Abstract: A data code generator produces a data code, while a reference code generator produces a reference code. The data code is phase-shifted by the data code generator in a predetermined sweep range, according to a sweep command signal given by a phase difference detector. The phase difference detector compares the phase of the data code with that of the reference code to obtain phase difference data. Based on the phase difference data, a correction signal generator produces a correction signal to keep the data code in phase with the reference, code. The phase setter optimizes the phase of the data code according to the correction signal.

Abstract: A transmission unit emits an electromagnetic wave having the same frequency f as an output signal from a sending unit in a direction of a measurement axis. A detecting unit performs synchronous detection on a reflected wave detected by a directional coupler by an in-phase signal and a quadrature signal of the transmission signal, and by extracting DC component from the detection signal, detects the in-phase component and quadrature component of the reflected wave. An analysis signal generating unit mixes the in-phase component and quadrature component of the reflected wave and signals having periodicity corresponding to a prescribed distance, and using only one of the resulting side bands, generates an analysis signal. Fourier transform unit finds distance to the object of measurement from a profile obtained by Fourier transform of the analysis signal.

Abstract: A spread spectrum radar apparatus includes: a transmission unit which generates a spread signal that is a spectrum-spread signal, using a first oscillator signal, a second oscillator signal, and a transmission PN code, and which emits the spread signal as a detection radio wave; and a reception unit which receives, as a reception signal, the detection radio wave reflected from an object, and which generates an intermediate frequency signal by despreading the reception signal based on the first oscillator signal and a reception PN code obtained by delaying the transmission PN code.

Abstract: Provided is a pulse radar system capable of measuring the distance to an obstacle with high accuracy irrespective of the distance to an obstacle by securing distance resolution with respect to a reflective wave from an obstacle at a short distance, and preventing a decline in S/N ratio with respect to a reflective wave from an obstacle at a long distance. A pulse radar system includes a transmitting circuit, a transmitting antenna, a receiving antenna, a receiving circuit, and a gain control circuit. The gain control circuit generates a gain control signal corresponding to the amplitude of the reception pulse obtained in response to a gain control transmission pulse wave transmitted from the transmitting circuit, and controls the gain of a reception pulse wave or a reception pulse obtained in response to a measurement transmission pulse wave transmitted from the transmitting circuit after the gain control transmission pulse wave.

Abstract: Array antenna calibration verification coupling interrogator and responder with mode-related interrogation signal having a previous calibration phase angle, producing in responder a characteristic interrogation response. Conjugate signal is generated by reversing phase of interrogation signal, producing in responder a characteristic conjugate response. Interrogation and conjugate responses sensed and combined to determine difference characteristic for responder array element. Responder difference characteristic iteratively determined for elements in antenna array representative of present calibration verification state. Present and previous calibration verification states compared, with significant variation adapting array to desired calibration verification state. Verification processor controls interrogator, responders, and signals providing built-in missile RADAR calibration verification.

Abstract: In a method for suppressing interferences while detecting objects in a target area, a transmitter transmits a sequence of pulses into the target area, and a receiver detects the resulting reflection signal of the pulses reflected from the objects, within successive time windows that are referenced to the moment of transmitting an individual pulse and thus represent distance gates. The time spacing between the successive individual pulses is variable and randomized according to the pseudo-noise principle within predetermined limits, and the time windows are adapted accordingly. The received reflection signal may be sampled, digitized, digitally pre-processed and digitally filtered in the individual distance gates. A non-linear digital filter, preferably a sliding median filter, is used for the filtering to suppress transient disturbances. The median is determined from an odd number of consecutive sampled values of a reflection signal detected within a distance gate.

Abstract: Array antenna calibration verification coupling interrogator and responder with mode-related interrogation signal having a previous calibration phase angle, producing in responder a characteristic interrogation response. Conjugate signal is generated by reversing phase of interrogation signal, producing in responder a characteristic conjugate response. Interrogation and conjugate responses sensed and combined to determine difference characteristic for responder array element. Responder difference characteristic iteratively determined for elements in antenna array representative of present calibration verification state. Present and previous calibration verification states compared, with significant variation adapting array to desired calibration verification state. Verification processor controls interrogator, responders, and signals providing built-in missile RADAR calibration verification.

