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: Described herein is an implementation of the IRAMS processing based upon a multi-delay-resolution framework applied to SAR image data measured at different aspect angles. The power of this new embodiment of IRAMS is that it produces a good separation of immediate response scatterer and delayed response scatterer data for the case of anisotropic scattering events, i.e., those in which the scattering intensity depends upon the aspect angle. Two sources of delayed response scattering include multiple reflection scattering events and delayed responses arising from the physical material composition of the scatterer. That is, this multi-delay-resolution IRAMS processing separates immediate response and delayed response scattering for cases in which there exist delayed response scattering data in the original SAR image data at some aspect angles, but the intensity of these delayed response scattering data is weak or non-existent at different aspect angles.

Abstract: Systems and methods for avoidance of partial pulse interference in radar. The systems and methods include a radar processor for generating control signals that direct the generation and transmission of two consecutive radar pulses using a waveform and pulse train generator and transmitter. The systems and methods also include receiving reflected echoes corresponding to the transmitted pulses using a receiver and processing the echoes using an analog to digital converter, filter, and digital signal processor to separate echoes from each pulse, process them, and combine the results to avoid partial pulse interference while maintaining pulse energy and an acceptable signal to noise ratio.

Abstract: Very efficient sidelobe suppression of Barker codes is achieved through the use of a mismatched filter, which is comprised of a conventional matched filter cascaded with a computationally efficient filter based on multiplicative expansion. Several constant parameters are introduced in the terms of the expansion and are optimized to improve the performance of the filter. Optimized mismatched filters for length 13, 11, 7 and 5 Barker codes are presented. For each of these codes, filters with one, two and three stages are studied. The technique is extended to compound Barker codes based on their representation in a factored form in the z-domain. Hardware requirements for the filters discussed in the disclosure are also presented.

Abstract: A method of detecting weather on an aircraft uses a weather radar system. The method adapts the weather radar system in accordance with a seasonal parameter, a time-of-day parameter, or a location parameter. The method includes determining the particular parameter and automatically adjusting the weather radar system to display the weather in response to the parameter. The system can be implemented in hardware or software and advantageously can more precisely predict and identify weather and/or weather hazards.

Abstract: The invention relates to a system, device, and method for using radar signals to measure the distance (h) to a surface from said device, the device comprising a transmitter and a transmitting antenna for transmitting radar signals, and a receiver and a receiving antenna for receiving a radar signal. The device may also comprise a first additional reflecting object separate from the receiving antenna, which additional reflector is designed so as to introduce a first predetermined alteration in radar signals upon reflection, with the device being equipped with means to differ between received signals with and without said predetermined alteration. The first predetermined alteration introduced by the first separate reflector can be, for example, a modulation shift or a shift in the polarization of the signal. In a typical embodiment the additional reflector is located close to the radar unit creating a double transition from radar unit to the surface.

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: Systems and method of detection and discrimination of targets in the presence of interference are disclosed. A system transmits a signal and then receives signals including interference and reflections of transmitted signals. The system processes the received signals and transmitted signals to generate a 2D representation of the STAP cube with one of the dimensions collapsed. The system then reduces the interference contributions and identifies angle and Doppler component of potential targets. The system then computes slices, which are one dimensional representation of cross-ambiguity functions of the received and transmitted signals. It reduces the interference contributions in the slices and determines range components of the targets.

Abstract: A radar receiver system includes a receiver, a processor, and a detector. The processor is programmed with a Multistatic Adaptive Pulse Compression (MAPC) algorithm for estimating adaptively a pulse compression filter, for each range cell of a plurality of range cells, and for each of a plurality of radar return signals, to remove interference between the radar return signals. MAPC may also include reiterative minimum mean-square error estimation for applying to each of the range cells in order to adaptively estimate a unique pulse compression filter for each cell. MAPC adaptively mitigates the masking problem that results from the autocorrelation of a waveform which produces range sidelobes scaled by the target amplitudes as well as the cross-correlation between waveforms. MAPC can also be applied when only 1 or some subset of the available illuminated radar range profiles are desired, with undesired information then discarded.

