Abstract: The invention relates to a method for pre-detecting responses in a secondary radar. It applies in particular to the detection of mode S responses. An aim of the invention is to process the signals received before decoding the responses so as to allow the detection of mixed responses, and avoid the detection of ghost responses. For this purpose, the invention has in particular as subject a method for pre-detecting responses in a secondary radar, the responses to be pre-detected comprising a message coded by a modulated signal, characterized in that the presence of a signal exhibiting modulation characteristics in accordance with those of a message of a response to be pre-detected is identified; the duration of the signal identified is measured; this duration is compared with a minimum duration, this minimum duration being determined on the basis of the duration of the messages of the responses to be pre-detected.

Abstract: A device and a method for eliminating interference between a radar working on the L frequency band and an aeronautical radio navigation equipment item, such as DME (Distance Measurement Equipment). When the radio navigation equipment operates, the radar emits periodically in all or part of the frequency band and then halts its emissions, each emission has a given duration and being separated from the previous emission by an interval of silence.

Abstract: A system and method are provided to reduce the effect of an interfering signal in a radar return signal for a frequency modulated continuous wave (FMCW) radar. Once the interfering signal is detected, an extent of the interfering signal is determined and the data that was corrupted by the interfering signal is not included in the processing of the radar return signal. This allows the radar to detect a target in the presence of the interfering signal. The system and method can benefit any FMCW radar that is within the range of an interfering radar source (e.g. another FMCW radar, a police radar gun, a pulse radar, etc.) operating in the same frequency band as the FMCW radar. An alternative arrangement provides a system and method for determining the frequency of the interfering signal and then avoiding transmitting power in that portion of the frequency spectrum where the interfering signal is present.

Abstract: One preferred embodiment of the present invention provides a system and method for suppressing motion interference in a radar detection system. Briefly described, in architecture, one embodiment of the system, among others, can be implemented as follows. The system includes a signal generator that transmits microwave signals toward a target area. Also, the system includes a data control system to collect data from reflected microwave signals from the target area and to analyze the data in order to suppress unwanted motion interference generated by movement of the radar detection system. Other systems and methods are also provided.

Abstract: A method for mitigating multipath impacts on azimuth accuracy in a monopulse interrogator is accomplished by calculating samples of monopulse ratio for samples of antenna boresight angles based on data received from an interrogation of a target. Samples of traditional target azimuth from the samples of monopulse ratio are calculated. A mean of the samples of traditional target azimuth is calculated. An alternative target azimuth from the samples of monopulse ratio is calculated. Whether a multipath signal exists is determined from observing a standard deviation of the samples of traditional target azimuth, and using the mean of the traditional target azimuth if a multipath signal does not exist and using the alternative target azimuth if a multipath signal does exist.

Abstract: Various embodiments are described herein relating to a radar system and associated methods for detecting targets in the presence of certain types of clutter. The radar system generally comprises hardware operatively configured to obtain first and second sets of radar return signals concurrently, first circuitry operatively configured to detect targets in the first and second sets of radar return signals, and second circuitry operatively configured to identify detected targets due to clutter.

Abstract: A dither clock generating section 1 generates a dither clock. A transmission pulse generating section 2a generates a transmission pulse emitted to the outside from a transmitting antenna 2c on the basis of the dither clock. A sample hold section 6 samples a reception pulse, received by a receiving antenna 3a, on the basis of a sample pulse obtained by time sweeping of the changing timing of the dither clock, so as to produce a long-period reception pulse that is obtained by expanding the reception pulse on a time axis.

Abstract: A coal-mining machine uses a ground-penetrating radar based on a software-definable transmitter for launching pairs of widely separated and coherent continuous waves. Each pair is separated by a constant or variable different amount double-sideband suppressed carrier modulation such as 10 MHz, 20 MHz, and 30 MHz. Processing suppresses the larger first interface reflection and emphasizes the smaller second, third, etc. reflections. Processing determines the electrical parameter of the natural medium adjacent to the antenna. Deep reflections at 90-degrees and 270-degrees create maximum reflection and will be illuminated with modulation signal peaks. Quadrature detection, mixing, and down-conversion result in 0-degree and 180-degree reflections effectively dropping out in demodulation.