Abstract: Image reconstruction approaches that use standard Cartesian-sampled, frequency-domain SAR data, which can be collected by a platform with a single radar antenna, together with its associated metadata as the input and generate an output comprised of a set of images that show the directions of moving targets, estimates of their motions, and focused images of these moving targets.

Abstract: A computer system for processing interferometric synthetic aperture radar (SAR) images includes a database for storing SAR images to be processed, and a processor for processing interferometric SAR images from the database. The processing includes receiving first and second complex SAR data sets of a same scene, with the second complex SAR data set being offset in phase with respect to the first complex SAR data set. Each complex SAR data set includes a plurality of pixels. An interferogram is formed based on the first and second complex SAR data sets for providing a phase difference therebetween. A complex anisotropic diffusion algorithm is applied to the interferogram. The interferogram includes a real and an imaginary part for each pixel. A shock filter is applied to the interferogram. The processing further includes performing a two-dimensional variational phase unwrapping on the interferogram after application of the shock filter.

Abstract: A system for simultaneously propagating dual polarized signals in a polarimetric radar system includes a system for coding at least one of the two signals. The simultaneous dual polarization weather radar transmits signals in both the horizontal and vertical orientations at the same time. Upon reception, the signals in each channel are decoded and a number of standard and polarimetric parameters characterizing atmospheric conditions are determined. The accuracy upon which these parameters can be determined depends partially upon the interference between these two channels. The system and method isolates the vertical and horizontal channels to minimize the interference.

Abstract: A monopulse radar operating at low angles of elevation (LOE) receives returns from a target by a direct path and by a path including a reflection from that portion of the Earth's surface lying between the radar and the target. The surface-reflected signal tends to cause errors in the estimate of the elevation of the target. A radar system directs at least upper and lower overlapping beams at LOE toward the target for receiving returns. The upper and lower beams may be sequential or simultaneous. Real and imaginary portions of the sum (?) and difference (?) signals are generated for each beam. The monopulse estimates of elevation ê derived from the real portion of the ? and ? signals are processed to produce correction signals for upper and lower beams. Each correction signal is weighted and summed to correct the estimate of elevation.

Abstract: A system and method of using a standard ADS-B transmitter and encoder to identify targets to provide a collision avoidance system, wherein the method includes the steps of providing a standard ADS-B transmitter and encoder, a phase modulator including a digital synthesizer, radio-frequency electronics, antennas, and a radar transceiver; synthesizing digital-based band signals from the ADS-B transmitter with additional random phase modulation using the digital synthesizer; using the antennas to both transmit and receive signals; and estimating angles-of-arrival for every target in a field-of-view. The method may include the steps of demodulating the signals received by the antennas, providing a digital signal processor, and performing matched filtering on received signals. The method may also include the step of estimating a target range of identified targets using the digital signal processor.

Abstract: A FM-CW radar system comprises a frequency modulated continuous wave digital generator that produces both in-phase (I) and quadrature-phase (Q) outputs to orthogonally oriented transmitter antennas. A linearly polarized beam is output from a switched antenna array that allows a variety of I-and-Q pairs of bowtie antennas to be alternately connected to the transmitter and receiver. The receiver inputs I-and-Q signals from another bowtie antenna in the array and mixes these with samples from the transmitter. Such synchronous detection produces I-and-Q beat frequency products that are sampled by dual analog-to-digital converters (ADC's). The digital samples receive four kinds of compensation, including frequency-and-phase, wiring delay, and fast Fourier transform (FFT). The compensated samples are then digitally converted by an FFT-unit into time-domain signals. Such can then be processed conventionally for range information to the target that has returned the FM-CW echo signal.

Abstract: A pulsed radar system uses phase noise compensation to reduce phase noise due to drift of the reference oscillator to enable detection of micro movements and particularly human motion such as walking, breathing or heartbeat. The noise level due to A/D sampling must be sufficiently low for the phase noise compensation to be effective. As this is currently beyond state-of-the-art for high bandwidth A/D converters used in traditional receiver design, the receiver is suitably reconfigured to use analog range gates and narrowband A/D sampling having sufficiently low noise level. As technology continues to improve, the phase compensation techniques may be directly applicable to the high bandwidth A/D samples in traditional receiver designs.