Abstract: Systems and method of detection and discrimination of targets in the presence of interference are disclosed. A system transmits a signal and then receives signals including interference and reflections of transmitted signals. The system processes the received signals and transmitted signals to generate a 2D representation of the STAP cube with one of the dimensions collapsed. The system then reduces the interference contributions and identifies angle and Doppler component of potential targets. The system then computes slices, which are one dimensional representation of cross-ambiguity functions of the received and transmitted signals. It reduces the interference contributions in the slices and determines range components of the targets.

Abstract: A synthetic aperture radar acquires an image of one or more objects and identifies them as targets. The objects are located in the proximity of clutter within the image such of trees, or a tree line. The radar acquires a SAR image having pixels descriptive of the clutter and the object(s). Regions having object pixels are identified within the synthetic aperture image using an object identification (algorithm), where the object identification (algorithm) utilizes one or more historically known target characteristics and one or more measured characteristic to obtain an output. Boundaries are identified for the one or more objects within the output using an object isolation, such as, for example, a Watershed transform. Clutter pixels are identified external to the one or more objects. The clutter pixels are suppressed from the synthetic aperture image thereby generating a clutter reduced image containing the one or more objects.

Abstract: A system and method for determining position of, for example, a robot based on reflected signals comprises a transmitter for transmitting signals in a number of directions within a range of directions and a receiver for receiving echoes of the signals from any direction in the range. The transmitter has a first rotatable antenna and the receiver has a second rotatable antenna which is mechanically couplable to the second antenna. The received echoes are processed by a processor to derive echo data signals indicative of the distance of the system to one or more reflective surfaces and the direction of the reflective surface(s) relative to the system. The processor is arranged to determine the position of the system relative to a starting position from the derived echo data signals indicative of the distance of the system to the reflective surface(s) and the direction of the reflective surface(s) relative to the system.

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: The invention discloses a radar system (100) for the detection of low RCS-objects (110, 140, 150, 160, 190) such as forest fires, said system comprising a first plurality of stations (120) for transmitting radar energy, said stations having mechanically fixed antennas (220), and a second plurality of receive stations (130) for receiving reflections of radar energy transmitted from the transmit stations, said stations having mechanically fixed antennas (220). The antennas (220) of said transmit and receive stations have a main beam (221) which is essentially parallel to the ground, and at least a sub-set of the receive stations is equipped with means for recording a first and a second received signal, and means for subtracting one of said signals from the other of said signals. Said transmit and receive stations are arranged to function within the frequency range of 10-100 MHz.

Abstract: Interfering clutter in radar pulses received by an airborne radar system from a radar transponder can be suppressed by developing a representation of the incoming echo-voltage time-series that permits the clutter associated with predetermined parts of the time-series to be estimated. These estimates can be used to estimate and suppress the clutter associated with other parts of the time-series.

Abstract: A radar for detecting a target wherein a standard deviation of the amplitude of a beat signal from a transmission signal and a reception signal is determined for a predetermined period. A threshold is determined by adding a predetermined value to the standard deviation or by multiplying the standard deviation by a predetermined coefficient. The presence or absence of interference on the beat signal is detected according to the presence or the absence of an amplitude greater than the threshold. For example, an amplitude exceeding the standard deviation×2 is considered a spike noise (SPN), i.e., as “presence of interference”. The threshold used for detecting peaks appearing on a frequency spectrum is then increased. This allows detection of the presence or the absence of a spike noise superposed on the beat signal to be performed more certainly, thereby enabling processing according to the presence or the absence of interference.

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: The search/detection apparatus modulates a carrier signal by a modulation signal, generates a probe signal for detecting the location of a target, and receives the probe signal reflected by the target as an echo signal. Then, the search/detection apparatus detects the existence of an interference signal other than the echo signal from the received signal and modifies the parameter of the modulation signal and/or carrier signal.

