Showing papers on "Pulse repetition frequency published in 2003"

Analysis of micro-Doppler signatures

Abstract: Mechanical vibration or rotation of a target or structures on the target may induce additional frequency modulations on the returned radar signal which generate sidebands about the target's Doppler frequency, called the micro-Doppler effect. Micro-Doppler signatures enable some properties of the target to be determined. In the paper, the micro-Doppler effect in radar is introduced and the mathematics of micro-Doppler signatures is developed. Computer simulations are conducted and micro-Doppler features in the joint time - frequency domain are exploited.

Dose-response and ghosting effects of an amorphous silicon electronic portal imaging device.

Abstract: The purpose of this study was to investigate the dose-response characteristics, including ghosting effects, of an amorphous silicon-based electronic portal imaging device (a-Si EPID) under clinical conditions. EPID measurements were performed using one prototype and two commercial a-Si detectors on two linear accelerators: one with 4 and 6 MV and the other with 8 and 18 MV x-ray beams. First, the EPID signal and ionization chamber measurements in a mini-phantom were compared to determine the amount of buildup required for EPID dosimetry. Subsequently, EPID signal characteristics were studied as a function of dose per pulse, pulse repetition frequency (PRF) and total dose, as well as the effects of ghosting. There was an over-response of the EPID signal compared to the ionization chamber of up to 18%, with no additional buildup layer over an air gap range of 10 to 60 cm. The addition of a 2.5 mm thick copper plate sufficiently reduced this over-response to within 1% at clinically relevant patient-detector air gaps (> 40 cm). The response of the EPIDs varied by up to 8% over a large range of dose per pulse values, PRF values and number of monitor units. The EPID response showed an under-response at shorter beam times due to ghosting effects, which depended on the number of exposure frames for a fixed frame acquisition rate. With an appropriate build-up layer and corrections for dose per pulse, PRF and ghosting, the variation in the a-Si EPID response can be reduced to well within +/- 1%.

Noise Radar for range/Doppler processing and digital beamforming using low-bit ADC

Abstract: Pulse compression radar is used in a great number of radar applications. Excellent range resolution and high resistance to electronic countermeasures (ECM) can be achieved by long wideband modulated pulses, which spread out the transmitted energy in frequency and time. By using random noise as the waveform, the range ambiguity can be suppressed as well. In this paper, noise radar for Doppler/range indication and digital beamforming is described. Main factors influencing the resolution and sidelobe level in range and Doppler are surveyed. In particular, the possible use of binary or low-bit analog-to-digital converters (ADCs) in noise radar is analyzed, which highly improves the signal-processing rate and reduces the costs. The very significant improvement of sidelobe suppression, when an extra noise signal is added before ADC, is explained theoretically and confirmed by simulation results. Mostly, the random signal is transmitted directly from a noise generating high-frequency source. A sine wave, which is phase or frequency modulated by random noise, is an alternative, giving lower range sidelobes, and higher transmitted mean power when peak-limited transmitters are applied. The dynamic requirements and the bandwidth of the modulating signal can be reduced as well.

Pulse energy enhancement in passive Q-switching operation with a class of Nd:GdxY1−xVO4 crystals

Abstract: Passive Q-switching operation with a class of Nd:GdxY1−xVO4 crystals has been demonstrated. Compared to Nd:YVO4 and Nd:GdVO4, the pulse energy produced with Nd:Gd0.64Y0.36VO4 under certain conditions was found to be enhanced by factors of 6.0 and 2.5, while the peak power enhanced by factors of 14.7 and 3.6, respectively. At the incident pump power of 9.6 W, 1.3 W of average output power was obtained, with the pulse energy, peak power, and pulse repetition frequency being 166 μJ, 24.5 kW, and 7.7 kHz, respectively.