Abstract: A method for discrimination of a target from clutter, comprising: providing phase-range data associated with a return pulse of a radar device and second phase-range data associated with a subsequent return pulse; comparing the phase-range data and the second phase-range data to obtain a difference; differentiating the differences with respect to range; and discriminating the target from the clutter by identifying coordinates from the differentiated differences satisfying velocity thresholds associated with the clutter. In one embodiment, the subsequent return pulse is drawn after skipping one or more pulses after the return pulse. In another embodiment, the subsequent return pulse is drawn successive to the return pulse. In other aspects, the invention can be a detection system and/or computer-readable medium adapted implement the method.

Abstract: A ground-penetrating radar comprises a software-definable transmitter for launching pairs of widely separated and coherent continuous waves. Each pair is separated by a constant or variable different amount double-sideband suppressed carrier modulation such as 10 MHz, 20 MHz, and 30 MHz Processing suppresses the larger first interface reflection and emphasizes the smaller second, third, etc. reflections. Processing determines the electrical parameter of the natural medium adjacent to the antenna. The modulation process may be the variable or constant frequency difference between pairs of frequencies. If a variable frequency is used in modulation, pairs of tunable resonant microstrip patch antennas (resonant microstrip patch antenna) can be used in the antenna design. If a constant frequency difference is used in the software-defined transceiver, a wide-bandwidth antenna design is used featuring a swept or stepped-frequency continuous-wave (SFCW) radar design.

Abstract: The time compression processor coding methodology gives rise to an exceedingly fast clutter covariance processor compressor (CCPC). The CCPC includes a look up memory containing a very small number of predicted clutter covariances (PCCs) that are suitably designed off-line (e.g., in advance) using a discrete number of clutter to noise ratios (CNRs) and shifted antenna patterns (SAPs), where the SAPs are mathematical computational artifices not physically implemented. The on-line selection of the best PCC is achieved by investigating for each case, e.g., each range bin, the actual CNR, as well as the clutter cell centroid (CCC), which conveys information about the best SAP to select. The advanced CCPC is a ‘lossy’ processor coder that inherently arises from a novel practical and theoretical foundation for signal processing, namely, processor coding, that is the time compression signal processing dual of space compression source coding.

Abstract: A method for determining a variable associated with an object, the object having a plurality of points suitable for reflecting measuring signals, a probability of reflections occurring at these points is taken into account for evaluating at least one measuring signal.

Abstract: Methods and systems are disclosed for investigating a region of interest with a radar. A radar signal is propagated to the region of interest. Sampled time-domain radar data scattered within the region of interest are collected. A likelihood function is calculated with the sampled time-domain data within a parametric model of the region of interest for a defined set of parameters. The set of parameters in varied to find an extremum of the likelihood function.

Abstract: A system for reducing CFAR loss due to sea clutter is disclosed. The system includes a first channel tuned for CFAR gain in a spatially correlated background and a second channel tuned for low CFAR loss in spatially uncorrelated backgrounds. Each of the channels employs a distribution free CFAR using rank ordered statistics to establish a constant false alarm rate. The output of each channel is fused by a hit correlation function and the stream of combined hits is processed by a target centroiding function.

Abstract: A terrain awareness and warning system includes electronics for receiving radar returns and providing terrain and/or obstacle alerts or warnings in response to the radar returns. The electronics receives information from a database and the information is utilized to suppress false alerts or warnings.

Abstract: There is disclosed a method for filtering sea clutter in a radar echo using a hydrographic model. The method comprises the steps of determining parameter values of the hydrographic model using the radar echo, estimating the sea clutter corresponding to the sea surface as deduced from the hydrographic model and filtering of the estimated sea clutter from the radar echo.

Abstract: A system and method for improved validation of images is provided. Validation of any target image may be performed by creating a model of graphical components of a source image or a reference model and comparing the model of graphical components of the source image or reference model with a model of graphical components of the target image in order to detect differences between the graphical components. In one embodiment, a framework may be provided with an analysis engine for building a model of graphical components of a source image to be compared with a model of graphical components of a target image. In another embodiment, a framework may be provided with a synthesis engine for building a model of a synthesized graphical component to be compared with a model of graphical components of a target image.