Abstract: A radar system mounted on a vehicle includes a first radar and a second radar, each having a transmitter-receiver and a signal processor. The transmitter-receiver transmits radar waves to detect objects such as another vehicle or other obstacles. An operating cycle period T1, T2 and a transmission time X1, X2 during which the radar waves are transmitted are set in both radars to satisfy the formula: K·T2+X2+X1?T1?(K+1)·T2?X2?X1 under a condition that T1>T2, where K is a positive integer. By setting both radars in this manner, interference between two radars is avoided without using additional devices in the radar system, and a high detection accuracy is realized.

Abstract: A radar receiver system includes a receiver, a processor including a Doppler Compensated Adaptive Pulse Compressor (DCAPC) algorithm, possible other intermediate processing and a target detector. The DCAPC algorithm processes samples of a radar return signal, applies Minimum Mean Square Error (MMSE), or alternatively matched filtering, to the radar return signal to obtain initial radar impulse response estimates, computes power estimates, estimates a range cell Doppler shift for each range cell, computes range-dependent filters, applies the MMSE filters, and then repeats the cycle for subsequent reiterative stages until a desired length?L range window is reached, thereby resolving the scatterer from noise and other scatterers.

Abstract: A method for radar protection. The method includes recording energy events and calculating differences in recorded energy events to determine pulses. The method further includes sorting intervals between pulses into histogram bins, each bin representing a range of time intervals between two pulses, each pulse indicative of a radar frequency and limiting network traffic on a frequency based on a selected bin count.

Abstract: A transmitter for transmitting signals to targets and a receiver having a large-diameter array antenna for receiving signals reflected from targets are included. The transmitter has a function of outputting an FMCW signal for detecting direction and velocity of the target from a transmitting antenna. The receiver includes: a plurality of correlation processors for performing correlation processing to receiving signals received by respective interference blocks configured such that the large-diameter array antenna is divided into a plurality of equal blocks; and a synthesizer for vector-synthesizing same signal components of signals outputted from the plurality of correlation processors.

Abstract: A method for a radar for detecting a noise floor level of an electric signal corresponding to an incident radio wave received by the radar, the incident radio wave including a return of a radar wave that is transmitted from the radar toward a measuring range of the radar to detect target object characteristic including presence of a target object within the measuring range of the radar, a distance between the target object and the radar, and a relative speed of the target object to the radar is provided. The method includes steps of: calculating a histogram of intensities of frequency components, the frequency components exceeding a predetermined value relating to the measuring range, and extracting an intensity having the maximum height in the histogram as the noise floor level of the electric signal.

Abstract: There is provided a receiver comprising: an estimator configured to estimate an initial noise-plus-interference covariance matrix on the basis of a received signal; a calculator configured to calculate a parameter using the received signal; and a calculator configured to decrease magnitude of off-diagonal values of the estimated initial covariance matrix relative to diagonal values of the same matrix based on the calculated parameter in order to estimate a final noise-plus-interference covariance matrix.

Abstract: A method for detecting an occurrence of interference between a return of a radar wave which has been transmitted by a radar and has an oscillating amplitude in time and a radio wave transmitted by some other radar, Includes steps of: detecting extremal points of an incident radio wave in which the radio wave transmitted by the other radar is superposed on the return of the radar wave, extracting, sequentially in time, an emerging pattern of the extremal points of the incident radio wave within each of periods of time to obtain a series of emerging patterns of the extremal points, detecting a period during which the emerging pattern of the extremal points is irregular among the series of the emerging patterns of the extremal points, and determining that the interference occurs during the detected period of time.

Abstract: Combining signals includes receiving first signals having a first frequency and second signals having a second frequency. A first weight reflecting a signal-to-noise ratio associated with a first signal is determined for each first signal, and a first signal output is generate from the first signals in accordance with the first weights. A second weight reflecting a signal-to-noise ratio associated with a second signal is determined for each second signal, and a second signal output is generate from the second signals in accordance with the second weights. The first signal output and the second signal output are combined to yield a combined signal output.