Method and apparatus for physical layer radar pulse detection and estimation

Abstract: Radar Pulse detection and radar signal length detection are used to detect and provide information for identifying radar signals. Pulse detection estimates a radar pulse size when it is too short for meaningful measurement. Pulse detection identifies a radar by identification of an in-band pulse without a communication or data packet encoded therein, or a communication error is detected with the in-band pulse. Signal length detection counts the length of a received signal after the received signal exceeds a radar threshold. The count identifies the received signal length upon drop of the power. The signal is identified as a radar when the power drops before a PHY error occurs, or when the power drop occurs after a PHY error and a delay time equivalent to the shortest radar signal. A radar signal is also identified upon a timeout wait for a power drop after a PHY error.

Analysis and Correction of Dual PRF Velocity Data

Abstract: The dual pulse repetition frequency (dual PRF) technique for extension of the unambiguous velocity interval is available on many operational Doppler weather radars. Radial velocity data obtained from a C-band Doppler radar running in dual PRF mode have been analyzed quantitatively. The standard deviation of the velocity estimates and the fraction of dealiasing errors are extracted and related using a simple model. A postprocessing algorithm for dual PRF velocity data, which removes noise and corrects dealiasing errors, has been developed and tested. It is concluded that the algorithm is very efficient and produces high quality velocity data.

Automatic optimization methods and systems for doppler ultrasound imaging

Abstract: Methods and systems are provided for automatic optimization of spectral Doppler ultrasound imaging. One or more of the velocity scale (e.g., pulse repetition frequency), gain, baseline, dynamic range or other imaging parameters are optimized based on one or both of: (1) determining the optimum parameter based on data acquired at a standard or predetermined setting of the parameters and (2) identifying an artifact in the Doppler ultrasound data and discarding or minimizing the influence of the artifact on any determination of imaging parameter settings. One embodiment used for cardiac Doppler imaging identifies artifact signals using the maximum or minimum traces. For example, the velocity scale or pulse repetition frequency is set based on the maximum or minimum velocity value over one or more heartbeats identified from a maximum and minimum trace of the signal envelope or Doppler spectrum. Since flows in cardiology may contain high energy, high velocity, short duration signals caused by valve clicks, these artifacts are identified and discarded in determining the maximum and minimum values.

Automatic optimization for ultrasound medical imaging

Abstract: Methods and systems are provided for automatic optimization for ultrasound medical imaging. In one approach, velocity values are unwrapped to avoid aliasing artifacts. Multi-dimensional phase unwrapping is applied to the velocity data. The unwrapped velocity information is used to optimize one or both of the velocity scale (e.g., pulse repetition frequency) and the imaging frequency. For optimizing the scale setting, the distribution of unwrapped velocities from a systolic time period of the heart cycle are used to identify the pulse repetition frequency. For optimizing the imaging frequency, a correlation as a function of depth shows the penetration depth for a given imaging frequency. In a dependent or independent approach, one or more thresholds for velocity or energy in flow imaging are adaptively selected as a function of an amount of clutter. Velocity or other energy information in addition to the clutter information may be used for selecting the thresholds. In yet another dependent or independent approach, displacement of an imaging plane or other change is detected and used to trigger an automatic update of an imaging parameter for a same or different mode.

A 35-GHz Scanning Doppler Radar for Fog Observations

Abstract: To observe fog, a 35-GHz scanning Doppler radar was designed, assembled, and tested. The radar, mounted on a flatbed vehicle for portability, transmits peak powers of 100 kW in a pulse of 0.5-µs width and a beamwidth of 0.3°. Thus, a reflectivity factor Z of −20 dBZ at a range of 10 km generates a signal-to-noise ratio of 0 dB. Doppler velocity measurements are made by sampling the radio frequency phase within each pulse transmitted by a magnetron oscillator and referencing the phases of the received echoes to the transmitted phase. A Nyquist velocity of approximately 9.7 m s–1 is obtained in real time using the spaced pulse-pair method, and aliases of radial velocities are corrected using software. The three-dimensional structure of sea fog and its advection are depicted with the radar.