Abstract: A radar apparatus includes a PN code generator for generating a PN code, a variable delay device for delaying the PN code, an oscillator for generating a high-frequency signal, a transmission frequency multiplier for multiplying a frequency of a transmission differential signal obtained by being divided from the high-frequency signal by 3, a reception frequency multiplier for multiplying a frequency of a reception differential signal obtained by being divided from the high-frequency by 3, a transmitter for generating a radar wave by using the differential signal obtained through the multiplication by the transmission frequency multiplier and the PN code generated by the PN code generator, and a receiver for generating an in-phase signal and a quadrature signal from a reflected wave by using the differential signal obtained through the multiplication by the reception frequency multiplier and the PN code delayed by the delay device.

Abstract: Provide an on-vehicle radar device that performs transmission control of a monitoring signal, following fixed rules, so that interference with other radar devices can be avoided with certainty. An on-vehicle radar device comprises a transceiver which transmits/receives a monitoring signal at a specified frequency band and transmits a priority order signal at a frequency within the above-mentioned frequency band, and a controller which switches the signals transmitted by the transceiver. The transceiver receives a priority order signal of another radar device, and when interference with the signal of the other radar device is detected, the controller, based on the priority order of that other device and on the priority order of the device itself, shifts, by a specified frequency amount, the frequency band of the monitoring signal transmitted by the transceiver.

Abstract: Various regulatory domains promulgate standards to define how wireless devices should operate in certain frequency bands. The 5 GHz spectrum is of particular importance to certain regulatory domains because of radar systems also operating in this spectrum. To avoid interference with such radar systems, wireless devices operating in this spectrum should be able to detect radar and quickly vacate any channels currently used by the radar systems. Techniques are provided for performing startup scans for radar, identifying backup channels for a possible channel switch, and efficiently changing channels in the event of radar detection in the operating channel. These techniques advantageously meet current regulatory standards governing DFS while minimizing network startup delays and disruption to users during a radar event.

Abstract: A method for extension of unambiguous range and velocity of a weather radar. To avoid pulse overlaying, the pulse repetition time of a single pulse can be extended such that any return echo will arrive at the radar before the next pulse is transmitted. When pulse repetition time is increased, the maximum unambiguous range increases while the maximum unambiguous velocity decreases. The pulse overlaying can be avoided if consecutive pulses are sent on different frequencies that are far enough from each other to allow separation of pulses arriving simultaneously at the radar. When different frequencies are used an unknown phase difference is generated by distributed atmospheric targets to the return signals. This normally prevents use of the shorter pulse repetition time for velocity calculation.

Abstract: One aspect of this disclosure relates to a method for processing a received, modulated radar pulse to resolve a radar target from noise or other targets. According to an embodiment of the method, a radar return signal is received and samples of the radar return signal are obtained. A minimum mean-square error (MMSE) pulse compression filter is determined for each successive sample. The MMSE filter is separated into a number of components using contiguous blocking, where each component includes a piecewise MMSE pulse compression filter segment. An estimate of radar range profile is obtained from an initialization stage or a previous stage. The piecewise MMSE pulse compression filter segments are applied to improve accuracy of the estimate. The estimate is repeated for two or three stages to adaptively suppress range sidelobes to a level of a noise floor. Other aspects and embodiments are provided herein.

Abstract: A computer system for compressing synthetic aperture radar (SAR) images includes a database for storing SAR images to be compressed, and a processor for compressing a SAR image from the database. The compressing includes applying an anisotropic diffusion algorithm to the SAR image, and compressing the SAR image after applying the anisotropic diffusion algorithm thereto. Applying the anisotropic diffusion algorithm includes determining noise in the SAR, selecting a noise threshold for the SAR image based on the determined noise, and mathematically adjusting the anisotropic diffusion algorithm based on the selected noise threshold.

Abstract: A method of detecting weather using a weather radar onboard an aircraft. A range is selected at which weather is to be detected. A tilt angle of the weather radar is changed to detect weather below an altitude of the aircraft at a selected range when the selected range includes a maritime environment.

Abstract: A received data storage situation is monitored, and a covariance matrix Ri of the i-th range cell is calculated to be temporarily stored. Covariance matrices Ri of the number of training samples are called until the i becomes T from 1, covariance matrices Ri are averaged by adding, and averaged covariance matrix data R[1]rr is temporarily stored. Averaged covariance matrix data R[i?1]rr is called until the i becomes L from 2, Ri and Ri?4 are added to the data R[i?1]rr, Ri+3, and Ri?1 are subtracted from the data R[i?1]rr, the resulting data R[1]rr is temporarily stored, and a series of processing is terminated.

