing through almost any levels in society, the natural step with WBAN is using it in different medical, healthcare and wellbeing applications. The arguments for these are related to the modern lifestyle, in which people have increasingly more free time and are more interested in taking care of their health and wellbeing. Another challenge is the population composition, i.e., aging in developed countries which call for new solutions and procedures, particularly from cost wise. In this paper, we are evaluating UWB receivers based on the IEEE 802.15.6 physical layer definitions and capable of detecting differentially encoded modulation. The evaluation is performed using two different WBAN channel models. PMID:24110027

  16. A comprehensive study of channel estimation for WBAN-based healthcare systems: feasibility of using multiband UWB.

    PubMed

    Islam, S M Riazul; Kwak, Kyung Sup

    2012-06-01

    Wireless personal area network (WPAN) is an emerging in wireless technology for short range indoor and outdoor communication applications. A more specific category of WPAN is the wireless body area network (WBAN) used for health monitoring. On the other hand, multiband orthogonal frequency division multiplexing (MB-OFDM) ultra-wideband (UWB) comes with a number of desirable features at the physical layer for wireless communications, for example, very high data rate. One big challenge in adoption of multiband UWB in WBAN is the fact that channel estimation becomes difficult under the constraint of extremely low transmission power. Moreover, the heterogeneous environment of WBAN causes a dense multipath wireless channel. Therefore, effective channel estimation is required in the receiver of WBAN-based healthcare system that uses multiband UWB. In this paper, we first outline the MB-OFDM UWB system. Then, we present an overview of channel estimation techniques proposed/investigated for multiband UWB communications with emphasis on their strengths and weaknesses. Useful suggestions are given to overcome the weaknesses so that these methods can be particularly useful for WBAN channels. Also, we analyze the comparative performances of the techniques using computer simulation in order to find the energy-efficient channel estimation methods for WBAN-based healthcare systems. PMID:21046206

  17. SPIDYAN, a MATLAB library for simulating pulse EPR experiments with arbitrary waveform excitation.

    PubMed

    Pribitzer, Stephan; Doll, Andrin; Jeschke, Gunnar

    2016-02-01

    Frequency-swept chirp pulses, created with arbitrary waveform generators (AWGs), can achieve inversion over a range of several hundreds of MHz. Such passage pulses provide defined flip angles and increase sensitivity. The fact that spectra are not excited at once, but single transitions are passed one after another, can cause new effects in established pulse EPR sequences. We developed a MATLAB library for simulation of pulse EPR, which is especially suited for modeling spin dynamics in ultra-wideband (UWB) EPR experiments, but can also be used for other experiments and NMR. At present the command line controlled SPin DYnamics ANalysis (SPIDYAN) package supports one-spin and two-spin systems with arbitrary spin quantum numbers. By providing the program with appropriate spin operators and Hamiltonian matrices any spin system is accessible, with limits set only by available memory and computation time. Any pulse sequence using rectangular and linearly or variable-rate frequency-swept chirp pulses, including phase cycling can be quickly created. To keep track of spin evolution the user can choose from a vast variety of detection operators, including transition selective operators. If relaxation effects can be neglected, the program solves the Liouville-von Neumann equation and propagates spin density matrices. In the other cases SPIDYAN uses the quantum mechanical master equation and Liouvillians for propagation. In order to consider the resonator response function, which on the scale of UWB excitation limits bandwidth, the program includes a simple RLC circuit model. Another subroutine can compute waveforms that, for a given resonator, maintain a constant critical adiabaticity factor over the excitation band. Computational efficiency is enhanced by precomputing propagator lookup tables for the whole set of AWG output levels. The features of the software library are discussed and demonstrated with spin-echo and population transfer simulations. PMID:26773526

  18. SPIDYAN, a MATLAB library for simulating pulse EPR experiments with arbitrary waveform excitation

    NASA Astrophysics Data System (ADS)

    Pribitzer, Stephan; Doll, Andrin; Jeschke, Gunnar

    2016-02-01

    Frequency-swept chirp pulses, created with arbitrary waveform generators (AWGs), can achieve inversion over a range of several hundreds of MHz. Such passage pulses provide defined flip angles and increase sensitivity. The fact that spectra are not excited at once, but single transitions are passed one after another, can cause new effects in established pulse EPR sequences. We developed a MATLAB library for simulation of pulse EPR, which is especially suited for modeling spin dynamics in ultra-wideband (UWB) EPR experiments, but can also be used for other experiments and NMR. At present the command line controlled SPin DYnamics ANalysis (SPIDYAN) package supports one-spin and two-spin systems with arbitrary spin quantum numbers. By providing the program with appropriate spin operators and Hamiltonian matrices any spin system is accessible, with limits set only by available memory and computation time. Any pulse sequence using rectangular and linearly or variable-rate frequency-swept chirp pulses, including phase cycling can be quickly created. To keep track of spin evolution the user can choose from a vast variety of detection operators, including transition selective operators. If relaxation effects can be neglected, the program solves the Liouville-von Neumann equation and propagates spin density matrices. In the other cases SPIDYAN uses the quantum mechanical master equation and Liouvillians for propagation. In order to consider the resonator response function, which on the scale of UWB excitation limits bandwidth, the program includes a simple RLC circuit model. Another subroutine can compute waveforms that, for a given resonator, maintain a constant critical adiabaticity factor over the excitation band. Computational efficiency is enhanced by precomputing propagator lookup tables for the whole set of AWG output levels. The features of the software library are discussed and demonstrated with spin-echo and population transfer simulations.

  19. S – C – L triple wavelength superluminescent source based on an ultra-wideband SOA and FBGs

    SciTech Connect

    Ahmad, H; Zulkifli, M Z; Hassan, N A; Muhammad, F D; Harun, S W

    2013-10-31

    We propose and demonstrate a wide-band semiconductor optical amplifier (SOA) based triple-wavelength superluminescent source with the output in the S-, C- and L-band regions. The proposed systems uses an ultra-wideband SOA with an amplification range from 1440 to 1620 nm as the linear gain medium. Three fibre Bragg gratings (FBGs) with centre wavelengths of 1500, 1540 and 1580 nm are used to generate the lasing wavelengths in the S-, Cand L-bands respectively, while a variable optical attenuator is used to finely balance the optical powers of the lasing wavelengths. The ultra-wideband SOA generates an amplified spontaneous emission (ASE) spectrum with a peak power of -33 dBm at the highest SOA drive current, and also demonstrates a down-shift in the centre wavelength of the generated spectrum due to the spatial distribution of the carrier densities. The S-band wavelength is the dominant wavelength at high drive currents, with an output power of -6 dBm as compared to the C- and L-bands, which only have powers of -11 and -10 dBm, respectively. All wavelengths have a high average signal-to-noise ratio more than 60 dB at the highest drive current of 390 mA, and the system also shows a high degree of stability, with power fluctuations of less than 3 dB within 70 min. The proposed system can find many applications where a wide-band and stable laser source is crucial, such as in communications and sensing. (control of laser radiation parameters)

  20. A magnetometer-free indoor human localization based on loosely coupled IMU/UWB fusion.

    PubMed

    Zihajehzadeh, Shaghayegh; Yoon, Paul K; Park, Edward J

    2015-08-01

    The magnetic distortions in indoor environment affects the accuracy of yaw angle estimation using magnetometer. Thus, the accuracy of indoor localization based on inertial-magnetic sensors will be affected as well. To address this issue, this paper proposes a magnetometer-free solution for indoor human localization and yaw angle estimation. The proposed algorithm fuses a wearable inertial sensor consisting of MEMS-based accelerometer and gyroscope with a portable ultra-wideband (UWB) localization system in a cascaded two-step filter consisting of a tilt Kalman filter and a localization Kalman filter. By benchmarking against an optical motion capture system, the experimental results show that the proposed algorithm can accurately track position and velocity as well as the yaw angle without using magnetometer. PMID:26736958

  1. UWB-WBAN sensor node design.

    PubMed

    Keong, Ho Chee; Yuce, M R

    2011-01-01

    In this paper, we discuss the hardware development of a UWB sensor node for wireless body area networks. A few unique UWB pulse generation techniques have been discussed. The sensor node transmits multiple pulses per bit to increase the average power of the transmitted signal in order to improve the bit-error rate (BER) performance. The multiple-pulse per bit technique is also used as the coding scheme to identify the individual sensor nodes when more than one sensor forms a network. The sensors nodes are able to transmit body signals up to 2 m with a BER lower than 10(-5). PMID:22254770

  2. Detection of buried objects using ultra-wideband radar: newly launched mine detection project in South Korea

    NASA Astrophysics Data System (ADS)

    Kam, Kyungryul; Kim, Kangwook

    2008-04-01

    Korea is one of the heavily mined countries in the world. The demand for mine detection and clearance techniques has always been high in South Korea. In support of this, a new project on ground penetrating radar (GPR) for landmine detection has been launched in South Korea. The GPR under development is an ultra wideband sensor system that requires high-resolution imaging of buried targets and database construction based on target signals in various ground conditions. For initial experiments, a simple GPR has been built using a resistive vee dipole antenna and a vector network analyzer. The GPR is scanned over a sand tank with an area of 2.5m 2.5m and a depth of 1.5m, which is used for target burial. During the first stage of the project, the data obtained by scanning the GPR antenna over a target are processed to evaluate various radar signal waveforms, performance of various antennas, and other system configurations. Based on the evaluation, an advanced GPR system will be built and used to construct the database during the second stage of the project. A description for motivation for the GPR project, overview of the GPR project, experiment setup, and initial experiment results are presented in this paper.

  3. Ultra-Wideband Indoor Double-Directional Channel Estimation Using Transformation between Frequency and Time Domain Signals

    NASA Astrophysics Data System (ADS)

    Iwakiri, Naohiko; Kobayashi, Takehiko

    This paper proposes an ultra-wideband double-directional spatio-temporal channel sounding technique using transformation between frequency- and time-domain (FD and TD) signals. Virtual antenna arrays, composed of omnidirectional antennas and scanners, are used for transmission and reception in the FD. After Fourier transforming the received FD signals to TD ones, time of arrival (TOA) is estimated using a peak search over the TD signals, and then angle of arrivals (AOA) and angle of departure (AOD) are estimated using a weighted angle histogram with a multiple signal classification (MUSIC) algorithm applied to the FD signals, inverse-Fourier transformed from the TD signals divided into subregions. Indoor channel sounding results validated that an appropriate weighting reduced a spurious level in the angle histogram by a factor of 0.1 to 0.2 in comparison with that of non-weighting. The proposed technique successfully resolved dominant multipath components, including a direct path, a single reflection, and a single diffraction, in line-of-sight (LOS) and non-LOS environments. Joint TOA and AOA/AOD spectra were also derived from the sounding signals. The spectra illustrated the dominant multipath components (agreed with the prediction by ray tracing) as clusters.

  4. Reconfigurable UWB Bandpass Filter with Flexible Notch Characteristics

    NASA Astrophysics Data System (ADS)

    Dhwaj, Kirti

    The thesis reports a compact tunable ultra-wideband (UWB) notch filter using hybrid microstrip and coplanar waveguide (CPW) structure. The tunable notch is implemented to filter out the wireless local area network (WLAN) channels from 5GHz to 6GHz. The proposed structure utilizes the resonance of open ended stubs to achieve transmission zeroes in the filter passband. Varactors and by-pass capacitors are then introduced for dynamic tunability of notch. Further, the electromagnetic decoupling of the two resonators leads to tunable bandwidth of notch. DC bias circuitry is implemented to control the varactor capacitances. Rejection levels up to 25 dB are attained using this technique while maintaining insertion loss levels below 2.5 dB in the passband. The reconfigurability of bandwidth is shown by maintaining a constant bandwidth of 150 MHz across the WLAN band for the notch. The filter achieves an excellent wide bandwidth (from 2.5 GHz to 8.5 GHz) using multimode-resonator (MMR) based topology which makes the filter one wavelength long at the central frequency.

  5. A human body model for efficient numerical characterization of UWB signal propagation in wireless body area networks.

    PubMed

    Lim, Hooi Been; Baumann, Dirk; Li, Er-Ping

    2011-03-01

    Wireless body area network (WBAN) is a new enabling system with promising applications in areas such as remote health monitoring and interpersonal communication. Reliable and optimum design of a WBAN system relies on a good understanding and in-depth studies of the wave propagation around a human body. However, the human body is a very complex structure and is computationally demanding to model. This paper aims to investigate the effects of the numerical model's structure complexity and feature details on the simulation results. Depending on the application, a simplified numerical model that meets desired simulation accuracy can be employed for efficient simulations. Measurements of ultra wideband (UWB) signal propagation along a human arm are performed and compared to the simulation results obtained with numerical arm models of different complexity levels. The influence of the arm shape and size, as well as tissue composition and complexity is investigated. PMID:21062677

  6. Design and simulation of gain-flattened ultra wideband fiber amplifiers covering S-, C-, and L-bands

    NASA Astrophysics Data System (ADS)

    Cao, Yang

    A novel design of a gain-flattened amplifier that covers an ultra-wideband including the S-, C-, and L-bands is presented. The amplifier is comprised of a split-band structure, which amplifies the S-, C-, and L-band signals in separate paths then recombines the amplified signals for the final output to the transmission fiber. For C-band amplification, a two-stage erbium doped fiber amplifier (EDFA) with mid-stage gain equalization filter (GEF) topology was used, for L-band amplification, single-stage longer EDFA topology was used. While for S-band amplification, a Raman fiber amplifier (RFA) with counter-propagating multiple-pump configuration was adopted. Using the VPIcomponentMaker(TM) software package from VPI Systems(TM), the design was simulated and tested for optimization. Computer simulations analyzed the gain and noise-figure of the novel amplifier. Approximately 30-dB gain with an overall gain ripple less than 1.6 dB and low noise-figure, and gain-bandwidth over 120 nm can be achieved. It encompasses more than 144 ITU-T channels at 100 GHz spacing. Comparing with previous reported work in the literature, the amplification range of the novel fiber amplifier not only covers the C- and L-bands, but also covers the S-band, which is the first investigation of this type. And hasn't been reported in literature by others for discrete amplification. This makes the novel amplifier described here as having the widest gain-flattened amplification bandwidth range among the discrete fiber amplifiers investigated till today.

  7. A Wireless FSCV Monitoring IC With Analog Background Subtraction and UWB Telemetry.

    PubMed

    Dorta-Quinones, Carlos I; Wang, Xiao Y; Dokania, Rajeev K; Gailey, Alycia; Lindau, Manfred; Apsel, Alyssa B

    2016-04-01

    A 30- μW wireless fast-scan cyclic voltammetry monitoring integrated circuit for ultra-wideband (UWB) transmission of dopamine release events in freely-behaving small animals is presented. On-chip integration of analog background subtraction and UWB telemetry yields a 32-fold increase in resolution versus standard Nyquist-rate conversion alone, near a four-fold decrease in the volume of uplink data versus single-bit, third-order, delta-sigma modulation, and more than a 20-fold reduction in transmit power versus narrowband transmission for low data rates. The 1.5- mm(2) chip, which was fabricated in 65-nm CMOS technology, consists of a low-noise potentiostat frontend, a two-step analog-to-digital converter (ADC), and an impulse-radio UWB transmitter (TX). The duty-cycled frontend and ADC/UWB-TX blocks draw 4 μA and 15 μA from 3-V and 1.2-V supplies, respectively. The chip achieves an input-referred current noise of 92 pArms and an input current range of ±430 nA at a conversion rate of 10 kHz. The packaged device operates from a 3-V coin-cell battery, measures 4.7 × 1.9 cm(2), weighs 4.3 g (including the battery and antenna), and can be carried by small animals. The system was validated by wirelessly recording flow-injection of dopamine with concentrations in the range of 250 nM to 1 μM with a carbon-fiber microelectrode (CFM) using 300-V/s FSCV. PMID:26057983

  8. A Wireless FSCV Monitoring IC with Analog Background Subtraction and UWB Telemetry

    PubMed Central

    Dorta-Quiñones, Carlos I.; Wang, Xiao Y.; Dokania, Rajeev K.; Gailey, Alycia; Lindau, Manfred; Apsel, Alyssa B.

    2015-01-01

    A 30-μW wireless fast-scan cyclic voltammetry monitoring integrated circuit for ultra-wideband (UWB) transmission of dopamine release events in freely-behaving small animals is presented. On-chip integration of analog background subtraction and UWB telemetry yields a 32-fold increase in resolution versus standard Nyquist-rate conversion alone, near a four-fold decrease in the volume of uplink data versus single-bit, third-order, delta-sigma modulation, and more than a 20-fold reduction in transmit power versus narrowband transmission for low data rates. The 1.5-mm2 chip, which was fabricated in 65-nm CMOS technology, consists of a low-noise potentiostat frontend, a two-step analog-to-digital converter (ADC), and an impulse-radio UWB transmitter (TX). The duty-cycled frontend and ADC/UWB-TX blocks draw 4 μA and 15 μA from 3-V and 1.2-V supplies, respectively. The chip achieves an input-referred current noise of 92 pArms and an input current range of ±430 nA at a conversion rate of 10 kHz. The packaged device operates from a 3-V coin-cell battery, measures 4.7 × 1.9 cm2, weighs 4.3 g (including the battery and antenna), and can be carried by small animals. The system was validated by wirelessly recording flow-injection of dopamine with concentrations in the range of 250 nM to 1 μM with a carbon-fiber microelectrode (CFM) using 300-V/s FSCV. PMID:26057983

  9. Hybrid UWB and WiMAX radio-over-multi-mode fibre for in-building optical networks

    NASA Astrophysics Data System (ADS)

    Perez, J.; Llorente, R.

    2014-01-01

    In this paper the use of hybrid WiMedia-defined ultra-wideband (UWB) and IEEE 802.16d WiMAX radio-over-fibre is proposed and experimentally demonstrated for multi-mode based in-building optical networks with the advantage of great immunity to optical transmission impairments. In the proposed approach, spectral coexistence of both signals must be achieved with negligible mutual interference. The experimental study performed addressed an indoor configuration with 50 μm multi-mode fibres (MMF) and 850 nm vertical-cavity surface-emitting laser (VCSEL) transmitters. The results indicate that the impact of the wireless convergence in radio-over-multi-mode fibre (RoMMF) is significant for UWB transmissions, mainly due to MMF dispersion and electrooptical (EO) devices with limited bandwidth. On the other hand, WiMAX transmission is feasible for a 300 m MMF and 30 m wireless link in the presence of UWB, with -31 dBm WiMAX EVM.

  10. Low-power wide-locking-range injection-locked frequency divider for OFDM UWB systems

    NASA Astrophysics Data System (ADS)

    Jiangwei, Yin; Ning, Li; Renliang, Zheng; Wei, Li; Junyan, Ren

    2009-05-01

    This paper describes a divide-by-two injection-locked frequency divider (ILFD) for frequency synthesizers as used in multiband orthogonal frequency division multiplexing (OFDM) ultra-wideband (UWB) systems. By means of dual-injection technique and other conventional tuning techniques, such as DCCA and varactor tuning, the divider demonstrates a wide locking range while consuming much less power. The chip was fabricated in the Jazz 0.18 μm RF CMOS process. The measurement results show that the divider achieves a locking range of 4.85 GHz (6.23 to 11.08 GHz) at an input power of 8 dBm. The core circuit without the test buffer consumes only 3.7 mA from a 1.8 V power supply and has a die area of 0.38 × 0.28 mm2. The wide locking range combined with low power consumption makes the ILFD suitable for its application in UWB systems.

  11. A Novel Compact UWB Monopole Antenna with Bluetooth and Triple Notch Band

    NASA Astrophysics Data System (ADS)

    Li, Li; Zhou, Zhi-Li; Hong, Jing-Song

    2013-01-01

    A novel technique to add an extra Bluetooth band and triple notch bands simultaneously to a compact ultra-wideband (UWB) monopole antenna is presented. This scissors-shaped UWB antenna, covering 2.9 GHz-12.5 GHz, is fed by a special microstrip line. To create an extra Bluetooth band centered at 2.45 GHz, an arc-shaped stub is attached to the high concentrated current area right of the feed line and a rectangular slot is etched in the radiation patch. Besides, a notch band for WLAN (5.6 GHz-6.15 GHz) is also obtained. In addition, by connecting two asymmetric stubs to the feed line, two other notch bands in 3.28 GHz-3.8 GHz for WiMAX and 7.1 GHz-7.76 GHz for downlink of X-band satellite communication systems are achieved. The proposed antenna with compact size of 20 mm × 26 mm is fabricated and measured, showing stable antenna gain and good omni-directional radiation patterns in H-plane.

  12. Subbanding of temporal and spatial UWB SAR imagery of buried mines

    NASA Astrophysics Data System (ADS)

    Wong, David C.; Carin, Lawrence

    1998-09-01

    A numerical algorithm has been developed for the modeling of ultra-wideband (UWB) plane-wave scattering from a class of buried mines. In particular, the model assumes that a mine can be simulated as a body of revolution (BOR). The numerical results indicate that there are particular frequency subbands in which a given target is excited most strongly, with the subband depending strongly on the target type. Moreover, these optimal subbands are also dependent on the depression angle; therefore, the synthetic aperture radar (SAR) aperture must be limited (spatial-spectrum subbanding) so that the desired depression angle is achieved over the aperture used for imaging. These results indicate that the scattered response from particular buried mines can be highlighted by proper processing of the temporal and spatial spectrum. So motivated, we have applied subbanding to data measured by the Army Research Laboratory (ARL) UWB SAR, which collects fully polarimetric data over the 50 - 1200 MHz bandwidth. The measured data, when processed appropriately corroborate the theoretical expectations of where example anti-personnel and anti-tank mines scatter optimally. In particular, we consider the Valmara anti-personnel mine and the M20 anti-tank mine, using data collected at Yuma Proving Grounds. After validating the theory, we present frequency subbanding that will highlight one mine over another, a technique of potential application to the discrimination of targets from clutter.

  13. Design of UWB monopole antenna with dual notched bands using one modified electromagnetic-bandgap structure.

    PubMed

    Liu, Hao; Xu, Ziqiang

    2013-01-01

    A modified electromagnetic-bandgap (M-EBG) structure and its application to planar monopole ultra-wideband (UWB) antenna are presented. The proposed M-EBG which comprises two strip patch and an edge-located via can perform dual notched bands. By properly designing and placing strip patch near the feedline, the proposed M-EBG not only possesses a simple structure and compact size but also exhibits good band rejection. Moreover, it is easy to tune the dual notched bands by altering the dimensions of the M-EBG. A demonstration antenna with dual band-notched characteristics is designed and fabricated to validate the proposed method. The results show that the proposed antenna can satisfy the requirements of VSWR < 2 over UWB 3.1-10.6 GHz, except for the rejected bands of the world interoperability for microwave access (WiMAX) and the wireless local area network (WLAN) at 3.5 GHz and 5.5 GHz, respectively. PMID:24170984

  14. Ultra-wideband microwave photonic phase shifter with a 360° tunable phase shift based on an erbium-ytterbium co-doped linearly chirped FBG.

    PubMed

    Liu, Weilin; Yao, Jianping

    2014-02-15

    A simple photonic approach to implementing an ultra-wideband microwave phase shifter based on an erbium-ytterbium (Er/Yb) co-doped linearly chirped fiber Bragg grating (LCFBG) is proposed and experimentally demonstrated. The LCFBG is designed to have a constant magnitude response over a reflection band, and a phase response that is linear and nonlinear in two sections in the reflection band. When an optical single-sideband with carrier (OSSB+C) signal is sent to the LCFBG, by locating the optical carrier at the section corresponding to the nonlinear phase response and the sideband at the section corresponding to the linear phase response, a phase shift is introduced to the optical carrier, which is then translated to the microwave signal by beating the optical carrier and the sideband at a photodetector. The tuning of the phase shift is realized by optically pumping the Er/Yb co-doped LCFBG by a 980-nm laser diode. The proposed ultra-wideband microwave photonic phase shifter is experimentally demonstrated. A phase shifter with a full 360° phase shift with a bandwidth from 10 to 40 GHz is experimentally demonstrated. PMID:24562242

  15. An ultra-wideband tunable multi-wavelength Brillouin fibre laser based on a semiconductor optical amplifier and dispersion compensating fibre in a linear cavity configuration

    SciTech Connect

    Zulkifli, M Z; Ahmad, H; Hassan, N A; Jemangin, M H; Harun, S W

    2011-07-31

    A multi-wavelength Brillouin fibre laser (MBFL) with an ultra-wideband tuning range from 1420 nm to 1620 nm is demonstrated. The MBFL uses an ultra-wideband semiconductor optical amplifier (SOA) and a dispersion compensating fibre (DCF) as the linear gain medium and nonlinear gain medium, respectively. The proposed MBFL has a wide tuning range covering the short (S-), conventional (C-) and long (L-) bands with a wavelength spacing of 0.08 nm, making it highly suitable for DWDM system applications. The output power of the observed Brillouin Stokes ranges approximately from -5.94 dBm to -0.41 dBm for the S-band, from -4.34 dBm to 0.02 dBm for the C-band and from -2.19 dBm to 0.39 dBm for the L-band. The spacing between each adjacent wavelengths of all the three bands is about 0.08 nm, which is approximately 10.7 GHz for the frequency domain. (lasers)

  16. A Low-Cost and Energy-Efficient Multiprocessor System-on-Chip for UWB MAC Layer

    NASA Astrophysics Data System (ADS)

    Xiao, Hao; Isshiki, Tsuyoshi; Khan, Arif Ullah; Li, Dongju; Kunieda, Hiroaki; Nakase, Yuko; Kimura, Sadahiro

    Ultra-wideband (UWB) technology has attracted much attention recently due to its high data rate and low emission power. Its media access control (MAC) protocol, WiMedia MAC, promises a lot of facilities for high-speed and high-quality wireless communication. However, these benefits in turn involve a large amount of computational load, which challenges the traditional uniprocessor architecture based implementation method to provide the required performance. However, the constrained cost and power budget, on the other hand, makes using commercial multiprocessor solutions unrealistic. In this paper, a low-cost and energy-efficient multiprocessor system-on-chip (MPSoC), which tackles at once the aspects of system design, software migration and hardware architecture, is presented for the implementation of UWB MAC layer. Experimental results show that the proposed MPSoC, based on four simple RISC processors and shared-memory infrastructure, achieves up to 45% performance improvement and 65% power saving, but takes 15% less area than the uniprocessor implementation.

  17. Exact Error Rate Analysis for Pulsed DS- and Hybrid DS/TH-CDMA in Nakagami Fading

    NASA Astrophysics Data System (ADS)

    Rahman, Mohammad Azizur; Sasaki, Shigenobu; Kikuchi, Hisakazu; Harada, Hiroshi; Kato, Shuzo

    Exact bit error probabilities (BEP) are derived in closed-form for binary pulsed direct sequence (DS-) and hybrid direct sequence time hopping code division multiple access (DS/TH-CDMA) systems that have potential applications in ultra-wideband (UWB) communications. Flat Nakagami fading channel is considered and the characteristic function (CF) method is adopted. An exact expression of the CF is obtained through a straightforward method, which is simple and good for any arbitrary pulse shape. The CF is then used to obtain the exact BEP that requires less computational complexity than the method based on improved Gaussian approximation (IGA). It is shown under identical operating conditions that the shape of the CF, as well as, the BEP differs considerably for the two systems. While both the systems perform comparably in heavily faded channel, the hybrid system shows better BEP performance in lightly-faded channel. The CF and BEP also strongly depend on chip length and chip-duty that constitute the processing gain (PG). Different combinations of the parameters may result into the same PG and the BEP of a particular system for a constant PG, though remains nearly constant in a highly faded channel, may vary substantially in lightly-faded channel. A comparison of the results from the exact method with those from the standard Gaussian approximation (SGA) reveals that the SGA, though accurate for both the systems in highly-faded channel, becomes extremely optimistic for low-duty systems in lightly-faded channel. The SGA also fails to track several other system trade-offs.

  18. A Multiuser Detector Based on Artificial Bee Colony Algorithm for DS-UWB Systems

    PubMed Central

    Liu, Xiaohui

    2013-01-01

    Artificial Bee Colony (ABC) algorithm is an optimization algorithm based on the intelligent behavior of honey bee swarm. The ABC algorithm was developed to solve optimizing numerical problems and revealed premising results in processing time and solution quality. In ABC, a colony of artificial bees search for rich artificial food sources; the optimizing numerical problems are converted to the problem of finding the best parameter which minimizes an objective function. Then, the artificial bees randomly discover a population of initial solutions and then iteratively improve them by employing the behavior: moving towards better solutions by means of a neighbor search mechanism while abandoning poor solutions. In this paper, an efficient multiuser detector based on a suboptimal code mapping multiuser detector and artificial bee colony algorithm (SCM-ABC-MUD) is proposed and implemented in direct-sequence ultra-wideband (DS-UWB) systems under the additive white Gaussian noise (AWGN) channel. The simulation results demonstrate that the BER and the near-far effect resistance performances of this proposed algorithm are quite close to those of the optimum multiuser detector (OMD) while its computational complexity is much lower than that of OMD. Furthermore, the BER performance of SCM-ABC-MUD is not sensitive to the number of active users and can obtain a large system capacity. PMID:23983638

  19. Time-lapse imaging of human heart motion with switched array UWB radar.

    PubMed

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

    2014-10-01

    Radar systems for detection of human heartbeats have mostly been single-channel systems with limited spatial resolution. In this paper, a radar system for ultra-wideband (UWB) imaging of the human heart is presented. To make the radar waves penetrate the human tissue the antenna is placed very close to the body. The antenna is an array with eight elements, and an antenna switch system connects the radar to the individual elements in sequence to form an image. Successive images are used to build up time-lapse movies of the beating heart. Measurements on a human test subject are presented and the heart motion is estimated at different locations inside the body. The movies show rhythmic motion consistent with the beating heart, and the location and shape of the reflections correspond well with the expected response form the heart wall. The spatial dependent heart motion is compared to ECG recordings, and it is confirmed that heartbeat modulations are seen in the radar data. This work shows that radar imaging of the human heart may provide valuable information on the mechanical movement of the heart. PMID:25350945

  20. Flexible, Polarization-Diverse UWB Antennas for Implantable Neural Recording Systems.

    PubMed

    Bahrami, Hadi; Mirbozorgi, S Abdollah; Ameli, Reza; Rusch, Leslie A; Gosselin, Benoit

    2016-02-01

    Implanted antennas for implant-to-air data communications must be composed of material compatible with biological tissues. We design single and dual-polarization antennas for wireless ultra-wideband neural recording systems using an inhomogeneous multi-layer model of the human head. Antennas made from flexible materials are more easily adapted to implantation; we investigate both flexible and rigid materials and examine performance trade-offs. The proposed antennas are designed to operate in a frequency range of 2-11 GHz (having S11 below -10 dB) covering both the 2.45 GHz (ISM) band and the 3.1-10.6 GHz UWB band. Measurements confirm simulation results showing flexible antennas have little performance degradation due to bending effects (in terms of impedance matching). Our miniaturized flexible antennas are 12 mm×12 mm and 10 mm×9 mm for single- and dual-polarizations, respectively. Finally, a comparison is made of four implantable antennas covering the 2-11 GHz range: 1) rigid, single polarization, 2) rigid, dual polarization, 3) flexible, single polarization and 4) flexible, dual polarization. In all cases a rigid antenna is used outside the body, with an appropriate polarization. Several advantages were confirmed for dual polarization antennas: 1) smaller size, 2) lower sensitivity to angular misalignments, and 3) higher fidelity. PMID:25794394

  1. Meander-line-based inhomogeneous anisotropic artificial material for gain enhancement of UWB Vivaldi antenna

    NASA Astrophysics Data System (ADS)

    Pandey, Gaurav Kumar; Singh, Hari Shankar; Meshram, Manoj Kumar

    2016-02-01

    An inhomogeneous anisotropic (IA) artificial material (AM) is proposed having epsilon-near-zero (ENZ) characteristics and effective refractive index >1, simultaneously, in the same direction. Further, the proposed IA-AM is utilized for the gain enhancement of Vivaldi antenna for ultra-wideband (UWB) applications. The IA-AM consists of two types of compact meandered line-based anisotropic artificial material with ENZ characteristics in two adjacent narrow bands of 5.5-8.5 and 8-11.5 GHz. However, the non-resonant behavior of the artificial material in other direction appears with high refractive index property in broadband region. The combination of both the unit cells with broadband ENZ and high refractive index property is used to improve the gain of the Vivaldi antenna in broadband. The proposed IA-AM-loaded Vivaldi antenna exhibits a gain enhancement of up to 2 dBi compared to the original antenna in the operating frequency band of 3.1-12 GHz with | S 11| < -10 dB. The proposed antenna shows nearly stable unidirectional radiation patterns with high directivity and nearly flat group delay.

  2. A multiuser detector based on artificial bee colony algorithm for DS-UWB systems.

    PubMed

    Yin, Zhendong; Liu, Xiaohui; Wu, Zhilu

    2013-01-01

    Artificial Bee Colony (ABC) algorithm is an optimization algorithm based on the intelligent behavior of honey bee swarm. The ABC algorithm was developed to solve optimizing numerical problems and revealed premising results in processing time and solution quality. In ABC, a colony of artificial bees search for rich artificial food sources; the optimizing numerical problems are converted to the problem of finding the best parameter which minimizes an objective function. Then, the artificial bees randomly discover a population of initial solutions and then iteratively improve them by employing the behavior: moving towards better solutions by means of a neighbor search mechanism while abandoning poor solutions. In this paper, an efficient multiuser detector based on a suboptimal code mapping multiuser detector and artificial bee colony algorithm (SCM-ABC-MUD) is proposed and implemented in direct-sequence ultra-wideband (DS-UWB) systems under the additive white Gaussian noise (AWGN) channel. The simulation results demonstrate that the BER and the near-far effect resistance performances of this proposed algorithm are quite close to those of the optimum multiuser detector (OMD) while its computational complexity is much lower than that of OMD. Furthermore, the BER performance of SCM-ABC-MUD is not sensitive to the number of active users and can obtain a large system capacity. PMID:23983638

  3. High speed Radix-4 soft-decision Viterbi decoder for MB-OFDM UWB system

    NASA Astrophysics Data System (ADS)

    Liang, Guixuan; Portilla, Jorge; Riesgo, Teresa

    2013-05-01

    In this paper, a 64 state soft decision Viterbi Decoder (VD) system by using a high speed radix-4 Add Compare Select (ACS) architecture is presented. The proposed VD system can support different data rate (from 53.5 Mbps to 480 Mbps) for Multiband Orthogonal Frequency-division Multiplexing (MB-OFDM) Ultra-Wideband (UWB) system when implemented onto the FPGA board. The proposed VD employs efficient two steps Radix 4 architecture, which is responsible of calculating two steps of 64 state Radix 4 Branch Metrics (BM) within one clock cycle. The branch metrics are calculated using a uniform distance measurement algorithm, which equals to the symbol itself when compared to logic-0 and equal to its one's complement when compared to logic-1. By employing the modified Modulo Normalization algorithm, it is possible to use only a 10- bit memory block to restore each of the 64 state metrics, with the advantage of avoiding errors caused by overflow during the updating process for state metrics, and simplifying the comparator circuit of the ACS unit. The Two Pointer Even Algorithm, which is considered to be very simple and more hardware-efficient than the register exchange algorithm, is used for tracing back the survivor sequence and output the decoded data stream. 3-bit soft decision input sequences are used for gathering the experimental results. The sampling frequency of the MBOFDM UWB system is 528 MHz, by using the proposed two steps Radix 4 VD architecture we can process 4 input signals in parallel within one clock cycle, therefore only 132 MHz operating frequency is needed for the proposed VD system. This will dramatically reduce the dynamic power consumption for hardware implementation. Final results of the implementation show that the proposed VD architecture can support a maximum working frequency of 152.5 MHz on Xilinx XUPV5-LX110T Evaluation Platform.

  4. UWB channel estimation using new generating TR transceivers

    DOEpatents

    Nekoogar, Faranak; Dowla, Farid U.; Spiridon, Alex; Haugen, Peter C.; Benzel, Dave M.

    2011-06-28

    The present invention presents a simple and novel channel estimation scheme for UWB communication systems. As disclosed herein, the present invention maximizes the extraction of information by incorporating a new generation of transmitted-reference (Tr) transceivers that utilize a single reference pulse(s) or a preamble of reference pulses to provide improved channel estimation while offering higher Bit Error Rate (BER) performance and data rates without diluting the transmitter power.