Abstract: A radar device is provided that can reliably display sensed image data of an object, regardless of the state of the object (echo) within a sensed range and of the surrounding environment. A behavior data detector 11 generates current level detection data by detecting a level behavior of sensed image data X(n) handled by a W data generator 7 from sensed data x(n) that is output from a sweep memory 4. Previous behavior data constituted by level detection data of several past scans is stored in a behavior data memory 12, and the behavior detector 11 updates the previous behavior data with the current level detection data and outputs the result to the W data generator 7. Detecting characteristics of the sensed image data of corresponding pixels from the behavior data, the W data generator 7 selects filter calculation data W(n), the current sensed image data X(n) or specific filter calculation data Z(n) and outputs the selected result as written image data Y(n).

Abstract: The invention refers to a method and an arrangement for signal processing for a target detecting device (1) where a return signal (8) is divided into two parallel branches where a first compression filter (15) compresses the signal in the first branch and where a second compression filter (17) compresses the signal in the second branch. The second compression filter (17) compresses the return signal (8) to a higher degree than the first compression filter (15). A delay filter (19) delays the first compressed signal (16a) compensating for a delay ?T. Detectors (21, 22) processes the compressed signals (16b, 18) giving rise to detector signals (21, 23). The detector signals are compared and the minimum value of the compared detector signals (21, 23) is selected for all time frames, giving rise to a first output signal (25) comprising the minimum values from the first and second detector signals (21, 23).

Abstract: Embodiments of the present invention provide a method, apparatus and system of radar detection. The method, according to some demonstrative embodiments of the invention, may include comparing an energy level of signals received over a wireless communication channel to a threshold; during operation of a processor, if the energy level is above the threshold, determining independently of the processor one or more time values related to said signals; and if the energy level decreases to or below the threshold, interrupting the operation of the processor to determine, based on the time values, one or more parameters of a detection time period during which the energy level was above the threshold. Other embodiments are described and claimed.

Abstract: A weather radar system includes processing electronics. The processing electronics sense weather and determine significant weather based upon the altitude of the weather. The altitude of the weather can be compared to a flight path to determine its significance. A display can provide visual indicia of the significant weather in response to the processing electronics.

Abstract: A method and apparatus for signal detection is provided herein. During operation logic circuitry will determine if a de-sensing signal exists within any received signal and, if a de-sensing signal exists, then it will be assumed that a radar pattern exists where the de-sensing signal exists within the signal. Any received signal pattern is then correlated to known radar transmission pattern in order to determine whether or not a radar transmission pattern was received. If a known transmission pattern was received then logic circuitry will prevent further transmission.

Abstract: A system and method are provided to reduce 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 interfering signal is removed from 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.

Abstract: A new method for transmitter-receiver design that enhances the desired signal output from the receiver while minimizing the total interference and noise output from the receiver at the decision making instant is presented here. Further the new design scheme proposed here can be used for simultaneous savings of transmit signal energy and bandwidth compared to any traditional waveform without sacrificing the performance level. As a result, compared to a traditional transmit waveform, simultaneous savings in transmit signal energy as well as the more “premium” signal bandwidth can be realized without sacrificing the system performance level in terms of the output Signal to Interference plus Noise power Ratio (SINR).

Abstract: A method of classifying radar emitters includes the steps of: (a) receiving pulses from multiple radar emitters; (b) categorizing received pulses based on pulse data descriptors (PDWs); (c) forming clusters of received pulses based on the PDWs; and (d) de-interleaving pulses from the cluster using one of a differential time of arrival (DTOA) histogram technique, a spectrum estimation technique, or a Hough transform technique. Step (a) includes receiving the pulses during a predetermined time interval and storing the received pulses as a snapshot representing the pulses present during the predetermined time interval.