Medium PRF radar PRF selection using evolutionary algorithms

Abstract: Evolutionary algorithms are applied to the optimization of pulse repetition frequency (PRF), for both eight-and nine PRFs, in medium PRF radar while considering the detailed effects of sidelobe clutter and many other technical factors. The algorithm presented also ensures that all the solutions produced are fully decodable and have no blind velocities. The evolutionary algorithm was able to identify near-optimum PRF sets for a realistic radar system with only a modest computational effort.

A novel pulse compression scheme based on minimum mean-square error reiteration [radar signal processing]

Abstract: This paper presents an alternative approach to pulse compression that is based upon iterative minimum mean-square error (MMSE) estimation It is similar to the well known least squares (LS) approach but does not suffer from the adverse effects caused by scatterers closer than some nominal range This results in a more robust estimate of the radar returns while maintaining nearly the same sidelobe level Furthermore, the proposed pulse compression scheme is highly parallelizable in range and therefore can be computed efficiently

A Novel Pulse Compression Scheme Based on Minimum Mean-Square Error Reiteration

Abstract: — This paper presents an alternative approach to pulse compression that is based upon iterative Minimum Mean-Square Error (MMSE) estimation. It is similar to the well-known least squares (LS) approach but does not suffer from the adverse effects caused by scatterers closer than some nominal range. This results in a more robust estimate of the radar returns while maintaining nearly the same sidelobe level. Furthermore, the proposed pulse compression scheme is highly parallelizable in range and therefore can be computed efficiently. I. I NTRODUCTION Pulse compression allows a radar to obtain the range resolution of a short pulse without the need for very high peak transmit power. This is accomplished by transmitting a long pulse that is phase or frequency modulated to generate a wideband signal. The wideband signal is reflected back to the radar by scatterers in the beam of the radar which can be viewed as the convolution of the wideband signal with a channel that is representative of the range profile illuminated by the radar. The purpose of pulse compression is then to estimate the radar channel based on the known transmitted signal and the received radar return signal. The classical approach to pulse compression is known as matched filtering [1] which has been shown to maximize the received signal-to-noise ratio (SNR) and is accomplished by convolving the transmitted signal with the received radar return signal. One can represent matched filtering in the digital domain as the filtering operation ˆ

Pulse picking by phase-coherent additive pulse generation in an external cavity.

Abstract: We have implemented a simple method for generating an "amplified" phase-coherent light pulse in which a pulse train of phase-coherent, equidistant input light pulses from a mode-locked Ti:sapphire laser is coupled into a ring cavity resonator whose length is matched to the mode-locked pulse repetition frequency at 82 MHz. Pulses are thus coherently superimposed and added inside the buildup cavity and form an intense pulse that is switched out from the cavity via a fast acousto-optic modulator. The method thus provides a pulse train at a reduced and controlled repetition frequency and with higher pulse energies than the original mode-locked pulses.

Removing autocorrelation sidelobes by overlaying orthogonal coding on any train of identical pulses

Abstract: A coherent train of identical linear FM (LFM) pulses is used extensively in radar because of its good range and Doppler resolution. Its relatively high autocorrelation function (ACF) sidelobes are sometimes reduced through spectrum shaping (e.g., nonlinear FM, or intrapulse weighting on receive). We show how to completely remove most of the ACF sidelobes about the mainlobe peak, without any increase to the mainlobe width, by diversifying the pulses through overlaying them with orthonormal coding. A helpful byproduct of this design is reduced ACF recurrent lobes. The overlaid signal also results in reduced Doppler tolerance, which can be considered as a drawback for some applications. The method is applied to several trains of identical pulses (LFM and others) using several orthonormal codes. The effect on the three important properties of the radar signal: ACF, ambiguity function (AY), and frequency spectrum is presented. The effect on Doppler tolerance is studied, and implementation issues are discussed. The new design is also compared with complementary and sub-complementary pulse trains and is shown to be superior in many aspects.