Abstract: The number of times for averaging operation for averaging a correlation value of a received signal and a reference signal is properly controlled. When the correlation value is not averaged, since a lower limit value TH_A of a correlation level of a distribution of timings of which a path exists is larger than an upper limit value TH_B of a correlation level of a distribution of timings of which a path does not exist, the correlation value of a path is hidden by noise. Since the averaging operation is repeated until the relation of TH_A>TH_B is satisfied, the averaging operation is stopped when the relation is satisfied. The TH_A and TH_B are decided in accordance with RSCP and ISCP of a pilot channel and RSSI of a received base band signal.

Abstract: A directional coupler, for example a rat-race coupler, for use in radar engineering is disclosed. In one embodiment, the directional coupler includes at least three ports which are electrically connected to one another by a number of line branches, all line branches being constructed as balanced pairs of lines.

Abstract: A method of Partial Parallel Interference Cancellation (PPIC) is provided for recursively eliminating the Multiple Access Interference from a received signal. Such method is to use a recursion way to eliminate all the Multiple Access Interference (MAI) one by one from the received signal. Moreover, the present invention is to take the output of the pre-stage as the input of the present stage with the recursion method so that we can use only one operating circuit to obtain the function the MAI eliminating.

Abstract: In a radar system, a monopulse calibration table is constructed from live targets of opportunity. A center of gravity or weighted average of normalized signals ?V received at SUM and DIFF channels from a live target are used to determine the target's actual azimuth. Off bore sight angles (OBA) of the target are then determined from the target's actual azimuth. Normalized received signal values of ?V are converted to nearest-valued integers. The OBA s that correspond to each integer-valued normalized received signal are averaged and can then be plotted as a function of normalized received signal value ?V. Different tables or plots can be constructed for elevation angles. An equation of a best-fit line the matches or at least closely approximates the plotted data is determined to smooth the actual data.

Abstract: A complex image is apodized to suppress sidelobes. An original complex image of an object is received. The complex image comprises a plurality of data points and sidelobes. The complex image is transformed to a k-space image which is then trimmed to remove all points outside of a geometric shape. This trimming is done with the shape overlaying the image and being at a first angle with respect to the image. The trimming produces a trimmed k-space image. The trimmed k-space image is then converted back to a new complex image having a sidelobe structure different from the original complex image. The new complex image is then normalized by adjusting its intensity such that its peak amplitude matches a peak amplitude in the original complex image. A minimum function is then performed on the magnitudes of the original and new complex images. The result is an apodized image with suppressed sidelobe structure.

Abstract: In order to generate a signal for canceling a chirped signal, a transmitter generates a cancellation signal along with the transmitted signal, using a single term variable complex gain multiplier adapted to cancel the chirped signal only at its instantaneous frequency, rather than attempting to cancel it with a complex FIR filter that works over the entire bandwidth of the chirped signal. The cancellation signal is varied in amplitude and phase as a function of the frequency of the chirped transmit signal for which it is intended to compensate. Since the signal that is to be cancelled is essentially sinusoidal but swept through a frequency range, the cancellation signal for the instantaneous transmit signal needs to be swept in both amplitude and phase in unison with the change in frequency of the transmit signal in order to accommodate gain and phase changes in the transmitted signal as a function of frequency.

Abstract: System for dynamically tracking a position of a target with an antenna in a communication system. The system includes an antenna system (410) configured for generating a sum and difference antenna pattern (201-1, 201-2). A sum RF channel (401) is coupled to a sum channel output of the antenna system. A difference RF channel (402) is coupled to a difference channel output of the antenna system. An RF coupler (422-1) is provided that has a first input coupled to the sum RF channel and a second input coupled to the RF difference channel. One or more coupling control devices (418-1, 418-2) selectively vary an effective coupling value as between the difference channel and the sum channel. An antenna tracking error signal is generated at an output of the coupler.