Abstract: Described herein are frequency-domain back-projection processes for forming spotlight synthetic aperture radar (“SAR”) images that are not corrupted by the effects of multiple-bounce ghosting artifacts. These processes give an approximately exact reconstruction of the multiple bounce reflectivity function (MBRF) ƒ(x,y,?). Specifically, the evaluation of ƒ(x,y,?) in the ?=0 plane gives an approximately exact reconstruction of the true object scattering centers which is uncorrupted by multiple-bounce contributions to the phase history data G(?,?). In addition, the non-zero dependence of ƒ(x,y,?) upon the MB coordinate ? can be used to facilitate the identification of features-interest within the imaged region.

Abstract: The method and system provide provisions for generating a respective detection state value associated with each of a plurality of RF receive beams. A first state value is indicative of a detection. The method and system further provide provisions, for each of the detection state values equal to the first state value, for generating a respective detection range value. The method and system further provide provisions for selecting one of the detection state values equal to the first state value and verifying the selected detection state value to provide one of a positive verification and a negative verification associated with the selected detection state value. The method and system further provide provisions for setting the selected detection state value to be equal to the second state value in response to a negative verification.

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 subject invention pertains to a frequency modulation continuous wave (FMCW) radar system. Embodiments relate to methods of improving the performance of such a FMCW system and improving the value of the information provided by such a FMCW system. In an embodiment of the subject invention, the IF level can be monitored while sweeping the frequency of the system through at least a portion of the frequency range of the system. In a specific embodiment, the system is then set to the frequency that produces the minimum IF level, which is the frequency that produces the minimum AM signal level. Embodiments of the invention pertain to techniques for expediting the adaptation of the comb filter to the signal when the system is turned on. In an embodiment, in order to reduce the number of detection calculations a processor performs every frame, a method of quickly determining the largest peaks in the RDM is implemented.

Abstract: A bistatic radar system having a transmitter that generates unique signals at spatially independent transmitter degrees of freedom and a receiver that filters the signal at each receiver degree of freedom into a group of signals identical in number to the number of transmitter degrees of freedom. The receiver formats the filtered signals into a 2-dimensional array of elements. The receiver rotates the array so that the new axes are aligned with the Doppler gradient. The data is then re-sampled and projected to linearize the clutter signal. The receiver may be integrated with a broad class of adaptive and non-adaptive clutter mitigation approaches such as electronic clutter tuning and projected bistatic space-time adaptive processing, or STAP.

Abstract: A method and system is provided for detecting and characterizing pulsed threat radar emitters through heavy in-band interference. System includes an advanced digital signal processing method provides spatial and temporal interference cancellation, super-resolution direction-finding, and high resolution spectrum analysis techniques. The system receives the digitized output of a discriminator bank and produces highly accurate threat pulse radio frequency estimates. The invention further provides a two-channel configuration for a DF subsystem, to perform adjacent-beam direction-finding through severe interference environments. The invention provides increased sensitivity, increased frequency accuracy, and up to 40 dB of increased interference look-through capability in ES system but remains transparent to ES system functioning and to ES system operators.

Abstract: For suppressing secondary lobes in pulsed radar systems, the antenna characteristics of the transmitting antenna and the receiving antenna are designed so that the dominant secondary lobes appear mutually offset and their maximums and minimums are mutually suppressed. This increases the safety against detection of false targets.

Abstract: A system and method are provided for filtering noise from a pulsed input signal comprising cyclically producing a change in an output signal only if changes in an input signal occur at least a desired time after a respective immediately previous change in the input signal, and otherwise rejecting the changes in the input signal; and counting the rejected changes in the input signal. More than one duration or frequency may be used for the filtering, enabling classification of noise by frequency. Resulting counts may be used to determine rates of occurrence of noise for evaluation of performance of equipment, installation of the equipment, and changes in performance over time.

Abstract: A polarimetric radar system transmits a signal which is nominally the desired polarization, but which may deviate therefrom. A calibration operation is performed using a symmetrical radar reflector, to determine the gains and phases of reception of two mutually orthogonal components of the received reflected signal which result in nulling of the two polarization components of the reflected signal. These gains and phases represent receive corrections which result in a simulation of perfect polarization purity on both transmission and reception. The corrections established during calibration are applied to the receive signals during normal (non-calibration) operation, to improve the effective polarization of the transmission and reception.