  5. Ultra-wideband ladder filter using SH(0) plate wave in thin LiNbO(3) plate and its application to tunable filter.

    PubMed

    Kadota, Michio; Tanaka, Shuji

    2015-05-01

    A cognitive radio terminal using vacant frequency bands of digital TV (DTV) channels, i.e., TV white space, strongly requires a compact tunable filter covering a wide frequency range of the DTV band (470 to 710 MHz in Japan). In this study, a T-type ladder filter using ultra-wideband shear horizontal mode plate wave resonators was fabricated, and a low peak insertion loss of 0.8 dB and an ultra-large 6 dB bandwidth of 240 MHz (41%) were measured in the DTV band. In addition, bandpass filters with different center frequencies of 502 and 653 MHz at 6 dB attenuation were numerically synthesized based on the same T-type ladder filter in conjunction with band rejection filters with different frequencies. The results suggest that the combination of the wideband T-type ladder filter and the band rejection filters connected with variable capacitors enables a tunable filter with large tunability of frequency and bandwidth as well as large rejection at the adjacent channels of an available TV white space. PMID:25965686

  6. An Ultra-Wideband, Microwave Radar for Measuring Snow Thickness on Sea Ice and Mapping Near-Surface Internal Layers in Polar Firn

    NASA Technical Reports Server (NTRS)

    Panzer, Ben; Gomez-Garcia, Daniel; Leuschen, Carl; Paden, John; Rodriguez-Morales, Fernando; Patel, Azsa; Markus, Thorsten; Holt, Benjamin; Gogineni, Prasad

    2013-01-01

    Sea ice is generally covered with snow, which can vary in thickness from a few centimeters to >1 m. Snow cover acts as a thermal insulator modulating the heat exchange between the ocean and the atmosphere, and it impacts sea-ice growth rates and overall thickness, a key indicator of climate change in polar regions. Snow depth is required to estimate sea-ice thickness using freeboard measurements made with satellite altimeters. The snow cover also acts as a mechanical load that depresses ice freeboard (snow and ice above sea level). Freeboard depression can result in flooding of the snow/ice interface and the formation of a thick slush layer, particularly in the Antarctic sea-ice cover. The Center for Remote Sensing of Ice Sheets (CReSIS) has developed an ultra-wideband, microwave radar capable of operation on long-endurance aircraft to characterize the thickness of snow over sea ice. The low-power, 100mW signal is swept from 2 to 8GHz allowing the air/snow and snow/ ice interfaces to be mapped with 5 c range resolution in snow; this is an improvement over the original system that worked from 2 to 6.5 GHz. From 2009 to 2012, CReSIS successfully operated the radar on the NASA P-3B and DC-8 aircraft to collect data on snow-covered sea ice in the Arctic and Antarctic for NASA Operation IceBridge. The radar was found capable of snow depth retrievals ranging from 10cm to >1 m. We also demonstrated that this radar can be used to map near-surface internal layers in polar firn with fine range resolution. Here we describe the instrument design, characteristics and performance of the radar.

  7. Experimental results for a photonic time reversal processor for the adaptive control of an ultra wideband phased array antenna

    NASA Astrophysics Data System (ADS)

    Zmuda, Henry; Fanto, Michael; McEwen, Thomas

    2008-04-01

    This paper describes a new concept for a photonic implementation of a time reversed RF antenna array beamforming system. The process does not require analog to digital conversion to implement and is therefore particularly suited for high bandwidth applications. Significantly, propagation distortion due to atmospheric effects, clutter, etc. is automatically accounted for with the time reversal process. The approach utilizes the reflection of an initial interrogation signal from off an extended target to precisely time match the radiating elements of the array so as to re-radiate signals precisely back to the target's location. The backscattered signal(s) from the desired location is captured by each antenna and used to modulate a pulsed laser. An electrooptic switch acts as a time gate to eliminate any unwanted signals such as those reflected from other targets whose range is different from that of the desired location resulting in a spatial null at that location. A chromatic dispersion processor is used to extract the exact array parameters of the received signal location. Hence, other than an approximate knowledge of the steering direction needed only to approximately establish the time gating, no knowledge of the target position is required, and hence no knowledge of the array element time delay is required. Target motion and/or array element jitter is automatically accounted for. Presented here are experimental results that demonstrate the ability of a photonic processor to perform the time-reversal operation on ultra-short electronic pulses.

  8. Adaptive modulation and intra-symbol frequency-domain averaging scheme for multiband OFDM UWB over fiber system

    NASA Astrophysics Data System (ADS)

    He, Jing; Li, Teng; Wen, Xuejie; Deng, Rui; Chen, Ming; Chen, Lin

    2016-01-01

    To overcome the unbalanced error bit distribution among subcarriers caused by inter-subcarriers mixing interference (ISMI) and frequency selective fading (FSF), an adaptive modulation scheme based on 64/16/4QAM modulation is proposed and experimentally investigated in the intensity-modulation direct-detection (IM/DD) multiband orthogonal frequency division multiplexing (MB-OFDM) ultra-wideband (UWB) over fiber system. After 50 km standard single mode fiber (SSMF) transmission, at the bit error ratio (BER) of 1×10-3, the experimental results show that the power penalty of the IM/DD MB-OFDM UWBoF system with 64/16/4QAM adaptive modulation scheme is about 3.6 dB, compared to that with the 64QAM modulation scheme. Moreover, the receiver sensitivity has been improved about 0.52 dB when the intra-symbol frequency-domain averaging (ISFA) algorithm is employed in the IM/DD MB-OFDM UWBoF system based on the 64/16/4QAM adaptive modulation scheme. Meanwhile, after 50 km SSMF transmission, there is a negligible power penalty in the adaptively modulated IM/DD MB-OFDM UWBoF system, compared to the optical back-to-back case.

  9. A Modified λ0/4 Short-Circuited Stub Bandpass Filter for UWB Applications Utilizing LTCC Technology

    NASA Astrophysics Data System (ADS)

    Duong, Thai Hoa; Lee, Kye San; Kim, Ihn S.

    In this paper, we utilize low temperature co-fired ceramic technology (LTCC) to realize a modified short-circuited stub bandpass filter suitable for ultra-wideband (UWB) applications. By modifying the conventional short-circuited stub bandpass filter structure with stubs and connecting lines of lower characteristic impedances, the number of stubs has been reduced from 5 to 2 on a high dielectric constant substrate (εr=40). A wireless local area network (WLAN) stopband in the frequency range of 5.15 to 5.825GHz has been inserted into the filter characteristic using three short-circuited coupled lines. The filter is fabricated and measurement results show that it has an insertion loss less than 1.0dB and return loss better than 10dB in the pass bands. A bandwidth ratio of 109.49% has been achieved. Measurement results agree well with simulation results. The dimensions of the filter are 4×8×0.57mm3.

  10. A UWB Radar Signal Processing Platform for Real-Time Human Respiratory Feature Extraction Based on Four-Segment Linear Waveform Model.

    PubMed

    Hsieh, Chi-Hsuan; Chiu, Yu-Fang; Shen, Yi-Hsiang; Chu, Ta-Shun; Huang, Yuan-Hao

    2016-02-01

    This paper presents an ultra-wideband (UWB) impulse-radio radar signal processing platform used to analyze human respiratory features. Conventional radar systems used in human detection only analyze human respiration rates or the response of a target. However, additional respiratory signal information is available that has not been explored using radar detection. The authors previously proposed a modified raised cosine waveform (MRCW) respiration model and an iterative correlation search algorithm that could acquire additional respiratory features such as the inspiration and expiration speeds, respiration intensity, and respiration holding ratio. To realize real-time respiratory feature extraction by using the proposed UWB signal processing platform, this paper proposes a new four-segment linear waveform (FSLW) respiration model. This model offers a superior fit to the measured respiration signal compared with the MRCW model and decreases the computational complexity of feature extraction. In addition, an early-terminated iterative correlation search algorithm is presented, substantially decreasing the computational complexity and yielding negligible performance degradation. These extracted features can be considered the compressed signals used to decrease the amount of data storage required for use in long-term medical monitoring systems and can also be used in clinical diagnosis. The proposed respiratory feature extraction algorithm was designed and implemented using the proposed UWB radar signal processing platform including a radar front-end chip and an FPGA chip. The proposed radar system can detect human respiration rates at 0.1 to 1 Hz and facilitates the real-time analysis of the respiratory features of each respiration period. PMID:25667357

  11. FIR Filter of DS-CDMA UWB Modem Transmitter

    NASA Astrophysics Data System (ADS)

    Kang, Kyu-Min; Cho, Sang-In; Won, Hui-Chul; Choi, Sang-Sung

    This letter presents low-complexity digital pulse shaping filter structures of a direct sequence code division multiple access (DS-CDMA) ultra wide-band (UWB) modem transmitter with a ternary spreading code. The proposed finite impulse response (FIR) filter structures using a look-up table (LUT) have the effect of saving the amount of memory by about 50% to 80% in comparison to the conventional FIR filter structures, and consequently are suitable for a high-speed parallel data process.

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

    PubMed

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

    2008-01-01

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

  13. 47 CFR 15.507 - Marketing of UWB equipment.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 1 2013-10-01 2013-10-01 false Marketing of UWB equipment. 15.507 Section 15... Operation § 15.507 Marketing of UWB equipment. In some cases, the operation of UWB devices is limited to... state or local government. The marketing of UWB devices must be directed solely to parties eligible...

  14. 47 CFR 15.507 - Marketing of UWB equipment.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 1 2012-10-01 2012-10-01 false Marketing of UWB equipment. 15.507 Section 15... Operation § 15.507 Marketing of UWB equipment. In some cases, the operation of UWB devices is limited to... state or local government. The marketing of UWB devices must be directed solely to parties eligible...

  15. 47 CFR 15.507 - Marketing of UWB equipment.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 1 2014-10-01 2014-10-01 false Marketing of UWB equipment. 15.507 Section 15... Operation § 15.507 Marketing of UWB equipment. In some cases, the operation of UWB devices is limited to... state or local government. The marketing of UWB devices must be directed solely to parties eligible...

  16. 47 CFR 15.507 - Marketing of UWB equipment.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 1 2011-10-01 2011-10-01 false Marketing of UWB equipment. 15.507 Section 15... Operation § 15.507 Marketing of UWB equipment. In some cases, the operation of UWB devices is limited to... state or local government. The marketing of UWB devices must be directed solely to parties eligible...

  17. 47 CFR 15.507 - Marketing of UWB equipment.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false Marketing of UWB equipment. 15.507 Section 15... Operation § 15.507 Marketing of UWB equipment. In some cases, the operation of UWB devices is limited to... state or local government. The marketing of UWB devices must be directed solely to parties eligible...

  18. Accuracy of an UWB-based position tracking system used for time-motion analyses in game sports.

    PubMed

    Leser, Roland; Schleindlhuber, Armin; Lyons, Keith; Baca, Arnold

    2014-01-01

    The main aim of this study was to determine the accuracy of the ultra-wideband (UWB)-based positioning system Ubisense, which is used for time-motion analysis in sports. Furthermore, some alternatives for positioning the system's transponders on the atheletes, as well as the accuracy depending on the location of measurement, were tested. Therefore, in a pre-study, some basic issues were examined (measurement assumptions and consistency and location of the system's transponder used for position detection), and position measurements at the borders and in the centre of a basketball field were performed. In the main study, 13 male basketball players (15.8 years ± 0.6; 187.9 height ± 3.4; 77.5 weight ± 3.7), equipped with a Ubisense transponder mounted on top of their heads, handled a trundle wheel during simulated match play. The players with the trundle wheel participated passively in the match by following one of the ten competing players. The distance measurements of the trundle wheel were used as reference values and compared to the Ubisense distance estimations. Best results were found with the measurements of a single mounted transponder on top of the athlete's heads. No differences were detectable in the accuracy between measurements in the centre and at the borders of the basketball field. The (Ubisense) system's difference to the (trundle wheel) reference was 3.45 ± 1.99%, resulting in 95% limits of agreement of -0.46-7.35%. The study indicates the examined system's sufficient accuracy for time-motion analysis in basketball. PMID:24512176

  19. Design of the 1.5 MW, 30-96 MHz ultra-wideband 3 dB high power hybrid coupler for Ion Cyclotron Resonance Frequency (ICRF) heating in fusion grade reactor.

    PubMed

    Yadav, Rana Pratap; Kumar, Sunil; Kulkarni, S V

    2016-01-01

    Design and developmental procedure of strip-line based 1.5 MW, 30-96 MHz, ultra-wideband high power 3 dB hybrid coupler has been presented and its applicability in ion cyclotron resonance heating (ICRH) in tokamak is discussed. For the high power handling capability, spacing between conductors and ground need to very high. Hence other structural parameters like strip-width, strip thickness coupling gap, and junction also become large which can be gone upto optimum limit where various constrains like fabrication tolerance, discontinuities, and excitation of higher TE and TM modes become prominent and significantly deteriorates the desired parameters of the coupled lines system. In designed hybrid coupler, two 8.34 dB coupled lines are connected in tandem to get desired coupling of 3 dB and air is used as dielectric. The spacing between ground and conductors are taken as 0.164 m for 1.5 MW power handling capability. To have the desired spacing, each of 8.34 dB segments are designed with inner dimension of 3.6 × 1.0 × 40 cm where constraints have been significantly realized, compensated, and applied in designing of 1.5 MW hybrid coupler and presented in paper. PMID:26827337

  20. Design of the 1.5 MW, 30-96 MHz ultra-wideband 3 dB high power hybrid coupler for Ion Cyclotron Resonance Frequency (ICRF) heating in fusion grade reactor

    NASA Astrophysics Data System (ADS)

    Yadav, Rana Pratap; Kumar, Sunil; Kulkarni, S. V.

    2016-01-01

    Design and developmental procedure of strip-line based 1.5 MW, 30-96 MHz, ultra-wideband high power 3 dB hybrid coupler has been presented and its applicability in ion cyclotron resonance heating (ICRH) in tokamak is discussed. For the high power handling capability, spacing between conductors and ground need to very high. Hence other structural parameters like strip-width, strip thickness coupling gap, and junction also become large which can be gone upto optimum limit where various constrains like fabrication tolerance, discontinuities, and excitation of higher TE and TM modes become prominent and significantly deteriorates the desired parameters of the coupled lines system. In designed hybrid coupler, two 8.34 dB coupled lines are connected in tandem to get desired coupling of 3 dB and air is used as dielectric. The spacing between ground and conductors are taken as 0.164 m for 1.5 MW power handling capability. To have the desired spacing, each of 8.34 dB segments are designed with inner dimension of 3.6 × 1.0 × 40 cm where constraints have been significantly realized, compensated, and applied in designing of 1.5 MW hybrid coupler and presented in paper.

  1. A DS-UWB Cognitive Radio System Based on Bridge Function Smart Codes

    NASA Astrophysics Data System (ADS)

    Xu, Yafei; Hong, Sheng; Zhao, Guodong; Zhang, Fengyuan; di, Jinshan; Zhang, Qishan

    This paper proposes a direct-sequence UWB Gaussian pulse of cognitive radio systems based on bridge function smart sequence matrix and the Gaussian pulse. As the system uses the spreading sequence code, that is the bridge function smart code sequence, the zero correlation zones (ZCZs) which the bridge function sequences' auto-correlation functions had, could reduce multipath fading of the pulse interference. The Modulated channel signal was sent into the IEEE 802.15.3a UWB channel. We analysis the ZCZs's inhibition to the interference multipath interference (MPI), as one of the main system sources interferences. The simulation in SIMULINK/MATLAB is described in detail. The result shows the system has better performance by comparison with that employing Walsh sequence square matrix, and it was verified by the formula in principle.

  2. Design and implementation of a digital impulse generator for a 24GHz UWB radar

    NASA Astrophysics Data System (ADS)

    Kim, Sang-Dong; Lee, Jong-Hun

    2011-06-01

    In this paper, we design and implement a digital impulse generator using a DCM block and an OSERDES block for a 24GHz UWB impulse-Doppler radar. The Federal Communications Commission (FCC) has confirmed the spectrum from 22 to 29GHz for UWB radar with a limit power of -41.3dBm/MHz. UWB signal possesses an absolute bandwidth larger than 500MHz or a relative bandwidth up to 20%. The vehicle radar is the key technology with the inherent advantage detected the distance and the velocity regardless of weather. Radar has a role to measure the distance and the velocity of long-distance vehicle. But, the radar with 1m resolution is difficult to satisfy the detection performance in the blind spot zone because the blind spot zone needs high resolution. So, UWB impulse-Doppler radar with 30cm resolution is suitable for the blind spot zone. The designed impulse generator has a 2ns pulse width and 100us PRI. We perform simulations through Xilinx ISE; experiments use a spectrum analyzer and a digital oscilloscope. For UWB radar, we use an AD9779 DAC module with a 1Gsps maximum sampling rate. For equipment, we use a TDS5104B oscilloscope of Tektronix with 3dB bandwidth at 1GHz for the analysis of the time domain and an E4448A spectrum analyzer of Agilent with a 50GHz spectrum for the analysis of the frequency domain. The results of the digital impulse measurement show a 2ns pulse width in the time domain, a 500MHz bandwidth, and a 10KHz spectrum peak in the frequency domain.

  3. UWB Antennas Integration Effects for Wireless Communication Applications

    NASA Astrophysics Data System (ADS)

    Mellah, M.-A.; Roblin, C.; Sibille, A.

    In this chapter, a return loss measurement campaign was achieved to study the effect of the close environment on antenna's behavior in wireless application scenarios. Five different planar ultra-wideband antennas were measured on different devices (keyboard, screen, Internet box, and two laptops). General similarities in the bandwidth and matching efficiency behaviors were noticed for the antennas when mounted on the same devices in the same positions. In a purpose of modeling, the results can be used to classify the antennas and describe general behaviors on common used devices in wireless applications.

  4. Characteristics of trap-filled gallium arsenide photoconductive switches used in high gain pulsed power applications

    SciTech Connect

    ISLAM,N.E.; SCHAMILOGLU,E.; MAR,ALAN; LOUBRIEL,GUILLERMO M.; ZUTAVERN,FRED J.; JOSHI,R.P.

    2000-05-30

    The electrical properties of semi-insulating (SI) Gallium Arsenide (GaAs) have been investigated for some time, particularly for its application as a substrate in microelectronics. Of late this material has found a variety of applications other than as an isolation region between devices, or the substrate of an active device. High resistivity SI GaAs is increasingly being used in charged particle detectors and photoconductive semiconductor switches (PCSS). PCSS made from these materials operating in both the linear and non-linear modes have applications such as firing sets, as drivers for lasers, and in high impedance, low current Q-switches or Pockels cells. In the non-linear mode, it has also been used in a system to generate Ultra-Wideband (UWB) High Power Microwaves (HPM). The choice of GaAs over silicon offers the advantage that its material properties allow for fast, repetitive switching action. Furthermore photoconductive switches have advantages over conventional switches such as improved jitter, better impedance matching, compact size, and in some cases, lower laser energy requirement for switching action. The rise time of the PCSS is an important parameter that affects the maximum energy transferred to the load and it depends, in addition to other parameters, on the bias or the average field across the switch. High field operation has been an important goal in PCSS research. Due to surface flashover or premature material breakdown at higher voltages, most PCSS, especially those used in high power operation, need to operate well below the inherent breakdown voltage of the material. The lifetime or the total number of switching operations before breakdown, is another important switch parameter that needs to be considered for operation at high bias conditions. A lifetime of {approximately} 10{sup 4} shots has been reported for PCSS's used in UWB-HPM generation [5], while it has exceeded 10{sup 8} shots for electro-optic drivers. Much effort is currently being channeled in the study related to improvements of these two parameters high bias operation and lifetime improvement for switches used in pulsed power applications. The contact material and profiles are another important area of study. Although these problems are being pursued through the incorporation of different contact materials and introducing doping near contacts, it is important that the switch properties and the conduction mechanism in these switches be well understood such that the basic nature of the problems can be properly addressed. In this paper the authors report on these two basic issues related to the device operation, i.e., mechanisms for increasing the hold-off characteristics through neutron irradiation, and the analysis of transport processes at varying field conditions in trap dominated SI GaAs in order to identify the breakdown mechanism during device operation. It is expected that this study would result in a better understanding of photoconductive switches, specifically those used in high power operation.

  5. Non-Invasive UWB Sensing of Astronauts' Breathing Activity

    PubMed Central

    Baldi, Marco; Cerri, Graziano; Chiaraluce, Franco; Eusebi, Lorenzo; Russo, Paola

    2015-01-01

    The use of a UWB system for sensing breathing activity of astronauts must account for many critical issues specific to the space environment. The aim of this paper is twofold. The first concerns the definition of design constraints about the pulse amplitude and waveform to transmit, as well as the immunity requirements of the receiver. The second issue concerns the assessment of the procedures and the characteristics of the algorithms to use for signal processing to retrieve the breathing frequency and respiration waveform. The algorithm has to work correctly in the presence of surrounding electromagnetic noise due to other sources in the environment. The highly reflecting walls increase the difficulty of the problem and the hostile scenario has to be accurately characterized. Examples of signal processing techniques able to recover breathing frequency in significant and realistic situations are shown and discussed. PMID:25558995

  6. On Integration and Validation of a Very Low Complexity ATC UWB System for Muscle Force Transmission.

    PubMed

    Sapienza, Stefano; Crepaldi, Marco; Motto Ros, Paolo; Bonanno, Alberto; Demarchi, Danilo

    2016-04-01

    The thresholding of Surface ElectroMyoGraphic (sEMG) signals, i.e., Average Threshold Crossing (ATC) technique, reduces the amount of data to be processed enabling circuit complexity reduction and low power consumption. This paper investigates the lowest level of complexity reachable by an ATC system through measurements and in-vivo experiments with an embedded prototype for wireless force transmission, based on asynchronous Impulse-Radio Ultra Wide Band (IR-UWB). The prototype is composed by the acquisition unit, a wearable PCB 23 × 34 mm, which includes a full custom IC integrating a UWB transmitter (chip active silicon area 0.016 mm (2), 1 mW power consumption), and the receiver. The system is completely asynchronous, it acquires a differential sEMG signal, generates the ATC events and triggers a 3.3 GHz IR-UWB transmission. ATC robustness relaxes filters constraints: two passive first order filters have been implemented, bandwidth from 10 Hz up to 1 kHz . Energy needed for the single pulse generation is 30 pJ while the whole PCB consumes 5.65 mW. The pulses radiated by the acquisition unit TX are received by a short-range and low complexity threshold-based 130 nm CMOS IR-UWB receiver with an Ultra Low Power (ULP) baseband unit capable of robustly receiving generic quasi-digital pulse sequences. The acquisition unit have been tested with 10 series of in vivo isometric and isotonic contractions, while the transmission channel with over-the-air and cable measurements obtained with a couple of planar monopole antennas and an integrated 0.004 mm (2) transmitter, the same used for the acquisition unit, with realistic channel conditions. The entire system, acquisition unit and receiver, consumes 15.49 mW. PMID:26011867

  7. Ultra-wideband tomography of land cover

    NASA Astrophysics Data System (ADS)

    Kochetkova, Tatiana D.; Zapasnoy, Andrey S.; Klokov, Andrey V.; Shipilov, Sergey E.; Yakubov, Vladimir P.; Yurchenko, Alexey V.

    2014-11-01

    This paper describes a comprehensive approach which combines the application of OKO-2 ground penetrating radar, conventional method of cross sectioning accepted in edaphology, soil-testing parameters, mobile and laboratory research of dielectric permittivity for stratified soil cover research. Dielectric characteristics measurements of selected contact samples by the waveguide-coaxial technique showed a correlation between electrophysic characteristics of soil with soil moisture and density. Location of deep aquifers was detected and the real local topography was restored. Research was performed within the Timiryazevskoye forest district near Tomsk. Comparing the results of radar non-destructive sounding and contact measurements demonstrated high correlation of detected structural soil features. The suggested approach provides a solid basis for verifying the non-contact radiophysical methods of research in the interests of rational nature management and land utilization.

  8. Airy pulsed beams.

    PubMed

    Kaganovsky, Yan; Heyman, Ehud

    2011-06-01

    The Airy beam (AiB) has attracted a lot of attention recently because of its intriguing features; the most distinctive ones are the propagation along curved trajectories in free space and the weak diffraction. We have previously shown that the AiB is, in fact, a caustic of the rays that radiate from the tail of the Airy function aperture distribution. Here we derive a class of ultra wideband Airy pulsed beams (AiPBs), which are the extension of the AiB into the time domain. We introduce a frequency scaling of the initial aperture field that renders the ray skeleton of the field, including the caustic, frequency independent, thus ensuring that all the frequency components propagate along the same curved trajectory and that the AiPB does not disperse. The resulting AiPB preserves the intriguing features of the time-harmonic AiB discussed above. An exact closed-form solution for the AiPB is derived using the spectral theory of transients. We also derive wavefront approximations for the field in the time window around the pulse arrival, which are valid uniformly in the vicinity of the caustic. These approximations are based on the so-called uniform geometrical optics, which is extended here to the time domain. PMID:21643410

  9. A Novel Low-Ringing Monocycle Picosecond Pulse Generator Based on Step Recovery Diode

    PubMed Central

    Zhou, Jianming; Yang, Xiao; Lu, Qiuyuan; Liu, Fan

    2015-01-01

    This paper presents a high-performance low-ringing ultra-wideband monocycle picosecond pulse generator, formed using a step recovery diode (SRD), simulated in ADS software and generated through experimentation. The pulse generator comprises three parts, a step recovery diode, a field-effect transistor and a Schottky diode, used to eliminate the positive and negative ringing of pulse. Simulated results validate the design. Measured results indicate an output waveform of 1.88 peak-to-peak amplitude and 307ps pulse duration with a minimal ringing of -22.5 dB, providing good symmetry and low level of ringing. A high degree of coordination between the simulated and measured results is achieved. PMID:26308450

  10. Band-notched reconfigurable CPW-fed UWB antenna

    NASA Astrophysics Data System (ADS)

    Majid, H. A.; Rahim, M. K. A.; Hamid, M. R.; Murad, N. A.; Samsuri, N. A.; Yusof, M. F. M.; Kamarudin, M. R.

    2016-04-01

    A reconfigurable band-notched CPW-fed UWB antenna using electromagnetic bandgap (EBG) structure is proposed. Two structures are positioned adjacent to the transmission line of the UWB antenna. The band-notched characteristic can be disabled by switching the state of switch place at the strip line. The EBG structure produces reconfigurable band notched at 4.0 GHz, which covers C-band satellite communication (3.625-4.2 GHz) systems. The proposed antenna is suitable for UWB systems, which requires reconfigurable band reject function.

  11. Definition on SAR image quality measurements for UWB SAR

    NASA Astrophysics Data System (ADS)

    Vu, Viet T.; Sjögren, Thomas K.; Pettersson, Mats I.; Gustavsson, Anders

    2008-10-01

    Analyses in this study show that measurements under currently used definitions on SAR image quality measurement may be unsuitable for UWB SAR. The main objective of this paper is therefore to propose a definition based on the shape of a single point target in a SAR image which is more suitable for UWB SAR. We use both real and simulated data based on the airborne UWB low frequency SAR CARABAS-II in experiments. The time-domain algorithm Global Backprojection (GBP) is selected for the image formation in this study.

  12. Breakdown Behavior of a Wireless Communication Network Under UWB Impact

    NASA Astrophysics Data System (ADS)

    Rohe, M.; Koch, M.

    Systems with high priority to safety and reliability such as monitoring systems on airports have to work properly. Fast information transmission, continuous access to databases, as well as the management of air traffic are most important for effective and safe operation. Sources of Intentional Electromagnetic Interference can be manufactured relatively easy using commercially available components by civilian persons with relevant expertise and can be used for sabotage or blackmail purposes. For analyzing the weak points of a system existing on airports, it is necessary to reproduce its setup. In this investigation a UHF transmitter of a wireless communication device is developed and its breakdown behavior to unipolar fast rise pulses (UWB) is determined. A breakdown is a non-permanent damage, but includes a type of upset, that requires manual reset or at least stops communications for some period of time. The transmitter consists of three main components connected by data cables: power supply, microcontroller, and loop antenna. The immunity tests are accomplished as a function of the electromagnetic field direction to the device using an open TEM waveguide.

  13. UWB radar technique for arc detection in coaxial cables and waveguides

    SciTech Connect

    Maggiora, R.; Salvador, S.

    2009-11-26

    As spread spectrum technology has revolutionized the communications industry, Ultra Wide Band (UWB) technology is dramatically improving radar performances. These advanced signal processing techniques have been adapted to coaxial cables and waveguides to provide new features and enhanced performance on arc detection. UWB signals constituted by a sequence of chips (properly chosen to reduce side lobes and to improve detection accuracy) are transmitted along the transmission lines at a specified Pulse Repetition Frequency (PRF) and their echoes are received by means of directional couplers. The core of the receiver is an ultra high-speed correlator implemented in a Digital Signal Processor (DSP). When a target (arc) is detected, its position and its 'radar cross section' are calculated to be able to provide the arc position along the transmission line and to be able to classify the type of detected arc. The 'background scattering' is routinely extracted from the received signal at any pulse. This permits to be resilient to the background structure of transmission lines (bends, junctions, windows, etc.). Thanks to the localization feature, segmentation is also possible for creating sensed and non-sensed zones (for example, to be insensitive to antenna load variations)

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

    PubMed Central

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

    2008-01-01

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

  15. 47 CFR 15.519 - Technical requirements for hand held UWB systems.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... information to an associated receiver. The UWB intentional radiator shall cease transmission within 10 seconds... received. An acknowledgment of reception must continue to be received by the UWB intentional radiator...

  16. 47 CFR 15.519 - Technical requirements for hand held UWB systems.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... information to an associated receiver. The UWB intentional radiator shall cease transmission within 10 seconds... received. An acknowledgment of reception must continue to be received by the UWB intentional radiator...

  17. 47 CFR 15.519 - Technical requirements for hand held UWB systems.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... information to an associated receiver. The UWB intentional radiator shall cease transmission within 10 seconds... received. An acknowledgment of reception must continue to be received by the UWB intentional radiator...

  18. Pulse

    MedlinePlus

    ... pulse rate can help determine if the patient's heart is pumping. Pulse measurement has other uses as well. During or immediately after exercise, the pulse rate gives information about your fitness level and health.

  19. Optical channel impact over the PSD of UWB over FSO links

    NASA Astrophysics Data System (ADS)

    Arvizu-Mondragón, A.; Villarreal-Reyes, S.; Pérez-Ramos, A. E.; Santos-Aguilar, J.; Muller, M.; Abib, G. I.; Lepers, C.

    2015-03-01

    The power restrictions limit the communication range of UWB devices to just a few meters, which produce UWB wireless networks operating in stand-alone mode. With the purpose of increasing the coverage area and achieving seamless communications between stand-alone networks UWBoF technology has been proposed. However, the deployment of fiber connecting stand-alone UWB networks is not always feasible. We propose and implement a UWB over free space optic (FSO) horizontal link. Initial results presenting the effects of the optical wireless channel over the UWB signal PSD are demonstrated. These results are analyzed and implementation recommendations are provided based on them.

  20. A Novel UWB Antenna with Dual Band-Notched Characteristics

    NASA Astrophysics Data System (ADS)

    Lin, Yongfan; Liang, Jiangang; Wu, Goucheng; Xu, Zhiyong; Niu, Xuebin

    2015-11-01

    In this article, started from analyzing the basic principle of band-notched characteristics, a feasibly method used for band-notched antenna is demonstrated and the equivalent circuit for this method is designed. A novel UWB antenna is designed. Based on this method, two stubs which can be equivalent to shorted stubs in parallel configuration are added to realize dual band-notched characteristics. Simulated and measured results all show that the UWB antenna yields an impendence bandwidth of 2.0-10.6 GHz by defining VSWR ≦ 2, and two obvious band-notched functions (3.27-3.83 GHz, 4.60-5.90 GHz) occur at the working bandwidth of WIMAX (3.3-3.7 GHz) and HiperLAN/2 (5.15-5.35 GHz, 5.47-5.725 GHz), so the electromagnetic interference between UWB application and WIMAX, HiperLAN/2 can be suppressed.

  1. 2-Dimensional Imaging of Human Bodies with UWB Radar Using Approximately Uniform Walking Motion along a Straight Line with the SEABED Algorithm

    NASA Astrophysics Data System (ADS)

    Sakamoto, Takuya; Sato, Toru

    UWB (Ultra Wide-Band) pulse radar is a promising candidate for surveillance systems designed to prevent crimes and terror-related activities. The high-speed SEABED (Shape Estimation Algorithm based on BST and Extraction of Directly scattered waves) imaging algorithm, is used in the application of UWB pulse radar in fields that require realtime operations. The SEABED algorithm assumes that omni-directional antennas are scanned to observe the scattered electric field in each location. However, for surveillance systems, antenna scanning is impractical because it restricts the setting places of the devices. In this paper, movement of a body is used to replace antenna scanning. The instantaneous velocity of any given motion is an unknown variable that changes as a function of time. A pair of antennas is used to analyze delay time to estimate the unknown motion. We propose a new algorithm to estimate the shape of a human body using data obtained from a human body passing stationary antennas.

  2. [Focusing properties of picosecond electric pulses in non-invasive cancer treatment].

    PubMed

    Long, Zaiquan; Yao, Chenguo; Li, Chengxiang; Mi, Yan; Sun, Caixin

    2010-10-01

    In the light of optical theory, we advanc an ultra-wideband impulse radiating antenna (IRA) which is composed of an ellipsoidal reflector and a cone radiator. The high-intensity ultra-short electric pulses radiated by IRA can be transferred into the deep target in tissue non-invasively and be focused effectively. With the focused picosecond electric pulses, the organelles (mitochondria) transmembrane potential shall change to collapse under which the tumor cells will be targetly induced to apoptosis, so the method of non-invasive treatment of tumors would be achieved. Based on the time-domain electromagnetic field theory, the propagation characteristics of picosecond electric pulses were analyzed with and without the context of biological tissue, respectively. The results show that the impulse characteristics of input pulse were maintained and the picosecond electric pulses can keep high resolution in target areas. Meanwhile, because of the dispersive nature of medium, the pulse amplitude of the pulses will attenuate and the pulse width will be broadened. PMID:21089684

  3. Susceptibility of personal computer systems to electromagnetic pulses with double exponential character

    NASA Astrophysics Data System (ADS)

    Camp, M.; Garbe, H.

    2004-05-01

    In this paper the susceptibility of personal computer systems to fast transient electromagnetic pulses with double exponential pulse shapes (EMP, UWB) is determined. The influence of the computer generation, RAM-values, different program states and the pulse shape, as well as the destruction thresholds of single PC-components (CPU, RAM, BIOS, Mainboard) have been investigated.

  4. UWB EMI To Aircraft Radios: Field Evaluation on Operational Commercial Transport Airplanes. Volume 1

    NASA Technical Reports Server (NTRS)

    Oria, A. J. (Editor); Ely, Jay J.; Martin, Warren L.; Shaver, Timothy W.; Fuller, Gerald L.; Zimmerman, John; Fuschino, Robert L.; Larsen, William E.

    2005-01-01

    Ultrawideband (UWB) transmitters may soon be integrated into a wide variety of portable electronic devices (PEDs) that passengers routinely carry on board commercial airplanes. Airlines and the FAA will have difficulty controlling passenger use of UWB transmitters during flights with current airline policies and existing wireless product standards. The aeronautical community is concerned as to whether evolving FCC UWB rules are adequate to protect legacy and emerging aeronautical radio systems from electromagnetic interference (EMI) from emerging UWB products. To address these concerns, the NASA Office of Space Communications and Chief Spectrum Managers assembled a multidisciplinary team from NASA LaRC, NASA JPL, NASA ARC, FAA, United Airlines, Sky West Airlines, and Eagles Wings Inc. to carry out a comprehensive series of tests aimed at determining the nature and extent of any EMI to aeronautical communication and navigation systems from UWB devices meeting FCCapproved and proposed levels for unlicensed handheld transmitters.

  5. Integrated cm- and mm-Wave UWB Transceiver for M-Sequence-Based Sensors

    NASA Astrophysics Data System (ADS)

    Kmec, M.; Müller, J.; Rauschenbach, P.; Rentsch, S.; Sachs, J.; Yang, B.

    An integrated, completely balanced broadband transceiver front end for operation in the cm- and mm-wave range is presented. It is compatible with our ultra-wideband M-sequence baseband system. The transceiver front end is based on the application of specific integrated circuits (ASICs) designed for a 0.25 μm SiGe process with f T/f max = 180/220 GHz. To achieve an optimum reasonable compromise between flexibility, complexity, and the system performance, we decided to design three different front-end ASICs - an up-converter, a down-converter, and a LO unit. All of them are mounted on an RF-LTCC (low-temperature co-fired ceramics) test board for optimal RF wiring. The final goal is to provide an integrated transceiver module which covers the whole RF part from the antennas to the IF stage. First measurement results will be shown.