Abstract: In one aspect, a method to generate radar signatures for multiple objects includes performing in parallel a shooting and bouncing (SBR) technique to solve for physical optics and multi-bounce characteristics of a plurality of objects in motion, a physical theory (PTD) technique to solve for material edges of the objects and a incremental length diffraction coefficient (ILDC) to solve for material boss/channel. The method also includes coherently integrating the results from the SBR, PTD and ILDC techniques by frequency and generating the radar cross section (RCS) values of the plurality of objects. Performing the SBR technique includes evaluating rays independently.

Abstract: Systems and methods that adapt to the weather and clutter in a weather radar signal and apply a frequency domain approach that uses a Gaussian clutter model to remove ground clutter over a variable number of spectral components that is dependent on the assumed clutter width, signal power, Nyquist interval and number of samples. A Gaussian weather model is used to iteratively interpolate over the components that have been removed, if any, thus restoring any overlapped weather spectrum with minimal bias caused by the clutter filter. The system uses a DFT approach. In one embodiment, the process is first performed with a Hamming window and then, based on the outcome, the Hamming results are kept or a portion of the process is repeated with a different window. Thus, proper windows are utilized to minimize the negative impact of more aggressive windows.

Abstract: A system and method for processing data related to weather phenomena in a meteorological radar system. The method includes receiving an echo signal generated by transmitting a long pulse and employing a mismatched windowed filter on the echo signal such that the echo signal is compressed in time to achieve fine range resolution without substantially degrading sensitivity and while achieving low range time side lobes for Doppler velocities expected to be measured by the meteorological radar system.

Abstract: A radar detector is operated to suppress nuisance radar alerts by identifying a first signal in radar band of interest, e.g., having a frequency that is a harmonic of a first nuisance local oscillator frequency leaked from a nearby radar detector and identifying a second signal having a frequency that is a harmonic of a second nuisance local oscillator frequency leaked from the radar detector where the first and second local oscillators are companion signals. A detector is also provided that suppresses nuisance radar alerts by detecting a first signal in a radar band, providing a first alert designating the detection of the first signal, determining that the first signal is a nuisance signal, providing a second alert designating that the first signal is a false alarm, and turning off the second alert after a predetermined period.

Abstract: In one aspect, a method of radar altimeter operation including a time dependent gain control is described. The method comprises triggering a Sensitivity Time Control (STC) gain control signal at a pulse repetition frequency (PRF) of a transmit pulse to attenuate interference from at least one of an antenna leakage signal and a signal reflected from equipment. The method also includes shaping the STC gain control signal from no attenuation at a first time, before a transmitter sends the transmit pulse, to a stable maximum attenuation at the time the transmitter sends the transmit pulse, to no attenuation at a second time, after the transmitter sends the transmit pulse. The method also includes matching a bandwidth of an intermediate frequency (IF) amplifier to the pulse width of a transmitted pulse.

Abstract: Methods for suppressing cross-track clutter in a sounding radar utilize polarimetric selectivity in two ways: (1) transmitting full-beam circular polarization and separating the desired signal of interest from the clutter based on the signal and clutter having different polarizations, and (2) transmitting and receiving circular polarization at the radar's nadir and elliptical polarization at the radar's off-nadir regions and filtering out the elliptical polarization.

Abstract: A method, computer program product, apparatus and system are provided. In one exemplary embodiment, a method includes: receiving at a second unit periodic energy bursts transmitted by a first unit; blanking a transmitter of the second unit in accordance with the received periodic energy bursts such that the transmitter is unable to transmit when the second unit is receiving a periodic energy burst; and transmitting a plurality of instances of a same data from the second unit to the first unit.

Abstract: Methods and systems for tracking signals with diverse polarization properties address both sensitivity and antenna tracking performance issues. In one embodiment, complex weightings for matching a polarization of an incident signal on a data channel are determined, and the complex weightings are applied to a tracking channel such that an antenna system polarization is matched to the polarization of the incident signal. In another embodiment, orthogonally polarized tracking channel components of an incident signal are processed to make a determination as to which of the orthogonally polarized tracking channel components is stronger, and this determination is used to select a polarization of a data channel to reduce a polarization mismatch loss.