Abstract: A method and a device for adaptively controlling power in a radar device having a radar transmitter and a radar receiver are provided, in particular for applications in vehicles. The radar signals are emitted, and radar signals reflected off of target objects are received and checked for irregularities. The transmitting power of the radar transmitter is reduced when irregularities occur which are attributable to interference caused by neighboring radar transmitters.

Abstract: To achieve a purpose of the present invention, a pulse wave radar device related to the present invention modulates a first transmitting pulse and a second transmitting pulse which are separated from each other by a predetermined lapse of time and transmits a transmitting pulse wave and, if a lapse of time from transmission of the transmitting pulse wave corresponding to the first transmitting pulse to outputting of a pulse by the receiving circuit is equal to a lapse of time from transmission of the transmitting pulse wave corresponding to the second transmitting pulse to outputting of a pulse by the receiving circuit, decides that the pulses are a receiving pulse reflected from a target.

Abstract: Methods and apparatuses for target radial extent determination using deconvolution are presented. One embodiment features a method for determining a radial extent of an target using an active sensor performing noise reduction on a received signal, deconvolving the noise reduced received signal by a transmit signal to produce a target profile, where both the noise reduced received signal and the transmit signal are over-sampled, and determining the target radial extent using the target profile. Another embodiment further features transforming the digitized transmit signal, transforming the digitized receive signal, thresholding the transformed digitized receive signal, dividing the noise reduced, transformed digitized receive signal by the transformed digitized transmit signal, and inverse transforming the divided signal.

Abstract: An FMCW radar device executes a frequency analysis for a beat signal in a frequency increase interval and a frequency decrease interval, to obtain frequency components in a predetermined high frequency range exceeding a frequency range corresponding to a target detection frequency range within which a target object for detection should be detected. Then the FMCW radar device calculates a value related to a sum of intensities of frequency components within the high frequency range respectively for each of the frequency increase interval and the frequency decrease interval. In the case that one of the calculated integrals is larger than a threshold, the FMCW radar device determines that the FMCW radar device is interfered with by a nearby radar device.

Abstract: A method for generating a radar detection threshold includes computing a first plurality of percentile values associated with frequency domain values of frequency domain signals. The first plurality of percentile values is used to generate detection threshold values. Apparatus for generating a radar detection threshold includes a first percentile processor adapted to compute a first plurality of percentile values associated with frequency domain values of frequency domain signals. A threshold processor is adapted to use the plurality of percentile values to generate detection threshold values.

Abstract: A radar system in which a beat signal is generated by transmitting a transmission signal that is subjected to frequency modulation into a triangular wave and receiving a reflection signal from a target, the beat signal is sampled, and a window function is applied to yield a discrete frequency spectrum. When the window function is applied, a first window function having an amplitude that is gently attenuated from the center of the sampling period toward both sides thereof is applied in a lower frequency band in the frequency spectrum (at close range), and a second window function having an amplitude that is sharply attenuated from the center of the sampling period toward both sides thereof is applied in a higher frequency band in the frequency spectrum (at far range).

Abstract: This invention addresses the problem of radar target detection in severely heterogeneous clutter environments. Specifically, we present the performance of the normalized matched filter test in a background of disturbance consisting of clutter having a covariance matrix with known structure and unknown scaling plus background white Gaussian noise. It is shown that when the clutter covariance matrix is low rank, the (LRNMF) test retains invariance with respect to the unknown scaling as well as the background noise level and has an approximately constant false alarm rate (CFAR). Therefore, a technique known as self-censoring reiterative fast maximum likelihood/adaptive power residue (SCRFML/APR) is developed to treat this problem and its performance is discussed. The SCRFML/AP method is used to estimate the unknown covariance matrix in the presence of outliers. This covariance matrix estimate can then be used in the LRNAMF or any other eigen-based adaptive processing technique.