  6. Ultrawideband monocycle pulse generation based on delayed interference of π/2 phase-shift keying signal.

    PubMed

    Dai, Yongheng; Du, Jiangbing; Fu, Xuelei; Lei, Gordon K P; Shu, Chester

    2011-07-15

    We propose a scheme to generate ultrawideband (UWB) monocycle pulses using delayed interference of a π/2 phase-shift keying (PSK) signal. The PSK signal is generated with an optical phase modulator. A fiber-based delay interferometer is used to provide the delay together with a ±π/2 phase shift between the signals in its two arms before the interference. The two opposite phase shifts correspond to the generation of a pair of polarity-reversed UWB monocycle pulses. The full width at half maximum of the pulses is ~68 ps and the 10 dB fractional bandwidth is 168%. PMID:21765512

  7. Ultrawideband synthetic vision sensor for airborne wire detection

    NASA Astrophysics Data System (ADS)

    Fontana, Robert J.; Larrick, J. F.; Cade, Jeffrey E.; Rivers, Eugene P., Jr.

    1998-07-01

    A low cost, miniature ultra wideband (UWB) radar has demonstrated the ability to detect suspended wires and other small obstacles at distances exceeding several hundred feet using an average output power of less than 10 microwatts. Originally developed as a high precision UWB radar altimeter for the Navy's Program Executive Office for Unmanned Aerial Vehicles and Cruise Missiles, an improved sensitivity version was recently developed for the Naval Surface Warfare Center (NSWC Dahlgren Division) as part of the Marine Corps Warfighting Laboratory's Hummingbird program for rotary wing platforms. Utilizing a short pulse waveform of approximately 2.5 nanoseconds in duration, the receiver processor exploits the leading edge of the radar return pulse to achieve range resolutions of less than one foot. The resultant 400 MHz bandwidth spectrum produces both a broad frequency excitation for enhanced detection, as well as a low probability of intercept and detection (LPI/D) signature for covert applications. This paper describes the design and development of the ultra wideband sensor, as well as performance results achieved during field testing at NSWC's Dahlgren, VA facility. These results are compared with those achieved with a high resolution EHF radar and a laser-based detection system.

  8. Hex-Sided Rounded Dipole Antenna (HSRDA) For UWB Applications

    NASA Astrophysics Data System (ADS)

    Singhal, Sarthak; Verma, Nand Kishor; Singh, Amit Kumar

    2016-03-01

    A hex-sided rounded dipole antenna (HSRDA) for UWB applications is presented. It is designed by the addition of semi-elliptical patch sections at the edges of a square bow-tie antenna. The antenna structure is fed by a modified microstrip feedline for better impedance matching. An impedance bandwidth of 2.9-11.4 GHz is achieved. The antenna structure has quasi omnidirectional radiation patterns and reasonable gain over the same frequency range. A good agreement between the experimental and simulation results is observed. The proposed antenna structure has miniaturized size for the same bandwidth as compared to already reported antenna structures.

  9. Ultrawide-band electromagnetic pulses induced hypotension in rats.

    PubMed

    Lu, S T; Mathur, S P; Akyel, Y; Lee, J C

    The ultrawide-band (UWB) electromagnetic pulses are used as a new modality in radar technology. Biological effects of extremely high peak E-field, fast rise time, ultrashort pulse width, and ultrawide band have not been investigated heretofore due to the lack of animal exposure facilities. A new biological effects database is needed to establish personnel protection guidelines for these new type of radiofrequency radiation. Functional indices of the cardiovascular system (heart rate, systolic, mean, and diastolic pressures) were selected to represent biological end points that may be susceptible to the UWB radiation. A noninvasive tail-cuff photoelectric sensor sphygmomanometer was used. Male Wistar-Kyoto rats were subjected to sham exposure, 0.5-kHz (93 kV/m, 180 ps rise time, 1.00 ns pulse width, whole-body averaged specific absorption rate, SAR = 70 mW/kg) or a 1-kHz (85 kV/m, 200 ps rise time, 1.03 ns pulse width, SAR = 121 mW/kg) UWB fields in a tapered parallel plate GTEM cell for 6 min. Cardiovascular functions were evaluated from 45 min to 4 weeks after exposures. Significant decrease in arterial blood pressures (hypotension) was found. In contrast, heart rate was not altered by these exposures. The UWB radiation-induced hypotension was a robust, consistent, and persistent effect. PMID:10073476

  10. Ultrawide-band electromagnetic pulses induced hypotension in rats.

    PubMed

    Lu, S T; Mathur, S P; Akyel, Y; Lee, J C

    1999-09-01

    The ultrawide-band (UWB) electromagnetic pulses are used as a new modality in radar technology. Biological effects of extremely high peak E-field, fast rise time, ultrashort pulse width, and ultrawide band have not been investigated heretofore due to the lack of animal exposure facilities. A new biological effects database is needed to establish personnel protection guidelines for these new type of radiofrequency radiation. Functional indices of the cardiovascular system (heart rate, systolic, mean, and diastolic pressures) were selected to represent biological end points that may be susceptible to the UWB radiation. A noninvasive tail-cuff photoelectric sensor sphygmomanometer was used. Male Wistar-Kyoto rats were subjected to sham exposure, 0.5-kHz (93 kV/m, 180 ps rise time, 1.00 ns pulse width, whole-body averaged specific absorption rate, SAR = 70 mW/kg) or a 1-kHz (85 kV/m, 200 ps rise time, 1.03 ns pulse width, SAR = 121 mW/kg) UWB fields in a tapered parallel plate GTEM cell for 6 min. Cardiovascular functions were evaluated from 45 min to 4 weeks after exposures. Significant decrease in arterial blood pressures (hypotension) was found. In contrast, heart rate was not altered by these exposures. The UWB radiation-induced hypotension was a robust, consistent, and persistent effect. PMID:10497968

  11. Estimating the breast surface using UWB microwave monostatic backscatter measurements.

    PubMed

    Winters, David W; Shea, Jacob D; Madsen, Ernest L; Frank, Gary R; Van Veen, Barry D; Hagness, Susan C

    2008-01-01

    This paper presents an algorithm for estimating the location of the breast surface from scattered ultrawideband (UWB) microwave signals recorded across an antenna array. Knowing the location of the breast surface can improve imaging performance if incorporated as a priori information into recently proposed microwave imaging algorithms. These techniques transmit low-power microwaves into the breast using an antenna array, which in turn measures the scattered microwave signals for the purpose of detecting anomalies or changes in the dielectric properties of breast tissue. Our proposed surface identification algorithm consists of three procedures, the first of which estimates M points on the breast surface given M channels of measured microwave backscatter data. The second procedure applies interpolation and extrapolation to these M points to generate N > M points that are approximately uniformly distributed over the breast surface, while the third procedure uses these N points to generate a 3-D estimated breast surface. Numerical as well as experimental tests indicate that the maximum absolute error in the estimated surface generated by the algorithm is on the order of several millimeters. An error analysis conducted for a basic microwave radar imaging algorithm (least-squares narrowband beamforming) indicates that this level of error is acceptable. A key advantage of the algorithm is that it uses the same measured signals that are used for UWB microwave imaging, thereby minimizing patient scan time and avoiding the need for additional hardware. PMID:18232368

  12. Ultra-wideband, omni-directional, low distortion coaxial antenna

    DOEpatents

    Eubanks, Travis Wayne; Gibson, Christopher Lawrence

    2015-01-06

    An antenna for producing an omni-directional pattern, and using all frequencies of a frequency range simultaneously, is provided with first and second electrically conductive elements disposed coaxially relative to a central axis. The first element has a first surface of revolution about the axis, the first surface of revolution tapering radially outwardly while extending axially away from the second element to terminate at a first axial end of the first element. The second element has a second surface of revolution about the axis, the second surface of revolution tapering radially outwardly while extending axially toward the first element to terminate at a first axial end of the second element. The first and second surfaces of revolution overlap one another radially and axially, and are mutually non-conformal.

  13. 75 FR 62476 - Ultra-Wideband Transmission Systems

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-12

    ...'') in ET Docket No. 98-153, 70 FR 6771, February 9, 2005, that argues that the power level adopted for...-153, 67 FR 34852, May 16, 2002, amending part 15 of its rules to permit the marketing and the...&O'' and ``FNRPM'') in ET Docket No. 98-153, 68 FR 19746 and 68 FR 19773, April 22, 2003,...

  14. Accurate and Nonparametric Imaging Algorithm for Targets Buried in Dielectric Medium for UWB Radars

    NASA Astrophysics Data System (ADS)

    Akune, Ken; Kidera, Shouhei; Kirimoto, Tetsuo

    Ultra-wide band (UWB) pulse radar with high range resolution and dielectric permeability is promising as an internal imaging technique for non-destructive testing or breast cancer detection. Various imaging algorithms for buried objects within a dielectric medium have been proposed, such as aperture synthesis, the time reversal approach and the space-time beamforming algorithm. However, these algorithms mostly require a priori knowledge of the dielectric medium boundary in image focusing, and often suffer from inadequate accuracy to identify the detailed structure of buried targets, such as an edge or specular surface owing to employing the waveform focusing scheme. To overcome these difficulties, this paper proposes an accurate and non-parametric (i.e. using an arbitrary shape without target modeling) imaging algorithm for targets buried in a homogeneous dielectric medium by advancing the RPM (Range Points Migration) algorithm to internal imaging issues, which has been demonstrated to provide an accurate image even for complex-shaped objects in free-space measurement. Numerical simulations, including those for two-dimensional (2-D) and three-dimensional (3-D) cases, verify that the proposed algorithm enhances the imaging accuracy by less than 1/10 of the wavelength and significantly reduces the computational cost by specifying boundary extraction compared with the conventional SAR-based algorithm.

  15. Distortion effects in a switch array UWB radar for time-lapse imaging of human heartbeats

    NASA Astrophysics Data System (ADS)

    Brovoll, Sverre; Berger, Tor; Aardal, Åyvind; Lande, Tor S.; Hamran, Svein-Erik

    2014-05-01

    Cardiovascular diseases (CVD) are a major cause of deaths all over the world. Microwave radar can be an alternative sensor for heart diagnostics and monitoring in modern healthcare that aids early detection of CVD symptoms. In this paper measurements from a switch array radar system are presented. This UWB system operates below 3 GHz and does time-lapse imaging of the beating heart inside the human body. The array consists of eight fat dipole elements. With a switch system, every possible sequence of transmit/receive element pairs can be selected to build a radar image from the recordings. To make the radar waves penetrate the human tissue, the antenna array is placed in contact with the body. Removal of the direct signal leakage through the antennas and body surface are done by high-pass (HP) filtering of the data prior to image processing. To analyze the results, measurements of moving spheres in air and simulations are carried out. We see that removal of the direct signal introduces amplitude distortion in the images. In addition, the effect of small target motion between the collection times of data from the individual elements is analyzed. With low pulse repetition frequency (PRF) this motion will distort the image. By using data from real measurements of heart motion in simulations, we analyze how the PRF and the antenna geometry influence this distortions.

  16. An UWB antenna with metamaterial cladding in S/C-band

    NASA Astrophysics Data System (ADS)

    Jiang, Yan Nan; Cui Zhang, Wen; Wang, Jiao; Cao, Wei Ping; Lin, Yi Yu

    2016-01-01

    A compact and easy fabricated ultra-wideband antenna is proposed in this paper. It comprised of a monopole antenna and a single-side I-shaped structure (ISS) metamaterial (MM) cladding. The monopole itself resonates at 2.4 GHz and presents capacitive impedance at 4.8 GHz. The MM cladding resonates at the first frequency and acts as an inductive element at the second. The higher resonance frequency of 4.8 GHz can be efficiently produced without affecting the monopole resonance. By the ISS MM cladding, the impedance match bandwidth (i.e., |S11| ≤ -10 dB) of the proposed antenna is broadened to 1.98-5.80 GHz (a part of the S/C-band). In addition, the dynamic range of the main lobe directions is only about 17° and the gains are greater than 3.8 dBi over the entire band. The simulations and measurements are in a good agreement. Therefore, the proposed antenna is so charming for the extensive applications in wireless communication community. Contribution to the topical issue "Advanced Electromagnetics Symposium (AES 2014) - Elected submissions", edited by Adel Razek

  17. A 3.1-4.8 GHz CMOS receiver for MB-OFDM UWB

    NASA Astrophysics Data System (ADS)

    Guang, Yang; Wang, Yao; Jiangwei, Yin; Renliang, Zheng; Wei, Li; Ning, Li; Junyan, Ren

    2009-01-01

    An integrated fully differential ultra-wideband CMOS receiver for 3.1-4.8 GHz MB-OFDM systems is presented. A gain controllable low noise amplifier and a merged quadrature mixer are integrated as the RF front-end. Five order Gm-C type low pass filters and VGAs are also integrated for both I and Q IF paths in the receiver. The ESD protected chip is fabricated in a Jazz 0.18 μm RF CMOS process and achieves a maximum total voltage gain of 65 dB, an AGC range of 45 dB with about 6 dB/step, an averaged total noise figure of 6.4 to 8.8 dB over 3 bands and an in-band IIP3 of -5.1 dBm. The receiver occupies 2.3 mm2 and consumes 110 mA from a 1.8 V supply including test buffers and a digital module.

  18. Modeling, Real-Time Estimation, and Identification of UWB Indoor Wireless Channels

    SciTech Connect

    Olama, Mohammed M; Djouadi, Seddik M; Li, Yanyan; Fathy, Aly

    2013-01-01

    In this paper, stochastic differential equations (SDEs) are used to model ultrawideband (UWB) indoor wireless channels. We show that the impulse responses for time-varying indoor wireless channels can be approximated in a mean square sense as close as desired by impulse responses that can be realized by SDEs. The state variables represent the inphase and quadrature components of the UWB channel. The expected maximization and extended Kalman filter are employed to recursively identify and estimate the channel parameters and states, respectively, from online received signal strength measured data. Both resolvable and non-resolvable multipath received signals are considered and represented as small-scaled Nakagami fading. The proposed models together with the estimation algorithm are tested using UWB indoor measurement data demonstrating the method s viability and the results are presented.

  19. Wearable system-on-a-chip UWB radar for contact-less cardiopulmonary monitoring: present status.

    PubMed

    Zito, D; Pepe, D; Mincica, M; Zito, F; De Rossi, D; Lanata, A; Scilingo, E P; Tognetti, A

    2008-01-01

    The present status of the project aimed at the realization of an innovative wearable system-on-chip UWB radar for the cardiopulmonary monitoring is presented. The overall system consists of a wearable wireless interface including a fully integrated UWB radar for the detection of the heart beat and breath rates, and a IEEE 802.15.4 ZigBee low-power radio interface. The principle of operation of the UWB radar for the monitoring of the heart wall is summarized. With respect to the prior art, this paper reports the results of the experimental characterization of the intra-body channel loss, which has been carried out successfully in order to validate the theoretical model employed for the radar system analysis. Moreover, the main building blocks of the radar have been manufactured in 90 nm CMOS technology by ST-Microelectronics and the relevant performance are resulted in excellent agreement with those expected by post-layout simulations. PMID:19163907

  20. Smart container UWB sensor system for situational awareness of intrusion alarms

    DOEpatents

    Romero, Carlos E.; Haugen, Peter C.; Zumstein, James M.; Leach, Jr., Richard R.; Vigars, Mark L.

    2013-06-11

    An in-container monitoring sensor system is based on an UWB radar intrusion detector positioned in a container and having a range gate set to the farthest wall of the container from the detector. Multipath reflections within the container make every point on or in the container appear to be at the range gate, allowing intrusion detection anywhere in the container. The system also includes other sensors to provide false alarm discrimination, and may include other sensors to monitor other parameters, e.g. radiation. The sensor system also includes a control subsystem for controlling system operation. Communications and information extraction capability may also be included. A method of detecting intrusion into a container uses UWB radar, and may also include false alarm discrimination. A secure container has an UWB based monitoring system

  1. Combination of OFDM and CDMA for high data rate UWB

    NASA Astrophysics Data System (ADS)

    Guéguen, Emeric; Madaoui, Nadia; Hélard, Jean-François; Crussière, Matthieu

    2006-09-01

    For Wireless Personal Area Network (WPAN) systems, resource allocation between several users within a piconet and the coexistence of several piconets are very important points to take into consideration for the optimization of high data rate Ultra Wide Band (UWB) systems. To improve the performance of the Multi-Band OFDM (Orthogonal Frequency Division Multiplex) solution proposed by the Multi-Band OFDM Alliance (MBOA), the addition of a spreading component in the frequency domain is a good solution since it makes resource allocation easier and also offers better robustness against channel frequency selectivity and narrowband interference. The Spread Spectrum - Multi-Carrier - Multiple Access (SS-MC-MA) system proposed in this article offers not only the advantages of Multi-Carrier - Coded Division Multiple Access (MC-CDMA) brought by frequency spreading, but also a more effective dynamic resource allocation in a multi-user and multi-piconet context. These improvements are obtained without increasing the complexity of the radio-frequency part compared to the classical MBOA solution. To cite this article: E. Guéguen et al., C. R. Physique 7 (2006).

  2. Comparison between UWB and CW radar sensors for breath activity monitoring

    NASA Astrophysics Data System (ADS)

    Pisa, Stefano; Bernardi, Paolo; Cicchetti, Renato; Giusto, Roberto; Pittella, Erika; Piuzzi, Emanuele; Testa, Orlandino

    2014-05-01

    In this paper the ability of four radar sensors in detecting breath activity has been tested. In particular, range gating UWB, CMOS UWB, CW phase detecting, and FMCW radars have taken into account. Considering a realistic scenario, the radar antenna has been pointed towards the thorax of a breathing subject and the recorded signals have been compared with those of a piezoelectric belt placed around the thorax. Then the ability of the radars in detecting small movements has been tested by means of an oscillating copper plate placed at various distances from the radar antenna. All the considered radars were able to detect the plate movements with a distance-dependent resolution.

  3. Integrated navigation fusion strategy of INS/UWB for indoor carrier attitude angle and position synchronous tracking.

    PubMed

    Fan, Qigao; Wu, Yaheng; Hui, Jing; Wu, Lei; Yu, Zhenzhong; Zhou, Lijuan

    2014-01-01

    In some GPS failure conditions, positioning for mobile target is difficult. This paper proposed a new method based on INS/UWB for attitude angle and position synchronous tracking of indoor carrier. Firstly, error model of INS/UWB integrated system is built, including error equation of INS and UWB. And combined filtering model of INS/UWB is researched. Simulation results show that the two subsystems are complementary. Secondly, integrated navigation data fusion strategy of INS/UWB based on Kalman filtering theory is proposed. Simulation results show that FAKF method is better than the conventional Kalman filtering. Finally, an indoor experiment platform is established to verify the integrated navigation theory of INS/UWB, which is geared to the needs of coal mine working environment. Static and dynamic positioning results show that the INS/UWB integrated navigation system is stable and real-time, positioning precision meets the requirements of working condition and is better than any independent subsystem. PMID:25121111

  4. Integrated Navigation Fusion Strategy of INS/UWB for Indoor Carrier Attitude Angle and Position Synchronous Tracking

    PubMed Central

    Wu, Yaheng; Hui, Jing; Wu, Lei; Zhou, Lijuan

    2014-01-01

    In some GPS failure conditions, positioning for mobile target is difficult. This paper proposed a new method based on INS/UWB for attitude angle and position synchronous tracking of indoor carrier. Firstly, error model of INS/UWB integrated system is built, including error equation of INS and UWB. And combined filtering model of INS/UWB is researched. Simulation results show that the two subsystems are complementary. Secondly, integrated navigation data fusion strategy of INS/UWB based on Kalman filtering theory is proposed. Simulation results show that FAKF method is better than the conventional Kalman filtering. Finally, an indoor experiment platform is established to verify the integrated navigation theory of INS/UWB, which is geared to the needs of coal mine working environment. Static and dynamic positioning results show that the INS/UWB integrated navigation system is stable and real-time, positioning precision meets the requirements of working condition and is better than any independent subsystem. PMID:25121111

  5. Position Estimation of Transceivers in Communication Networks

    SciTech Connect

    Dowla, F; Kent, C

    2004-01-20

    With rapid developments in wireless sensor networks, there is a growing need for transceiver position estimation independent of GPS, which may not be available in indoor networks. Our approach is to use range estimates from time-of-flight (TOF) measurements, a technique well suited to large bandwidth physical links, such as in ultra-wideband (UWB) systems. In our UWB systems, pulse duration less than 200 psecs can easily be resolved to less than a foot. Assuming an encoded UWB physical layer, we first test positioning accuracy using simulations. We are interested in sensitivity to range errors and the required number of ranging nodes, and we show that in a high-precision environment, such as UWB, the optimal number of transmitters is four. Four transmitters with {+-}20ft. range error can locate a receiver to within one or two feet. We then implement these algorithms on an 802.11 wireless network and demonstrate the ability to locate a network access point to approximately 20 feet.

  6. Optical generation of polarity- and shape-switchable ultrawideband pulses using a chirped intensity modulator and a first-order asymmetric Mach-Zehnder interferometer.

    PubMed

    Pan, Shilong; Yao, Jianping

    2009-05-01

    We propose and demonstrate a simple method to generate ultrawideband (UWB) pulses in the optical domain using a chirped intensity modulator and an asymmetric Mach-Zehnder interferometer (AMZI). Polarity- and shape-switchable UWB Gaussian monocycle, doublet, and triplet pulses with fractional bandwidths of 158%, 134%, and 100% and center frequencies of 6.52, 9.78, and 10.1 GHz are experimentally generated by controlling the dc bias of the intensity modulator and adjusting the polarization controller in the AMZI. PMID:19412256

  7. 47 CFR 15.521 - Technical requirements applicable to all UWB devices.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 1 2014-10-01 2014-10-01 false Technical requirements applicable to all UWB devices. 15.521 Section 15.521 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL RADIO FREQUENCY... prohibition in § 2.201(f) and 15.5(d) of this chapter against Class B (damped wave) emissions does not...

  8. 47 CFR 15.521 - Technical requirements applicable to all UWB devices.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 1 2013-10-01 2013-10-01 false Technical requirements applicable to all UWB devices. 15.521 Section 15.521 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL RADIO FREQUENCY... prohibition in § 2.201(f) and 15.5(d) of this chapter against Class B (damped wave) emissions does not...

  9. 47 CFR 15.521 - Technical requirements applicable to all UWB devices.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false Technical requirements applicable to all UWB devices. 15.521 Section 15.521 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL RADIO FREQUENCY... prohibition in § 2.201(f) and 15.5(d) of this chapter against Class B (damped wave) emissions does not...

  10. 47 CFR 15.517 - Technical requirements for indoor UWB systems.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... emission limit, following the procedures described in § 15.521. (f) UWB systems operating under the... necessity to operate with a fixed indoor infrastructure, e.g., a transmitter that must be connected to the... considered to operate indoors provided the emissions are directed towards the ground. (5) A...

  11. Bistability and hysteresis in the emergence of pulses in microstrip Gunn-diode circuits

    SciTech Connect

    Yurchenko, V. B.; Yurchenko, L. V.

    2014-12-15

    We develop time-domain simulations of microwave and THz radiation sources built as arrays of active devices when the radiation wavelength is small as compared to spacing between electronic components. We pursue an approach when the system is represented by equations with time-delay feedback that could generate chaos and other forms of complicated dynamics. The approach simplifies simulations of ultra-wideband effects and exceeds capabilities of frequency-domain methods. As a model case, we simulated a microstrip circuit with Gunn diode and a remote resonator emitting the radiation towards infinity. We observed the emergence of either the continuous waves or the trains of high-frequency pulses depending on the bias conditions. We found bistability and hysteresis in the onset of different oscillation modes that depends on the way of driving the bias voltage into the domain of instability of the given system. The results would allow one to improve the design of THz radiation sources with time-delay coupling between components.

  12. Novel Multistatic Adaptive Microwave Imaging Methods for Early Breast Cancer Detection

    NASA Astrophysics Data System (ADS)

    Xie, Yao; Guo, Bin; Li, Jian; Stoica, Petre

    2006-12-01

    Multistatic adaptive microwave imaging (MAMI) methods are presented and compared for early breast cancer detection. Due to the significant contrast between the dielectric properties of normal and malignant breast tissues, developing microwave imaging techniques for early breast cancer detection has attracted much interest lately. MAMI is one of the microwave imaging modalities and employs multiple antennas that take turns to transmit ultra-wideband (UWB) pulses while all antennas are used to receive the reflected signals. MAMI can be considered as a special case of the multi-input multi-output (MIMO) radar with the multiple transmitted waveforms being either UWB pulses or zeros. Since the UWB pulses transmitted by different antennas are displaced in time, the multiple transmitted waveforms are orthogonal to each other. The challenge to microwave imaging is to improve resolution and suppress strong interferences caused by the breast skin, nipple, and so forth. The MAMI methods we investigate herein utilize the data-adaptive robust Capon beamformer (RCB) to achieve high resolution and interference suppression. We will demonstrate the effectiveness of our proposed methods for breast cancer detection via numerical examples with data simulated using the finite-difference time-domain method based on a 3D realistic breast model.

  13. A dielectric logging tool with insulated collar for formation fluid detection around borehole

    NASA Astrophysics Data System (ADS)

    Wang, Bin; Li, Kang; Kong, Fan-Min; Zhao, Jia

    2015-08-01

    A dielectric tool with insulated collar for analyzing fluid saturation outside a borehole was introduced. The UWB (ultra-wideband) antenna mounted on the tool was optimized to launch a transient pulse. The broadband evaluation method provided more advantages when compared with traditional dielectric tools. The EM (electromagnetic) power distribution outside the borehole was studied, and it was shown that energy was propagated in two modes. Furthermore, the mechanism of the modes was discussed. In order to increase this tools' investigation depth, a novel insulated collar was introduced. In addition, operation in difference formations was discussed and this tool proved to be able to efficiently launch lateral EM waves. Response voltages indicated that the proposed scheme was able to evaluate the fluid saturation of reservoir formations and dielectric dispersion properties. It may be used as an alternative tool for imaging logging applications.

  14. An enantiomorphic blumlein impulse generator

    SciTech Connect

    Rinehart, L.F.; Buttram, M.T.; Crowe, W.R.; Clark, R.S.; Lundstrom, J.M.; Patterson, P.E.

    1992-01-01

    Working designs exist for 1 GW, 1 kHz ultra-wideband (UWB) sources (e.g. SNIPER). As these generators are pressed to higher peak powers and repetition rates, insulation, energy loss due to stray capacitance, and system efficiency (including power supplies and modulators) become critical issues. The EnantioMorphic (mirror image) BLumlein (EMBL) is a new type of vector inversion transmission line pulser which is designed to alleviate some of these problems. The design goals for EMBL are : >500 kV, {approximately}1 kHz rep-rate and <100 ps risetime in a 50 ohm geometry. In addition to the pulse forming line (PFL), EMBL also requires a high rep-rate modulator, primary switch, and peaking switch which will be described. Empirical design equations for peaking switch performance are included.

  15. An enantiomorphic blumlein impulse generator

    SciTech Connect

    Rinehart, L.F.; Buttram, M.T.; Crowe, W.R.; Clark, R.S.; Lundstrom, J.M.; Patterson, P.E.

    1992-07-01

    Working designs exist for 1 GW, 1 kHz ultra-wideband (UWB) sources (e.g. SNIPER). As these generators are pressed to higher peak powers and repetition rates, insulation, energy loss due to stray capacitance, and system efficiency (including power supplies and modulators) become critical issues. The EnantioMorphic (mirror image) BLumlein (EMBL) is a new type of vector inversion transmission line pulser which is designed to alleviate some of these problems. The design goals for EMBL are : >500 kV, {approximately}1 kHz rep-rate and <100 ps risetime in a 50 ohm geometry. In addition to the pulse forming line (PFL), EMBL also requires a high rep-rate modulator, primary switch, and peaking switch which will be described. Empirical design equations for peaking switch performance are included.

  16. Simulation and signal processing of through wall UWB radar for human being's periodic motions detection

    NASA Astrophysics Data System (ADS)

    Li, Jing; Liu, Fengshan; Xu, Penglong; Zeng, Zhaofa

    2013-05-01

    The human's Micro-Doppler signatures resulting from breathing, arm, foot and other periodic motion can provide valuable information about the structure of the moving parts and may be used for identification and classification purposes. In this paper, we carry out simulate with FDTD method and through wall experiment with UWB radar for human being's periodic motion detection. In addition, Advancements signal processing methods are presented to classify and to extract the human's periodic motion characteristic information, such as Micro-Doppler shift and motion frequency. Firstly, we apply the Principal Component Analysis (PCA) with singular value decomposition (SVD) to denoise and extract the human motion signal. Then, we present the results base on the Hilbert-Huang transform (HHT) and the S transform to classify and to identify the human's micro-Doppler shift characteristics. The results demonstrate that the combination of UWB radar and various processing methods has potential to detect human's Doppler signatures effectively.

  17. Location detection and tracking of moving targets by a 2D IR-UWB radar system.

    PubMed

    Nguyen, Van-Han; Pyun, Jae-Young

    2015-01-01

    In indoor environments, the Global Positioning System (GPS) and long-range tracking radar systems are not optimal, because of signal propagation limitations in the indoor environment. In recent years, the use of ultra-wide band (UWB) technology has become a possible solution for object detection, localization and tracking in indoor environments, because of its high range resolution, compact size and low cost. This paper presents improved target detection and tracking techniques for moving objects with impulse-radio UWB (IR-UWB) radar in a short-range indoor area. This is achieved through signal-processing steps, such as clutter reduction, target detection, target localization and tracking. In this paper, we introduce a new combination consisting of our proposed signal-processing procedures. In the clutter-reduction step, a filtering method that uses a Kalman filter (KF) is proposed. Then, in the target detection step, a modification of the conventional CLEAN algorithm which is used to estimate the impulse response from observation region is applied for the advanced elimination of false alarms. Then, the output is fed into the target localization and tracking step, in which the target location and trajectory are determined and tracked by using unscented KF in two-dimensional coordinates. In each step, the proposed methods are compared to conventional methods to demonstrate the differences in performance. The experiments are carried out using actual IR-UWB radar under different scenarios. The results verify that the proposed methods can improve the probability and efficiency of target detection and tracking. PMID:25808773

  18. Location Detection and Tracking of Moving Targets by a 2D IR-UWB Radar System

    PubMed Central

    Nguyen, Van-Han; Pyun, Jae-Young

    2015-01-01

    In indoor environments, the Global Positioning System (GPS) and long-range tracking radar systems are not optimal, because of signal propagation limitations in the indoor environment. In recent years, the use of ultra-wide band (UWB) technology has become a possible solution for object detection, localization and tracking in indoor environments, because of its high range resolution, compact size and low cost. This paper presents improved target detection and tracking techniques for moving objects with impulse-radio UWB (IR-UWB) radar in a short-range indoor area. This is achieved through signal-processing steps, such as clutter reduction, target detection, target localization and tracking. In this paper, we introduce a new combination consisting of our proposed signal-processing procedures. In the clutter-reduction step, a filtering method that uses a Kalman filter (KF) is proposed. Then, in the target detection step, a modification of the conventional CLEAN algorithm which is used to estimate the impulse response from observation region is applied for the advanced elimination of false alarms. Then, the output is fed into the target localization and tracking step, in which the target location and trajectory are determined and tracked by using unscented KF in two-dimensional coordinates. In each step, the proposed methods are compared to conventional methods to demonstrate the differences in performance. The experiments are carried out using actual IR-UWB radar under different scenarios. The results verify that the proposed methods can improve the probability and efficiency of target detection and tracking. PMID:25808773

  19. A Very Compact and Low Profile UWB Planar Antenna with WLAN Band Rejection.

    PubMed

    Syed, Avez; Aldhaheri, Rabah W

    2016-01-01

    A low-cost coplanar waveguide fed compact ultrawideband (UWB) antenna with band rejection characteristics for wireless local area network (WLAN) is proposed. The notch band characteristic is achieved by etching half wavelength C-shaped annular ring slot in the radiating patch. By properly choosing the radius and position of the slot, the notch band can be adjusted and controlled. With an overall size of 18.7 mm × 17.6 mm, the antenna turns out to be one of the smallest UWB antennas with band-notched characteristics. It has a wide fractional bandwidth of 130% (2.9-13.7 GHz) with VSWR < 2 and rejecting IEEE 802.11a and HIPERLAN/2 frequency band of 5.1-5.9 GHz. Stable omnidirectional radiation patterns in the H plane with an average gain of 4.4 dBi are obtained. The band-notch mechanism of the proposed antenna is examined by HFSS simulator. A good agreement is found between measured and simulated results indicating that the proposed antenna is well suited for integration into portable devices for UWB applications. PMID:27088125

  20. A Very Compact and Low Profile UWB Planar Antenna with WLAN Band Rejection

    PubMed Central

    Syed, Avez; Aldhaheri, Rabah W.

    2016-01-01

    A low-cost coplanar waveguide fed compact ultrawideband (UWB) antenna with band rejection characteristics for wireless local area network (WLAN) is proposed. The notch band characteristic is achieved by etching half wavelength C-shaped annular ring slot in the radiating patch. By properly choosing the radius and position of the slot, the notch band can be adjusted and controlled. With an overall size of 18.7 mm × 17.6 mm, the antenna turns out to be one of the smallest UWB antennas with band-notched characteristics. It has a wide fractional bandwidth of 130% (2.9–13.7 GHz) with VSWR < 2 and rejecting IEEE 802.11a and HIPERLAN/2 frequency band of 5.1–5.9 GHz. Stable omnidirectional radiation patterns in the H plane with an average gain of 4.4 dBi are obtained. The band-notch mechanism of the proposed antenna is examined by HFSS simulator. A good agreement is found between measured and simulated results indicating that the proposed antenna is well suited for integration into portable devices for UWB applications. PMID:27088125

  1. Measurement and positioning of moving array shape by IR-UWB

    NASA Astrophysics Data System (ADS)

    He, Hongkun; Shi, Haoshan

    2006-11-01

    Based on impulse radio ultra wide band (IR-UWB) technology, the measuring and positioning of moving array shape are discussed. Because there are no conditions of fixed receivers and clock synchronization in real outdoor or field surroundings, only choice is unusual asynchronous measurement method, therefore, the scheme of measuring and processing must be changed, though the current TOA (Time Of Arrival) method is used. The array shape and positions of moving objects are both required in the most situations. The direct approach is to increase the number of measuring point, and the positioning problem would be resolved by triangular surveying method. The solution is generic at first sight, but its sensitivity to time-of-arrival accuracy imposes the choice of impulse radio ultra wide band hard ware and soft ware in the very context. The algorithm scheme mitigates the impact of non-line of sight ranging errors on positioning accuracy without any additional protocol hook. More particularly, the realistic IR-UWB ranging error models we use take into account UWB channel effects, as well as relative clock drifts. By error analyzing and simulation under the proper operation model, results are provided to illustrate the relevance of such a solution.

  2. 47 CFR 15.513 - Technical requirements for medical imaging systems.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false Technical requirements for medical imaging systems. 15.513 Section 15.513 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL RADIO FREQUENCY DEVICES Ultra-Wideband Operation § 15.513 Technical requirements for medical imaging systems. (a) The UWB bandwidth of an imaging system...

  3. 47 CFR 15.511 - Technical requirements for surveillance systems.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 1 2012-10-01 2012-10-01 false Technical requirements for surveillance systems... DEVICES Ultra-Wideband Operation § 15.511 Technical requirements for surveillance systems. (a) The UWB... surveillance systems operated by law enforcement, fire or emergency rescue organizations or by...

  4. 47 CFR 15.511 - Technical requirements for surveillance systems.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 1 2013-10-01 2013-10-01 false Technical requirements for surveillance systems... DEVICES Ultra-Wideband Operation § 15.511 Technical requirements for surveillance systems. (a) The UWB... surveillance systems operated by law enforcement, fire or emergency rescue organizations or by...

  5. 47 CFR 15.511 - Technical requirements for surveillance systems.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 1 2011-10-01 2011-10-01 false Technical requirements for surveillance systems... DEVICES Ultra-Wideband Operation § 15.511 Technical requirements for surveillance systems. (a) The UWB... surveillance systems operated by law enforcement, fire or emergency rescue organizations or by...

  6. 47 CFR 15.511 - Technical requirements for surveillance systems.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false Technical requirements for surveillance systems... DEVICES Ultra-Wideband Operation § 15.511 Technical requirements for surveillance systems. (a) The UWB... surveillance systems operated by law enforcement, fire or emergency rescue organizations or by...