Radar measurement device, especially for a motor vehicle, and method for operating a radar measurement device

Abstract: The invention relates to a radar measurement device which has a simple structure and which enables reliable distance measurement even when a mixed signal is reset to zero. The invention also relates to a method for operating a measurement device. The radar measurement device comprises a high-frequency oscillator (11) emitting two different carrier frequency signals (F1,F2), a first switching device (14) for switching the carrier frequency signals (F1, F2) according to first pulse signals (P1) and for emitting radar pulse signals (T1,2), a transmission aerial (16) and a reception aerial (18), a second switching device (24) for switching carrier frequency signals according to a delayed second pulse signal (P2) and for emitting delayed radar pulse signals (S1,2), a mixing device (21) for mixing received radar signals (R1,R2) with the delayed radar pulse signals (S1,S2) and for emitting mixed signals (M1,M2). The phase difference between the received radar signals (R1,R2) and delayed radar pulse signals (S1,S2) varies according to a predefined value when the two carrier frequency signals (F1,2) are emitted. An amplitude signal is determined from the first and second mixed signals (M1, 2).

Physical-Layer Modeling of UWB Interference Effects

Abstract: : The NETEX program is focused initially on understanding the effects of interference from ultra-wideband (UWB) transmitters on legacy military radio receivers, nearly all of which are narrowband (NB) relative to the UWB signal, which can have a bandwidth on the order of 1 GHz The purpose of this report is to document a set of mathematical models which have been developed to analyze the impact of UWB signals on NB receivers This analysis work is being done in parallel with a UWB interference testing program being conducted by other parties There are two main components to the work presented here The first is a detailed analysis of the power spectral density (PSD) of the UWB signal, which shows the distribution of the UWB transmit power over frequency The PSD is determined by (1) the spectrum of the basic UWB pulse; and (2) pulse position modulation/dithering and pulse amplitude modulation A clear understanding of the PSD is important, because the main factor that determines the impact on a NB receiver is the total average UWB interference power within the receiver passband This is demonstrated by the second main component of the report, which is a set of models describing the impact of UWB interference on several different representative receiver types, both digital and analog The PSD gives the average power-per-Hz as a function of frequency for the UWB signal The UWB PSD models developed here allow the PSD to be computed analytically for a wide range of different UWB signal types, and include the effects of pulse-position modulation (PPM), random or periodic pseudo-random dithering of the pulse position, modulation or random (or pseudo-random) coding of the pulse amplitude, modulation symbols that include multiple UWB frames (giving integration gain), and modulation of the actual pulse repetition frequency (PRF) by either a periodic PRF-modulating signal or by a random process such as a data signal

Cloud profiling radar for EarthCARE mission

Abstract: Concept and expected performance of cloud profiling radar (CPR) for EarthCARE are described based on preliminary design study conducted to date. High sensitivity and Doppler capability are two significant new features in this CPR. Particularly, Doppler capability is the first attempt to spaceborne atmospheric radar, which requires great efforts in technical development and feasibility validation. We have developed a new numerical simulation method to assess Doppler velocity accuracy applicable to this application, and results are compared with conventional approximation method. Validity and limitation of the approximation method are indicated from comparison with numerical method. It is shown that requirements to radar sensitivity and Doppler measurements will be satisfied. However, because these requirements to CPR are very tough, further detailed study on both design optimization and assessment technique development are necessary. Under radar operation with very high pulse repetition frequency (PRF) required in this CPR, surface clutter interference caused through antenna sidelobes is an important issue. Analysis on this issue and preliminary requirements to the antenna sidelobes are also discussed.

Variable pulse repetition frequency for the Global Precipitation Measurement Project (GPM)

Abstract: Pulse patterns are designed by adopting variable pulse repetition frequency (VPRF) for space missions involving beam scans in the cross-track direction, especially intended for the Global Precipitation Measurement Project (GPM). To cope with large variance in range from a satellite, which is caused by the beam swing and the Earth oblateness, a systematic algorithm is proposed, increasing sampling rates.