Abstract: Apparatus and a method utilizing correlation interferometer direction finding for determining the azimuth and elevation to an aircraft at long range and flying at low altitudes above water with a transmitting radar while resolving multipath signals. The signals from the radar are received both directly and reflected from the surface of the water using horizontally polarized and vertically polarized antenna arrays, are digitized and are stored in separate covariant matrices. Eigenvalues for the eigenvectors of the matrices processed on signal samples recorded on horizontally polarized X arrays are compared to the eigenvalues for the eigenvectors of the covariance matrices processed on signal samples recorded on vertically polarized X arrays. Incident field polarization is associated with the antenna array measurements that yield the strongest eigenvalue. The eigenvector and eigenvalues for the strongest signal are selected and used for subsequent signal processing.

Abstract: A circuit for providing gain compensation to a swept frequency response in an ultra-wideband system includes using a variable amplitude IF signal into a gigahertz mixer to control the amplitude of a ultra-wideband transmitter. The variable amplitude IF signal is generated by a multiplier receiving a fixed-level intermediate frequency (IF) signal and a gain control input. The gain control input being provided by an digital-to-analog converter controlled by gain control values in a look-up table. The values of the look-up table are generated by inverting, normalizing, and scaling the uncompensated gain response of the ultra-wideband system. The gain compensated system produces a substantially flat amplitude response at the output of a quadrature receiver.

Abstract: A radar pulse compression repair (RPCR) system includes a receiver for receiving a radar return signal, a matched filter for applying matched filtering to the radar return signal to generate a matched filter output, a processor programmed for applying Radar Pulse Compression Repair (RPCR) to the matched filter output to suppress a plurality of range sidelobes from the matched filter output, and a detector for receiving the RPCR-processed output. The RPCR invention in operating upon the output of the matched filter enables RPCR to be employed as a post-processing stage in systems where it is not feasible to replace the existing pulse compression apparatus. RCPR can also be selectively employed when it is possible that large targets are present that may be masking smaller targets, thereby keeping computational complexity to a minimum.

Abstract: A receiver that selectively samples a received signal in order to suppress an interference component of the signal while recovering a desired component. The selective sampling may be accomplished by low cost, low complex analog or digital circuitry. The receiver includes a first input that receives a first signal, including a desired signal component and an interference signal component and a second input that receives a second signal including the interference component only. The first and second signals are then provided to the sampling circuitry. First, the phase of the interference component of the both the first and second signals is aligned. Next, the points in a wave cycle that the second signal is at a power minimum are detected. Finally, first signal is sampled close to the point when the second signal is at the power minimum to recover the desired signal component and suppress the interference component.

Abstract: A method for detecting an object using a transmitting antenna and an array of receiving antennas. The method comprises the step of transmitting a signal from the transmitting antenna. The magnitude and phase of a respective received signal at each of the receiving antennas is then measured. Next, the magnitude of a weighted sum of respective phase-compensated signals related to each of the receiving antennas is determined. The magnitude of the weighted sum is compared against a first predetermined threshold value and, optionally, a second predetermined threshold value. An object may be detected by considering a ratio of the magnitude of the weighted sum to the first predetermined threshold value and, optionally, to the second predetermined threshold value. In some embodiments, a second array of receiving antennas may be provided to facilitate the determination of the location of the object.

Abstract: The present invention relates to a radar detector and a radar detecting method for WLAN systems according to 802.11 wireless communication standards, and particularly concerns the radar detection for 802.11 h dynamic frequency selection mechanism. The essence of the innovation consists in projecting the received phase vector on the signal subspace orthogonal to the expected radar pulse subspace and taking the norm of the resulting vector. The closer the norm is to zero, the more likely the received signal is to be a radar pulse. The invention is able to detect both, sinusoidal radar signals and chirp-like radar signals.

Abstract: This monopulse processor provides target position information having an RMS error which is less than that of a conventional monopulse processor. A ?±j? vs. ? processor is modified to provide a position output signal equal to the smaller in absolute magnitude of the results obtained from the ?+j? vs. ? and the ??j? vs. ? processing. A conventional monopulse processor is modified to provide an output signal having a value equal to Re(?/?)/[1+|Im(?/?)|].