  7. 47 CFR 15.511 - Technical requirements for surveillance systems.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 1 2014-10-01 2014-10-01 false Technical requirements for surveillance systems... DEVICES Ultra-Wideband Operation § 15.511 Technical requirements for surveillance systems. (a) The UWB... surveillance systems operated by law enforcement, fire or emergency rescue organizations or by...

  8. 47 CFR 15.525 - Coordination requirements.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 1 2012-10-01 2012-10-01 false Coordination requirements. 15.525 Section 15.525 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL RADIO FREQUENCY DEVICES Ultra-Wideband Operation § 15.525 Coordination requirements. (a) UWB imaging systems require coordination through the FCC before the equipment may be used....

  9. 47 CFR 15.515 - Technical requirements for vehicular radar systems.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 1 2014-10-01 2014-10-01 false Technical requirements for vehicular radar... DEVICES Ultra-Wideband Operation § 15.515 Technical requirements for vehicular radar systems. (a..., changing gears, or engaging a turn signal. (b) The UWB bandwidth of a vehicular radar system...

  10. 47 CFR 15.515 - Technical requirements for vehicular radar systems.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false Technical requirements for vehicular radar... DEVICES Ultra-Wideband Operation § 15.515 Technical requirements for vehicular radar systems. (a..., changing gears, or engaging a turn signal. (b) The UWB bandwidth of a vehicular radar system...

  11. 47 CFR 15.515 - Technical requirements for vehicular radar systems.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 1 2011-10-01 2011-10-01 false Technical requirements for vehicular radar... DEVICES Ultra-Wideband Operation § 15.515 Technical requirements for vehicular radar systems. (a..., changing gears, or engaging a turn signal. (b) The UWB bandwidth of a vehicular radar system...

  12. 47 CFR 15.515 - Technical requirements for vehicular radar systems.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 1 2012-10-01 2012-10-01 false Technical requirements for vehicular radar... DEVICES Ultra-Wideband Operation § 15.515 Technical requirements for vehicular radar systems. (a..., changing gears, or engaging a turn signal. (b) The UWB bandwidth of a vehicular radar system...

  13. 47 CFR 15.515 - Technical requirements for vehicular radar systems.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 1 2013-10-01 2013-10-01 false Technical requirements for vehicular radar... DEVICES Ultra-Wideband Operation § 15.515 Technical requirements for vehicular radar systems. (a..., changing gears, or engaging a turn signal. (b) The UWB bandwidth of a vehicular radar system...

  14. Numerical simulation of the coupling of ultra-wide band electromagnetic pulse into landmine by aperture

    NASA Astrophysics Data System (ADS)

    Gao, Zhen-Ru; Zhao, Hui-Chang; Yang, Li; Wang, Feng-Shan

    2015-09-01

    The modern landmine’s electronic fuse is susceptible to strong interference or can even be damaged by the ultra-wide band electromagnetic pulse (UWB-EMP). The finite-difference time-domain (FDTD) method in lossy media with cylindrical coordinates is used to study the interactions of the UWB-EMP with the landmine. First, the coupling of UWB-EMP into the landmine shielding shell through an aperture is numerically simulated. Second, the coupled electromagnetic field of mine shells made of different shielding materials and with apertures of different sizes is plotted. Third, the aperture coupling laws of UWB-EMP into shells are analyzed and categorized. Such an algorithm is capable of effectively preventing ladder similar errors, and consequently improving the calculation precision, and in addition to adopting the message passing interface (MPI) parallel method to divide the total calculating range into more sub-ranges, the overall calculating efficiency is greatly increased. These calculations are surely a constructive reference for modern landmine design against electromagnetic damage. Project supported by the Postdoctoral Science Foundation of China (Grant No. 2014M552610).

  15. Techniques for Clutter Suppression in the Presence of Body Movements during the Detection of Respiratory Activity through UWB Radars

    PubMed Central

    Lazaro, Antonio; Girbau, David; Villarino, Ramon

    2014-01-01

    This paper focuses on the feasibility of tracking the chest wall movement of a human subject during respiration from the waveforms recorded using an impulse-radio (IR) ultra-wideband radar. The paper describes the signal processing to estimate sleep apnea detection and breathing rate. Some techniques to solve several problems in these types of measurements, such as the clutter suppression, body movement and body orientation detection are described. Clutter suppression is achieved using a moving averaging filter to dynamically estimate it. The artifacts caused by body movements are removed using a threshold method before analyzing the breathing signal. The motion is detected using the time delay that maximizes the received signal after a clutter removing algorithm is applied. The periods in which the standard deviations of the time delay exceed a threshold are considered macro-movements and they are neglected. The sleep apnea intervals are detected when the breathing signal is below a threshold. The breathing rate is determined from the robust spectrum estimation based on Lomb periodogram algorithm. On the other hand the breathing signal amplitude depends on the body orientation respect to the antennas, and this could be a problem. In this case, in order to maximize the signal-to-noise ratio, multiple sensors are proposed to ensure that the backscattered signal can be detected by at least one sensor, regardless of the direction the human subject is facing. The feasibility of the system is compared with signals recorded by a microphone. PMID:24514883

  16. Photonic ultrawideband monocycle pulse generation using a single electro-optic modulator.

    PubMed

    Li, Jianqiang; Fu, Songnian; Xu, Kun; Wu, Jian; Lin, Jintong; Tang, Ming; Shum, P

    2008-02-01

    A compact approach to photonic-assisted ultrawideband (UWB) monocycle pulse generation is proposed and experimentally demonstrated based on the wavelength dependence of the half-wave voltage of a Mach-Zehnder modulator (MZM). By employing a single MZM with dual-wavelength injection at around 1310 and 1550 nm, a pair of polarity-reversed monocycle pulses with the full width at half-maximum of about 80 ps and the fractional bandwidth of greater than 160% can be generated. The experiment results agree well with the theoretical prediction. The simple setup and the convenience to control the monocycle pulse polarity are favorable for future applications. PMID:18246157

  17. Multichannel neural recording with a 128 Mbps UWB wireless transmitter for implantable brain-machine interfaces.

    PubMed

    Ando, H; Takizawa, K; Yoshida, T; Matsushita, K; Hirata, M; Suzuki, T

    2015-08-01

    To realize a low-invasive and high accuracy BMI (Brain-machine interface) system, we have already developed a fully-implantable wireless BMI system which consists of ECoG neural electrode arrays, neural recording ASICs, a Wi-Fi based wireless data transmitter and a wireless power receiver with a rechargeable battery. For accurate estimation of movement intentions, it is important for a BMI system to have a large number of recording channels. In this paper, we report a new multi-channel BMI system which is able to record up to 4096-ch ECoG data by multiple connections of 64-ch ASICs and time division multiplexing of recorded data. This system has an ultra-wide-band (UWB) wireless unit for transmitting the recorded neural signals to outside the body. By preliminary experiments with a human body equivalent liquid phantom, we confirmed 4096-ch UWB wireless data transmission at 128 Mbps mode below 20 mm distance. PMID:26737195

  18. Photonic generation of bipolar direct-sequence UWB signals based on optical spectral shaping and incoherent frequency-to-time conversion

    NASA Astrophysics Data System (ADS)

    Mu, Hongqian; Wang, Muguang; Ye, Jun; Jian, Shuisheng

    2016-06-01

    A novel technology to obtain binary phase-coded ultrawideband (UWB) signals for direct-sequence spread-spectrum communication systems is investigated by using a cost-effective incoherent source. The bipolar encoding is performed based on an all-fiber spectrum shaper composed of two FBG arrays to tailor the optical spectrum, and a section of single-mode fiber to achieve incoherent frequency-to-time conversion. We demonstrate a 1.325-Gb/s UWB encoding system by the use of binary spreading codes of 4-chip length via computer simulations. The proposed bipolar UWB encoding technology can be applied to high-speed UWB-over-fiber communication systems.

  19. Applications of time-frequency signature analysis to target identification

    NASA Astrophysics Data System (ADS)

    Gaunaurd, Guillermo C.; Strifors, Hans C.

    1999-03-01

    The overlapping subjects of target identification, inverse scattering and active classification have many applications that differ depending on specific sensors. Many useful techniques for these relevant subjects have been developed in the frequency and the time domains. A more recent approach views the target signatures in the combined or coupled time-frequency domain. For either ultra-wideband (UWB) projectors, or UWB processing these joint time- frequency techniques are particularly advantageous. Such analysis requires the use of some of the scores of non- linear distributions that have been proposed and studied over the years. Basic ones, such as the Wigner distribution and its many relatives, have been shown to belong to the well-studied `Cohen Class.' We will select half-a-dozen of these distributions to study applications that we have addressed and solved in several areas such as: (1) active sonar, (2) underwater mine classification using pulses from explosive sources, (3) identification of submerged shells having different fillers using dolphin bio-sonar `clicks,' and (4) broadband radar pulses to identify aircraft, other targets covered with dielectric absorbing layers, and also (land) mine-like objects buried underground, using a ground penetrating radar. These examples illustrate how the informative identifying features required for accurate target identification are extracted and displayed in this general time-frequency domain.

  20. A Compact 5.5 GHz Band-Rejected UWB Antenna Using Complementary Split Ring Resonators

    PubMed Central

    Islam, M. M.; Faruque, M. R. I.; Islam, M. T.

    2014-01-01

    A band-removal property employing microwave frequencies using complementary split ring resonators (CSRRs) is applied to design a compact UWB antenna wishing for the rejection of some frequency band, which is meanwhile exercised by the existing wireless applications. The reported antenna comprises optimization of a circular radiating patch, in which slotted complementary SRRs are implanted. It is printed on low dielectric FR4 substrate material fed by a partial ground plane and a microstrip line. Validated results exhibit that the reported antenna shows a wide bandwidth covering from 3.45 to more than 12 GHz, with a compact dimension of 22 × 26 mm2, and VSWR < 2, observing band elimination of 5.5 GHz WLAN band. PMID:24971379

  1. Design of CPW fed printed slot antenna with circular polarization for UWB application

    NASA Astrophysics Data System (ADS)

    Choudhary, N.; Tiwari, A.; Jangid, K. G.; Sharma, B. R.; Saini, J. S.; Kulhar, V. S.; Bhatnagar, D.

    2016-03-01

    This paper reports the design and performance of a CPW-fed circularized polarized elliptical slot antenna for UWB (ultra wide band) applications. The circular polarization is achieved by applying triangular stubs in the ground plane. The overall volume of this antenna is 40mm × 40 mm × 1.59 mm. The proposed antenna is simulated by applying CST Microwave Studio simulator. This elliptical patch slot antenna provides broad impedance bandwidth (3.1GHz to 10.6 GHz) with maximum gain 4.31dB at 4.45GHz. The simulated 3-dB axial ratio bandwidth is close to 2.51GHz (from 4.76GHz to 7.27GHz) which is 41.76% with respect to the central frequency 6.01GHz.

  2. A compact 5.5 GHz band-rejected UWB antenna using complementary split ring resonators.

    PubMed

    Islam, M M; Faruque, M R I; Islam, M T

    2014-01-01

    A band-removal property employing microwave frequencies using complementary split ring resonators (CSRRs) is applied to design a compact UWB antenna wishing for the rejection of some frequency band, which is meanwhile exercised by the existing wireless applications. The reported antenna comprises optimization of a circular radiating patch, in which slotted complementary SRRs are implanted. It is printed on low dielectric FR4 substrate material fed by a partial ground plane and a microstrip line. Validated results exhibit that the reported antenna shows a wide bandwidth covering from 3.45 to more than 12 GHz, with a compact dimension of 22 × 26 mm(2), and VSWR < 2, observing band elimination of 5.5 GHz WLAN band. PMID:24971379

  3. A 10.6mm3 Fully-Integrated, Wireless Sensor Node with 8GHz UWB Transmitter

    PubMed Central

    Kim, Hyeongseok; Kim, Gyouho; Lee, Yoonmyung; Foo, Zhiyoong; Sylvester, Dennis; Blaauw, David; Wentzloff, David

    2015-01-01

    This paper presents a complete, autonomous, wireless temperature sensor, fully encapsulated in a 10.6mm3 volume. The sensor includes solar energy harvesting with an integrated 2 μAh battery, optical receiver for programming, microcontroller and memory, 8GHz UWB transmitter, and miniaturized custom antennas with a wireless range of 7 meters. Full, stand-alone operation was demonstrated for the first time for a system of this size and functionality. PMID:26855848

  4. Design of ultra wideband microwave absorber effectual for objects of arbitrary shape

    NASA Astrophysics Data System (ADS)

    Gong, Yuan-Xun; Zhou, Zhong-Xiang; Jiang, Jian-Tang; Zhao, Hong-Jie

    2015-12-01

    In this paper, we present the design of multilayer microwave absorbers comprised of CoFe alloy nano-particles and nano-flakes as fillers. The thickness of the unite layer is optimized by using the Genetic Algorithm. Efficient microwave absorptions over a wide frequency band and a range of incident angles are achieved by using multilayer absorbers. We show that the absorbers are effective not only for a planar surface but also for arbitrarily shaped objects as well.

  5. Ultra-wideband microwave photonic phase shifter with configurable amplitude response.

    PubMed

    Pagani, M; Marpaung, D; Eggleton, B J

    2014-10-15

    We introduce a new principle that enables separate control of the amplitude and phase of an optical carrier, simply by controlling the power of two stimulated Brillouin scattering (SBS) pumps. This technique is used to implement a microwave photonic phase shifter with record performance, which solves the bandwidth limitation of previous gain-transparent SBS-based phase shifters, while achieving unprecedented minimum power fluctuations, as a function of phase shift. We demonstrate 360° continuously tunable phase shift, with less than 0.25 dB output power fluctuations, over a frequency band from 1.5 to 31 GHz, limited only by the measurement equipment. PMID:25361102

  6. On-chip programmable ultra-wideband microwave photonic phase shifter and true time delay unit.

    PubMed

    Burla, Maurizio; Cortés, Luis Romero; Li, Ming; Wang, Xu; Chrostowski, Lukas; Azaña, José

    2014-11-01

    We proposed and experimentally demonstrated an ultra-broadband on-chip microwave photonic processor that can operate both as RF phase shifter (PS) and true-time-delay (TTD) line, with continuous tuning. The processor is based on a silicon dual-phase-shifted waveguide Bragg grating (DPS-WBG) realized with a CMOS compatible process. We experimentally demonstrated the generation of delay up to 19.4 ps over 10 GHz instantaneous bandwidth and a phase shift of approximately 160° over the bandwidth 22-29 GHz. The available RF measurement setup ultimately limits the phase shifting demonstration as the device is capable of providing up to 300° phase shift for RF frequencies over a record bandwidth approaching 1 THz. PMID:25361309

  7. Experimental demonstration of ultra-wideband and high-efficiency terahertz spoof surface plasmon polaritons coupler

    NASA Astrophysics Data System (ADS)

    Tang, Heng-He; Ma, Tian-Jun; Liu, Pu-Kun

    2016-05-01

    Spoof surface plasmon polaritons (SSPPs) are promising for subwavelength waveguiding in the terahertz (THz) frequency range. However, they cannot be efficiently excited from spatial propagating or guided waves due to the mismatched momenta. In this paper, a THz coupler is designed to smoothly bridge SSPPs and guided (or propagating) waves. By using a tapered parallel-plate waveguide, the incident energies are efficiently compressed and coupled into a subwavelength gap. Then, the momenta differences are mitigated with a graded grating. The numerical simulations show that the relative bandwidth of the coupler reaches up to 127%, and the maximum coupling efficiency is 99%. More importantly, experiment results in the 0.22 THz-0.33 THz frequency range are also presented to verify the good performance of the coupler. The work provides a technical support for terahertz waveguiding.

  8. Short range, ultra-wideband radar with high resolution swept range gate

    DOEpatents

    McEwan, Thomas E.

    1998-05-26

    A radar range finder and hidden object locator is based on ultra-wide band radar with a high resolution swept range gate. The device generates an equivalent time amplitude scan with a typical range of 4 inches to 20 feet, and an analog range resolution as limited by a jitter of on the order of 0.01 inches. A differential sampling receiver is employed to effectively eliminate ringing and other aberrations induced in the receiver by the near proximity of the transmit antenna, so a background subtraction is not needed, simplifying the circuitry while improving performance. Uses of the invention include a replacement of ultrasound devices for fluid level sensing, automotive radar, such as cruise control and parking assistance, hidden object location, such as stud and rebar finding. Also, this technology can be used when positioned over a highway lane to collect vehicle count and speed data for traffic control.

  9. Short range, ultra-wideband radar with high resolution swept range gate

    DOEpatents

    McEwan, T.E.

    1998-05-26

    A radar range finder and hidden object locator is based on ultra-wide band radar with a high resolution swept range gate. The device generates an equivalent time amplitude scan with a typical range of 4 inches to 20 feet, and an analog range resolution as limited by a jitter of on the order of 0.01 inches. A differential sampling receiver is employed to effectively eliminate ringing and other aberrations induced in the receiver by the near proximity of the transmit antenna, so a background subtraction is not needed, simplifying the circuitry while improving performance. Uses of the invention include a replacement of ultrasound devices for fluid level sensing, automotive radar, such as cruise control and parking assistance, hidden object location, such as stud and rebar finding. Also, this technology can be used when positioned over a highway lane to collect vehicle count and speed data for traffic control. 14 figs.

  10. Accurate permittivity measurements for microwave imaging via ultra-wideband removal of spurious reflectors

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The use of microwave imaging is becoming more prevalent for detection of interior hidden defects in manufactured and packaged materials. In applications for detection of hidden moisture, microwave tomography can be used to image the material and then perform an inverse calculation to derive an estim...

  11. Ultra Wideband Radar Mapping of Near Surface Internal Layers: Systems, Results and Analysis

    NASA Astrophysics Data System (ADS)

    Gogineni, S.; Kanagaratnam, P.; Parthasarathy, R.; Akins, T. L.; Braaten, D.; Jezek, K. C.

    2004-12-01

    We developed two radar systems for mapping near-surface internal layers. We developed one of these systems to operate over the frequency range 500 to 2000 MHz for surface-based measurements, and the other to operate over the frequency range from 600 to 900 MHz for airborne measurements. Both systems are designed to operate in frequency modulated continuous wave (FM-CW) mode with less than 200 mW of transmit power. We have used the airborne system to collect data over flight lines flown by a NASA P-3 aircraft as a part of NASA's Program for Arctic Regional Climate Assessment (PARCA) initiative during the 2002 and 2003 field seasons. These data show that we can map layers to a depth of about of 150 m in the dry snow zone, 50 m in the percolation zone, and 20 m in the melt zone. During the 2002 field season, one of the flight lines passed over the NASA-U_1 ice core site with coordinates of 73.84° N and 49.49° W. The ice core was analyzed to determine density at a mean sampling interval of 1.04 m and a variance of 0.05 m. Using these density data, we generated the dielectric profile, which was input into the radar waveform simulator to generate the radar return as a function of depth at the core site. We compared the simulated waveform with the measured data to identify and date a few layers. We tracked the dated layers over a distance of several kilometers to compute spatial and temporal variations in the accumulation rate. During the 2004 field season, we used the surface-based system to collect data over a 10 km x 10 km area at the Summit Camp in Greenland, in conjunction with several in-situ measurements of snow density and layering. The results from the surface-based experiment show that we can map annual layers to a depth of about 200 m and with about 10 cm resolution. We will provide an overview of the radars developed for mapping of near-surface layers and the waveform simulator. We will show results from airborne and surface-based experiments and compare theoretical and experimental data.

  12. Ultra-Wideband, Dual-Polarized, Beam-Steering P-Band Array Antenna

    NASA Technical Reports Server (NTRS)

    duToit, Cornelis

    2014-01-01

    A dual-polarized, wide-bandwidth (200 MHz for one polarization, 100 MHz for the orthogonal polarization) antenna array at P-band was designed to be driven by NASA's EcoSAR digital beam former. EcoSAR requires two wide P-band antenna arrays mounted on the wings of an aircraft, each capable of steering its main beam up to 35deg off-boresight, allowing the twin radar beams to be steered at angles to the flight path. The science requirements are mainly for dual-polarization capability and a wide bandwidth of operation of up to 200 MHz if possible, but at least 100 MHz with high polarization port isolation and low cross-polarization. The novel design geometry can be scaled with minor modifications up to about four times higher or down to about half the current design frequencies for any application requiring a dual-polarized, wide-bandwidth steerable antenna array. EcoSAR is an airborne interferometric P-band synthetic aperture radar (SAR) research application for studying two- and three-dimensional fine-scale measurements of terrestrial ecosystem structure and biomass, which will ultimately aid in the broader study of the carbon cycle and climate change. The two 2×8 element Pband antenna arrays required by the system will be separated by a baseline of about 25 m, allowing for interferometry measurements. The wide 100-to- 200-MHz bandwidth dual-polarized beams employed will allow the determination of the amount of biomass and even tree height on the ground. To reduce the size of the patches along the boresight dimension in order to fit them into the available space, two techniques were employed. One technique is to add slots along the edges of each patch where the main electric currents are expected to flow, and the other technique is to bend the central part of the patch away from the ground plane. The latter also facilitates higher mechanical rigidity. The high port isolation of more than 40 dB was achieved by employing a highly symmetrical feed mechanism for each pair of elements: three apertures coupling to the patch elements were placed along the two symmetry lines of the antenna element pair. Two apertures were used in tandem to excite two of the stacked patch elements for one polarization; the other was used to excite one element from one side and the other element from the other side, opposite in phase, taking care of the remaining polarization. The apertures narrow down to a small gap where they are excited by a crossing microstrip line to prevent any asymmetrical excitation of the two sides of the aperture gap, minimizing port-to-port coupling. Using patches that are non-planar leads to higher mechanical rigidity and smaller patch sizes to fit into the available space. Aperture coupling minimizes direct metal-to-metal connections. Using an aperture coupling feed mechanism results in a feed network for two antenna elements with a total of three feed points, plus one simple in-phase combiner to reduce it to two ports. It greatly reduces the complexity of the alternative, but more conventional, way of feeding a pair of two dual-polarized elements with high port isolation.

  13. Power-efficient ultra wideband LNAs for the world's largest radio telescope

    NASA Astrophysics Data System (ADS)

    Panahi, M.; Bhaumik, S.; George, D.

    2014-12-01

    This paper reports two Low Noise Amplifiers (LNA) for Aperture Array system of the international Square Kilometre Array (SKA) project. LNA design for SKA is a step change in traditional LNA design approach for radio astronomy applications as the defining aspects of performance are low noise along with low power consumption and adequate gain. The LNAs are designed, fabricated and characterised for frequency range of 20 -1000 MHz. One LNA has single ended input to single ended output configuration (LNA1) while the other LNA has balanced input to single ended output (LNA2). The S-parameter, noise figure (NF) and large signal response of the LNAs are measured at room temperature. Both LNAs show flat gain of higher than 30 dB over specified frequency range. Average NF values of LNA1 and LNA2 are 0.55 dB and 0.75 dB respectively. Mixed mode S-parameter response based on theoretical analysis of differential configuration is presented. The LNAs have exceptionally low power consumption of less than 25 mW; 20 times lower than the other reported LNAs available for the SKA and also covering complete frequency band with less than 1 dB NF. Therefore implication of these LNAs is a significant step forward as the projected number of LNAs required for the lower frequency band of SKA Aperture Array system is 5,600,000 (Dewdney et al., Proc. IEEE 97(8), 1482-1496, 2009; Faulkner et al. 2010).

  14. The National Geoelectromagnetic Facility - an open access resource for ultra wideband electromagnetic geophysics (Invited)

    NASA Astrophysics Data System (ADS)

    Schultz, A.; Urquhart, S.; Slater, M.

    2010-12-01

    At present, the US academic community has access to two national electromagnetic (EM) instrument pools that support long-period magnetotelluric (MT) equipment suitable for crust-mantle scale studies. The requirements of near surface geophysics, hydrology, glaciology, as well as the full range of crust and mantle investigations require development of new capabilities in data acquisition with broader frequency bandwidth than these existing units, increased instrument numbers, and concomitant developments in 3D/4D data interpretation. NSF Major Research Instrumentation support has been obtained to meet these requirements by developing an initial set of next-generation instruments as a National Geoelectromagnetic Facility (NGF), available to all PIs on a cost recovery basis, and operated by Oregon State University (OSU). In contrast to existing instruments with data acquisition systems specialized to operate within specific frequency bands and for specific electromagnetic methods, the NGF model "Zen/5" instruments being co-developed by OSU and Zonge Research and Engineering Organization are based on modular receivers with a flexible number of digital and analog input channels, designed to acquire EM data at dc, and from frequencies ranging from micro-Hz to MHz. These systems can be deployed in a compact, low power configuration for extended deployments (e.g. for crust-mantle scale experiments), or in a high frequency sampling mode for near surface work. The NGF is also acquiring controlled source EM transmitters, so that investigators may carry out magnetotelluric, audio-MT, radiofrequency-MT, as well as time-domain/transient EM and DC resistivity studies. The instruments are designed to simultaneously accommodate multiple electric field dipole sensors, magnetic fluxgates and induction coil sensors. Sample rates as high as 2.5 MHz with resolution between 24 and 32 bits, depending on sample rate, are specified to allow for high fidelity recording of waveforms. The NGF is accepting instrument use requests from investigators planning electromagnetic surveys via webform submission on its web site ngf.coas.oregonstate.edu. The site is also a port of entry to request access to the 46 long period magnetotelluric instruments also operated by OSU as national instrument pools. Cyberinfrastructure support is available to investigators, including field computers, EM data processing software, and access to a hybrid CPU-GPU parallel computing environment, currently configured with dual Intel Westmere hexacore CPUs and 960 NVidia Tesla and 1792 Nvidia Fermi GPU cores. The capabilities of the Zen/5 receivers will be presented, with examples of data acquired from a recent shallow water marine controlled source experiment conducted in coastal Oregon as part of an effort to locate a buried submarine pipeline, using a 1.1 KW 256 Hz signal source imposed on the pipeline from shore. A Zen/5 prototype instrument, modified for marine use through support by the Oregon Wave Energy Trust, demonstrated the marine capabilities of the NGF instrument design.

  15. Ultra-wideband RF/microwave MEMS switches for wireless communications

    NASA Astrophysics Data System (ADS)

    Jha, A. R.

    2006-03-01

    Microelectromechanical System (MEMS) switches offer outstanding performance over wide bandwidth, minimum weight, sue, and power consumption, and significantly improved reliability unmatched by any other electronic switches deploying GaAS FETs or GaAs PIN-diodes or GaAs HEMTs. These switches are best suited for applications that require high signal purity in terms of signal linearity, insertion loss, isolation, and power consumption. RF-MEMS switches offer reliability exceeding ten billion life cycles and low insertion loss and high isolation while operating over uh-wideband. Design parameters and fabrication aspects of RF-MEMS shunt and series switches are investigated, which will permit switch operation over 60 to 94 GHz range.

  16. Graphene as a high impedance surface for ultra-wideband electromagnetic waves

    SciTech Connect

    Aldrigo, Martino; Costanzo, Alessandra; Dragoman, Mircea; Dragoman, Daniela

    2013-11-14

    The metals are regularly used as reflectors of electromagnetic fields emitted by antennas ranging from microwaves up to THz. To enhance the reflection and thus the gain of the antenna, metallic high impedance surfaces (HIS) are used. HIS is a planar array of continuous metallic periodic cell surfaces able to suppress surface waves, which cause multipath interference and backward radiation in a narrow bandwidth near the cell resonance. Also, the image currents are reduced, and therefore the antenna can be placed near the HIS. We demonstrate that graphene is acting as a HIS surface in a very large bandwidth, from microwave to THz, suppressing the radiation leakages better than a metal.

  17. Graphene as a high impedance surface for ultra-wideband electromagnetic waves

    NASA Astrophysics Data System (ADS)

    Aldrigo, Martino; Dragoman, Mircea; Constanzo, Alessandra; Dragoman, Daniela

    2013-11-01

    The metals are regularly used as reflectors of electromagnetic fields emitted by antennas ranging from microwaves up to THz. To enhance the reflection and thus the gain of the antenna, metallic high impedance surfaces (HIS) are used. HIS is a planar array of continuous metallic periodic cell surfaces able to suppress surface waves, which cause multipath interference and backward radiation in a narrow bandwidth near the cell resonance. Also, the image currents are reduced, and therefore the antenna can be placed near the HIS. We demonstrate that graphene is acting as a HIS surface in a very large bandwidth, from microwave to THz, suppressing the radiation leakages better than a metal.

  18. SEMICONDUCTOR INTEGRATED CIRCUITS: A 3.1-4.8 GHz transmitter with a high frequency divider in 0.18 μm CMOS for OFDM-UWB

    NASA Astrophysics Data System (ADS)

    Renliang, Zheng; Junyan, Ren; Wei, Li; Ning, Li

    2009-12-01

    A fully integrated low power RF transmitter for a WiMedia 3.1-4.8 GHz multiband orthogonal frequency division multiplexing ultra-wideband system is presented. With a separate transconductance stage, the quadrature up-conversion modulator achieves high linearity with low supply voltage. The co-design of different resonant frequencies of the modulator and the differential to single (D2S) converter ensures in-band gain flatness. By means of a series inductor peaking technique, the D2S converter obtains 9 dB more gain without extra power consumption. A divided-by-2 divider is used for carrier signal generation. The measurement results show an output power between -10.7 and -3.1 dBm with 7.6 dB control range, an OIP3 up to 12 dBm, a sideband rejection of 35 dBc and a carrier rejection of 30 dBc. The ESD protected chip is fabricated in the Jazz 0.18 μm RF CMOS process with an area of 1.74 mm2 and only consumes 32 mA current (at 1.8 V) including the test associated parts.

  19. Wearable system-on-a-chip UWB radar for health care and its application to the safety improvement of emergency operators.

    PubMed

    Zito, Domenico; Pepe, Domenico; Neri, Bruno; De Rossi, Danilo; Lanatà, Antonio; Tognetti, Alessandro; Scilingo, Enzo Pasquale

    2007-01-01

    A new wearable system-on-a-chip UWB radar for health care systems is presented. The idea and its applications to the safety improvement of emergency operators are discussed. The system consists of a wearable wireless interface including a fully integrated UWB radar for the detection of the heart beat and breath rates, and a IEEE 802.15.4 ZigBee radio interface. The principle of operation of the UWB radar for the monitoring of the heart wall is explained hereinafter. The results obtained by the feasibility study regarding its implementation on a modern standard silicon technology (CMOS 90 nm) are reported, demonstrating (at simulation level) the effectiveness of such an approach and enabling the standard silicon technology for new generations of wireless sensors for heath care and safeguard wearable systems. PMID:18002540

  20. SEMICONDUCTOR INTEGRATED CIRCUITS: A low-spurious fast-hopping MB-OFDM UWB synthesizer

    NASA Astrophysics Data System (ADS)

    Danfeng, Chen; Wei, Li; Ning, Li; Junyan, Ren

    2010-06-01

    A frequency synthesizer for the ultra-wide band (UWB) group #1 is proposed. The synthesizer uses a phase-locked loop (PLL) and single-sideband (SSB) mixers to generate the three center frequencies of the first band group by mixing 4224 MHz with ±264 MHz and 792 MHz, respectively. A novel multi-QSSB mixer is designed to combine the function of frequency selection and frequency conversion for low power and high linearity. The synthesizer is fabricated in Jazz 0.18-μm RF CMOS technology. The measured reference spur is as low as -69 dBc and the maximum spur is the LO leakage of -32 dBc. A low phase noise of -110 dBc/Hz @ 1 MHz offset and an integrated phase noise of 1.86° are achieved. The hopping time between different bands is less than 1.8 ns. The synthesizer consumes 30 mA from a 1.8 V supply.

  1. Efficient Management of Multiple Piconets in an MC-CDMA-Based UWB System

    NASA Astrophysics Data System (ADS)

    Gong, Peng; Xue, Peng; Piao, Cheng Jie; Kim, Duk Kyung

    With multiple overlapped piconets, the IEEE 802.15.3 Medium Access Control (MAC) protocol uses a Parent/Child (P/C) or Parent/Neighbor (P/N) configuration to avoid inter-piconet interference. However, the throughput of a P/N or P/C configuration cannot exceed that of a single piconet. In the present paper we propose an efficient means of managing multiple piconets to cooperate with a Multi-Carrier Code Division Multiple Access (MC-CDMA) based UWB system. The proposed management approach uses an Intermediate Device (IDEV) to connect Piconet Coordinators (PNCs). A senior PNC adaptively arranges two simultaneous data transmission links with the proposed spreading matrices in each Channel Time Allocation (CTA) instead of a P/C or P/N configuration, which supports only a single link in each CTA. Simulation results demonstrate the proposed scheme can achieve a higher throughput with an acceptable compromise of link success probability in multiple overlapped piconets.

  2. UWB Band-notched Adjustable Antenna Using Concentric Split-ring Slots Structure

    NASA Astrophysics Data System (ADS)

    Yin, Y.; Hong, J. S.

    2014-09-01

    In this paper, a kind of concentric split-ring slots structure is utilized to design a novel triple-band-notched UWB antenna. Firstly, a concentric split-ring slots structure that has a higher VSWR than that of a single slot at notch frequency is presented. What's more, the structure is very simple and feasible to obtain notched-band at different frequency by adjustment of the length of slot. Secondly, a triple-band-notched antenna, whose notched bands are at 3.52-3.81 GHz for WiMAX and 5.03-5.42 GHz and 5.73-56.17 GHz for WLAN, is designed by using this structure. At last, a compact size of 24 × 30 mm2 of the proposed antenna has been fabricated and measured and it is shown that the proposed antenna has a broadband matched impedance (3.05-14 GHz, VSWR < 2), relatively stable gain and good omnidirectional radiation patterns at low bands.

  3. Design and Performance Evaluation of a UWB Communication and Tracking System for Mini-AERCam

    NASA Technical Reports Server (NTRS)

    Barton, Richard J.

    2005-01-01

    NASA Johnson Space Center (JSC) is developing a low-volume, low-mass, robotic free-flying camera known as Mini-AERCam (Autonomous Extra-vehicular Robotic Camera) to assist the International Space Station (ISS) operations. Mini-AERCam is designed to provide astronauts and ground control real-time video for camera views of ISS. The system will assist ISS crewmembers and ground personnel to monitor ongoing operations and perform visual inspections of exterior ISS components without requiring extravehicular activity (EAV). Mini-AERCam consists of a great number of subsystems. Many institutions and companies have been involved in the R&D for this project. A Mini-AERCam ground control system has been studied at Texas A&M University [3]. The path planning and control algorithms that direct the motions of Mini-AERCam have been developed through the joint effort of Carnegie Mellon University and the Texas Robotics and Automation Center [5]. NASA JSC has designed a layered control architecture that integrates all functions of Mini-AERCam [8]. The research described in this report is part of a larger effort focused on the communication and tracking subsystem that is designed to perform three major tasks: 1. To transmit commands from ISS to Mini-AERCam for control of robotic camera motions (downlink); 2. To transmit real-time video from Mini-AERCam to ISS for inspections (uplink); 3. To track the position of Mini-AERCam for precise motion control. The ISS propagation environment is unique due to the nature of the ISS structure and multiple RF interference sources [9]. The ISS is composed of various truss segments, solar panels, thermal radiator panels, and modules for laboratories and crew accommodations. A tracking system supplemental to GPS is desirable both to improve accuracy and to eliminate the structural blockage due to the close proximity of the ISS which could at times limit the number of GPS satellites accessible to the Mini-AERCam. Ideally, the tracking system will be a passive component of the communication system which will need to operate in a time-varying multipath environment created as the robot camera moves over the ISS structure. In addition, due to many interference sources located on the ISS, SSO, LEO satellites and ground-based transmitters, selecting a frequency for the ISS and Mini-AERCam link which will coexist with all interferers poses a major design challenge. To meet all of these challenges, ultrawideband (UWB) radio technology is being studied for use in the Mini-AERCam communication and tracking subsystem. The research described in this report is focused on design and evaluation of passive tracking system algorithms based on UWB radio transmissions from mini-AERCam.