Method and radar system for determining the directional angle of radar objects

Abstract: A method for determining the directional angle of radar objects using a multibeam radar, including the steps of: (a) recording the frequency spectra of the radar echoes for a plurality of beams; (b) seeking a measuring frequency near a frequency maximum assigned to the radar object; and (c) comparing the phases and/or amplitudes of the radar echoes at the measuring frequency with reference patterns known for various directional angles, steps (b) and (c) being executed repeatedly, each time for different measuring frequencies, and the directional angles obtained for the various measuring frequencies being checked for consistency.

Focusing range image in VCO based FMCW radar

Abstract: This paper presents a simple method for focusing images in VCO based cheap FMCW radar. Image defocusing is caused by non-linear distortions in the voltage controlled oscillator (VCO, very often YIG type). To obtain good quality FMCW radar images, a linear frequency modulated (LMF) signal is required. Even small changes in voltage-frequency VCO characteristics cause range defocusing, and therefore decrease of radar sensitivity and resolution. The method, derived from the polynomial model of non-linear LFM signal phase, is based on a generalized chirp transform of the video (intermediate frequency IF) signal obtained by mixing the transmitted LFM signal with the received (delayed) signal. To avoid complicated laboratory equipment (such as optical delay lines) the whole procedure is performed on live radar signals, using a maximum contrast approach.

Thresholds for retinal injury from multiple near-infrared ultrashort laser pulses

Abstract: Multiple-pulse lasers are routinely used in the laboratory for research, manufacturing, medical procedures, and in military applications. In order to provide a safe work environment for personnel using these lasers, safety standards have been established and have been in use for many years. These safety standards have addressed laser pulses of nanosecond duration and longer. Recently, safety standards have been updated to address laser pulses as short as 100 femtoseconds in duration. In order to tie these "ultrashort" laser pulses to hazard trends in currently established standards for multiple-pulse exposures with repetition rates less than several kilohertz, this experiment was conducted. Reported herein are minimum visible lesion thresholds in the paramacula of the primate retina using an 800-nm wavelength laser with 1,000 pulses per second, at 130 femtoseconds (fs) pulse duration. The minimum visible lesion (MVL) thresholds were determined at 1 h and 24 h post exposure for 1, 10, 100, 1,000, and 10,000 pulses and are compared with thresholds reported by other researchers. These new data are evaluated relative to the current safety standards for retinal exposure limits as a function of the number of pulses for femtosecond-pulse duration. Data from this study show that the retinal ED50 thresholds/pulse in the paramacula decrease by almost a factor of four as the number of pulses goes from one to ten and then decrease very little for an increase of three decades more in the number of pulses. The MVL-ED50 at the threshold decreased from 0.55 microJ for a single pulse to 0.15 microJ/pulse for 10 pulses and then only to 0.11 microJ/pulse for 10,000 pulses.

Device for, in particular, bistatic radar applications

Abstract: The invention relates to a device for, in particular, bistatic radar applications in which at least two interspaced radar sensors (11, 12) are provided with separate carrier frequency oscillators (21, 22) that do not have to be phase-synchronized. The pulse modulation synchronously ensues in all transmitter and receiver pairs. Cross-echo signals can be evaluated by means of an evaluating device (4) inside of which a mixing (7) of the transmitted and received signals ensues.

Time correlation of ultrafast laser pulses

Abstract: Time-correlation methods for determining pulse characteristics from a modelocked ultrafast laser include a cross-correlation method and an auto-correlation method. In the cross-correlation method, pulses from the laser and pulses from another modelocked laser are incident on a two-photon detector that responds when the pulses overlap in time. The lasers are synchronized to the same frequency and the phase difference between pulses from the two lasers is varied to vary the temporal pulse overlap while recording the detector response. Pulse characteristics are determined from recorded data representing the detector response as a function of phase difference. In the auto-correlation method, pulses from one laser are divided into two components. One component follows a fixed delay path before being temporally overlapped at the detector with another component that has not been delayed. The temporal overlap is varied by varying the pulse repetition frequency. Pulse characteristics are determined from recorded data representing the detector response as a function of phase difference.