Abstract: A Quadrature Error Corrected Digital Waveform Synthesizer (QECDWS) employs frequency dependent phase error corrections to, in effect, pre-distort the phase characteristic of the chirp to compensate for the frequency dependent phase nonlinearity of the RF and microwave subsystem. In addition, the QECDWS can employ frequency dependent correction vectors to the quadrature amplitude and phase of the synthesized output. The quadrature corrections cancel the radars' quadrature upconverter (mixer) errors to null the unwanted spectral image. A result is the direct generation of an RF waveform, which has a theoretical chirp bandwidth equal to the QECDWS clock frequency (1 to 1.2 GHz) with the high Spurious Free Dynamic Range (SFDR) necessary for high dynamic range radar systems such as SAR. To correct for the problematic upconverter local oscillator (LO) leakage, precision DC offsets can be applied over the chirped pulse using a pseudo-random noise dither.

Abstract: A method and apparatus for generating accurate estimates of a radar target's azimuth and elevation angles for a phased-phased array rotating radar. Scan modulated coherently integrated (SMCI) monopulse curves are generated from a measured one-way transmit antenna pattern and three receive antenna patterns. The SMCI monopulse curves are calculated in advance for the expected beam steers. To utilize the SMCI monopulse curves, two-way Sum, Delta-Azimuth and Delta-Elevation target returns are coherently integrated, the target's monopulse ratios calculated, and the SMCI monopulse curves or polynomials used to calculate the target's U-offset and V-offset sine-space angles, which are added to the radar's beam steer to get an improved estimate of the target's sine-space angular position denoted as Utgt and Vtgt. A coordinate system transformation transforms Utgt and Vtgt to azimuth and elevation angles in a non-rotating coordinate system.

Abstract: A transmitter emits into an intended search space a radar wave having a predetermined frequency pulse-modulated by a trigger pulse of a predetermined width. A receiver receives a reflected wave of the radar wave and outputs a receive signal. A local pulse generator outputs a local pulse signal having the predetermined frequency pulse-modulated by the trigger pulse delayed by the delay unit. A correlation value detector detects a strength correlation value between the receive signal and the local pulse signal. A delay time changing unit changes the delay time sequentially within a range of a predetermined period representing a generation period of the trigger pulse. A correlation value storage unit stores the strength correlation value detected for each delay time changed. A frequency distribution generator generates a frequency distribution of a stored correlation value against the delay time.

Abstract: Disclosed herein is a computer-readable medium having stored thereon computer-executable instructions for providing phase-range data associated with a return pulse of a radar device and second phase-range data associated with a successive return pulse of the radar device. The computer-executable instructions are preferably also for comparing the phase-range data and the second phase-range data to obtain a difference, and for differentiating the difference. In some embodiments of the invention, the computer-executable instructions are preferably also for discriminating a target from clutter by using the differentiated difference to identify coordinates satisfying a velocity threshold associated with the clutter. Embodiments of the invention preferably enable phase-coherent operation of a non-coherent radar device by processing backscattered clutter return, and in some aspects, do so using clutter distributed in range as a reference.

Abstract: A method for determining the distance between a base station (SLG) and a mobile object (DT1–DT3). A HF carrier frequency and an offset frequency (df) are predetermined for a QAM modulation. The HF carrier frequency is increased and decreased by the offset frequency in sequence over time in such a way that the HF carrier base frequencies (fo+df, fo?df) resulting in an HF carrier signal (TS) thus modulated exhibit an identical phase when the frequency is changed. The HF carrier signal is subsequently transmitted and simultaneously mixed (MIX) with an HF carrier signal (RS) that has been backscattered by the mobile object to obtain a carrier phase signal (PS). The corresponding carrier phase (PH1, PH2) for the two HF carrier base frequencies is determined in sequence over time. The difference (dPH) between these phases is used to calculate the distance between the base station and the respective mobile object.

Abstract: An IFM receiver includes a hybrid for outputting I and Q signals from a received input signal; a first ADC for digitizing the I signal to produce a first digital signal at a sampling rate of 1/?, and a second ADC for digitizing the Q signal to produce a second digital signal at the same sampling rate. A processor is configured to (a) delay the first and second digital signals by at least one sample time of ?, (b) count the number of samples produced having predetermined phase shifts, and (c) determine the frequency of the received input signal, based on the number of samples having the predetermined phase shifts. The first and second ADCs are each 1-bit analog-to-digital converters. The predetermined phase shifts of 0°, 90°, ?90° and 180° are counted by the processor over a predetermined time interval.