  4. A Negative Index Metamaterial-Inspired UWB Antenna with an Integration of Complementary SRR and CLS Unit Cells for Microwave Imaging Sensor Applications

    PubMed Central

    Islam, Mohammad Tariqul; Islam, Md. Moinul; Samsuzzaman, Md.; Faruque, Mohammad Rashed Iqbal; Misran, Norbahiah

    2015-01-01

    This paper presents a negative index metamaterial incorporated UWB antenna with an integration of complementary SRR (split-ring resonator) and CLS (capacitive loaded strip) unit cells for microwave imaging sensor applications. This metamaterial UWB antenna sensor consists of four unit cells along one axis, where each unit cell incorporates a complementary SRR and CLS pair. This integration enables a design layout that allows both a negative value of permittivity and a negative value of permeability simultaneous, resulting in a durable negative index to enhance the antenna sensor performance for microwave imaging sensor applications. The proposed MTM antenna sensor was designed and fabricated on an FR4 substrate having a thickness of 1.6 mm and a dielectric constant of 4.6. The electrical dimensions of this antenna sensor are 0.20 λ × 0.29 λ at a lower frequency of 3.1 GHz. This antenna sensor achieves a 131.5% bandwidth (VSWR < 2) covering the frequency bands from 3.1 GHz to more than 15 GHz with a maximum gain of 6.57 dBi. High fidelity factor and gain, smooth surface-current distribution and nearly omni-directional radiation patterns with low cross-polarization confirm that the proposed negative index UWB antenna is a promising entrant in the field of microwave imaging sensors. PMID:26007721

  5. PULSE GENERATOR

    DOEpatents

    Roeschke, C.W.

    1957-09-24

    An improvement in pulse generators is described by which there are produced pulses of a duration from about 1 to 10 microseconds with a truly flat top and extremely rapid rise and fall. The pulses are produced by triggering from a separate input or by modifying the current to operate as a free-running pulse generator. In its broad aspect, the disclosed pulse generator comprises a first tube with an anode capacitor and grid circuit which controls the firing; a second tube series connected in the cathode circuit of the first tube such that discharge of the first tube places a voltage across it as the leading edge of the desired pulse; and an integrator circuit from the plate across the grid of the second tube to control the discharge time of the second tube, determining the pulse length.

  6. Pulse stretcher

    DOEpatents

    Horton, J.A.

    1994-05-03

    Apparatus for increasing the length of a laser pulse to reduce its peak power without substantial loss in the average power of the pulse is disclosed. The apparatus uses a White cell having a plurality of optical delay paths of successively increasing number of passes between the field mirror and the objective mirrors. A pulse from a laser travels through a multi-leg reflective path between a beam splitter and a totally reflective mirror to the laser output. The laser pulse is also simultaneously injected through the beam splitter to the input mirrors of the optical delay paths. The pulses from the output mirrors of the optical delay paths go simultaneously to the laser output and to the input mirrors of the longer optical delay paths. The beam splitter is 50% reflective and 50% transmissive to provide equal attenuation of all of the pulses at the laser output. 6 figures.

  7. Flexible sixteen monopole antenna array for microwave breast cancer detection.

    PubMed

    Bahrami, H; Porter, E; Santorelli, A; Gosselin, B; Popovic, M; Rusch, L A

    2014-01-01

    Radar based microwave imaging (MI) has been widely studied for breast cancer detection in recent times. Sensing dielectric property differences of tissues over a wide frequency band has been made possible by ultra-wideband (UWB) techniques. In this paper, a flexible, compact monopole antenna on a 100 μm Kapton polyimide is designed, using a high frequency structure simulator (HFSS), to be in contact with biological breast tissues over the 2-5GHz frequency range. The antenna parameters are optimized to obtain a good impedance match over the required frequency range. The designed antenna size is 18mm × 18mm. Further, a flexible conformal 4×4 ultra-wideband antenna array, in a format similar to that of a bra, was developed for a radar-based breast cancer detection system. PMID:25570813

  8. Pulse Voltammetry

    NASA Astrophysics Data System (ADS)

    Stojek, Zbigniew

    The idea of imposing potential pulses and measuring the currents at the end of each pulse was proposed by Barker in a little-known journal as early as in 1958 [1]. However, the first reliable trouble-free and affordable polarographs offering voltammetric pulse techniques appeared on the market only in the 1970s. This delay was due to some limitations on the electronic side. In the 1990s, again substantial progress in electrochemical pulse instrumentation took place. This was related to the introduction of microprocessors, computers, and advanced software.

  9. Pulse oximetry

    PubMed Central

    Jubran, Amal

    1999-01-01

    Pulse oximetry is one of the most commonly employed monitoringmodalities in the critical care setting. This review describes the latesttechnological advances in the field of pulse oximetry. Accuracy of pulseoximeters and their limitations are critically examined. Finally, the existingdata regarding the clinical applications and cost-effectiveness of pulseoximeters are discussed. PMID:11094477

  10. The Applications of Decision-Level Data Fusion Techniques in the Field of Multiuser Detection for DS-UWB Systems

    PubMed Central

    Gu, Yebo; Yang, Minglei; Shi, Zhenguo; Wu, Zhilu

    2015-01-01

    In this paper, the decision-level data fusion techniques are extended to the multiuser detection (MUD) field. Then two novel MUD algorithms, that is the chairman arbitrating decision-level fusion criterion (CA-DFC) based MUD algorithm and the veto logic decision-level fusion criterion (VL-DFC) based MUD algorithm, are proposed for DS-UWB communication systems. In CA-DFC based method, the chairman can make his arbitration among the preliminary decisions from sub-optimal detectors by his own rule. In the VL-DFC based method, the undetermined bits in these preliminary decisions are considered to construct a simplified solution space, and then the chairman can make his final decision within this space. Simulation results demonstrate that the performances of CA-DFC and VL-DFC based MUD algorithms are superior to those of other sub-optimal MUD algorithms, and even close to that of OMD. Moreover, both of these proposed algorithms have lower computational complexity than OMD, which reveals their efficiency. Compared with CA-DFC, VL-DFC based algorithm achieves a little improvement in its performance, at the cost of the increment in its computational complexity. Thus, they can be applied to different practical situations. PMID:26404273

  11. PULSE AMPLIFIER

    DOEpatents

    Johnstone, C.W.

    1958-06-17

    The improvement of pulse amplifiers used with scintillation detectors is described. The pulse amplifier circuit has the advantage of reducing the harmful effects of overloading cause by large signal inputs. In general the pulse amplifier circuit comprises two amplifier tubes with the input pulses applied to one amplifier grid and coupled to the second amplifier tube through a common cathode load. The output of the second amplifier is coupled from the plate circuit to a cathode follower tube grid and a diode tube in connected from grid to cathode of the cathode follower tube. Degenerative feedback is provided in the second amplifier by coupling a signal from the cathode follower cathode to the second amplifier grid. The circuit proqides moderate gain stability, and overload protection for subsequent pulse circuits.

  12. Design and optimization of an ultra-wideband and compact microwave antenna for radiometric monitoring of brain temperature

    PubMed Central

    Maccarini, Paolo F.; Salahi, Sara; Oliveira, Tiago R.; Pereira, Pedro J. S.; Limão-Vieira, Paulo; Snow, Brent W.; Reudink, Doug; Stauffer, Paul R.

    2014-01-01

    We present the modeling efforts on antenna design and frequency selection to monitor brain temperature during prolonged surgery using non-invasive microwave radiometry. A tapered log-spiral antenna design is chosen for its wideband characteristics that allow higher power collection from deep brain. Parametric analysis with HFSS is used to optimize antenna performance for deep brain temperature sensing. Radiometric antenna efficiency (η) is evaluated in terms of the ratio of power collected from brain to total power received by the antenna. Anatomical information extracted from several adult computed tomography (CT) scans is used to establish design parameters for constructing an accurate layered 3D tissue phantom. This head phantom includes separate brain and scalp regions, with tissue equivalent liquids circulating at independent temperatures on either side of an intact skull. The optimized frequency band is 1.1–1.6 GHz producing an average antenna efficiency of 50.3% from a 2 turn log-spiral antenna. The entire sensor package is contained in a lightweight and low profile 2.8 cm diameter by 1.5 cm high assembly that can be held in place over the skin with an electromagnetic interference (EMI) shielding adhesive patch. The calculated radiometric equivalent brain temperature tracks within 0.4°C of measured brain phantom temperature when the brain phantom is lowered 10°C and then returned to original temperature (37°C) over a 4.6-hour experiment. The numerical and experimental results demonstrate that the optimized 2.5 cm log-spiral antenna is well suited for the non-invasive radiometric sensing of deep brain temperature. PMID:24759979

  13. Ultra-wideband microwave absorber by connecting multiple absorption bands of two different-sized hyperbolic metamaterial waveguide arrays.

    PubMed

    Yin, Xiang; Long, Chang; Li, Junhao; Zhu, Hua; Chen, Lin; Guan, Jianguo; Li, Xun

    2015-01-01

    Microwave absorbers have important applications in various areas including stealth, camouflage, and antenna. Here, we have designed an ultra-broadband light absorber by integrating two different-sized tapered hyperbolic metamaterial (HMM) waveguides, each of which has wide but different absorption bands due to broadband slow-light response, into a unit cell. Both the numerical and experimental results demonstrate that in such a design strategy, the low absorption bands between high absorption bands with a single-sized tapered HMM waveguide array can be effectively eliminated, resulting in a largely expanded absorption bandwidth ranging from 2.3 to 40 GHz. The presented ultra-broadband light absorber is also insensitive to polarization and robust against incident angle. Our results offer a further step in developing practical artificial electromagnetic absorbers, which will impact a broad range of applications at microwave frequencies. PMID:26477740

  14. Ultra wideband (0.5-16 kHz) MR elastography for robust shear viscoelasticity model identification

    NASA Astrophysics Data System (ADS)

    Liu, Yifei; Yasar, Temel K.; Royston, Thomas J.

    2014-12-01

    Changes in the viscoelastic parameters of soft biological tissues often correlate with progression of disease, trauma or injury, and response to treatment. Identifying the most appropriate viscoelastic model, then estimating and monitoring the corresponding parameters of that model can improve insight into the underlying tissue structural changes. MR Elastography (MRE) provides a quantitative method of measuring tissue viscoelasticity. In a previous study by the authors (Yasar et al 2013 Magn. Reson. Med. 70 479-89), a silicone-based phantom material was examined over the frequency range of 200 Hz-7.75 kHz using MRE, an unprecedented bandwidth at that time. Six viscoelastic models including four integer order models and two fractional order models, were fit to the wideband viscoelastic data (measured storage and loss moduli as a function of frequency). The ‘fractional Voigt’ model (spring and springpot in parallel) exhibited the best fit and was even able to fit the entire frequency band well when it was identified based only on a small portion of the band. This paper is an extension of that study with a wider frequency range from 500 Hz to 16 kHz. Furthermore, more fractional order viscoelastic models are added to the comparison pool. It is found that added complexity of the viscoelastic model provides only marginal improvement over the ‘fractional Voigt’ model. And, again, the fractional order models show significant improvement over integer order viscoelastic models that have as many or more fitting parameters.

  15. Design and optimization of an ultra wideband and compact microwave antenna for radiometric monitoring of brain temperature.

    PubMed

    Rodrigues, Dario B; Maccarini, Paolo F; Salahi, Sara; Oliveira, Tiago R; Pereira, Pedro J S; Limao-Vieira, Paulo; Snow, Brent W; Reudink, Doug; Stauffer, Paul R

    2014-07-01

    We present the modeling efforts on antenna design and frequency selection to monitor brain temperature during prolonged surgery using noninvasive microwave radiometry. A tapered log-spiral antenna design is chosen for its wideband characteristics that allow higher power collection from deep brain. Parametric analysis with the software HFSS is used to optimize antenna performance for deep brain temperature sensing. Radiometric antenna efficiency (η) is evaluated in terms of the ratio of power collected from brain to total power received by the antenna. Anatomical information extracted from several adult computed tomography scans is used to establish design parameters for constructing an accurate layered 3-D tissue phantom. This head phantom includes separate brain and scalp regions, with tissue equivalent liquids circulating at independent temperatures on either side of an intact skull. The optimized frequency band is 1.1-1.6 GHz producing an average antenna efficiency of 50.3% from a two turn log-spiral antenna. The entire sensor package is contained in a lightweight and low-profile 2.8 cm diameter by 1.5 cm high assembly that can be held in place over the skin with an electromagnetic interference shielding adhesive patch. The calculated radiometric equivalent brain temperature tracks within 0.4 °C of the measured brain phantom temperature when the brain phantom is lowered 10 °C and then returned to the original temperature (37 °C) over a 4.6-h experiment. The numerical and experimental results demonstrate that the optimized 2.5-cm log-spiral antenna is well suited for the noninvasive radiometric sensing of deep brain temperature. PMID:24759979

  16. Ultra-wideband microwave absorber by connecting multiple absorption bands of two different-sized hyperbolic metamaterial waveguide arrays

    NASA Astrophysics Data System (ADS)

    Yin, Xiang; Long, Chang; Li, Junhao; Zhu, Hua; Chen, Lin; Guan, Jianguo; Li, Xun

    2015-10-01

    Microwave absorbers have important applications in various areas including stealth, camouflage, and antenna. Here, we have designed an ultra-broadband light absorber by integrating two different-sized tapered hyperbolic metamaterial (HMM) waveguides, each of which has wide but different absorption bands due to broadband slow-light response, into a unit cell. Both the numerical and experimental results demonstrate that in such a design strategy, the low absorption bands between high absorption bands with a single-sized tapered HMM waveguide array can be effectively eliminated, resulting in a largely expanded absorption bandwidth ranging from 2.3 to 40 GHz. The presented ultra-broadband light absorber is also insensitive to polarization and robust against incident angle. Our results offer a further step in developing practical artificial electromagnetic absorbers, which will impact a broad range of applications at microwave frequencies.

  17. Ultra-wideband microwave absorber by connecting multiple absorption bands of two different-sized hyperbolic metamaterial waveguide arrays

    PubMed Central

    Yin, Xiang; Long, Chang; Li, Junhao; Zhu, Hua; Chen, Lin; Guan, Jianguo; Li, Xun

    2015-01-01

    Microwave absorbers have important applications in various areas including stealth, camouflage, and antenna. Here, we have designed an ultra-broadband light absorber by integrating two different-sized tapered hyperbolic metamaterial (HMM) waveguides, each of which has wide but different absorption bands due to broadband slow-light response, into a unit cell. Both the numerical and experimental results demonstrate that in such a design strategy, the low absorption bands between high absorption bands with a single-sized tapered HMM waveguide array can be effectively eliminated, resulting in a largely expanded absorption bandwidth ranging from 2.3 to 40 GHz. The presented ultra-broadband light absorber is also insensitive to polarization and robust against incident angle. Our results offer a further step in developing practical artificial electromagnetic absorbers, which will impact a broad range of applications at microwave frequencies. PMID:26477740

  18. Ultra Wideband (0.5 – 16 kHz) MR Elastography for Robust Shear Viscoelasticity Model Identification

    PubMed Central

    Liu, Yifei; Yasar, Temel K.; Royston, Thomas J.

    2014-01-01

    Changes in the viscoelastic parameters of soft biological tissues often correlate with progression of disease, trauma or injury, and response to treatment. Identifying the most appropriate viscoelastic model, then estimating and monitoring the corresponding parameters of that model can improve insight into the underlying tissue structural changes. MR Elastography (MRE) provides a quantitative method of measuring tissue viscoelasticity. In a previous study of the authors [Mag. Res. Med. 70:479–89;2013. doi: 10.1002/mrm.24495], a silicone-based phantom material was examined over the frequency range of 200 Hz to 7.75 kHz using MRE, an unprecedented bandwidth at that time. Six viscoelastic models including four integer order models and two fractional order models, were fit to the wideband viscoelastic data (measured storage and loss moduli as a function of frequency). The “fractional Voigt” model (spring and springpot in parallel) exhibited the best fit and was even able to fit the entire frequency band well when it was identified based only on a small portion of the band. This paper is an extension of that study with a wider frequency range from 500 Hz to 16 kHz. Furthermore, more fractional order viscoelastic models are added to the comparison pool. It is found that added complexity of the viscoelastic model provides only marginal improvement over the “fractional Voigt” model. And, again, the fractional order models show significant improvement over integer order viscoelastic models that have as many or more fitting parameters. PMID:25419651

  19. Time-domain calculation of sub-nanosecond pulse launched by a proton beam

    SciTech Connect

    Chan, Kwok-Chi Dominic; Cooper, R.K.

    1990-01-01

    Using the finite-difference time-domain code TBCI, we have numerically calculated the radiation from a sub-nanosecond 800-MeV proton bunch as it is launched into space. The calculation is compared to measurements of the time history of the radiated fields and good agreement is found. A movie showing the development of the radiation pattern will be shown during the presentation at this conference, namely, the First Los Alamos Symposium on Ultra-Wideband Radar. 6 refs., 7 figs.

  20. Pulse stretcher

    DOEpatents

    Horton, James A.

    1994-01-01

    Apparatus (20) for increasing the length of a laser pulse to reduce its peak power without substantial loss in the average power of the pulse. The apparatus (20) uses a White cell (10) having a plurality of optical delay paths (18a-18d) of successively increasing number of passes between the field mirror (13) and the objective mirrors (11 and 12). A pulse (26) from a laser (27) travels through a multi-leg reflective path (28) between a beam splitter (21) and a totally reflective mirror (24) to the laser output (37). The laser pulse (26) is also simultaneously injected through the beam splitter (21) to the input mirrors (14a-14d) of the optical delay paths (18a-18d). The pulses from the output mirrors (16a-16d) of the optical delay paths (18a-18d) go simultaneously to the laser output (37) and to the input mirrors ( 14b-14d) of the longer optical delay paths. The beam splitter (21) is 50% reflective and 50% transmissive to provide equal attenuation of all of the pulses at the laser output (37).

  1. Wideband Array for C, X, and Ku-Band Applications with 5.3:1 Bandwidth

    NASA Technical Reports Server (NTRS)

    Novak, Markus H.; Volakis, John L.; Miranda, Félix A.

    2015-01-01

    Satellite communication has largely been accomplished using reflector antennas. However, such antennas are inherently bulky, and rely on mechanical steering. For this reason, ultra-wideband (UWB) and beam forming arrays have received strong interest. These lower weight, size,and cost arrays can combine many satellite applicationsspread throughout the C–Ka bands (4–40 GHz).To this end, we seek to develop an UWB Tightly-Coupled Dipole Array (TCDA) with the following attributes: UWB band operation (3.5–18.5 GHz) with low loss; 45° or more scanning in all planes; Low-cost Printed Circuit Board (PCB) fabrication; Scalable to Ka-band and above.

  2. Channel models for wireless body area networks.

    PubMed

    Takizawa, Kenichi; Aoyagi, Akahiro; Takada, Jun-Ichi; Katayama, Norihiko; Yekeh, Kamya; Takehiko, Yazdandoost; Kohno, Kobayashi Ryuji

    2008-01-01

    Wireless patient monitoring using wearable sensors is a promising application. This paper provides stochastic channel models for wireless body area network (WBAN) on the human body. Parameters of the channel models are extracted from measured channel transfer functions (CTFs) in a hospital room. Measured frequency bands are selected so as to include permissible bands for WBAN; ultra wideband (UWB), the industry, science and medical (ISM) bands, and wireless medical telemetry system (WMTS) bands. As channel models, both a path loss model and a power delay profile (PDP) model are considered. But, even though path loss models are derived for the all frequency bands, PDP model is only for the UWB band due to the highly frequency selectiveness of UWB channels. The parameters extracted from the measurement results are summarized for each channel model. PMID:19162968

  3. PULSE COUNTER

    DOEpatents

    Trumbo, D.E.

    1959-02-10

    A transistorized pulse-counting circuit adapted for use with nuclear radiation detecting detecting devices to provide a small, light weight portable counter is reported. The small size and low power requirements of the transistor are of particular value in this instance. The circuit provides an adjustable count scale with a single transistor which is triggered by the accumulated charge on a storage capacitor.

  4. Pulse Oximetry

    MedlinePlus

    ... you are exercising or if you travel to high altitude. Having a pulse oximeter in these cases will allow you to monitor your blood oxygen level and know when you need to increase your supplemental oxygen flow rate. Ask your health care provider what oxygen ...

  5. Analysis of hyperbolic signatures from small discontinuities using an UWB ground-coupled radar: FDTD simulations and field experiments

    NASA Astrophysics Data System (ADS)

    Sagnard, Florence; Tebchrany, Elias; Baltazart, Vincent

    2013-04-01

    Ground penetrating radar (GPR) is a well-known non-destructive technique based on electromagnetic wave propagation that is able to detect by reflection or scattering of waves dielectric discontinuities in the underground. Our application is mainly concerned with civil engineering to perform supervision, inventory, and soil characterization. Because the air-coupled radar suffers from a significant reflection at the ground interface that reduces energy transfer of electromagnetic radiation in the sub-surface and penetration depth, we have developed an ultra-wide band (UWB) ground-coupled radar made of a pair of partially shielded compact planar bowtie slot antennas. As the antenna dimension (36*23 cm2) is close to the A4 sheet size, the maturity of the microstrip technology has allowed to design a particular geometry on the FR4 substrate (h=1.5 mm) which is able to operate at frequencies from 460 MHz to beyond 4 GHz in air. Contrary to a commercial GPR where details on antenna design are not available, it appears here possible to know and control the radiation characteristics and develop full-wave FDTD modeling that can represent field experiments for comparisons and analyses. The objective of this work is to improve, by means of a parametric study, the knowledge of physical phenomena involved in dielectric polarization when waves interact with buried discontinuities and particularly cracks, pipes, delaminations that can be distinguished by their shape, size, dielectric contrast with the surrounding medium, orientation relative to the electric field Thus, we have first characterized by FDTD modeling and field measurements in a wet sand the radar link in two perpendicular polarizations (parallel and mirror) in the presence of a common soil (epsilon'=5.5, sigma=0.01 S/m) considering variable offsets. Afterwards, we have studied and analyzed the hyperbola signatures generated by the presence of buried canonical objects (pipes, strips) with several dielectric properties (dielectric and conductive) in a wet sand with a small lateral dimension (less than 20 mm) in both polarizations. Comparisons with FDTD simulations including the detailed structure of the antennas appear promising as they have allowed to interpret the measurements and take advantage of signal polarization to extract information associated with the discontinuities. After cluster removal using classical data processing (SVD, median value substraction), the analytical model based on the ray theory and including the antenna size has allowed to first analyze the hyperbola responses. This study is supposed to prepare the development of data processing associated with B-scans to extract quantitative information from the electromagnetic probing of the subsurface in a very large frequency band.

  6. Pulsed hydrojet

    DOEpatents

    Bohachevsky, I.O.; Torrey, M.D.

    1986-06-10

    An underwater pulsed hydrojet propulsion system is provided for accelerating and propelling a projectile or other vessel. A reactant, such as lithium, is fluidized and injected into a water volume. The resulting reaction produces an energy density in a time effective to form a steam pocket. Thrust flaps or baffles direct the pressure from the steam pocket toward an exit nozzle for accelerating a water volume to create thrust. A control system regulates the dispersion of reactant to control thrust characteristics.

  7. Measurement of EM Field Inside a Cruising Aircraft: Potential Problems for the Use of Mobile Phones on Board

    NASA Astrophysics Data System (ADS)

    Kohmura, A.; Picard, J.; Yonemoto, N.; Yamamoto, K.

    Electromagnetic (EM) emissions from portable electronic devices (PEDs) carried onboard aircraft can interfere with avionic systems. Several onboard systems using EM waves have been planned, such as mobile communications and UWB (ultra-wideband) entertainment services distribution. Manufacturers of this system develop schemes to avoid electromagnetic interference by the transmissions (emissions) of mobile phones with avionic systems; some local-specific problems still remain. The purpose of this chapter is to investigate to what extent non-GSM transmissions from the ground base stations reach inside a cruising aircraft. The EM field at the base station frequency bands is measured in a cruising small aircraft.

  8. Tapered pulse tube for pulse tube refrigerators

    DOEpatents

    Swift, Gregory W.; Olson, Jeffrey R.

    1999-01-01

    Thermal insulation of the pulse tube in a pulse-tube refrigerator is maintained by optimally varying the radius of the pulse tube to suppress convective heat loss from mass flux streaming in the pulse tube. A simple cone with an optimum taper angle will often provide sufficient improvement. Alternatively, the pulse tube radius r as a function of axial position x can be shaped with r(x) such that streaming is optimally suppressed at each x.

  9. ADJUSTABLE DOUBLE PULSE GENERATOR

    DOEpatents

    Gratian, J.W.; Gratian, A.C.

    1961-08-01

    >A modulator pulse source having adjustable pulse width and adjustable pulse spacing is described. The generator consists of a cross coupled multivibrator having adjustable time constant circuitry in each leg, an adjustable differentiating circuit in the output of each leg, a mixing and rectifying circuit for combining the differentiated pulses and generating in its output a resultant sequence of negative pulses, and a final amplifying circuit for inverting and square-topping the pulses. (AEC)

  10. Long pulse production from short pulses

    DOEpatents

    Toeppen, John S.

    1994-01-01

    A method of producing a long output pulse (SA) from a short pump pulse (P), using an elongated amplified fiber (11) having a doped core (12) that provides an amplifying medium for light of one color when driven into an excited state by light of a shorter wavelength and a surrounding cladding 13. A seed beam (S) of the longer wavelength is injected into the core (12) at one end of the fiber (11) and a pump pulse (P) of the shorter wavelength is injected into the cladding (13) at the other end of the fiber (11). The counter-propagating seed beam (S) and pump pulse (P) will produce an amplified output pulse (SA) having a time duration equal to twice the transit time of the pump pulse (P) through the fiber (11) plus the length of the pump pulse (P).

  11. Long pulse production from short pulses

    DOEpatents

    Toeppen, J.S.

    1994-08-02

    A method of producing a long output pulse from a short pump pulse is disclosed, using an elongated amplified fiber having a doped core that provides an amplifying medium for light of one color when driven into an excited state by light of a shorter wavelength and a surrounding cladding. A seed beam of the longer wavelength is injected into the core at one end of the fiber and a pump pulse of the shorter wavelength is injected into the cladding at the other end of the fiber. The counter-propagating seed beam and pump pulse will produce an amplified output pulse having a time duration equal to twice the transit time of the pump pulse through the fiber plus the length of the pump pulse. 3 figs.

  12. Emerging Communication Technologies (ECT) Phase 3 Final Report

    NASA Technical Reports Server (NTRS)

    Bastin, Gary L.; Harris, William G.; Bates, Lakesha D.; Nelson, Richard A.

    2004-01-01

    The Emerging Communication Technology (ECT) project investigated three First Mile communication technologies in support of NASA s Second Generation Reusable Launch Vehicle (2nd Gen RLV), Orbital Space Plane, Advanced Range Technology Working Group (ARTWG) and the Advanced Spaceport Technology Working Group (ASTWG). These First Mile technologies have the purpose of interconnecting mobile users with existing Range Communication infrastructures. ECT was a continuation of the Range Information System Management (RISM) task started in 2002. RISM identified the three advance communication technologies investigated under ECT. These were Wireless Ethernet (Wi-Fi), Free Space Optics (FSO), and Ultra Wideband (UWB). Due to the report s size, it has been broken into three volumes: 1) Main Report 2) Appendices 3) UWB.

  13. Emerging Communication Technologies (ECT) Phase 2 Report. Volume 2; Appendices

    NASA Technical Reports Server (NTRS)

    Bastin, Gary L.; Harris, William G.; Chiodini, Robert; Nelson, Richard A.; Huang, PoTien; Kruhm, David A.

    2003-01-01

    The Emerging Communication Technology (ECT) project investigated three First Mile communication technologies in support of NASA s Second Generation Reusable Launch Vehicle (2nd Gen RLV), Orbital Space Plane, Advanced Range Technology Working Group (ARTWG) and the Advanced Spaceport Technology Working Group (ASTWG). These First Mile technologies have the purpose of interconnecting mobile users with existing Range Communication infrastructures. ECT was a continuation of the Range Information System Management (RISM) task started in 2002. RISM identified the three advance communication technologies investigated under ECT. These were Wireless Ethernet (Wi-Fi), Free Space Optics (FSO), and Ultra Wideband (UWB). Due to the report s size, it has been broken into three volumes: 1) Main Report 2) Appendices 3) UWB

  14. Compressive sampling for time critical microwave imaging applications

    PubMed Central

    O'Halloran, Martin; McGinley, Brian; Conceicao, Raquel C.; Kilmartin, Liam; Jones, Edward; Glavin, Martin

    2014-01-01

    Across all biomedical imaging applications, there is a growing emphasis placed on reducing data acquisition and imaging times. This research explores the use of a technique, known as compressive sampling or compressed sensing (CS), as an efficient technique to minimise the data acquisition time for time critical microwave imaging (MWI) applications. Where a signal exhibits sparsity in the time domain, the proposed CS implementation allows for sub-sampling acquisition in the frequency domain and consequently shorter imaging times, albeit at the expense of a slight degradation in reconstruction quality of the signals as the compression increases. This Letter focuses on ultra wideband (UWB) radar MWI applications where reducing acquisition is of critical importance therefore a slight degradation in reconstruction quality may be acceptable. The analysis demonstrates the effectiveness and suitability of CS with UWB applications. PMID:26609368

  15. Adaptive target detection in foliage-penetrating SAR images using alpha-stable models.

    PubMed

    Banerjee, A; Burlina, P; Chellappa, R

    1999-01-01

    Detecting targets occluded by foliage in foliage-penetrating (FOPEN) ultra-wideband synthetic aperture radar (UWB SAR) images is an important and challenging problem. Given the different nature of target returns in foliage and nonfoliage regions and very low signal-to-clutter ratio in UWB imagery, conventional detection algorithms fail to yield robust target detection results. A new target detection algorithm is proposed that (1) incorporates symmetric alpha-stable (SalphaS) distributions for accurate clutter modeling, (2) constructs a two-dimensional (2-D) site model for deriving local context, and (3) exploits the site model for region-adaptive target detection. Theoretical and empirical evidence is given to support the use of the SalphaS model for image segmentation and constant false alarm rate (CFAR) detection. Results of our algorithm on real FOPEN images collected by the Army Research Laboratory are provided. PMID:18267459

  16. Emerging Communication Technologies (ECT) Phase 2 Report. Volume 1; Main Report

    NASA Technical Reports Server (NTRS)

    Bastin, Gary L.; Harris, William G.; Chiodini, Robert; Nelson, Richard A.; Huang, PoTien; Kruhm, David A.

    2003-01-01

    The Emerging Communication Technology (ECT) project investigated three First Mile communication technologies in support of NASA s Second Generation Reusable Launch Vehicle (2nd Gen RLV), Orbital Space Plane, Advanced Range Technology Working Group (ARTWG) and the Advanced Spaceport Technology Working Group (ASTWG). These First Mile technologies have the purpose of interconnecting mobile users with existing Range Communication infrastructures. ECT was a continuation of the Range Information System Management (RISM) task started in 2002. RISM identified the three advance communication technologies investigated under ECT. These were Wireless Ethernet (Wi-Fi), Free Space Optics (FSO), and Ultra Wideband (UWB). Due to the report s size, it has been broken into three volumes: 1) Main Report 2) Appendices 3) UWB.

  17. Exploring intense attosecond pulses

    NASA Astrophysics Data System (ADS)

    Charalambidis, D.; Tzallas, P.; Benis, E. P.; Skantzakis, E.; Maravelias, G.; Nikolopoulos, L. A. A.; Peralta Conde, A.; Tsakiris, G. D.

    2008-02-01

    After introducing the importance of non-linear processes in the extreme-ultra-violet (XUV) spectral regime to the attosecond (asec) pulse metrology and time domain applications, we present two successfully implemented techniques with excellent prospects in generating intense asec pulse trains and isolated asec pulses, respectively. For the generation of pulse trains two-color harmonic generation is exploited. The interferometric polarization gating technique appropriate for the generation of intense isolated asec pulses is discussed and compared to other relevant approaches.

  18. Multifunctional pulse sequence generator for pulse NMR

    NASA Astrophysics Data System (ADS)

    Wang, Dongsheng

    1988-06-01

    A new multifunctional pulse sequence generator has been designed and constructed. It can conveniently generate various pulse sequences used in nuclear-magnetic resonance (NMR) to measure the spin-lattice relaxation time T1, the spin-spin relaxation time T2, and the spin-locking relaxation time T1 ρ. It can also be used in pulse Fourier transform NMR and double resonance. The intervals of pulses can increase automatically with sequence repetitions and the generator can be used in two-dimensional spectrum measurement and spin-density imaging research. The sequences can be generated through four different triggering methods and there are two synchronous pulse outputs and fifteen auxiliary pulse outputs, so the generator can be conveniently interfaced with a computer or other instruments. The circuitry, functions, and features of the generator are described in this article.

  19. DIFFERENTIAL PULSE HEIGHT DISCRIMINATOR

    DOEpatents

    Test, L.D.

    1958-11-11

    Pulse-height discriminators are described, specifically a differential pulse-height discriminator which is adapted to respond to pulses of a band of amplitudes, but to reject pulses of amplitudes greater or less than tbe preselected band. In general, the discriminator includes a vacuum tube having a plurality of grids adapted to cut off plate current in the tube upon the application of sufficient negative voltage. One grid is held below cutoff, while a positive pulse proportional to the amplltude of each pulse is applled to this grid. Another grid has a negative pulse proportional to the amplitude of each pulse simultaneously applied to it. With this arrangement the tube will only pass pulses which are of sufficlent amplitude to counter the cutoff bias but not of sufficlent amplitude to cutoff the tube.

  20. Laser pulse stacking method

    DOEpatents

    Moses, E.I.

    1992-12-01

    A laser pulse stacking method is disclosed. A problem with the prior art has been the generation of a series of laser beam pulses where the outer and inner regions of the beams are generated so as to form radially non-synchronous pulses. Such pulses thus have a non-uniform cross-sectional area with respect to the outer and inner edges of the pulses. The present invention provides a solution by combining the temporally non-uniform pulses in a stacking effect to thus provide a more uniform temporal synchronism over the beam diameter. 2 figs.

  1. Pulse to pulse klystron diagnosis system

    SciTech Connect

    Nowak, J.; Davidson, V.; Genova, L.; Johnson, R.; Reagan, D.

    1981-03-01

    This report describes a system used to study the behavior of SLAC high powered klystrons operating with a twice normal pulse width of 5 ..mu..s. At present, up to eight of the klystrons installed along the accelerator can be operated with long pulses and monitored by this system. The report will also discuss some of the recent findings and investigations.

  2. Alternate drop pulse polarography

    USGS Publications Warehouse

    Christie, J.H.; Jackson, L.L.; Osteryoung, R.A.

    1976-01-01

    The new technique of alternate drop pulse polarography is presented. An experimental evaluation of alternate drop pulse polarography shows complete compensation of the capacitative background due to drop expansion. The capillary response phenomenon was studied in the absence of faradaic reaction and the capillary response current was found to depend on the pulse width to the -0.72 power. Increased signal-to-noise ratios were obtained using alternate drop pulse polarography at shorter drop times.

  3. Electrical pulse generator

    DOEpatents

    Norris, Neil J.

    1979-01-01

    A technique for generating high-voltage, wide dynamic range, shaped electrical pulses in the nanosecond range. Two transmission lines are coupled together by resistive elements distributed along the length of the lines. The conductance of each coupling resistive element as a function of its position along the line is selected to produce the desired pulse shape in the output line when an easily produced pulse, such as a step function pulse, is applied to the input line.

  4. Optically pulsed electron accelerator

    DOEpatents

    Fraser, John S.; Sheffield, Richard L.

    1987-01-01

    An optically pulsed electron accelerator can be used as an injector for a free electron laser and comprises a pulsed light source, such as a laser, for providing discrete incident light pulses. A photoemissive electron source emits electron bursts having the same duration as the incident light pulses when impinged upon by same. The photoemissive electron source is located on an inside wall of a radio frequency powered accelerator cell which accelerates the electron burst emitted by the photoemissive electron source.

  5. Optically pulsed electron accelerator

    DOEpatents

    Fraser, J.S.; Sheffield, R.L.

    1985-05-20

    An optically pulsed electron accelerator can be used as an injector for a free electron laser and comprises a pulsed light source, such as a laser, for providing discrete incident light pulses. A photoemissive electron source emits electron bursts having the same duration as the incident light pulses when impinged upon by same. The photoemissive electron source is located on an inside wall of a radiofrequency-powered accelerator cell which accelerates the electron burst emitted by the photoemissive electron source.

  6. Constant potential pulse polarography

    USGS Publications Warehouse

    Christie, J.H.; Jackson, L.L.; Osteryoung, R.A.