Abstract: A wavefront curvature effect associated with a complex image produced by a synthetic aperture radar (SAR) can be mitigated based on which of a plurality of possible flight paths is taken by the SAR when capturing the image. The mitigation can be performed differently for different ones of the flight paths.

Abstract: In an aircraft-mounted Doppler radar clutter rejection system, a flexible, sharp band pass filter uses Taylor weighting, an FFT and a module for selecting which of the Doppler cells are to be activated, thus to control the band pass characteristic and set the clutter line to the speed of the aircraft.

Abstract: A ground-penetrating radar comprises a transmitter for launching pairs of widely separated and coherent continuous waves. Each pair is separated by a different amount, such as 10 MHz, 20 MHz, and 30 MHz. These are equivalent to modulation that have a phase range that starts at 0-degrees at the transmitter antenna which is near the ground surface. Deep reflectors at 90-degrees and 270-degrees will be illuminated with modulation signal peaks. Quadrature detection, mixing, and down-conversion result in 0-degree and 180-degree reflections effectively dropping out in demodulation.

Abstract: An external primary spectrum user detector (ESUD) is used to take over the role of integral radar detectors, and relieve user devices of the constraints associated with Primary Spectrum User detection. The ESUD can establish a relationship with the user devices by means of a cryptographic signature. The ESUD installation includes assigning it a frequency band to scan for primary spectrum user signals and the type of signals to be detected. Once activated, the ESUD will scan its assigned frequencies and emit to types of messages, “All Clear” and “Primary Spectrum User detected.” User devices on the network listen for the ESUD messages. In the absence of messages from the ESUD, the user devices activate their internal primary spectrum user detectors until ESUD messages are received.

Abstract: For detection of an electromagnetic signal, which is transmitted from a transmitting antenna (1), by means of at least two at least essentially identical receiving antennas (3, 4), whose sensitivity curve has a maximum (M) with falling flanks as well as sidelobes (SL) adjacent to it with sensitivity increased again at a reception angle symmetrically with respect to a basic alignment, with angle determination for an object which reflects the transmitted signal being carried out by the two receiving antennas (3, 4) by phase determination in an unambiguous interval (?u) whose boundaries (L) are predetermined by the distance (d) between the receiving antennas (3, 4), the distance (d) is chosen such that the boundaries (L) of the unambiguity area (?u) intersect the sidelobes (SL), and the reflective object is detected by means of vectorial addition of the signals from the receiving antennas (3, 4), after which the parameters R, v are determined.

Abstract: This invention relates to a target detection device and its detection method, comprising: a transmitting unit for transmitting a detecting pulse to detect target which then reflects the detecting pulse to generate a reflected pulse; a plurality of measuring units, located at different positions respectively which receive said reflected pulse and generates measured values of distance and measured values of velocity according to the reflected pulse received; a plurality of two-stage linear Kalman filters, corresponding to said plural measuring units respectively, each of said plural two-stage linear Kalman filters proceeds an operation according to the measured values produced by corresponding measuring unit so as to generate respectively the estimation values of distance, velocity and acceleration; an arithmetic unit connecting to said plural two-stage linear Kalman filters, which proceeds a triangulation operation according to said estimation values so as to generate distance component values, velocity compon

Abstract: A transmit signal is output from a transmitter towards a target and towards interference. A combination signal is received at a receiver, wherein the combination signal includes the transmit signal modified by interacting with the target and the interference along with noise. The receiver has a filter having a transfer function and the filter acts on the combination signal to form a receiver output signal having a receiver output signal waveform. The receiver output signal has a receiver output signal waveform that describes an output signal to interference to noise ratio (SINR) performance. Bandwidth and signal energy of the transmit signal are reduced simultaneously by modifying the transmit signal waveform and receiver output signal waveforms without sacrificing the output SINR performance level.

Abstract: The present invention refers to an airborne radar device (1) comprising at least two antennas (2, 3) and clutter suppressing means (4). The radar device is arranged, via the antennas (2, 3) to send out radar pulses focused in main lobes (5) and the antennas are arranged to receive reflecting pulses. The antennas (2, 3) are separated from each other vertically. The radar device (1) comprises means (6) for transforming the received radar pulses into complex video signals in the form sequences of range bins (Rk). The video signals are represented in a first channel (K1) and a second channel (K2).