Abstract: A radar equipment of the present invention amplifies a reception signal with feedback based on the delay amount obtained from the correlation detection result. Accordingly, it becomes possible to maintain the reception signal (demodulated signal) level to a proper level depending on the distance to the target, and accurate measurement can be achieved with high precision. Namely, the reception signal is amplified depending on the distance to the target, and the reception signal level is made within a tolerable input level range of a logic circuit for performing correlation calculation. In particular, during tracking the target, even when a reflected signal is received with abrupt level variation caused by noise or a reflected signal from an object other than the target, incorrect detection of the target can be avoided by disabling the correlation calculation.

Abstract: Detailed is radar imaging apparatus including a single transmit antenna and at least one receive antenna, scanning apparatus (e.g. a pantograph) for mechanically scanning the antennas over a surface of interest, position providing apparatus (e.g. a computer driving the pantograph via an X-Y drive and a stepper motor) providing a position signal indicative of the instantaneous position of the transceiver and a control system for operating the transmit antenna in a stepped frequency continuous wave mode. The amplitude and phase components of the receive antenna signal are analysed and the output combined with the position signal as in a synthetic aperture array to provide a radar image signal of the surface and underlying features. The scan is two-dimensional (random or boustrophedral).

Abstract: A frequency-stepped radar may be used to detect buried landmines by sequentially inducing vibrations of different frequencies in the landmine. A sensor detects signals associated with the vibrations, and a processor processes the signals to detect the landmine.

Abstract: Method and apparatus for extracting coherent information from in-phase (I) and quadrature (Q) signals. In a form, signals from an antenna array are mixed to form a plurality of I and Q signals that combined to form respective complex vectors. Each vector is adjusted in phase and magnitude to compensate for variations in field signal patterns, summed with other vectors, spatially and temporally filtered, and processed using spectral analysis algorithms to extract coherent spatial information. The coherent spatial information may be used to detect the presence, number and activity of insects within a structure in the near field of the antenna.

Abstract: A FM-CW radar system comprises a frequency modulated continuous wave digital generator that produces both in-phase (I) and quadrature-phase (Q) outputs to orthogonally oriented transmitter antennas. A linearly polarized beam is output from a switched antenna array that allows a variety of I-and-Q pairs of bowtie antennas to be alternately connected to the transmitter and receiver. The receiver inputs I-and-Q signals from another bowtie antenna in the array and mixes these with samples from the transmitter. Such synchronous detection produces I-and-Q beat frequency products that are sampled by dual analog-to-digital converters (ADC's). The digital samples receive four kinds of compensation, including frequency-and-phase, wiring delay, and fast Fourier transform (FFT). The compensated samples are then digitally converted by an FFT-unit into time-domain signals. Such can then be processed conventionally for range information to the target that has returned the FM-CW echo signal.

Abstract: System and method for determining the height of an object reflecting a real beam radar signal by receiving the reflected signal with a first and second vertically spaced antennas. Receivers provide two signals indicating the phase of the reflected signals received by the two antennas. A digital processor determines the phase difference between the two signals and calculates the object height.

Abstract: An in-phase and guadrature (IQ) imbalance error-correction method includes estimating, on the basis of a constellation error in a received orthogonal frequency division multiplexing (OFDM) signal, an extent of an I/Q imbalance error, caused by direct IQ conversion of the received OFDM signal. On the basis of that extent, an equalizing transformation that reduces that error is estimated.

Abstract: The system and method for radar calibration using antenna leakage is a simplified means of calibrating the channels in amplitude and phase using natural signal leakage between antennas. It utilizes as calibration signal a wideband sinusoidal Frequency Modulated Continuous Wave (FMCW) waveform with a modulation index and modulation frequency chosen to generate spectral components (or discrete signal frequencies) that fall within the receiver Doppler passband of the radar. The calibration signal is radiated out of the transmitting antenna and enters the radar receiver front-end through the transmit-to-receive antenna leakage which occurs naturally. This technique provides a low-complexity (simpler hardware realization) means for achieving a wideband calibration rapidly and is a practical alternative to the conventional calibration approach that relies on generating offset Doppler signals that are coupled into the radar receiver front-end through the use of couplers and cabling within the radar.