    1976-01-01

    The new technique of constant potential pulse polarography, In which all pulses are to be the same potential, is presented theoretically and evaluated experimentally. The response obtained is in the form of a faradaic current wave superimposed on a constant capacitative component. Results obtained with a computer-controlled system exhibit a capillary response current similar to that observed In normal pulse polarography. Calibration curves for Pb obtained using a modified commercial pulse polarographic instrument are in good accord with theoretical predictions.

  7. Collapse of optical pulses.

    PubMed

    Silberberg, Y

    1990-11-15

    Under the combined effect of diffraction, anomalous dispersion, and nonlinear refraction, an optical pulse can collapse simultaneously in time and space. Such a collapse could yield short pulses with extremely large optical fields. Light bullets-pulses that propagate without change in space or time-are also possible. The condition for such a collapse and possible experiments are discussed. PMID:19771066

  8. SEMICONDUCTOR INTEGRATED CIRCUITS: A monolithic 3.1-4.8 GHz MB-OFDM UWB transceiver in 0.18-μm CMOS

    NASA Astrophysics Data System (ADS)

    Renliang, Zheng; Xudong, Jiang; Wang, Yao; Guang, Yang; Jiangwei, Yin; Jianqin, Zheng; Junyan, Ren; Wei, Li; Ning, Li

    2010-06-01

    A monolithic RF transceiver for an MB-OFDM UWB system in 3.1-4.8 GHz is presented. The transceiver adopts direct-conversion architecture and integrates all building blocks including a gain controllable wideband LNA, a I/Q merged quadrature mixer, a fifth-order Gm-C bi-quad Chebyshev LPF/VGA, a fast-settling frequency synthesizer with a poly-phase filter, a linear broadband up-conversion quadrature modulator, an active D2S converter and a variable-gain power amplifier. The ESD protected transceiver is fabricated in Jazz Semiconductor's 0.18-μm RF CMOS with an area of 6.1 mm2 and draws a total current of 221 mA from 1.8-V supply. The receiver achieves a maximum voltage gain of 68 dB with a control range of 42 dB in 6 dB/step, noise figures of 5.5-8.8 dB for three sub-bands, and an in-band/out-band IIP3 better than -4 dBm/+9 dBm. The transmitter achieves an output power ranging from -10.7 to -3 dBm with gain control, an output P1dB better than -7.7 dBm, a sideband rejection about 32.4 dBc, and LO suppression of 31.1 dBc. The hopping time among sub-bands is less than 2.05 ns.

  9. A case study on the feasibility and performance of an UWB-AoA real time location system for resources management of civil construction projects

    NASA Astrophysics Data System (ADS)

    Mok, Esmond; Xia, Linyuan; Retscher, Guenther; Tian, Hui

    2010-06-01

    The application of integrated satellite and modern wireless positioning technologies for ubiquitous real-time resources management in large scale civil engineering projects can greatly optimize the time and cost in the construction process, and is now the trend for modern construction project management. As the outdoor conditions of most civil construction sites are open to sky, satellite positioning with the popularly used Global Positioning System (GPS) has been proved to be very efficient and effective. However, the condition in indoor and underground construction site is very complicated due to the fact that different construction activities would be carried out in different congested areas, involving heavy construction plant, equipment, professionals and technical personnel. Nowadays different emerging technologies such as Wi-Fi and ZigBee can be adopted for position and tracking in indoor environments. Nevertheless, under the very complicated construction site conditions these technologies may fail due to movement of human resources and construction plant, variation of metrological conditions, and serious multipath effects of signals. It is considered that Ultra Wide Band (UWB) technology is more suitable for indoor construction site environments. In this paper, a case study on the attempt of integrating GPS with Ubisense Real-time Location System (RTLS) for resources management in an underground railway construction site is discussed. Laboratory and field tests have shown that the RTLS can provide better resources management capability in terms of positioning accuracy and stability than Wi-Fi and ZigBee technologies under complicated construction environments. The test results show that the system can normally achieve better than 15 cm accuracy, and better than 1 m under adverse geometrical site condition. However, the high instrumental set up cost and the requirement for high quality data transmission cable for high precision time synchronization between sensors may deter wide application of similar system for resources management in construction sites.

  10. Stress pulse phenomena

    SciTech Connect

    McGlaun, M.

    1993-08-01

    This paper is an introductory discussion of stress pulse phenomena in simple solids and fluids. Stress pulse phenomena is a very rich and complex field that has been studied by many scientists and engineers. This paper describes the behavior of stress pulses in idealized materials. Inviscid fluids and simple solids are realistic enough to illustrate the basic behavior of stress pulses. Sections 2 through 8 deal with the behavior of pressure pulses. Pressure is best thought of as the average stress at a point. Section 9 deals with shear stresses which are most important in studying solids.

  11. Hybrid chirped pulse amplification system

    DOEpatents

    Barty, Christopher P.; Jovanovic, Igor

    2005-03-29

    A hybrid chirped pulse amplification system wherein a short-pulse oscillator generates an oscillator pulse. The oscillator pulse is stretched to produce a stretched oscillator seed pulse. A pump laser generates a pump laser pulse. The stretched oscillator seed pulse and the pump laser pulse are directed into an optical parametric amplifier producing an optical parametric amplifier output amplified signal pulse and an optical parametric amplifier output unconverted pump pulse. The optical parametric amplifier output amplified signal pulse and the optical parametric amplifier output laser pulse are directed into a laser amplifier producing a laser amplifier output pulse. The laser amplifier output pulse is compressed to produce a recompressed hybrid chirped pulse amplification pulse.

  12. Laser fusion pulse shape controller

    DOEpatents

    Siebert, Larry D.

    1977-01-01

    An apparatus for controlling the pulse shape, i.e., the pulse duration and intensity pattern, of a pulsed laser system, and which is particularly well adapted for controlling the pellet ignition pulse in a laser-driven fusion reaction system. The apparatus comprises a laser generator for providing an optical control pulse of the shape desired, a pulsed laser triggered by the control pulse, and a plurality of optical Kerr-effect gates serially disposed at the output of the pulsed laser and selectively triggered by the control pulse to pass only a portion of the pulsed laser output generally corresponding in shape to the control pulse.

  13. PULSE DURATION LENGTHENER

    DOEpatents

    Aiken, W.R.

    1958-02-01

    This patent pertains to pulse modifying apparatus and, more particularly, describes a device to provide a rise time and time base expander for signal pulses having a very short duration. The basic element of the device is a vacuum tube comprising a charged particie beam, grid control means, an accelerating electrode, a drift tube, and a collector electrode. As the short duration input pulse modulates the particle beam through the grid control means, the voltage between the drift tube and accelerating electrode is caused to vary, whereby the output signal from the collector is a pulse having longer rise time, expanded duration and proportionate characteristics of the original pulse. The invention is particuiarly useful where subsequent pulse circultry does not have the frequency bandwidth to handle the short duration pulse without distorting it.

  14. PULSE AMPLITUDE ANALYZER

    DOEpatents

    Gray, G.W.; Jensen, A.S.

    1957-10-22

    A pulse-height analyzer system of improved design for sorting and counting a series of pulses, such as provided by a scintillation detector in nuclear radiation measurements, is described. The analyzer comprises a main transmission line, a cathode-ray tube for each section of the line with its deflection plates acting as the line capacitance; means to bias the respective cathode ray tubes so that the beam strikes a target only when a prearranged pulse amplitude is applied, with each tube progressively biased to respond to smaller amplitudes; pulse generating and counting means associated with each tube to respond when the beam is deflected; a control transmission line having the same time constant as the first line per section with pulse generating means for each tube for initiating a pulse on the second transmission line when a pulse triggers the tube of corresponding amplitude response, the former pulse acting to prevent successive tubes from responding to the pulse under test. This arrangement permits greater deflection sensitivity in the cathode ray tube and overcomes many of the disadvantages of prior art pulse-height analyzer circuits.

  15. PULSE HEIGHT ANALYZER

    DOEpatents

    Goldsworthy, W.W.

    1958-06-01

    A differential pulse-height discriminator circuit is described which is readily adaptable for operation in a single-channel pulse-height analyzer. The novel aspect of the circuit lies in the specific arrangement of differential pulse-height discriminator which includes two pulse-height discriminators having a comnnon input and an anticoincidence circuit having two interconnected vacuum tubes with a common cathode resistor. Pulses from the output of one discriminator circuit are delayed and coupled to the grid of one of the anticoincidence tubes by a resistor. The output pulses from the other discriminator circuit are coupled through a cathode follower circuit, which has a cathode resistor of such value as to provide a long time constant with the interelectrode capacitance of the tube, to lenthen the output pulses. The pulses are then fed to the grid of the other anticoincidence tube. With such connections of the circuits, only when the incoming pulse has a pesk value between the operating levels of the two discriminators does an output pulse occur from the anticoincidence circuit.

  16. PULSE AMPLITUDE ANALYZER

    DOEpatents

    Greenblatt, M.H.

    1958-03-25

    This patent pertains to pulse amplitude analyzers for sorting and counting a serles of pulses, and specifically discloses an analyzer which ls simple in construction and presents the puise height distribution visually on an oscilloscope screen. According to the invention, the pulses are applied to the vertical deflection plates of an oscilloscope and trigger the horizontal sweep. Each pulse starts at the same point on the screen and has a maximum amplitude substantially along the same vertical line. A mask is placed over the screen except for a slot running along the line where the maximum amplitudes of the pulses appear. After the slot has been scanned by a photocell in combination with a slotted rotating disk, the photocell signal is displayed on an auxiliary oscilloscope as vertical deflection along a horizontal time base to portray the pulse amplitude distribution.

  17. PULSE AMPLITUDE ANALYSERS

    DOEpatents

    Lewis, I.A.D.

    1956-05-15

    This patent pentains to an electrical pulse amplitude analyzer, capable of accepting input pulses having a separation between adjacent pulses in the order of one microsecond while providing a large number of channels of classification. In its broad aspect the described pulse amplitude analyzer utilizes a storage cathode ray tube und control circuitry whereby the amplitude of the analyzed pulses controls both the intensity and vertical defiection of the beam to charge particular spots in horizontal sectors of the tube face as the beam is moved horizontally across the tube face. As soon as the beam has swept the length of the tube the information stored therein is read out by scanning individually each horizontal sector corresponding to a certain range of pulse amplitudes and applying the output signal from each scan to separate indicating means.

  18. PULSED INDICATOR CIRCUIT

    DOEpatents

    Linlor, W.I.; Kerns, Q.A.

    1960-11-15

    A system is given for detecting incremental changes in a transducer impedance terminating a transmission line. Principal novelty resides in the transducer impedance terminating the line in a mismatch and a pulse generator being provided to apply discrete pulses to the input end of the line. The amplitudes of the pulses reflected to the input end of the line from the mismatched transducer impedance are then observed as a very accurate measure of the instantaneous value of the latter.

  19. PulseSoar

    SciTech Connect

    Carter, P.; Peglow, S.

    1992-07-21

    This paper is an introduction to the PulseSoar concept. PulseSoar is a hypervelocity airplane that uses existing airport facilities and current technologies to fly at the very edge of space. It will be shown that PulseSoar can fly between any two points on the globe in less than two hours with fuel efficiency exceeding current state of the art commercial airliners. In addition, it will be shown that PulseSoar avoids environmental issues concerning the ozone layer and sonic booms because of its unique flight profile. All of this can be achieved with current technology. PulseSoar does not require the development of enabling technology. It is a concept which can be demonstrated today. The importance of this idea goes beyond the technical significance`s of PulseSoar in terms of feasibility and performance. PulseSoar could provide a crucial economic advantage to America`s largest export market: commercial aircraft. PulseSoar is a breakthrough concept for addressing the emerging markets of long range and high speed aircraft. Application of PulseSoar to commercial transport could provide the US Aerospace industry a substantial lead in offering high speed/long range aircraft to the world`s airlines. The rapid emergence of a US developed high speed aircraft could also be important to our competitiveness in the Pacific Rim and South American economies. A quick and inexpensive demonstration vehicle is proposed to bang the concept to reality within two years. This discussion will address all the major technical subjects encompassed by PulseSoar and identifies several near-term, and low risk, applications which may be further explored with the initial demonstration vehicle. What is PulseSoar? PulseSoar could enable high speed, high altitude and long range flight without many of the difficulties encountered by traditional hypersonic vehicles.

  20. High voltage pulse conditioning

    DOEpatents

    Springfield, Ray M.; Wheat, Jr., Robert M.

    1990-01-01

    Apparatus for conditioning high voltage pulses from particle accelerators in order to shorten the rise times of the pulses. Flashover switches in the cathode stalk of the transmission line hold off conduction for a determinable period of time, reflecting the early portion of the pulses. Diodes upstream of the switches divert energy into the magnetic and electrostatic storage of the capacitance and inductance inherent to the transmission line until the switches close.

  1. Pulse Tube Refrigerator

    NASA Astrophysics Data System (ADS)

    Matsubara, Yoichi

    The pulse tube refrigerator is one of the regenerative cycle refrigerators such as Stirling cycle or Gifford-McMahon cycle which gives the cooling temperature below 150 K down to liquid helium temperature. In 1963, W. E. Gifford invented a simple refrigeration cycle which is composed of compressor, regenerator and simple tube named as pulse tube which gives a similar function of the expander in Stirling or Gifford-McMahon cycle. The thermodynamically performance of this pulse tube refrigerator is inferior to that of other regenerative cycles. In 1984, however, Mikulin and coworkers made a significant advance in pulse tube configuration called as orifice pulse tube. After this, several modifications of the pulse tube hot end configuration have been developed. With those modifications, the thermodynamic performance of the pulse tube refrigerator became the same order to that of Stirling and Gifford-McMahon refrigerator. This article reviews the brief history of the pulse tube refrigerator development in the view point of its thermodynamically efficiency. Simplified theories of the energy flow in the pulse tube have also been described.

  2. PULSE HEIGHT ANALYZER

    DOEpatents

    Johnstone, C.W.

    1958-01-21

    An anticoincidence device is described for a pair of adjacent channels of a multi-channel pulse height analyzer for preventing the lower channel from generating a count pulse in response to an input pulse when the input pulse has sufficient magnitude to reach the upper level channel. The anticoincidence circuit comprises a window amplifier, upper and lower level discriminators, and a biased-off amplifier. The output of the window amplifier is coupled to the inputs of the discriminators, the output of the upper level discriminator is connected to the resistance end of a series R-C network, the output of the lower level discriminator is coupled to the capacitance end of the R-C network, and the grid of the biased-off amplifier is coupled to the junction of the R-C network. In operation each discriminator produces a negative pulse output when the input pulse traverses its voltage setting. As a result of the connections to the R-C network, a trigger pulse will be sent to the biased-off amplifier when the incoming pulse level is sufficient to trigger only the lower level discriminator.

  3. Pulsed Fission Propulsion Concept

    NASA Technical Reports Server (NTRS)

    1999-01-01

    In the 1960's U.S. Government laboratories, under Project Orion, investigated a pulsed nuclear fission propulsion system. Small nuclear pulse units would be sequentially discharged from the aft end of the vehicle. A blast shield and shock absorber system would protect the crew and convert the shock loads into a continuous propusive force.

  4. Pulsed Fission Propulsion Concept

    NASA Technical Reports Server (NTRS)

    1999-01-01

    In the 1960's U.S. Government laboratories, under Project Orion, investigated a pulsed nuclear fission propulsion system. Small nuclear pulse units would be sequentially discharged from the aft end of the vehicle. A blast shield and shock absorber system would protect the crew and convert the shock loads into a continuous propulsive force.

  5. Pulsed Laser Tissue Interaction

    NASA Astrophysics Data System (ADS)

    Walsh, Joseph T.; van Leeuwen, Ton G.; Jansen, E. Duco; Motamedi, Massoud; Welch, Ashley J.

    Pulsed lasers, by virtue of their ability to deliver energy in a spatially and temporally confined fashion, are able to micromachine biological tissues. The clinical success of pulsed laser treatment, however, is often limited by the extent of damage that is caused to the tissue in the vicinity of the ablation crater. In general, pulsed ablation is a trade off between thermal damage to surrounding tissue, caused by relatively long pulses (>100 ms), and mechanical damage to surrounding tissue, caused by relatively short pulses (<1 ms). To identify the origin of pulsed laser induced damage, the possible laser tissue interactions and ablation are discussed here and in Chapter 14. The purpose of this chapter is to provide the reader with a condensed overview of the parameters that must be considered in the process of pulsed laser ablation of soft tissue. In this chapter, pulsed infrared ablation of biological soft tissue is used as a paradigm to illustrate the concepts and design considerations. Generally speaking, the absorption of laser light may lead to photothermal, photomechanical or photochemical interaction with the irradiated tissue [1-5]. The vast majority of therapeutic laser-tissue interactions is based on photothermal interactions where laser energy is converted into heat. Subsequent to thermalization of the absorbed optical energy, heat transfer mechanisms, in particular conduction allow thermal diffusion from high temperature areas to surrounding regions. When laser penetration depth is less than the laser spot radius, the thermal diffusion time, τ th, can be defined as:

  6. Conducting Pulsed Target

    NASA Astrophysics Data System (ADS)

    Yoshimura, Koji; Yamanoi, Yutaka; Sievers, Peter; Autin, Bruno

    2005-12-01

    Conducting pulsed target scheme has been studied as an alternative targetry solution used for a dedicated high-intense and bright muon source (PRISM). We made a conceptual design and have developed a pulse power supply and a mercury loop to be used for the proof-of-principle test.

  7. PULSE AMPLITUDE DISTRIBUTION RECORDER

    DOEpatents

    Cowper, G.

    1958-08-12

    A device is described for automatica1ly recording pulse annplitude distribution received from a counter. The novelty of the device consists of the over-all arrangement of conventional circuit elements to provide an easy to read permanent record of the pulse amplitude distribution during a certain time period. In the device a pulse analyzer separates the pulses according to annplitude into several channels. A scaler in each channel counts the pulses and operates a pen marker positioned over a drivable recorder sheet. Since the scalers in each channel have the sanne capacity, the control circuitry permits counting of the incoming pulses until one scaler reaches capacity, whereupon the input is removed and an internal oscillator supplies the necessary pulses to fill up the other scalers. Movement of the chart sheet is initiated wben the first scaler reaches capacity to thereby give a series of marks at spacings proportional to the time required to fill the remaining scalers, and accessory equipment marks calibration points on the recorder sheet to facilitate direct reading of the number of external pulses supplied to each scaler.

  8. Extrusion cooking: Legume pulses

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Extrusion is used commercially to produce high value breakfast and snack foods based on cereals such as wheat or corn. However, this processing method is not being commercially used for legume pulses seeds due to the perception that they do not expand well in extrusion. Extrusion cooking of pulses (...

  9. Composite Pulse Tube

    NASA Technical Reports Server (NTRS)

    Martin, Jerry L.; Cloyd, Jason H.

    2007-01-01

    A modification of the design of the pulse tube in a pulse-tube cryocooler reduces axial thermal conductance while preserving radial thermal conductance. It is desirable to minimize axial thermal conductance in the pulse-tube wall to minimize leakage of heat between the warm and cold ends of the pulse tube. At the same time, it is desirable to maximize radial thermal conductance at the cold end of the pulse tube to ensure adequate thermal contact between (1) a heat exchanger in the form of a stack of copper screens inside the pulse tube at the cold end and (2) the remainder of the cold tip, which is the object to which the heat load is applied and from which heat must be removed. The modified design yields a low-heat-leak pulse tube that can be easily integrated with a cold tip. A typical pulse tube of prior design is either a thin-walled metal tube or a metal tube with a nonmetallic lining. It is desirable that the outer surface of a pulse tube be cylindrical (in contradistinction to tapered) to simplify the design of a regenerator that is also part of the cryocooler. Under some conditions, it is desirable to taper the inner surface of the pulse tube to reduce acoustic streaming. The combination of a cylindrical outer surface and a tapered inner surface can lead to unacceptably large axial conduction if the pulse tube is made entirely of metal. Making the pulse-tube wall of a nonmetallic, lowthermal- conductivity material would not solve the problem because the wall would not afford the needed thermal contact for the stack of screens in the cold end. The modified design calls for fabricating the pulse tube in two parts: a longer, nonmetallic part that is tapered on the inside and cylindrical on the outside and a shorter, metallic part that is cylindrical on both the inside and the outside. The nonmetallic part can be made from G-10 fiberglass-reinforced epoxy or other low-thermal-conductivity, cryogenically compatible material. The metallic part must have high thermal conductivity in the cryogenic temperature range and would typically be made of pure copper to satisfy this requirement. The metallic part is bonded to the nonmetallic part with epoxy. Copper screens are inserted in the metallic part to form the cold-end heat exchanger, then the assembled pulse tube is inserted in the cold tip.

  10. Bipolar pulse generator for intense pulsed ion beam accelerator

    SciTech Connect

    Ito, H.; Igawa, K.; Kitamura, I.; Masugata, K.

    2007-01-15

    A new type of pulsed ion beam accelerator named ''bipolar pulse accelerator'' (BPA) has been proposed in order to improve the purity of intense pulsed ion beams. To confirm the principle of the BPA, we developed a bipolar pulse generator for the bipolar pulse experiment, which consists of a Marx generator and a pulse forming line (PFL) with a rail gap switch on its end. In this article, we report the first experimental result of the bipolar pulse and evaluate the electrical characteristics of the bipolar pulse generator. When the bipolar pulse generator was operated at 70% of the full charge condition of the PFL, the bipolar pulse with the first (-138 kV, 72 ns) and the second pulse (+130 kV, 70 ns) was successfully obtained. The evaluation of the electrical characteristics indicates that the developed generator can produce the bipolar pulse with fast rise time and sharp reversing time.

  11. Grid pulse generator

    NASA Astrophysics Data System (ADS)

    Jansweijer, P. P. M.; Vanes, J. T.

    A fast pulse generator was designed for the grid of the injector of the electron accelerator MEA in order to shoot the electrons emitted by the cathode into the bundle pipe where they are accelerated. The generator delivers a high voltage pulse of maximum 6000 V with a rise tile smaller than 50 ns. This results in a slow rate of more than 120,000 V/microsecond. A current of 8 A is required to charge the 60 pF capacity of the grid up to 6000 V is 50 ns. The maximul pulse length is 50 microseconds with a 500 Hz pulse repetition frequency. During these 5 microseconds the pulse amplitude stability is better than 0.1 percent.

  12. Pulsed hall thruster system

    NASA Technical Reports Server (NTRS)

    Hruby, Vladimir J. (Inventor); Pote, Bruce M. (Inventor); Gamero-Castano, Manuel (Inventor)

    2004-01-01

    A pulsed Hall thruster system includes a Hall thruster having an electron source, a magnetic circuit, and a discharge chamber; a power processing unit for firing the Hall thruster to generate a discharge; a propellant storage and delivery system for providing propellant to the discharge chamber and a control unit for defining a pulse duration .tau.<0.1d.sup.3.rho./m, where d is the characteristic size of the thruster, .rho. is the propellant density at standard conditions, and m is the propellant mass flow rate for operating either the power processing unit to provide to the Hall thruster a power pulse of a pre-selected duration, .tau., or operating the propellant storage and delivery system to provide a propellant flow pulse of duration, .tau., or providing both as pulses, synchronized to arrive coincidentally at the discharge chamber to enable the Hall thruster to produce a discreet output impulse.

  13. ELECTRIC PULSE GENERATOR

    DOEpatents

    Buntenbach, R.W.

    1959-06-01

    S>An electro-optical apparatus is described which produces electric pulses in programmed sequences at times and durations controlled with great accuracy. An oscilloscope CRT is supplied with signals to produce a luminous spot moving in a circle. An opaque mask with slots of variable width transmits light from the spot to a photoelectric transducer. For shorter pulse decay times a CRT screen which emits UV can be used with a UVtransmitting filter and a UV- sensitive photoelectric cell. Pulses are varied by changing masks or by using masks with variable slots. This device may be used in multiple arrangements to produce other pulse aT rangements, or it can be used to trigger an electronic pulse generator. (T.R.H.)

  14. Localized wave pulse experiments

    SciTech Connect

    Chambers, D L; Henderson, T L; Krueger, K L; Lewis, D K; Zilkowski, R N

    1999-06-01

    The Localized Wave project of the Strategic System Support Program has recently finished an experiment in cooperation with the Advanced SONAR group of the Applied Research Laboratory of the University of Texas at Austin. The purpose of the experiment was three-fold. They wanted to see if (1) the LW pulse could propagate over significant distances, to see if (2) a new type of array and drive system specifically designed for the pulse would increase efficiency over single frequency tone bursts, and to see if (3) the complexity of our 24 channel drivers resulted in better efficiency than a single equivalent pulse driving a piston. In the experiment, several LW pulses were launched from the Lake Travis facility and propagated over distances of either 100 feet or 600 feet, through a thermocline for the 600 foot measurements. The results show conclusively that the Localized Wave will propagate past the near field distance. The LW pulses resulted in extremely broad frequency band width pulses with narrow spatial beam patterns and unmeasurable side lobes. Their array gain was better than most tone bursts and further, were better than their equivalent piston pulses. This marks the first test of several Low Diffraction beams against their equivalent piston pulses, as well as the first propagation of LW pulses over appreciable distances. The LW pulse is now proven a useful tool in open water, rather than a laboratory curiosity. The experimental system and array were built by ARL, and the experiments were conducted by ARL staff on their standard test range. The 600 feet measurements were made at the farthest extent of that range.

  15. Attosecond pulse characterization.

    PubMed

    Laurent, G; Cao, W; Ben-Itzhak, I; Cocke, C L

    2013-07-15

    In this work we propose a novel procedure for the characterization of attosecond pulses. The method relies on the conversion of the attosecond pulse into electron wave-packets through photoionization of atoms in the presence of a weak IR field. It allows for the unique determination of the spectral phase making up the pulses by accurately taking into account the atomic physics of the photoionization process. The phases are evaluated by optimizing the fit of a perturbation theory calculation to the experimental result. The method has been called iPROOF (improved Phase Retrieval by Omega Oscillation Filtering) as it bears a similarity to the PROOF technique [Chini et al. Opt. Express 18, 13006 (2010)]. The procedure has been demonstrated for the characterization of an attosecond pulse train composed of odd and even harmonics. We observe a large phase shift between consecutive odd and even harmonics. The resulting attosecond pulse train has a complex structure not resembling a single attosecond pulse once per IR period, which is the case for zero phase. Finally, the retrieval procedure can be applied to the characterization of single attosecond pulses as well. PMID:23938540

  16. SHORT PULSE STRETCHER

    DOEpatents

    Branum, D.R.; Cummins, W.F.

    1962-12-01

    >A short pulse stretching circuit capable of stretching a short puise to enable it to be displayed on a relatively slow sweeping oscilloscope is described. Moreover, the duration of the pulse is increased by charging a capacitor through a diode and thereafter discharging the capacitor at such time as is desired. In the circuit the trigger pulse alone passes through a delay line, whereas the main signal passes through the diode only, and results in over-all circuit losses which are proportional to the low losses of the diode only. (AEC)

  17. Whispering Gallery Pulse Compressor

    SciTech Connect

    Hirshfield, J.; Kuzikov, S.V.; Petelin, M.I.; Pavelyev, V.G.

    2004-12-07

    A barrel-like cavity resonant at a whispering gallery mode is known as capable to provide a SLED-like rf pulse compression. To enhance the power handling capacity of the compressor, we propose to use a coupler based on a wave tunneling through a continuous slot. A modeling low power 11.4 GHz experiment proved to be consistent with theory. A preliminary technical design for an evacuated high-power compressor has also been developed. According to a theory, a twin-cavity version of the device can efficiently compress microwave pulses produced with sources of limited bandwidth, in particular frequency-chirped pulses.

  18. Investigations into sub-ns pulse generation using ferrite-loaded coaxial lines

    NASA Astrophysics Data System (ADS)

    Bolton, H. R.; Dolan, J. E.; Shapland, A. J.; Parkes, D. M.; Trafford, K.; Kerr, B.

    1995-03-01

    Systems such as Pockels Cell drivers and UWB radar require electrical pulses of less than 200 ps rise-time and amplitude of 10 kV or greater into 50 ohms. Desired p.r.f.'s may be 50 kHz or higher in burst mode. The output rise-time of high power and p.r.f. capable pulsers is generally of the order 2-20 ns, and ferrite-loaded coaxial lines are one means of reducing the leading edge 10-90% rise-time to the order of 100-200 ps. The development of the fast-rising leading edge in ferrite lines is due to the non-linearity of the magnetic medium, and the consequent formation of an 'electromagnetic shock front' at the pulse leading edge. Over the past decade, the use of magnets to bias the ferrite has been found to improve output rise-time and amplitude characteristics considerably. Steady-state analyses made by Soviet analysts in the 1960's do not explain the magnet-biased ferrite line characteristics, and a numerical approach will be presented which shows how the microwave characteristics of the ferrite may be combined with the TEM transmission line equations to model electromagnetic shock wave propagation in such ferrite-loaded lines. It now appears reasonably clear that ferrite lines may be effectively modelled and designed in terms of parameters including the ferrite saturation magnetisation, and the dimensions of the line and the ferrite beads. Second order effects such as conductor and dielectric losses may also be taken into account if required.

  19. Pulsed-neutron monochromator

    DOEpatents

    Mook, H.A. Jr.

    1984-01-01

    In one aspect, the invention is an improved pulsed-neutron monochromator of the vibrated-crystal type. The monochromator is designed to provide neutron pulses which are characterized both by short duration and high density. A row of neutron-reflecting crystals is disposed in a neutron beam to reflect neutrons onto a common target. The crystals in the row define progressively larger neutron-scattering angles and are vibrated sequentially in descending order with respect to the size of their scattering angles, thus generating neutron pulses which arrive simultaneously at the target. Transducers are coupled to one end of the crystals to vibrate them in an essentially non-resonant mode. The transducers propagate transverse waves in the crystal which progress longitudinally therein. The waves are absorbed at the undriven ends of the crystals by damping material mounted thereon. In another aspect, the invention is a method for generating neutron pulses characterized by high intensity and short duration.

  20. Pulsed-neutron monochromator

    DOEpatents

    Mook, Jr., Herbert A.

    1985-01-01

    In one aspect, the invention is an improved pulsed-neutron monochromator of the vibrated-crystal type. The monochromator is designed to provide neutron pulses which are characterized both by short duration and high density. A row of neutron-reflecting crystals is disposed in a neutron beam to reflect neutrons onto a common target. The crystals in the row define progressively larger neutron-scattering angles and are vibrated sequentially in descending order with respect to the size of their scattering angles, thus generating neutron pulses which arrive simultaneously at the target. Transducers are coupled to one end of the crystals to vibrate them in an essentially non-resonant mode. The transducers propagate transverse waves in the crystal which progress longitudinally therein. The wave are absorbed at the undriven ends of the crystals by damping material mounted thereon. In another aspect, the invention is a method for generating neutron pulses characterized by high intensity and short duration.

  1. HIGH POWER PULSED OSCILLATOR

    DOEpatents

    Singer, S.; Neher, L.K.

    1957-09-24

    A high powered, radio frequency pulse oscillator is described for generating trains of oscillations at the instant an input direct voltage is impressed, or immediately upon application of a light pulse. In one embodiment, the pulse oscillator comprises a photo-multiplier tube with the cathode connected to the first dynode by means of a resistor, and adjacent dynodes are connected to each other through adjustable resistors. The ohmage of the resistors progressively increases from a very low value for resistors adjacent the cathode to a high value adjacent the plate, the last dynode. Oscillation occurs with this circuit when a high negative voltage pulse is applied to the cathode and the photo cathode is bombarded. Another embodiment adds capacitors at the resistor connection points of the above circuit to increase the duration of the oscillator train.

  2. Pulsed mode cathode

    NASA Astrophysics Data System (ADS)

    Myers, Roger M.; Rawlin, Vinvent K.

    1994-10-01

    A cathode in an MPD thruster has an internal heater and utilizes low work function material. The cathode is preheated to operating temperature, and then the thruster is fired by discharging a capacitor bank in a pulse forming network.

  3. Pulsed mode cathode

    NASA Technical Reports Server (NTRS)

    Myers, Roger M. (Inventor); Rawlin, Vinvent K. (Inventor)

    1994-01-01

    A cathode in an MPD thruster has an internal heater and utilizes low work function material. The cathode is preheated to operating temperature, and then the thruster is fired by discharging a capacitor bank in a pulse forming network.

  4. Pulse magnetic welder

    DOEpatents

    Christiansen, D.W.; Brown, W.F.

    1984-01-01

    A welder is described for automated closure of fuel pins by a pulsed magnetic process in which the open end of a length of cladding is positioned within a complementary tube surrounded by a pulsed magnetic welder. Seals are provided at each end of the tube, which can be evacuated or can receive tag gas for direct introduction to the cladding interior. Loading of magnetic rings and end caps is accomplished automatically in conjunction with the welding steps carried out within the tube.

  5. Pulsed spallation neutron sources

    SciTech Connect

    Carpenter, J.M.

    1996-05-01

    This paper reviews the early history of pulsed spallation neutron source development ar Argonne and provides an overview of existing sources world wide. A number of proposals for machines more powerful than currently exist are under development, which are briefly described. The author reviews the status of the Intense Pulsed Neutron Source, its instrumentation, and its user program, and provide a few examples of applications in fundamental condensed matter physics, materials science and technology.

  6. Pulse measurement apparatus and method

    DOEpatents

    Marciante, John R. (Webster, NY); Donaldson, William R. (Pittsford, NY); Roides, Richard G. (Scottsville, NY)

    2011-10-25

    An embodiment of the invention is directed to a pulse measuring system that measures a characteristic of an input pulse under test, particularly the pulse shape of a single-shot, nano-second duration, high shape-contrast optical or electrical pulse. An exemplary system includes a multi-stage, passive pulse replicator, wherein each successive stage introduces a fixed time delay to the input pulse under test, a repetitively-gated electronic sampling apparatus that acquires the pulse train including an entire waveform of each replica pulse, a processor that temporally aligns the replicated pulses, and an averager that temporally averages the replicated pulses to generate the pulse shape of the pulse under test. An embodiment of the invention is directed to a method for measuring an optical or an electrical pulse shape. The method includes the steps of passively replicating the pulse under test with a known time delay, temporally stacking the pulses, and temporally averaging the stacked pulses. An embodiment of the invention is directed to a method for increasing the dynamic range of a pulse measurement by a repetitively-gated electronic sampling device having a rated dynamic range capability, beyond the rated dynamic range of the sampling device; e.g., enhancing the dynamic range of an oscilloscope. The embodied technique can improve the SNR from about 300:1 to 1000:1. A dynamic range enhancement of four to seven bits may be achieved.

  7. Fetal pulse oximetry.

    PubMed

    Luttkus, A K; Dudenhausen, J W

    1998-12-01

    Within the last ten years several groups adapted pulse oximetry to be used in the fetus. The obvious advantage of this technology is the fact that a biochemical parameter--the arterial oxygen saturation--can be measured continuously during delivery. Nevertheless, the continuous information about the fetal oxygenation during delivery has a couple of obstacles to surmount. It is well known that fetal reflectance pulse oximetry may be influenced by a number of artifacts. In addition, severe physiological considerations should remind us of the limited diagnostic value of saturation monitoring alone in order to predict fetal acidosis. Some recent articles deal with the predictive value of fetal pulse oximetry for fetal compromise. While it appears that the fetal wellbeing is more likely to be in accordance with a normal saturation measured by current pulse oximetry systems, the number of fetuses detected by pulse oximetry suffering from hypoxia seems to be low. Different authors describe a poor sensitivity to predict fetal compromise. One reason therefore may be the reduced precision of the oxysensor in the low saturation range. Therefore, we conclude that the current generation of fetal pulse oximetry sensors is not improving the quality of combined fetal monitoring of fetal heart rate and fetal scalp blood analysis. PMID:9866017

  8. SAR reduced pulse sequences

    SciTech Connect

    Prost, J.E.; Wehrli, F.W.; Drayer, B.; Froelich, J.; Hearshen, D.; Plewes, D.

    1988-03-01

    Three techniques were considered for reducing the RF (radiofrequency) power deposition in the body while maintaining scan time efficiency: reducing the RF peak amplitude while increasing the pulse width, substituting gradient echoes for spin echoes, and reducing the flip angle of the phase reversal pulse. The use of gradient echoes was found to be the most efficient means to reduce the power delivered to the patient and to obtain rapid data acquisition. The effect upon SAR (specific absorption rate) and SNR (signal-to-noise ratio) was demonstrated on a phantom when the phase reversal pulse was reduced from the standard 180 degrees to 90 degrees. Data in the body indicated a fairly constant SNR down to a refocusing flip angle between 110 degrees and 135 degrees. An initial clinical evaluation was performed at three institutions using the method of reducing the flip angle of the phase reversal pulse. The scan with theta = 120 degrees was rated by readers in a blinded study as having acceptable diagnostic image quality while the 135 degrees scan had comparable image quality to a conventional 90 degrees - 180 degrees pulse sequence. The use of reduced phase reversal pulses was seen as an efficient protocol to obtain T1-weighted images at rapid data rates while reducing the power delivered to the body by about 40%.