Repetitive short-pulsed generator using MPC and blumlein line

Abstract: Recently, repetitive pulsed power generators using magnetic pulse compression (MPC) and semiconductor switches have been developed. A repetitive short-pulsed generator for an ozonizer was studied and developed. In this work, the short-pulsed generator consists of a controller, a command charger, a high-speed thyristor, a MPC and a Blumlein line. The controller and the command charger are able to control the charging voltage to the MPC and the pulse repetition rate. The high-speed thyristor, which was improved in switching speed for the pulsed power applications, generated the primary pulse. The MPC has single stage pulse compression circuit using a pulse transformer and a saturable transformer. The saturable transformer has two functions, a step-up transformer and a magnetic switch. The Blumlein line is the final stage of the short-pulsed generator. The Blumlein line is three-coaxial geometry, which has an external electrode diameter of 110 mm, a middle electrode diameter of 20 mm, an internal electrode diameter of 4 mm, and a length of 500 mm. The short-pulsed generator which has an output voltage of about 65 kV, pulse repetition rate of 150 pulses per second (pps) and a pulse duration of less than 10 ns was used to generate ozone. The results of ozone production using the short-pulsed generator and a simple coaxial electrodes are reported. The attained concentration of ozone was 18 g/m/sup 3/.

Length measurement with radar

Abstract: In a method for determination of the length of objects in traffic, especially passenger cars, trucks, buses, motorbikes, bicycles and pedestrians, radar signals are transmitted by a vehicle, the radar signals are reflected by an object being measured, the reflected radar signals are received in the vehicle, the frequency spectra of the reflected radar signals are evaluated, and the reflection peaks contained in the frequency spectra are determined. Length measurement, by means of known radar sensors, from a vehicle is made possible by the fact that the width of the reflection peaks is determined, and that the length of the object being measured is determined by means of the determined width.