Abstract: Detection of moving targets in SAR images is improved by a radar on a moving platform for generating a focused synthetic aperture image of a scene The scene contains a target described by pixels within the SAR image. The radar has a monopulse antenna having a sum channel output and a difference channel output feeding analog to digital converters for converting the sum channel output and difference channel output into respective digital streams concurrently. The digital streams generate a difference channel SAR image and a sum channel SAR image. Target ratios are computed for those pixels descriptive of a target within the scene. Background ratios are computed for pixels around the target. Target ratios and background ratios define respective least square fit of angle discriminants. Comparing the target least square fit of angle discriminant with the background least square fit angle discriminant identifies an angle offset and a Doppler offset of the target with respect to the background.

Abstract: A unique hardware architecture that combines short pulse, stepped frequency and centerline processing. The inventive architecture implements a radar system having a transmitter for transmitting short pulses, each pulse being stepped in frequency and a receiver receiving the pulses and providing an output signal in response thereto. In the illustrative embodiment, the transmitter includes a frequency source, an RF switch coupled to the source and a controller for controlling the RF switch. The receiver includes a signal processor implemented with a center line roughing filter. The signal processor has multiple channels each of which has a range gate and a digital filter. The digital filter includes a Fast Fourier Transform adapted to output a range Doppler matrix.

Abstract: An invention is provided for determining the azimuth pointing angle of a moving monopulse antenna. Pulses of energy are broadcast at the surface of a planetary body. Reflected signals are received from the surface of the planetary body using a plurality of feeds. A monopulse ratio is then calculated based on a sum pattern and a difference pattern. The sum pattern is based on the sum of the reflected signals received using the feeds, and the difference pattern is based on a difference of the reflected signals received using the feeds. An azimuth pointing angle of a monopulse antenna is then calculated using the monopulse ratio.

Abstract: Methods and apparatus compress data, comprising an In-phase (I) component and a Quadrature (Q) component. Statistical characteristics of the data are utilized to convert the data into a form that requires fewer bits in accordance with the statistical characteristics. The data may be further compressed by transforming the data and by modifying the transformed data in accordance with a quantization conversion table that is associated with the processed data. Additionally, redundancy may be removed from the processed data with an encoder. Subsequent processing of the compressed data may decompress the compressed data in order to approximate the original data by reversing the process for compressing the data with corresponding inverse operations. Interleaved I and Q components can be processed rather than separating the components before processing the data. The processed data type may be determined by providing metadata to retrieve the appropriate quantization table from a knowledge database.

Abstract: In a device for bistatic radar applications, at least two spaced-apart radar sensors having separate carrier-frequency oscillators are provided, which do not require phase synchronization. The pulse modulation is carried out time-synchronously for all transmitter and receiver pairs. The cross-echo signals can be analyzed in an analyzing unit, in which a mixing of the transmitted and received signals takes place.

Abstract: A radio frequency device has an antenna for capturing an incoming signal for processing by the device or for radiating an outgoing signal from the device and a signal processor having one or more synchronous oscillators responsive to an input signal for providing an amplified output signal without using much power. An application is a radio frequency (RF) transponder (tag) for receiving an RF signal from an interrogator includes a tag antenna for receiving the RF signal from the interrogator and a receiver section connected to the tag antenna wherein the receiver consumes a significantly lower amount of power than conventional receiver technologies by using one or more synchronous oscillators.

Abstract: A receiver circuit including an oscillator, a mixer coupled to the oscillator, a switch coupled to an output of the mixer, and an envelope detector coupled to the oscillator, such that the envelope detector generates a timing signal for actuating the switch based on the envelope of a signal produced by the oscillator. In one exemplary embodiment, the receiver circuit may be used as part of a radar based sensor system.

Abstract: A target is detected under a forest canopy or other elevated clutter where the target is obscured by the elevated clutter. Radar returns reflected from the target on the surface, combined with those from the elevated clutter are digitized. Motion compensation is performed for the radar returns with respect to the target to obtain a focused first synthetic aperture image of the target. Next, the radar returns are motion compensated with respect to the elevated clutter at various heights above the surface to obtain images of the elevated clutter. The elevated clutter within the images at the various heights above the surface is identified and coherently subtracted from the original synthetic aperture images.