  9. Optimal chirped probe pulse length for terahertz pulse measurement.

    PubMed

    Peng, Xiao-Yu; Willi, Oswald; Chen, Min; Pukhov, Alexander

    2008-08-01

    A detailed analysis of the relationship between the duration of the chirped probe pulse and the bipolar terahertz (THz) pulse length in the spectral encoding technique is carried out. We prove that there is an optimal chirped probe pulse length (or an optimal chirp rate of the chirped probe pulse) matched to the input THz pulse length and derive a rigorous relationship between them. We find that only under this restricted condition the THz signal can be correctly retrieved. PMID:18679511

  10. Single attosecond pulse generation from multicycle nonlinear chirped pulses

    SciTech Connect

    Niu Yueping; Qi Yihong; Gong Shangqing; Xiang Yang

    2009-12-15

    We present a method of producing single attosecond pulses by high-order harmonic generation with multicycle nonlinear chirped driver laser pulses. The symmetry of the laser field in several optical cycles near the pulse center is broken, and then the photons near the cutoff burst only in half optical cycle. By selecting out the harmonics near the cutoff, an isolated attosecond pulse could be obtained. The results are almost independent of the length and chirp form of the driver laser pulse.

  11. Giant Pulses - A Brief Review

    NASA Astrophysics Data System (ADS)

    Johnston, S.; Romani, R. W.

    We briefly review observational manifestations of pulsars with giant pulse emission and consider quasi-giant pulse phenomena in other pulsars. We argue that power-law statistics give the best definition of giant pulses. Finally, we speculate as to the origin of the giant pulses and a possible link with high energy emission.

  12. Pulse shaping with transmission lines

    DOEpatents

    Wilcox, R.B.

    1985-08-15

    A method and apparatus for forming shaped voltage pulses uses passive reflection from a transmission line with nonuniform impedance. The impedance of the reflecting line varies with length in accordance with the desired pulse shape. A high voltage input pulse is transmitted to the reflecting line. A reflected pulse is produced having the desired shape and is transmitted by pulse removal means to a load. Light activated photoconductive switches made of silicon can be utilized. The pulse shaper can be used to drive a Pockels cell to produce shaped optical pulses.

  13. Pulse shaping with transmission lines

    DOEpatents

    Wilcox, Russell B.

    1987-01-01

    A method and apparatus for forming shaped voltage pulses uses passive reflection from a transmission line with nonuniform impedance. The impedance of the reflecting line varies with length in accordance with the desired pulse shape. A high voltage input pulse is transmitted to the reflecting line. A reflected pulse is produced having the desired shape and is transmitted by pulse removal means to a load. Light activated photoconductive switches made of silicon can be utilized. The pulse shaper can be used to drive a Pockels cell to produce shaped optical pulses.

  14. High voltage pulse generator

    DOEpatents

    Fasching, George E.

    1977-03-08

    An improved high-voltage pulse generator has been provided which is especially useful in ultrasonic testing of rock core samples. An N number of capacitors are charged in parallel to V volts and at the proper instance are coupled in series to produce a high-voltage pulse of N times V volts. Rapid switching of the capacitors from the paralleled charging configuration to the series discharging configuration is accomplished by using silicon-controlled rectifiers which are chain self-triggered following the initial triggering of a first one of the rectifiers connected between the first and second of the plurality of charging capacitors. A timing and triggering circuit is provided to properly synchronize triggering pulses to the first SCR at a time when the charging voltage is not being applied to the parallel-connected charging capacitors. Alternate circuits are provided for controlling the application of the charging voltage from a charging circuit to be applied to the parallel capacitors which provides a selection of at least two different intervals in which the charging voltage is turned "off" to allow the SCR's connecting the capacitors in series to turn "off" before recharging begins. The high-voltage pulse-generating circuit including the N capacitors and corresponding SCR's which connect the capacitors in series when triggered "on" further includes diodes and series-connected inductors between the parallel-connected charging capacitors which allow sufficiently fast charging of the capacitors for a high pulse repetition rate and yet allow considerable control of the decay time of the high-voltage pulses from the pulse-generating circuit.

  15. Efficient optical pulse stacker system

    DOEpatents

    Seppala, Lynn G.; Haas, Roger A.

    1982-01-01

    Method and apparatus for spreading and angle-encoding each pulse of a multiplicity of small area, short pulses into several temporally staggered pulses by use of appropriate beam splitters, with the optical elements being arranged so that each staggered pulse is contiguous with one or two other such pulses, and the entire sequence of stacked pulses comprising a single, continuous long pulse. The single long pulse is expanded in area, and then doubly passed through a nonstorage laser amplifier such as KrF. After amplification, the physically separated, angle-encoded and temporally staggered pulses are recombined into a single pulse of short duration. This high intensity output beam is well collimated and may be propagated over long distance, or used for irradiating inertial confinement fusion targets.

  16. Photoconductive circuit element pulse generator

    DOEpatents

    Rauscher, Christen (Alexandria, VA)

    1989-01-01

    A pulse generator for characterizing semiconductor devices at millimeter wavelength frequencies where a photoconductive circuit element (PCE) is biased by a direct current voltage source and produces short electrical pulses when excited into conductance by short laser light pulses. The electrical pulses are electronically conditioned to improve the frequency related amplitude characteristics of the pulses which thereafter propagate along a transmission line to a device under test.

  17. HydroPulse Drilling

    SciTech Connect

    J.J. Kolle

    2004-04-01

    Tempress HydroPulse{trademark} tool increases overbalanced drilling rates by generating intense suction pulses at the drill bit. This report describes the operation of the tool; results of pressure drilling tests, wear tests and downhole drilling tests; and the business case for field applications. The HydroPulse{trademark} tool is designed to operate on weighted drilling mud at conventional flow rates and pressures. Pressure drilling tests confirm that the HydroPulse{trademark} tool provides 33% to 200% increased rate of penetration. Field tests demonstrated conventional rotary and mud motor drilling operations. The tool has been operated continuous for 50 hours on weighted mud in a wear test stand. This level of reliability is the threshold for commercial application. A seismic-while-drilling version of the tool was also developed and tested. This tool was used to demonstrate reverse vertical seismic profiling while drilling an inclined test well with a PDC bit. The primary applications for the HydroPulse{trademark} tool are deep onshore and offshore drilling where rate of penetration drives costs. The application of the seismic tool is vertical seismic profiling-while-drilling and look-ahead seismic imaging while drilling.

  18. Pulse power linac

    DOEpatents

    Villa, Francesco

    1990-01-01

    A linear acceleration for charged particles is constructed of a plurality of transmission line sections that extend between a power injection region and an accelerating region. Each line section is constructed of spaced plate-like conductors and is coupled to an accelerating gap located at the accelerating region. Each gap is formed between a pair of apertured electrodes, with all of the electrode apertures being aligned along a particle accelerating path. The accelerating gaps are arranged in series, and at the injection region the line sections are connected in parallel. At the injection region a power pulse is applied simultaneously to all line sections. The line sections are graduated in length so that the pulse reaches the gaps in a coordinated sequence whereby pulse energy is applied to particles as they reach each of the gaps along the accelerating path.

  19. Pulsed neutron detector

    DOEpatents

    Robertson, deceased, J. Craig; Rowland, Mark S.

    1989-03-21

    A pulsed neutron detector and system for detecting low intensity fast neutron pulses has a body of beryllium adjacent a body of hydrogenous material the latter of which acts as a beta particle detector, scintillator, and moderator. The fast neutrons (defined as having En>1.5 MeV) react in the beryllium and the hydrogenous material to produce larger numbers of slow neutrons than would be generated in the beryllium itself and which in the beryllium generate hellium-6 which decays and yields beta particles. The beta particles reach the hydrogenous material which scintillates to yield light of intensity related to the number of fast neutrons. A photomultiplier adjacent the hydrogenous material (scintillator) senses the light emission from the scintillator. Utilization means, such as a summing device, sums the pulses from the photo-multiplier for monitoring or other purposes.

  20. Pulse shaping system

    DOEpatents

    Skeldon, M.D.; Letzring, S.A.

    1999-03-23

    Temporally shaped electrical waveform generation provides electrical waveforms suitable for driving an electro-optic modulator (EOM) which produces temporally shaped optical laser pulses for inertial confinement fusion (ICF) research. The temporally shaped electrical waveform generation is carried out with aperture coupled transmission lines having an input transmission line and an aperture coupled output transmission line, along which input and output pulses propagate in opposite directions. The output electrical waveforms are shaped principally due to the selection of coupling aperture width, in a direction transverse to the lines, which varies along the length of the line. Specific electrical waveforms, which may be high voltage (up to kilovolt range), are produced and applied to the EOM to produce specifically shaped optical laser pulses. 8 figs.

  1. Laser pulse sampler

    DOEpatents

    Vann, Charles (Fremont, CA)

    1998-01-01

    The Laser Pulse Sampler (LPS) measures temporal pulse shape without the problems of a streak camera. Unlike the streak camera, the laser pulse directly illuminates a camera in the LPS, i.e., no additional equipment or energy conversions are required. The LPS has several advantages over streak cameras. The dynamic range of the LPS is limited only by the range of its camera, which for a cooled camera can be as high as 16 bits, i.e., 65,536. The LPS costs less because there are fewer components, and those components can be mass produced. The LPS is easier to calibrate and maintain because there is only one energy conversion, i.e., photons to electrons, in the camera.

  2. Laser pulse sampler

    DOEpatents

    Vann, C.

    1998-03-24

    The Laser Pulse Sampler (LPS) measures temporal pulse shape without the problems of a streak camera. Unlike the streak camera, the laser pulse directly illuminates a camera in the LPS, i.e., no additional equipment or energy conversions are required. The LPS has several advantages over streak cameras. The dynamic range of the LPS is limited only by the range of its camera, which for a cooled camera can be as high as 16 bits, i.e., 65,536. The LPS costs less because there are fewer components, and those components can be mass produced. The LPS is easier to calibrate and maintain because there is only one energy conversion, i.e., photons to electrons, in the camera. 5 figs.

  3. Pulse shaping system

    DOEpatents

    Skeldon, Mark D.; Letzring, Samuel A.

    1999-03-23

    Temporally shaped electrical waveform generation provides electrical waveforms suitable for driving an electro-optic modulator (EOM) which produces temporally shaped optical laser pulses for inertial confinement fusion (ICF) research. The temporally shaped electrical waveform generation is carried out with aperture coupled transmission lines having an input transmission line and an aperture coupled output transmission line, along which input and output pulses propagate in opposite directions. The output electrical waveforms are shaped principally due to the selection of coupling aperture width, in a direction transverse to the lines, which varies along the length of the line. Specific electrical waveforms, which may be high voltage (up to kilovolt range), are produced and applied to the EOM to produce specifically shaped optical laser pulses.

  4. Pulsed welding plasma source

    NASA Astrophysics Data System (ADS)

    Knyaz'kov, A.; Pustovykh, O.; Verevkin, A.; Terekhin, V.; Shachek, A.; Tyasto, A.

    2016-04-01

    It is shown that in order to form the current pulse of a near rectangular shape, which provides conversion of the welding arc into a dynamic mode, it is rational to connect a forming element made on the basis of an artificial forming line in series to the welding DC circuit. The paper presents a diagram of a pulsed device for welding with a non-consumable electrode in argon which was developed using the forming element. The conversion of the arc into the dynamic mode is illustrated by the current and voltage oscillograms of the arc gap and the dynamic characteristic of the arc within the interval of one pulse generation time in the arc gap. The background current travels in the interpulse interval.

  5. Pulsed Artificial Electrojet Generation

    NASA Astrophysics Data System (ADS)

    Papadopoulos, K.

    2008-12-01

    Traditional techniques for generating low frequency signals in the ULF/ELF range (.1-100 Hz) and rely on ground based Horizontal Electric Dipole (HED) antennas. It is, furthermore, well known that a Vertical Electric Dipole (VED) is by more than 50 dB more efficient than a HED with the same dipole current moment. However, the prohibitively long length of VED antennas in the ELF/ULF range coupled with voltage limitations due to corona discharge in the atmosphere make them totally impracticable. In this paper we discuss a novel concept, inspired by the physics of the equatorial electrojet, that allows for the conversion of a ground based HED to a VED in the E-region of the equatorial ionosphere with current moment comparable to the driving HED. The paper focuses in locations near the dip-equator, where the earth's magnetic is in predominantly in the horizontal direction. The horizontal electric field associated with a pulsed HED drives a large Hall current in the ionospheric E-region, resulting in a vertical current. It is shown that the pulsed vertical current in the altitude range 80-130 km, driven by a horizontal electric field of, approximately, .1 mV/m at 100 km altitude, is of the order of kA. This results in a pulsed VED larger than 106 A-m. Such a pulsed VED will drive ELF/ULF pulses with amplitude in excess of .1 nT at a lateral range larger than few hundred kilometers. This is by three orders of magnitude larger than the one expected by a HED with comparable current moment. The paper will conclude with the description of a sneak-through technique that allows for creating pulsed electric fields in the ionosphere much larger than expected from steady state oscillatory HED antennas.

  6. Pulsed NMR spectroscopy

    NASA Technical Reports Server (NTRS)

    Burum, D. P.; Elleman, D. D.; Rhim, W.

    1978-01-01

    Method gives results approximating those of classical continuous-irradiation method but in less time. Method also makes it possible to measure chemical shifts and spin-lattice relaxation times with improved sensitivity. Equipment can be used for adiabatic demagnetization experiments, measurements of rotating-frame spin/lattice relaxation times, and accurate measurements of exact resonance points. When measuring relaxation times, pulse technique can be very effective since pulses may be limited in amplitude and length to prevent spin system from being driven into saturation.

  7. SNMR pulse sequence phase cycling

    DOEpatents

    Walsh, David O; Grunewald, Elliot D

    2013-11-12

    Technologies applicable to SNMR pulse sequence phase cycling are disclosed, including SNMR acquisition apparatus and methods, SNMR processing apparatus and methods, and combinations thereof. SNMR acquisition may include transmitting two or more SNMR pulse sequences and applying a phase shift to a pulse in at least one of the pulse sequences, according to any of a variety cycling techniques. SNMR processing may include combining SNMR from a plurality of pulse sequences comprising pulses of different phases, so that desired signals are preserved and indesired signals are canceled.

  8. Pulsed inductive HF laser

    NASA Astrophysics Data System (ADS)

    Razhev, A. M.; Churkin, D. S.; Kargapol'tsev, E. S.; Demchuk, S. V.

    2016-03-01

    We report the results of experimentally investigated dependences of temporal, spectral and spatial characteristics of an inductive HF-laser generation on the pump conditions. Gas mixtures H2 – F2(NF3 or SF66) and He(Ne) – H2 – F2(NF3 or SF6) were used as active media. The FWHM pulse duration reached 0.42 μs. This value corresponded to a pulsed power of 45 kW. For the first time, the emission spectrum of an inductive HF laser was investigated, which consisted of seven groups of bands with centres around the wavelengths of 2732, 2736, 2739, 2835, 2837, 2893 and 2913 nm. The cross section profile of the laser beam was a ring with a diameter of about 20 mm and width of about 5 mm. Parameters of laser operation in the repetitively pulsed regime were sufficiently stable. The amplitude instability of light pulses was no greater than 5% – 6%.

  9. Lectures on pulsed NMR

    SciTech Connect

    Pines, A.

    1986-09-01

    These lectures discuss some recent developments in pulsed NMR, emphasizing fundamental principles with selected illustrative applications. Major topics covered include multiple-quantum spectroscopy, spin decoupling, the interaction of spins with a quantized field, adiabatic rapid passage, spin temperature and statistics of cross-polarization, coherent averaging, and zero field NMR. 55 figs.

  10. Lectures on pulsed NMR

    SciTech Connect

    Pines, A.

    1988-08-01

    These lectures discuss some recent developments in pulsed NMR, emphasizing fundamental principles with selected illustrative applications. Major topics covered include multiple-quantum spectroscopy, spin decoupling, the interaction of spins with a quantized field, adiabatic rapid passage, spin temperature and statistics of cross-polarization, coherent averaging, and zero field NMR. 32 refs., 56 figs.

  11. Experiments in Pulsed Ultrasonics

    ERIC Educational Resources Information Center

    Palmer, S. B.; Forster, G. A.

    1970-01-01

    Describes and apparatus designed to generate and detect pulsed ultrasonics in solids and liquids over the frequency range 1-20 MHz. Experiments are suggested for velocity of sound, elastic constant and ultrasonic attenuation measurements on various materials over a wide temperature range. The equipment should be useful for demonstration purposes.…

  12. Pulsed electric fields

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The concept of pulsed electric fields (PEF) was first proposed in 1967 to change the behavior or microorganisms. The electric field phenomenon was identified as membrane rupture theory in the 1980s. Increasing the membrane permeability led to the application of PEF assisted extraction of cellular co...

  13. A comparative study of algorithms for radar imaging from gapped data

    NASA Astrophysics Data System (ADS)

    Xu, Xiaojian; Luan, Ruixue; Jia, Li; Huang, Ying

    2007-09-01

    In ultra wideband (UWB) radar imagery, there are often cases where the radar's operating bandwidth is interrupted due to various reasons, either periodically or randomly. Such interruption produces phase history data gaps, which in turn result in artifacts in the image if conventional image reconstruction techniques are used. The higher level artifacts severely degrade the radar images. In this work, several novel techniques for artifacts suppression in gapped data imaging were discussed. These include: (1) A maximum entropy based gap filling technique using a modified Burg algorithm (MEBGFT); (2) An alternative iteration deconvolution based on minimum entropy (AIDME) and its modified version, a hybrid max-min entropy procedure; (3) A windowed coherent CLEAN algorithm; and (4) Two-dimensional (2-D) periodically-gapped Capon (PG-Capon) and APES (PG-APES) algorithms. Performance of various techniques is comparatively studied.

  14. A Smile Face Monopole Antenna with Quadruple Band-Notched Characteristics

    NASA Astrophysics Data System (ADS)

    Yang, Xiao-Lin; Kong, Fang-Ling; Wang, Yan

    2015-05-01

    A compact planar ultra-wideband (UWB) monopole antenna with quadruple band-notched characteristics is presented. The notched band at 3.3-4.2 GHz (C-band) is obtained by embedding a pair of Z-shaped slots on the elliptical radiation patch. Meanwhile, a modified U-shaped slot is etched in the radiation patch to create the notched band at 4.9-5.4 GHz for WLAN. In addition, by introducing E-shaped stubs on the back layer, the notched bands at 5.5-6.1 GHz for WLAN and 7-8.15 GHz for downlink of X-band satellite communication system are obtained. The antenna is fabricated and measured, showing broadband matched impedance and good Omni-directional patterns with high fidelity and phase linearity (outside the notched bands).

  15. Echo simulation of lunar penetrating radar: based on a model of inhomogeneous multilayer lunar regolith structure

    NASA Astrophysics Data System (ADS)

    Dai, Shun; Su, Yan; Xiao, Yuan; Feng, Jian-Qing; Xing, Shu-Guo; Ding, Chun-Yu

    2014-12-01

    Lunar Penetrating Radar (LPR) based on the time domain Ultra-Wideband (UWB) technique onboard China's Chang'e-3 (CE-3) rover, has the goal of investigating the lunar subsurface structure and detecting the depth of lunar regolith. An inhomogeneous multi-layer microwave transfer inverse-model is established. The dielectric constant of the lunar regolith, the velocity of propagation, the reflection, refraction and transmission at interfaces, and the resolution are discussed. The model is further used to numerically simulate and analyze temporal variations in the echo obtained from the LPR attached on CE-3's rover, to reveal the location and structure of lunar regolith. The thickness of the lunar regolith is calculated by a comparison between the simulated radar B-scan images based on the model and the detected result taken from the CE-3 lunar mission. The potential scientific return from LPR echoes taken from the landing region is also discussed.

  16. Measurement and evaluation of radar cross section for furniture in an indoor propagation channel

    NASA Astrophysics Data System (ADS)

    Maw, M. M.; Supanakoon, P.; Promwong, S.; Takada, J.

    2014-11-01

    This paper has attempted to evaluate the radar cross section (RCS) of two furniture items in an indoor environment in a frequency range of 3-7 GHz of the ultra-wideband (UWB) range. The RCS evaluation is achieved through an extended version of the radar equation that incorporates the channel transfer function of scattering. The time-gating method was applied to remove the multipath effect, a phenomenon which typically occurs in the indoor environment. Two double-ridged waveguide horn antennas for both vertical and horizontal polarizations were used to obtain the transfer function of scattering of the furniture prior to analysis in order to derive their bistatic RCS. The RCS results validate the applicability of the proposed extended radar equation to the indoor propagation prediction.

  17. All about Heart Rate (Pulse)

    MedlinePlus

    ... Pressure High Blood Pressure Tools & Resources Stroke More All About Heart Rate (Pulse) Updated:Apr 19,2016 ... are the Symptoms of High Blood Pressure? 4 All About Heart Rate (Pulse) 5 How to Eat ...

  18. Two-Pulse Stitch Welding

    NASA Technical Reports Server (NTRS)

    Torborg, C. J.

    1985-01-01

    Second welding pulse at about 20 percent higher energy repairs bad single-pulse welds. Method used successfully to weld polytetrafluoroethyleneinsulated nickel wire to stainless-steel terminals in back-plane wiring.

  19. Wide spectrum microwave pulse measurement

    SciTech Connect

    King, R.J.

    1986-01-01

    Various techniques are postulated as diagnostics for wide band microwave pulses. The diagnostics include determinations of both the instantaneous amplitude and the frequency content of one-shot pulses. 6 refs., 11 figs. (WRF)

  20. Sequentially pulsed traveling wave accelerator

    DOEpatents

    Caporaso, George J.; Nelson, Scott D.; Poole, Brian R.

    2009-08-18

    A sequentially pulsed traveling wave compact accelerator having two or more pulse forming lines each with a switch for producing a short acceleration pulse along a short length of a beam tube, and a trigger mechanism for sequentially triggering the switches so that a traveling axial electric field is produced along the beam tube in synchronism with an axially traversing pulsed beam of charged particles to serially impart energy to the particle beam.

  1. Control of pulse-to-pulse fluctuations in visible supercontinuum.

    PubMed

    Kudlinski, A; Barviau, B; Leray, A; Spriet, C; Héliot, L; Mussot, A

    2010-12-20

    Long-pulse supercontinuum sources are initiated by modulation instability and consequently suffer from stochastic shot-to-shot variations of their spectral power density. In this paper, we provide a measurement of pulse-to-pulse fluctuations over the whole supercontinuum spectrum, and we show that their spectral dependence follows the group index curve of the fiber. Then, we demonstrate a significant reduction of supercontinuum pulse-to-pulse fluctuations in the visible by using a photonic crystal fiber with longitudinally tailored guidance properties. We finally show numerically that this new source would allow a significant improvement of the signal-to-noise ratio in fluorescence microscopy. PMID:21197020

  2. Pulsed excimer laser processing

    NASA Technical Reports Server (NTRS)

    Wong, D.

    1985-01-01

    The status of pulsed excimer laser processing of PV cells is presented. The cost effective feasibility of fabricating high efficiency solar cells on Czochralski wafers using a pulsed excimer laser for junction formation, surface passivation, and front metallization. Laser annealing results were promising with the best AR coated cell having an efficiency of 16.1%. Better results would be expected with larger laser spot size because there was some degradation in open circuit voltage caused by laser spot overlap and edge effects. Surface heating and photolytic decomposition by the laser was used to deposit tungsten from the reaction of tungsten hexafluoride and hydrogen. The line widths were 5 to 10 mils, and the depositions passed the tape adhesion test. Thinner lines are practical using an optimized optical system.

  3. Noisy homoclinic pulse dynamics.

    PubMed

    Eaves, T S; Balmforth, Neil J

    2016-04-01

    The effect of stochastic perturbations on nearly homoclinic pulse trains is considered for three model systems: a Duffing oscillator, the Lorenz-like Shimizu-Morioka model, and a co-dimension-three normal form. Using the Duffing model as an example, it is demonstrated that the main effect of noise does not originate from the neighbourhood of the fixed point, as is commonly assumed, but due to the perturbation of the trajectory outside that region. Singular perturbation theory is used to quantify this noise effect and is applied to construct maps of pulse spacing for the Shimizu-Morioka and normal form models. The dynamics of these stochastic maps is then explored to examine how noise influences the sequence of bifurcations that take place adjacent to homoclinic connections in Lorenz-like and Shilnikov-type flows. PMID:27131483

  4. Noisy homoclinic pulse dynamics

    NASA Astrophysics Data System (ADS)

    Eaves, T. S.; Balmforth, Neil J.

    2016-04-01

    The effect of stochastic perturbations on nearly homoclinic pulse trains is considered for three model systems: a Duffing oscillator, the Lorenz-like Shimizu-Morioka model, and a co-dimension-three normal form. Using the Duffing model as an example, it is demonstrated that the main effect of noise does not originate from the neighbourhood of the fixed point, as is commonly assumed, but due to the perturbation of the trajectory outside that region. Singular perturbation theory is used to quantify this noise effect and is applied to construct maps of pulse spacing for the Shimizu-Morioka and normal form models. The dynamics of these stochastic maps is then explored to examine how noise influences the sequence of bifurcations that take place adjacent to homoclinic connections in Lorenz-like and Shilnikov-type flows.

  5. 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.

  6. Laser pulse detector

    DOEpatents

    Mashburn, Douglas N.; Akerman, M. Alfred

    1981-01-01

    A laser pulse detector is provided which is small and inexpensive and has the capability of detecting laser light of any wavelength with fast response (less than 5 nanoseconds rise time). The laser beam is focused onto the receiving end of a graphite rod coaxially mounted within a close-fitting conductive, open-end cylindrical housing so that ablation and electric field breakdown of the resulting plasma occurs due to a bias potential applied between the graphite rod and housing. The pulse produced by the breakdown is transmitted through a matched impedance coaxial cable to a recording device. The cable is connected with its central lead to the graphite rod and its outer conductor to the housing.

  7. Laser pulse detector

    DOEpatents

    Mashburn, D.N.; Akerman, M.A.

    1979-08-13

    A laser pulse detector is provided which is small and inexpensive and has the capability of detecting laser light of any wavelength with fast response (less than 5 nanoseconds rise time). The laser beam is focused onto the receiving end of a graphite rod coaxially mounted within a close-fitting conductive, open-end cylindrical housing so that ablation and electric field breakdown of the resulting plasma occurs due to a bias potential applied between the graphite rod and housing. The pulse produced by the breakdown is transmitted through a matched impedance coaxial cable to a recording device. The cable is connected with its central lead to the graphite rod and its outer conductor to the housing.

  8. Pulse thermal loop

    NASA Technical Reports Server (NTRS)

    Weislogel, Mark M. (Inventor)

    2002-01-01

    A pulse thermal loop heat transfer system includes a means to use pressure rises in a pair of evaporators to circulate a heat transfer fluid. The system includes one or more valves that iteratively, alternately couple the outlets the evaporators to the condenser. While flow proceeds from one of the evaporators to the condenser, heating creates a pressure rise in the other evaporator, which has its outlet blocked to prevent fluid from exiting the other evaporator. When the flow path is reconfigured to allow flow from the other evaporator to the condenser, the pressure in the other evaporator is used to circulate a pulse of fluid through the system. The reconfiguring of the flow path, by actuating or otherwise changing the configuration of the one or more valves, may be triggered when a predetermined pressure difference between the evaporators is reached.

  9. Pulsed electron beam precharger

    SciTech Connect

    Finney, W.C.; Shelton, W.N.

    1989-01-01

    This is the fifth in a series of contracts and grants exploring the advanced particulate pollution control technology of electron beam precipitation. The chief goal of the current contract is to develop a laboratory scale electron beam precharger using a pulsed electric field to the proof-of-concept stage. Contract tasks leading to the achievement of this goal are generally divided up into two categories: tasks required to bring the Electron Beam Precipitator (EBP) test system up to an operational level for the contract work, and tasks concerning the actual experimental and analytical phase of the study. Not unexpectedly, the early portion of the contract duration will be devoted to the commissioning of the EBP and its many subsystems, while the latter portion will devote itself to testing the new pulsed electron beam precharger.

  10. Short pulse laser

    SciTech Connect

    Fork, R.L.; Gordon, J.P.; Yaldmanis, J.A.

    1988-02-23

    A laser is described comprising means for defining a single optical resonator; a saturable gain medium; an absorbing element optically coupled to the gain medium; the absorbing element being capable of deep saturation; means optically coupled to the absorbing element for deeply saturating the absorbing element; and means for generating group velocity dispersion to balance self phase modulation generated within the laser. The group velocity dispersion has a sign opposite to that of the self phase modulation. The saturable gain medium, the absorbing element and the group velocity dispersion generating means are positioned within the single optical resonator to facilitate optical coupling therebetween. The saturable gain medium and absorbing element restrict an optical pulse from the laser to have soliton type pulse shaping in the fundamental soliton mode.

  11. ELECTRONIC PULSE SCALING CIRCUITS

    DOEpatents

    Cooke-Yarborough, E.H.

    1958-11-18

    Electronic pulse scaling circults of the klnd comprlsing a serles of bi- stable elements connected ln sequence, usually in the form of a rlng so as to be cycllcally repetitive at the highest scallng factor, are described. The scaling circuit comprises a ring system of bi-stable elements each arranged on turn-off to cause, a succeeding element of the ring to be turned-on, and one being arranged on turn-off to cause a further element of the ring to be turned-on. In addition, separate means are provided for applying a turn-off pulse to all the elements simultaneously, and for resetting the elements to a starting condition at the end of each cycle.

  12. Computationally intelligent pulsed photoacoustics

    NASA Astrophysics Data System (ADS)

    Lukić, Mladena; Ćojbašić, Žarko; Rabasović, Mihailo D.; Markushev, Dragan D.

    2014-12-01

    In this paper, the application of computational intelligence in pulsed photoacoustics is discussed. Feedforward multilayer perception networks are applied for real-time simultaneous determination of the laser beam spatial profile and vibrational-to-translational relaxation time of the polyatomic molecules in gases. Networks are trained and tested with theoretical data adjusted for a given experimental set-up. Genetic optimization has been used for calculation of the same parameters, fitting the photoacoustic signals with a different number of generations. Observed benefits from the application of computational intelligence in pulsed photoacoustics and advantages over previously developed methods are discussed, such as real-time operation, high precision and the possibility of finding solutions in a wide range of parameters, similar to in experimental conditions. In addition, the applicability for practical uses, such as the real-time in situ measurements of atmospheric pollutants, along with possible further developments of obtained results, is argued.

  13. Network-Centric Maritime Radiation Awareness and Interdiction Experiments: C2 Experimentation

    SciTech Connect

    Bordetsky, A; Dougan, A D; Nekoogar, F

    2006-08-07

    The paper addresses technological and operational challenges of developing a global plug-and-play Maritime Domain Security testbed for the Global War on Terrorism mission. This joint NPS-LLNL project is based on the NPS Tactical Network Topology (TNT) composed of long-haul OFDM networks combined with self-forming wireless mesh links to air, surface, ground, and underwater unmanned vehicles. This long-haul network is combined with ultra-wideband (UWB) communications systems for wireless communications in harsh radio propagation channels. LLNL's UWB communication prototypes are designed to overcome shortcomings of the present narrowband communications systems in heavy metallic and constricted corridors inside ships. In the center of our discussion are networking solutions for the Maritime Interdiction Operation (MIO) Experiments in which geographically distributed command centers and subject matter experts collaborate with the Boarding Party in real time to facilitate situational understanding and course of action selection. The most recent experiment conducted via the testbed extension to the Alameda Island exercised several key technologies aimed at improving MIO. These technologies included UWB communications from within the ship to Boarding Party leader sending data files and pictures, advanced radiation detection equipment for search and identification, biometric equipment to record and send fingerprint files to facilitate rapid positive identification of crew members, and the latest updates of the NPS Tactical Network Topology facilitating reachback to LLNL, Biometric Fusion Center, USCG, and DTRA experts.

  14. Ultrawideband imaging radar based on OFDM: system simulation analysis

    NASA Astrophysics Data System (ADS)

    Garmatyuk, Dmitriy

    2006-05-01

    Orthogonal frequency division-multiplexing (OFDM) is rapidly emerging as a preferred method of UWB signaling in commercial applications aimed mainly at low-power, high data-rate communications. This paper explores the possibility of applying OFDM to use in imaging radar technology. Ultra-wideband nature of the signal provides for high resolution of the radar, whereas usage of multi-sub-carrier method of modulation allows for dynamic spectrum allocation. Robust multi-path performance of OFDM signals and heavy reliance of transceiver design on digital processors easily implemented in modern VLSI technology make a number of possible applications viable, e.g.: portable high-resolution indoor radar/movement monitoring system; through-the-wall/foliage synthetic aperture imaging radar with a capability of image transmission/broadcasting, etc. Our work is aimed to provide a proof-of-concept simulation scenario to explore numerous aspects of UWB-OFDM radar imaging through evaluating range and cross-range imaging performance of such a system with an eventual goal of software-defined radio (SDR) implementation. Stripmap SAR topology was chosen for modeling purposes. Range/cross-range profiles were obtained along with full 2-D images for multi-target in noise scenarios. Model set-up and results of UWB-OFDM radar imaging simulation study using Matlab/Simulink modeling are presented and discussed in this paper.

  15. Self-training algorithms for ultrawideband radar target detection

    NASA Astrophysics Data System (ADS)

    Mitra, Atindra K.; Lewis, Thomas L.; Paul, Anindya S.; Shaw, Arnab K.

    2003-09-01

    An ultra-wideband (UWB) synthetic aperture radar (SAR) simulation technique that employs physical and statistical models is developed and presented. This joint physics/statistics based technique generates images that have many of the "blob-like" and "spiky" clutter characteristics of UWB radar data in forested regions while avoiding the intensive computations required for the implementation of low-frequency numerical electromagnetic simulation techniques. Approaches towards developing "self-training" algorithms for UWB radar target detection are investigated using the results of this simulation process. These adaptive approaches employ some form of modified singular value decomposition (SVD) algorithm where small blocks of data in the neighborhood of a sliding test window are processed in real-time in an effort to estimate localized clutter characteristics. These real-time local clutter models are then used to cancel clutter in the sliding test window. Comparative results from three SVD-based approaches to adaptive and "self-trained" target detection algorithms are reported. These approaches are denoted as "Energy-Normalized SVD", "Condition-Statistic SVD", and "Terrain-Filtered SVD". The results indicate that the "Terrain-Filtered SVD" approach, where a pre-filter is applied in an effort to eliminate severe clutter discretes that adversely effect performance, appears promising for the purposes of developing "self-training" algorithms for applications that may require localized "on-the-fly" training due to a lack of accurate off-line training data.

  16. Pulsed gas laser

    DOEpatents

    Anderson, Louis W.; Fitzsimmons, William A.

    1978-01-01

    A pulsed gas laser is constituted by Blumlein circuits wherein space metal plates function both as capacitors and transmission lines coupling high frequency oscillations to a gas filled laser tube. The tube itself is formed by spaced metal side walls which function as connections to the electrodes to provide for a high frequency, high voltage discharge in the tube to cause the gas to lase. Also shown is a spark gap switch having structural features permitting a long life.

  17. 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.

  18. 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.

  19. Pulsed dose rate brachytherapy.

    PubMed

    Polo, A

    2008-06-01

    Pulsed dose rate (PDR) is a new modality for dose delivery in brachytherapy. It uses modern afterloading technology (miniaturized source, cable driven, software controlled), with source activities in the range of 1 Ci, which is actually one tenth of the normal activity used for high dose rate (HDR) brachytherapy. Modern technology allows dose optimization, and source strength in the above-mentioned range creates a new dose rate condition. For small fractions (pulses) with short interpulse intervals, PDR mimics the radiobiology of high dose rate brachytherapy, whereas for bigger doses per fraction, dose adjustments are needed to compensate for the loss of therapeutic ratio. Clinical series showed good figures for local control and toxicity. Almost every clinical site has been reported to have been treated with PDR, with some thousand of patients having been reported. Technical difficulties in some body sites can be overcome by slightly modifying the implant technique. PDR brachytherapy is an ideal environment for the development of new dose fractionation schedules. It creates unique conditions in which to operate. Knowledge of tissue repair kinetics is extremely important for adequate selection of dose per pulse and interpulse interval. Therapeutic ratio can be improved by adjusting interpulse intervals to the repair half-times for normal tissues. On the other hand, superfractionated schedules with low dose per pulse can be explored in conditions of tumor hypoxia, thanks to the predicted hypersensitivity at low dose per fraction. The use of chemical agents (nicotinamide and others) in concomitance with this superfractionated schedules is foreseen in controlled clinical trials. In conclusion, PDR brachytherapy can be considered a new paradigm for dose delivery. It is safe and reliable, can be used in the setting of image-guided radiation therapy, and exploit the differential effect of ionizing radiations by a thorough knowledge of tissue kinetics for an improved therapeutic ratio. PMID:18558579

  20. Pulsed rf operation analysis

    SciTech Connect

    Puglisi, M.; Cornacchia, M.