The dual-frequency precipitation radar for the GPM core satellite

Abstract: This paper outlines the development of the dual-frequency precipitation radar (DPR) to be flown on the Global Precipitation Mission's "core" spacecraft. I. INTRODUCTION In the Global Precipitation Mission (GPM), a dual- frequency precipitation radar (DPR) is planned to be flown on the "core" spacecraft. The "core" spacecraft serves as a high quality reference platform for training and calibrat- ing the rain retrieval algorithms used with the passive mi- crowave radiometers on the other "constellation" satellites. The dual-frequency radar is expected to provide accu- rate estimates of rainfall rate as well as drop size distribu- tion (DSD) parameters from the combination of Ku- and Ka-band radar returns. This paper outlines the present status of the DPR development. Following this introduc- tion, we discuss the critical issues that affect the designing of the DPR. II. DPR REQUIREMENTS A. Relevance of the DPR to GPM The relevance of the DPR to GPM lies in the radar's ca- pability of measuring storm structure, rainfall rates, drop- size distribution (DSD), path-integrated attenuation, and other useful parameters that cannot be obtained by pas- sive sensors. In the latest design, the DPR is composed of Ku-band and Ka-band channels. The Ku-band radar is approxi- mately the same as the TRMM Precipitation Radar (PR) with some improvements. The Ka-band radar provides high sensitivity to light rain and snow. The combination of data from two channels will provide accurate estimates of drop-size distribution parameters. The Ka-band radar will sample the echo data in two different modes simulta- neously. One is a high-sensitivity mode for light rain and snow detection, and the other is a matched-beam mode in which the sampling volumes of Ka- and Ku-band radar channels are matched for collecting dual-frequency echoes from the identical targets. The data collected in the lat- ter mode are used for the estimation of DSD parameters. In the matched-beam mode, a range resolution of 250 m is employed, while in the high-sensitivity mode, a range resolution of 500 m is planned. The current radar design adopts active phased array antennas in both radar chan- nels to make full use of TRMM experience. The DPR will provide three-dimensional information of hydrometeor distribution with high spatial resolution. Such data are very valuable for the study of storm struc- ture. The accurate rainfall estimates from the DPR are expected to be used for calibrating the corresponding esti- mates from the radiometer on the core satellite. The major importance of the DPR, however, lies in the fact that it can provide the regional and seasonal statistics of storm structure together with DSD parameters. Since rain re- trieval algorithms for passive microwave radiometers have to assume a vertical structure of storm either determinis- tically or statistically, reliable storm structure information is crucial for the accuracy of rain estimation. The statis- tics from the DPR can be used as a database in radiometer algorithms to reduce the uncertainties of the storm mod- els. How to utilize the information from radar data is a challenging issue. A possibility of improving the database used in a TMI rain retrieval algorithm by using TRMM's PR data is currently under examination. The DPR has three main roles in GPM. It will provide three-dimensional information of rain structure. The Ku- band radar is similar to, but not exactly the same as, the TRMM Precipitation Radar (PR). It is improved from the PR. The improvement is necessary because of three rea- sons. Firstly, the proposed orbit of the GPM core satellite is about 400 km and higher than the TRMM's orbit. This necessitates the improvement of the sensitivity to com- pensate for the increased range loss. The designed trans- mitting power is increased to 1000 W from PR's 500 W. (the actual Tx power of the PR turned out to be about 800 W.) Secondly, the orbital inclination is about 65 de- grees and larger than the TRMM's 35 degrees. Because of the oblate shape of the Earth, the altitude of the satel- lite changes more than 20 km at a 65-degree orbit which is much larger than 10 km at a 35-degree orbit. If we use a constant pulse repetition frequency (PRF) like the TRMM PR, we have to use a rather small PRF to absorb this large variation of rain echo range from the radar. The low PRF will result in a low signal-to-noise ratio. To max-

Challenges for a new integrated ultra-wideband (UWB) source

Abstract: This paper presents a description of a new method to generate a short impulse based on a counter designed on BiCMOS SiGe technology This architecture includes a new method to modify the PRF (pulse repetition frequency) by changing the counter division ratio and an easy way to control the impulse frequency center A pseudo-noise sequence prescaler modulates the impulses with specific modulation schemes, such as pulse position, bi-phase modulation or a combination of both The total power consumption is 65 mA at 7GHz

High range resolution radar system

Abstract: Described herein is a method and apparatus for improving high range resolution of a radar system. The method comprises phase shifting a radar pulse to be transmitted at substantially the radar transmission frequency and phase shifting the received radar pulse at substantially the radar transmission frequency. The phase shifting is implemented using a monolithic microwave integrated circuit (MMIC) (42) driven by a digital circuit (44) to provide a phase profile which is applied to radar pulse (52) produced by a radar generator (54) and which is also applied to a received radar pulse (60). A master clock and synchroniser (72) provides clock signals for an analogue to digital converter ((ADC) (68), the generator (54) and the digital circuit (44) so that the MMIC (42) is clocked at a frequency which is directly harmonically related to the ADC (68). This avoids spurious beat frequencies which could interfere with a wanted radar signal.

Linear frequency modulation superimposed on double sideband diplex radar

Abstract: A double side band diplex linear frequency modulated superimposed radar system determines the range of targets as a function of the amplitude variation of reflected target Doppler signals. The present invention includes a real radar system that accurately determines the range of fading targets and the magnitude of the velocity of the targets. The present invention also includes a complex radar system that determines the relative velocity of targets in addition to the range of targets. The present invention also includes a real radar system having BPSK modulation. The selection of BPSK modulation enables or facilitates. the implementation of a portion of the system in digital form.