Abstract: A computer system for decompressing synthetic aperture radar (SAR) images includes a database for storing SAR images to be decompressed, and a processor for decompressing a SAR image from the database. The decompressing includes receiving the SAR image, performing a dynamic range compression on the SAR image, and quantizing the compressed SAR image. The quantized compressed SAR image is then decompressed by applying an anistropic diffusion algorithm thereto.

Abstract: A weight calculation method begins by storing a target reflection signal of a radar pulse received via an antenna in cells corresponding to positions along with a reception timing for a plurality of processing range cells having lengths equivalent to prescribed ranges on a time axis. The method continues by calculating weights by stage for the phase and amplitude of the target reflection signal to form a reception composite beam so that arrival directions of spurious elements become zero to an arrival direction of the target reflection signal by using values stored in the plurality of processing cells. The calculating of the weights monitors changes of specific variables indicating correlation values among stages in the plurality of processing stages to stop a shift to the next processing stage at the time when the variables exceed a reference value.

Abstract: A time-reversal imaging radar system for acquiring an image of a remote target includes an antenna array having a plurality of spaced-apart antennas, and a transceiver coupled to the antenna array for alternately transmitting a radar signal via the antenna array toward the target and for receiving target-reflected radar signals. The transceiver includes means for multiple-pass time-reversing the transmitted and received radar signals whereby coherent beam focusing is realized at both the target and at the receiver to thereby enhance the resolution of the acquired target image.

Abstract: In a FM-CW or CW radar apparatus, when interference components are Contained in channel signals obtained as beat signals from array antenna elements of respective channels, and the interference components result from directly receiving transmitted CW radar waves from an external source, phase shifting is applied to each of the channel signals to shift respective phases of the interference components of the respective channels to a condition corresponding to reception of interference waves from a predetermined direction. The interference components are then eliminated, and reverse phase shifting is applied to restore remaining components of the channel signals to their original phase condition.

Abstract: Methods and systems for using ground penetrating radar (GPR) to obtain subsurface images. The depression angle, frequency, and polarization can all be adjusted for the soil conditions at hand. In particular, the depression angle is set at the “pseudo-Brewster angle” for improved ground penetration.

Abstract: A radar apparatus including units for transmitting and receiving an electric wave to detect a target, a unit for detecting wave interference caused by surroundings, a unit for controlling the modulation state of the transmitted wave, a communication unit for acquiring modulation state information being used by the other radar apparatuses, and a unit for selecting such a modulation state as to avoid interference with the modulation state information when the wave interference detecting unit detects the wave interference.

Abstract: A system and method is presented for detecting and classifying slow-moving and hovering helicopters from a missile's look-down Doppler radar that is compatible with the existing base of Doppler radars. This approach uses definable attributes of a helicopter rotor assembly and its extended Doppler rotor return to differentiate “rotor samples” from other samples (steps 123, 125), extract features such as bandwidth, activity, angle, and shape from the rotor samples (step 127), and classify a potential target as a helicopter or other based on the extracted rotor features and the known attributes of the helicopter rotor assembly (step 129). A target report including a classification target, range, range-rate, and angle of the extended rotor return is suitably passed to a tracking processor (step 121).

Abstract: A method of detecting interference noise at a radar altimeter. The method comprises periodically emitting a pulse from the pulsed radar altimeter, periodically detecting a noise level in a noise gate, and determining if the noise level detected during each noise-level-detection period exceeds a noise threshold. The period of emitting the pulse is a pulse repetition interval and the noise gate is offset from other gates in the altimeter. If the noise level detected during a noise-level-detection period is greater than the noise threshold, a counter value is incremented by a selected incremental value for that noise-level-detection period and it is determined if the counter value is greater than a count threshold.

Abstract: Methods and systems for tracking signals with diverse polarization properties address both sensitivity and antenna tracking performance issues. In one embodiment, complex weightings for matching a polarization of an incident signal on a data channel are determined, and the complex weightings are applied to a tracking channel such that an antenna system polarization is matched to the polarization of the incident signal. In another embodiment, orthogonally polarized tracking channel components of an incident signal are processed to make a determination as to which of the orthogonally polarized tracking channel components is stronger, and this determination is used to select a polarization of a data channel to reduce a polarization mismatch loss.