    1981-01-01

    The need for a very low final amplifier output impedance, always associated with class A operation, requires a very large power waste in the final tube. The recently suggested pulsed rf operation, while saving a large amount of power, increases the inherent final amplifier non linearity. A method is presented for avoiding the large signal non linear analysis and it is shown how each component of the beam induced voltage depends upon all the beam harmonics via some coupling coefficients which are evaluated.

  1. International magnetic pulse compression

    NASA Astrophysics Data System (ADS)

    Kirbie, H. C.; Newton, M. A.; Siemens, P. D.

    1991-04-01

    Although pulsed-power engineering traditionally has been practiced by a fairly small, close community in the areas of defense and energy research, it is becoming more common in high-power, high-energy commercial pursuits such as material processing and lasers. This paper is a synopsis of the Feb. 12-14, 1990 workshop on magnetic switching as it applies primarily to pulse compression (power transformation). During the course of the Workshop at Granlibakken, a great deal of information was amassed and a keen insight into both the problems and opportunities as to the use of this switching approach was developed. The segmented workshop format proved ideal for identifying key aspects affecting optimum performance in a variety of applications. Individual groups of experts addressed network and system modeling, magnetic materials, power conditioning, core cooling and dielectrics, and finally circuits and application. At the end, they came together to consolidate their input and formulate the workshop's conclusions, identifying roadblocks or suggesting research projects, particularly as they apply to magnetic switching's trump card - its high-average-power-handling capability (at least on a burst-mode basis). The workshop was especially productive both in the quality and quantity of information transfer in an environment conducive to a free and open exchange of ideas. We will not delve into the organization proper of this meeting, rather we wish to commend to the interested reader this volume, which provides the definitive and most up-to-date compilation on the subject of magnetic pulse compression from underlying principles to current state of the art as well as the prognosis for the future of magnetic pulse compression as a consensus of the workshop's organizers and participants.

  2. International magnetic pulse compression

    SciTech Connect

    Kirbie, H.C.; Newton, M.A.; Siemens, P.D.

    1991-04-01

    Although pulsed-power engineering traditionally has been practiced by a fairly small, close community in the areas of defense and energy research, it is becoming more common in high-power, high-energy commercial pursuits such as material processing and lasers. This paper is a synopsis of the Feb. 12--14, 1990 workshop on magnetic switching as it applies primarily to pulse compression (power transformation). During the course of the Workshop at Granlibakken, a great deal of information was amassed and a keen insight into both the problems and opportunities as to the use of this switching approach was developed. The segmented workshop format proved ideal for identifying key aspects affecting optimum performance in a variety of applications. Individual groups of experts addressed network and system modeling, magnetic materials, power conditioning, core cooling and dielectrics, and finally circuits and application. At the end, they came together to consolidate their input and formulate the workshop's conclusions, identifying roadblocks or suggesting research projects, particularly as they apply to magnetic switching's trump card -- its high-average-power-handling capability (at least on a burst-mode basis). The workshop was especially productive both in the quality and quantity of information transfer in an environment conducive to a free and open exchange of ideas. We will not delve into the organization proper of this meeting, rather we wish to commend to the interested reader this volume, which provides the definitive and most up-to-date compilation on the subject of magnetic pulse compression from underlying principles to current state of the art as well as the prognosis for the future of magnetic pulse compression as a consensus of the workshop's organizers and participants.

  3. GRAVITATIONAL PULSE ASTRONOMY

    SciTech Connect

    Gould, Andrew

    2011-03-10

    Thompson has argued that the Kozai mechanism is primarily responsible for driving white dwarf binary mergers and so generating type Ia supernovae (SNe). If so, the gravitational-wave signal from these systems will be characterized by isolated repeating pulses that are well approximated by parabolic encounters. I show that it is impossible to detect these with searches based on standard assumptions of circular binaries, nor could they be detected by analogs of the repeating-pulse searches that have been carried out at higher frequencies, even if these were modified to barycentric time as a function of putative sky position. Rather, new search algorithms are required that take account of the intrinsic three-body motion of the source as well as the motion of the Earth. If these eccentric binaries account for even a modest fraction of the observed SN rate, then there should be of order 1 pulse every 20 s coming from within 1 kpc, and there should be of order 200 detectable sources in this same volume. I outline methods of identifying these sources both to remove this very pernicious background to other signals and to find candidate SN Ia progenitors, and I sketch practical methods to find optical counterparts to these sources and so measure their masses and distances.

  4. MULTICHANNEL PULSE-HEIGHT ANALYZER

    DOEpatents

    Russell, J.T.; Lefevre, H.W.

    1958-01-21

    This patent deals with electronic computing circuits and more particularly to pulse-height analyzers used for classifying variable amplitude pulses into groups of different amplitudes. The device accomplishes this pulse allocation by by converting the pulses into frequencies corresponding to the amplitudes of the pulses, which frequencies are filtered in channels individually pretuned to a particular frequency and then detected and recorded in the responsive channel. This circuit substantially overcomes the disadvantages of prior annlyzers incorporating discriminators pre-set to respond to certain voltage levels, since small variation in component values is not as critical to satisfactory circuit operation.

  5. A 6-7 GHz, 40 dB receiver RF front-end with 4.5 dB minimum noise figure in 0.13 μm CMOS for IR-UWB applications

    NASA Astrophysics Data System (ADS)

    Xi, Qin; Yumei, Huang; Zhiliang, Hong

    2013-03-01

    A wideband receiver RF front-end for IR-UWB applications is implemented in 0.13 μm CMOS technology. Thanks to the direct sub-sampling architecture, there is no mixing process. Both LNA and VGA work at RF frequencies. To optimize noise as well as linearity, a differential common-source LNA with capacitive cross-coupling is used, which only consumes current of 1.8 mA from a 1.2 V power supply. Following LNA, a two-stage current-steering VGA is adopted for gain tuning. To extend the overall bandwidth, a three-stage staggered peaking technique is used. Measurement results show that the proposed receiver front-end achieves a gain tuning range from 5 to 40 dB within 6-7 GHz, a minimum noise figure of 4.5 dB and a largest IIP3 of -11 dBm. The core receiver (without test buffer) consumes 14 mW from a 1.2 V power supply and occupies 0.58 mm2 area.

  6. High frequency pulsed electromigration

    NASA Astrophysics Data System (ADS)

    Malone, David Wayne

    Electromigration life tests were performed on copper-alloyed aluminum test structures that were representative of modern CMOS metallization schemes, complete with Ti/TiN cladding layers and a tungsten-plug contact at the cathode. A total of 18 electrical stress treatments were applied. One was a DC current of 15 mA. The other 17 were pulsed currents, varied according to duty cycle and frequency. The pulse amplitude was 15 mA (2.7 10sp6 A/cmsp2) for all treatments. Duty cycles ranged from 33.3% to 80%, and frequencies fell into three rough ranges-100 KHz, 1 MHz, and 100 MHz. The ambient test temperature was 200spC in all experiments. Six to 9 samples were subjected to each treatment. Experimental data were gathered in the form of test stripe resistance versus time, R(t). For purposes of lifetime analysis, "failure" was defined by the criterion R(t)/R(0) = 1.10, and the median time to failure, tsb{50}, was used as the primary basis of comparison between test groups. It was found that the dependence of tsb{50} on pulse duty cycle conformed rather well to the so-called "average current density model" for duty cycles of 50% and higher. Lifetimes were less enhanced for a duty cycle of 33.3%, but they were still considerably longer than an "on-time" model would predict. No specific dependence of tsb{50} on pulse frequency was revealed by the data, that is, reasonably good predictions of tsb{50} could be made by recognizing the dominant influence of duty cycle. These findings confirm that IC miniaturization can be more aggressively pursued than an on-time prediction would allow. It is significant that this was found to be true for frequencies on the order of 100 MHz, where many present day digital applications operate. Post-test optical micrographs were obtained for each test subject in order to determine the location of electromigration damage. The pulse duty cycle was found to influence the location. Most damage occurred at the cathode contact, regardless of treatment conditions, but there was an increased incidence of damage farther downwind with decreasing duty cycle. This tendency and the deviation from the average current density model for small duty cycles were explained in terms of the Blech length, its dependence on microstructure and duty cycle, and its impact on the relative rates of damage and recovery.

  7. Petawatt pulsed-power accelerator

    DOEpatents

    Stygar, William A.; Cuneo, Michael E.; Headley, Daniel I.; Ives, Harry C.; Ives, legal representative; Berry Cottrell; Leeper, Ramon J.; Mazarakis, Michael G.; Olson, Craig L.; Porter, John L.; Wagoner; Tim C.

    2010-03-16

    A petawatt pulsed-power accelerator can be driven by various types of electrical-pulse generators, including conventional Marx generators and linear-transformer drivers. The pulsed-power accelerator can be configured to drive an electrical load from one- or two-sides. Various types of loads can be driven; for example, the accelerator can be used to drive a high-current z-pinch load. When driven by slow-pulse generators (e.g., conventional Marx generators), the accelerator comprises an oil section comprising at least one pulse-generator level having a plurality of pulse generators; a water section comprising a pulse-forming circuit for each pulse generator and a level of monolithic triplate radial-transmission-line impedance transformers, that have variable impedance profiles, for each pulse-generator level; and a vacuum section comprising triplate magnetically insulated transmission lines that feed an electrical load. When driven by LTD generators or other fast-pulse generators, the need for the pulse-forming circuits in the water section can be eliminated.

  8. Laser beam pulse formatting method

    DOEpatents

    Daly, Thomas P.; Moses, Edward I.; Patterson, Ralph W.; Sawicki, Richard H.

    1994-01-01

    A method for formatting a laser beam pulse (20) using one or more delay loops (10). The delay loops (10) have a partially reflective beam splitter (12) and a plurality of highly reflective mirrors (14) arranged such that the laser beam pulse (20) enters into the delay loop (10) through the beam splitter (12) and circulates therein along a delay loop length (24) defined by the mirrors (14). As the laser beam pulse (20) circulates within the delay loop (10) a portion thereof is emitted upon each completed circuit when the laser beam pulse (20) strikes the beam splitter (12). The laser beam pulse (20) is thereby formatted into a plurality of sub-pulses (50, 52, 54 and 56). The delay loops (10) are used in combination to produce complex waveforms by combining the sub-pulses (50, 52, 54 and 56) using additive waveform synthesis.

  9. Pulsed power packs a punch

    NASA Astrophysics Data System (ADS)

    Weldon, W. F.

    1985-03-01

    Utilities supply electric power routinely in a continuous flow, while in certain cases power must be delivered in short, huge bursts, taking into account applications such as thermonuclear-fusion research, high-energy particle accelerators, lasers, and electromagnetic launchers. For the delivery of this 'pulsed power', it is necessary to collect energy at low power, store it, and release it almost instantaneously. During the last decade, pulsed-power technology has become a recognized engineering discipline. Pulsed-power systems can now deliver gigajoules of energy, megamperes of current, or terawatts of power, while pulse widths range from microseconds to several seconds. Attention is given to capacitors as one of the oldest storage devices for electric energy, inductors, the linking of capacitors and inductors, pulse creation, the use of explosives to generate pulsed power, limitations regarding the effectiveness of batteries, low-cost energy storage provided by flywheels, dc machines, ac machines, and new applications for pulsed power.

  10. High-speed pulse-shape generator, pulse multiplexer

    DOEpatents

    Burkhart, Scott C.

    2002-01-01

    The invention combines arbitrary amplitude high-speed pulses for precision pulse shaping for the National Ignition Facility (NIF). The circuitry combines arbitrary height pulses which are generated by replicating scaled versions of a trigger pulse and summing them delayed in time on a pulse line. The combined electrical pulses are connected to an electro-optic modulator which modulates a laser beam. The circuit can also be adapted to combine multiple channels of high speed data into a single train of electrical pulses which generates the optical pulses for very high speed optical communication. The invention has application in laser pulse shaping for inertial confinement fusion, in optical data links for computers, telecommunications, and in laser pulse shaping for atomic excitation studies. The invention can be used to effect at least a 10.times. increase in all fiber communication lines. It allows a greatly increased data transfer rate between high-performance computers. The invention is inexpensive enough to bring high-speed video and data services to homes through a super modem.

  11. Propagation of cold pulses and heat pulses in ASDEX Upgrade

    NASA Astrophysics Data System (ADS)

    Ryter, F.; Neu, R.; Dux, R.; Fahrbach, H.-U.; Leuterer, F.; Pereverzev, G.; Schweinzer, J.; Stober, J.; Suttrop, W.; ASDEX Upgrade Team; DeLuca, F.; Jacchia, A.; Kinsey, J. E.

    2000-11-01

    Experiments on electron heat transport were performed in the tokamak ASDEX Upgrade, mainly in ohmically heated plasmas, applying either edge cooling with laser blow-off impurity injection or edge heat pulses with ECRH. Repetitive pulses within one plasma discharge were made allowing Fourier transformation of the temperature perturbation, yielding a good signal to noise ratio up to high harmonics and a detailed investigation of the pulse propagation. For densities lower than 1.8 × 1019m-3, an increase of central electron temperature was found as the response to edge cooling via impurity injection similar to observations made in the TEXT, TFTR, RTP and Tore Supra tokamaks. The inversion does not appear instantaneously, but with a time delay roughly compatible with diffusion. Modelling of the propagation of the cold pulses in the framework of the IFS-PPPL model yields qualitative agreement. However, the predicted increase of ion temperature is not observed experimentally on a fast timescale. The response to ECRH heat pulses is not perfectly symmetrical to cold pulse experiments, but the similarities suggest a common underlying physical mechanism. No inversion of the heat pulse is found, instead the initial pulse from the edge is associated with a second, much slower, heat pulse in the centre. This central reaction is in fact quite similar (and not symmetrical) to that of the cold pulses. By varying the position of the ECRH deposition it could be shown that the central increase is related to the arrival of the pulse close to the inversion radius and not to the initial pulse. Modelling was performed to investigate the possible physics mechanisms and for comparison with the cold pulses.

  12. Microwave and Pulsed Power

    SciTech Connect

    Freytag, E.K.

    1993-03-01

    The goals of the Microwave and Pulsed Power thrust area are to identify realizable research and development efforts and to conduct high-quality research in those pulse power and microwave technologies that support existing and emerging programmatic requirements at Lawrence Livermore National Laboratory (LLNL). Our main objective is to work on nationally important problems while enhancing our basic understanding of enabling technologies such as component design and testing, compact systems packaging, exploratory physics experiments, and advanced systems integration and performance. During FY-92, we concentrated our research efforts on the six project areas described in this report. (1) We are investigating the superior electronic and thermal properties of diamond that may make it an ideal material for a high-power, solid-state switch. (2) We are studying the feasibility of using advanced Ground Penetrating Imaging Radar technology for reliable non-destructive evaluation of bridges and other high-value concrete structures. These studies include conceptual designs, modeling, experimental verifications, and image reconstruction of simulated radar data. (3) We are exploring the efficiency of pulsed plasma processing techniques used for the removal of NO{sub x} from various effluent sources. (4) We have finished the investigation of the properties of a magnetically delayed low-pressure gas switch, which was designed here at LLNL. (5) We are applying statistical electromagnetic theory techniques to help assess microwave effects on electronic subsystems, by using a mode stirred chamber as our measurement tool. (6) We are investigating the generation of perfluoroisobutylene (PFIB) in proposed CFC replacement fluids when they are subjected to high electrical stresses and breakdown environments.

  13. High current transistor pulse generator

    SciTech Connect

    Nesterov, V.; Cassel, R.

    1991-05-01

    A solid state pulse generator capable of delivering high current trapezoidally shaped pulses into an inductive load has been developed at SLAC. Energy stored in the capacitor bank of the pulse generator is switched to the load through a pair of Darlington transistors. A combination of diodes and Darlington transistors is used to obtain trapezoidal or triangular shaped current pulses into an inductive load and to recover the remaining energy in the same capacitor bank without reversing capacitor voltage. The transistors work in the switch mode, and the power losses are low. The rack mounted pulse generators presently used at SLAC contain a 660 microfarad storage capacitor bank and can deliver 400 amps at 800 volts into inductive loads up to 3 mH. The pulse generators are used in several different power systems, including pulse to pulse bipolar power supplies and in application with current pulses distributed into different inductive loads. The current amplitude and discharge time are controlled by the central computer system through a specially developed multichannel controller. Several years of operation with the pulse generators have proven their consistent performance and reliability. 8 figs.

  14. Optimization of Adiabatic Selective Pulses

    NASA Astrophysics Data System (ADS)

    Rosenfeld, Daniel; Panfil, Shimon L.; Zur, Yuval

    1997-06-01

    Adiabatic RF pulses play an important role in spin inversion due to their robust behavior in presence of inhomogeneous RF fields. These pulses are characterized by the trajectory swept by the tip of theBeffvector and the rate of motion upon it. In this paper, a method is described for optimizing adiabatic inversion pulses to achieve a frequency-selective magnetization inversion over a given bandwidth in a shorter time and to improve slice profile. An efficient adiabatic pulse is used as an initial condition. This pulse allows for flexibility in choosing its parameters; in particular, the transition sharpness may be traded off against the inverted bandwidth. The considerations for selecting the parameters of the pulse according to the requirements of the design are discussed. The optimization process then improves the slice profile by optimizing the rate of motion along the trajectory of the pulse while preserving the trajectory itself. The adiabatic behavior of the optimized pulses is fully preserved over a twofold range of variation in the RF amplitude which is sufficient for imaging applications in commercial high-field MRI machines. Design examples demonstrate the superiority of the optimized pulses over the conventional sech/tanh pulse.

  15. Coiled transmission line pulse generators

    DOEpatents

    McDonald, Kenneth Fox

    2010-11-09

    Methods and apparatus are provided for fabricating and constructing solid dielectric "Coiled Transmission Line" pulse generators in radial or axial coiled geometries. The pour and cure fabrication process enables a wide variety of geometries and form factors. The volume between the conductors is filled with liquid blends of monomers, polymers, oligomers, and/or cross-linkers and dielectric powders; and then cured to form high field strength and high dielectric constant solid dielectric transmission lines that intrinsically produce ideal rectangular high voltage pulses when charged and switched into matched impedance loads. Voltage levels may be increased by Marx and/or Blumlein principles incorporating spark gap or, preferentially, solid state switches (such as optically triggered thyristors) which produce reliable, high repetition rate operation. Moreover, these Marxed pulse generators can be DC charged and do not require additional pulse forming circuitry, pulse forming lines, transformers, or an a high voltage spark gap output switch. The apparatus accommodates a wide range of voltages, impedances, pulse durations, pulse repetition rates, and duty cycles. The resulting mobile or flight platform friendly cylindrical geometric configuration is much more compact, light-weight, and robust than conventional linear geometries, or pulse generators constructed from conventional components. Installing additional circuitry may accommodate optional pulse shape improvements. The Coiled Transmission Lines can also be connected in parallel to decrease the impedance, or in series to increase the pulse length.

  16. PULSE SYNTHESIZING GENERATOR

    DOEpatents

    Kerns, Q.A.

    1963-08-01

    >An electronlc circuit for synthesizing electrical current pulses having very fast rise times includes several sinewave generators tuned to progressively higher harmonic frequencies with signal amplitudes and phases selectable according to the Fourier series of the waveform that is to be synthesized. Phase control is provided by periodically triggering the generators at precisely controlled times. The outputs of the generators are combined in a coaxial transmission line. Any frequency-dependent delays that occur in the transmission line can be readily compensated for so that the desired signal wave shape is obtained at the output of the line. (AEC)

  17. Ultrashort Pulsed Neutron Source

    NASA Astrophysics Data System (ADS)

    Pomerantz, I.; McCary, E.; Meadows, A. R.; Arefiev, A.; Bernstein, A. C.; Chester, C.; Cortez, J.; Donovan, M. E.; Dyer, G.; Gaul, E. W.; Hamilton, D.; Kuk, D.; Lestrade, A. C.; Wang, C.; Ditmire, T.; Hegelich, B. M.

    2014-10-01

    We report on a novel compact laser-driven neutron source with an unprecedented short pulse duration (<50 ps ) and high peak flux (>1018 n /cm2/s ), an order of magnitude higher than any existing source. In our experiments, high-energy electron jets are generated from thin (<3 μ m ) plastic targets irradiated by a petawatt laser. These intense electron beams are employed to generate neutrons from a metal converter. Our method opens venues for enhancing neutron radiography contrast and for creating astrophysical conditions of heavy element synthesis in the laboratory.

  18. Pulse Field Gel Electrophoresis.

    PubMed

    Sharma-Kuinkel, Batu K; Rude, Thomas H; Fowler, Vance G

    2016-01-01

    Pulse Field Gel Electrophoresis (PFGE) is a powerful genotyping technique used for the separation of large DNA molecules (entire genomic DNA) after digesting it with unique restriction enzymes and applying to a gel matrix under the electric field that periodically changes direction. PFGE is a variation of agarose gel electrophoresis that permits analysis of bacterial DNA fragments over an order of magnitude larger than that with conventional restriction enzyme analysis. It provides a good representation of the entire bacterial chromosome in a single gel with a highly reproducible restriction profile, providing clearly distinct and well-resolved DNA fragments. PMID:25682374

  19. Pulsed quantum optomechanics

    PubMed Central

    Vanner, M. R.; Pikovski, I.; Cole, G. D.; Kim, M. S.; Brukner, Č.; Hammerer, K.; Milburn, G. J.; Aspelmeyer, M.

    2011-01-01

    Studying mechanical resonators via radiation pressure offers a rich avenue for the exploration of quantum mechanical behavior in a macroscopic regime. However, quantum state preparation and especially quantum state reconstruction of mechanical oscillators remains a significant challenge. Here we propose a scheme to realize quantum state tomography, squeezing, and state purification of a mechanical resonator using short optical pulses. The scheme presented allows observation of mechanical quantum features despite preparation from a thermal state and is shown to be experimentally feasible using optical microcavities. Our framework thus provides a promising means to explore the quantum nature of massive mechanical oscillators and can be applied to other systems such as trapped ions. PMID:21900608

  20. Green Light Pulse Oximeter

    DOEpatents

    Scharf, John Edward

    1998-11-03

    A reflectance pulse oximeter that determines oxygen saturation of hemoglobin using two sources of electromagnetic radiation in the green optical region, which provides the maximum reflectance pulsation spectrum. The use of green light allows placement of an oximetry probe at central body sites (e.g., wrist, thigh, abdomen, forehead, scalp, and back). Preferably, the two green light sources alternately emit light at 560 nm and 577 nm, respectively, which gives the biggest difference in hemoglobin extinction coefficients between deoxyhemoglobin, RHb, and oxyhemoglobin, HbO.sub.2.

  1. Pulsed Plasma Thruster Technology

    NASA Technical Reports Server (NTRS)

    1996-01-01

    The continuing emphasis on reducing costs and downsizing spacecraft is forcing increased emphasis on reducing the subsystem mass and integration costs. For many commercial, scientific, and Department of Defense space missions, onboard propulsion is either the predominant spacecraft mass or it limits the spacecraft lifetime. Electromagnetic-pulsed-plasma thrusters (PPT's) offer the combined benefits of extremely low average electric power requirements (1 to 150 W), high specific impulse (approx. 1000 sec), and system simplicity derived from the use of an inert solid propellant. Potential applications range from orbit insertion and maintenance of small satellites to attitude control for large geostationary communications satellites.

  2. Focused pulsed neutron source

    SciTech Connect

    Friedman, M.; Drobot, A.; Wyeth, N.C.

    1995-09-08

    A non-reactor neutron source is disclosed that allows for a pulse intense current of ions to generate neutrons that are epithermal neutrons and provide low-energy neutron energy particularly suited for Boron Neutron Capture Therapy (BNCT) treatment. The present invention provides for a neutron fluence on a tumor which can be more than 10{sup 12} neutrons/cm{sup 2} and is generated into a time scale of less than 1 second. The radiation dose provided by the present invention is focused yet uniformly distributed so as to attack cancerous tissues and reduce collateral damage to healthy tissues.

  3. Heat driven pulse pump

    NASA Technical Reports Server (NTRS)

    Benner, Steve M (Inventor); Martins, Mario S. (Inventor)

    2000-01-01

    A heat driven pulse pump includes a chamber having an inlet port, an outlet port, two check valves, a wick, and a heater. The chamber may include a plurality of grooves inside wall of the chamber. When heated within the chamber, a liquid to be pumped vaporizes and creates pressure head that expels the liquid through the outlet port. As liquid separating means, the wick, disposed within the chamber, is to allow, when saturated with the liquid, the passage of only liquid being forced by the pressure head in the chamber, preventing the vapor from exiting from the chamber through the outlet port. A plurality of grooves along the inside surface wall of the chamber can sustain the liquid, which is amount enough to produce vapor for the pressure head in the chamber. With only two simple moving parts, two check valves, the heat driven pulse pump can effectively function over the long lifetimes without maintenance or replacement. For continuous flow of the liquid to be pumped a plurality of pumps may be connected in parallel.

  4. Compensated pulsed alternator

    DOEpatents

    Weldon, William F.; Driga, Mircea D.; Woodson, Herbert H.

    1980-01-01

    This invention relates to an electromechanical energy converter with inertial energy storage. The device, a single phase, two or multi-pole alternator with stationary field coils, and a rotating armature is provided. The rotor itself may be of laminated steel for slower pulses or for faster pulses should be nonmagnetic and electrically nonconductive in order to allow rapid penetration of the field as the armature coil rotates. The armature coil comprises a plurality of power generating conductors mounted on the rotor. The alternator may also include a stationary or counterrotating compensating coil to increase the output voltage thereof and to reduce the internal impedance of the alternator at the moment of peak outout. As the machine voltage rises sinusoidally, an external trigger switch is adapted to be closed at the appropriate time to create the desired output current from said alternator to an external load circuit, and as the output current passes through zero a self-commutating effect is provided to allow the switch to disconnect the generator from the external circuit.

  5. Switching power pulse system

    DOEpatents

    Aaland, K.

    1983-08-09

    A switching system for delivering pulses of power from a source to a load using a storage capacitor charged through a rectifier, and maintained charged to a reference voltage level by a transistor switch and voltage comparator. A thyristor is triggered to discharge the storage capacitor through a saturable reactor and fractional turn saturable transformer having a secondary to primary turn ratio N of n:l/n = n[sup 2]. The saturable reactor functions as a soaker'' while the thyristor reaches saturation, and then switches to a low impedance state. The saturable transformer functions as a switching transformer with high impedance while a load coupling capacitor charges, and then switches to a low impedance state to dump the charge of the storage capacitor into the load through the coupling capacitor. The transformer is comprised of a multilayer core having two secondary windings tightly wound and connected in parallel to add their output voltage and reduce output inductance, and a number of single turn windings connected in parallel at nodes for the primary winding, each single turn winding linking a different one of the layers of the multilayer core. The load may be comprised of a resistive beampipe for a linear particle accelerator and capacitance of a pulse forming network. To hold off discharge of the capacitance until it is fully charged, a saturable core is provided around the resistive beampipe to isolate the beampipe from the capacitance until it is fully charged. 5 figs.

  6. Pulsed Plasma Thruster Contamination

    NASA Technical Reports Server (NTRS)

    Myers, Roger M.; Arrington, Lynn A.; Pencil, Eric J.; Carter, Justin; Heminger, Jason; Gatsonis, Nicolas

    1996-01-01

    Pulsed Plasma Thrusters (PPT's) are currently baselined for the Air Force Mightysat II.1 flight in 1999 and are under consideration for a number of other missions for primary propulsion, precision positioning, and attitude control functions. In this work, PPT plumes were characterized to assess their contamination characteristics. Diagnostics included planar and cylindrical Langmuir probes and a large number of collimated quartz contamination sensors. Measurements were made using a LES 8/9 flight PPT at 0.24, 0.39, 0.55, and 1.2 m from the thruster, as well as in the backflow region behind the thruster. Plasma measurements revealed a peak centerline ion density and velocity of approx. 6 x 10(exp 12) cm(exp -3) and 42,000 m/s, respectively. Optical transmittance measurements of the quartz sensors after 2 x 10(exp 5) pulses showed a rapid decrease in plume contamination with increasing angle from the plume axis, with a barely measurable transmittance decrease in the ultraviolet at 90 deg. No change in optical properties was detected for sensors in the backflow region.

  7. Bipolar pulse forming line

    DOEpatents

    Rhodes, Mark A.

    2008-10-21

    A bipolar pulse forming transmission line module for linear induction accelerators having first, second, third, fourth, and fifth planar conductors which form an interleaved stack with dielectric layers between the conductors. Each conductor has a first end, and a second end adjacent an acceleration axis. The first and second planar conductors are connected to each other at the second ends, the fourth and fifth planar conductors are connected to each other at the second ends, and the first and fifth planar conductors are connected to each other at the first ends via a shorting plate adjacent the first ends. The third planar conductor is electrically connectable to a high voltage source, and an internal switch functions to short a high voltage from the first end of the third planar conductor to the first end of the fourth planar conductor to produce a bipolar pulse at the acceleration axis with a zero net time integral. Improved access to the switch is enabled by an aperture through the shorting plate and the proximity of the aperture to the switch.

  8. Pulsed atmospheric fluidized bed combustion

    SciTech Connect

    Not Available

    1992-05-01

    During this first quarter, a lab-scale water-cooled pulse combustor was designed, fabricated, and integrated with old pilot-scale PAFBC test systems. Characterization tests on this pulse combustor firing different kinds of fuel -- natural gas, pulverized coal and fine coal -- were conducted (without fluidized bed operation) for the purpose of finalizing PAFBC full-scale design. Steady-state tests were performed. Heat transfer performance and combustion efficiency of a coal-fired pulse combustor were evaluated.

  9. Optomechanical entanglement under pulse drive.

    PubMed

    Lin, Qing; He, Bing

    2015-09-21

    We report a study of optomechanical entanglement under the drive of one or a series of laser pulses with arbitrary detuning and different pulse shapes. Because of the non-existence of system steady state under pulsed driving field, we adopt a different approach from the standard treatment to optomechanical entanglement. The situation of the entanglement evolution in high temperature is also discussed. PMID:26406654

  10. Review of pulsed phase thermography

    NASA Astrophysics Data System (ADS)

    Ibarra-Castanedo, C.; Maldague, X. P.

    2015-05-01

    Pulsed phase thermography (PPT) was proposed in 1996 to enhance results from pulsed thermography experiments. PPT can be thought as the link between pulsed thermography (PT) and lock-in thermography (LT), since it provides phase delay (and amplitude) data (as in LT) from a PT configuration. PPT theory as well as some experimental investigations has been addressed in detail in previous works. In this paper, we review the basic theory and thee experimental aspects behind PPT and we discuss the latest developments.

  11. Low-noise pulse conditioner

    DOEpatents

    Bird, David A.

    1983-01-01

    A low-noise pulse conditioner is provided for driving electronic digital processing circuitry directly from differentially induced input pulses. The circuit uses a unique differential-to-peak detector circuit to generate a dynamic reference signal proportional to the input peak voltage. The input pulses are compared with the reference signal in an input network which operates in full differential mode with only a passive input filter. This reduces the introduction of circuit-induced noise, or jitter, generated in ground referenced input elements normally used in pulse conditioning circuits, especially speed transducer processing circuits.

  12. The Practice of Pulse Processing

    NASA Astrophysics Data System (ADS)

    Fowler, J. W.; Alpert, B. K.; Doriese, W. B.; Joe, Y.-I.; O'Neil, G. C.; Ullom, J. N.; Swetz, D. S.

    2015-12-01

    The analysis of data from X-ray microcalorimeters requires great care; their excellent intrinsic energy resolution cannot usually be achieved in practice without a statistically near-optimal pulse analysis and corrections for important systematic errors. We describe the essential parts of a pulse-analysis pipeline for data from X-ray microcalorimeters, including steps taken to reduce systematic gain variation and the unwelcome dependence of filtered pulse heights on the exact pulse-arrival time. We find these steps collectively to be essential tools for getting the best results from a microcalorimeter-based X-ray spectrometer.

  13. Mode Transition of Trichel pulses

    NASA Astrophysics Data System (ADS)

    Kexin, Zhang; Yongjun, Piao; Miao, Tang; Jingfeng, Tang; Liqiu, Wei; Chaohai, Zhang

    2015-11-01

    The trichel pulse is a typical kind of negative corona current observed in electronegative gases. In this work, stochastic behavior of the trichel pulse has been investigated. The experiment is performed in a negative corona reactor consisting of a stainless steel pin and a stainless steel powered by a dc high voltage source. The characteristic parameters distributions of corona current pulses, including the amplitude, rise time, half-wave time, and repetition frequency, are analyzed statistically. The results show there is a mode transition during the period of voltage increasing. This transition process happens in a certain voltage region, and change of pulse amplitude is the main difference between the two modes.

  14. Arterial pulse wave pressure transducer

    NASA Technical Reports Server (NTRS)

    Kim, C.; Gorelick, D.; Chen, W. (Inventor)

    1974-01-01

    An arterial pulse wave pressure transducer is introduced. The transducer is comprised of a fluid filled cavity having a flexible membrane disposed over the cavity and adapted to be placed on the skin over an artery. An arterial pulse wave creates pressure pulses in the fluid which are transduced, by a pressure sensitive transistor in direct contact with the fluid, into an electric signal. The electrical signal is representative of the pulse waves and can be recorded so as to monitor changes in the elasticity of the arterial walls.

  15. Population inversion by chirped pulses

    SciTech Connect

    Lu Tianshi

    2011-09-15

    In this paper, we analyze the condition for complete population inversion by a chirped pulse over a finite duration. The nonadiabatic transition probability is mapped in the two-dimensional parameter space of coupling strength and detuning amplitude. Asymptotic forms of the probability are derived by the interference of nonadiabatic transitions for sinusoidal and triangular pulses. The qualitative difference between the maps for the two types of pulses is accounted for. The map is used for the design of stable inversion pulses under specific accuracy thresholds.

  16. Fast pulse nonthermal plasma reactor

    DOEpatents

    Rosocha, Louis A.

    2005-06-14

    A fast pulsed nonthermal plasma reactor includes a discharge cell and a charging assembly electrically connected thereto. The charging assembly provides plural high voltage pulses to the discharge cell. Each pulse has a rise time between one and ten nanoseconds and a duration of three to twenty nanoseconds. The pulses create nonthermal plasma discharge within the discharge cell. Accordingly, the nonthermal plasma discharge can be used to remove pollutants from gases or break the gases into smaller molecules so that they can be more efficiently combusted.

  17. Ultra-short pulse generator

    DOEpatents

    McEwan, T.E.

    1993-12-28

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

  18. Pulsed helium ionization detection system

    DOEpatents

    Ramsey, R.S.; Todd, R.A.

    1985-04-09

    A helium ionization detection system is provided which produces stable operation of a conventional helium ionization detector while providing improved sensitivity and linearity. Stability is improved by applying pulsed dc supply voltage across the ionization detector, thereby modifying the sampling of the detectors output current. A unique pulse generator is used to supply pulsed dc to the detector which has variable width and interval adjust features that allows up to 500 V to be applied in pulse widths ranging from about 150 nsec to about dc conditions.

  19. Pulsed helium ionization detection system

    DOEpatents

    Ramsey, Roswitha S.; Todd, Richard A.

    1987-01-01

    A helium ionization detection system is provided which produces stable operation of a conventional helium ionization detector while providing improved sensitivity and linearity. Stability is improved by applying pulsed dc supply voltage across the ionization detector, thereby modifying the sampling of the detectors output current. A unique pulse generator is used to supply pulsed dc to the detector which has variable width and interval adjust features that allows up to 500 V to be applied in pulse widths ranging from about 150 nsec to about dc conditions.

  20. Ultra-short pulse generator

    DOEpatents

    McEwan, Thomas E.

    1993-01-01

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