Abstract: A method for operating a radar system includes the steps of overlapping mainlobe clutter interference and feedthrough interference in a Doppler output signal of a coherent pulse Doppler radar including the step of phase modulating each pulse of a transmit signal wherein the selected phase modulation is derived from a linear phase ramp required to shift the mainlobe clutter interference into alignment with the feedthrough interference while being held constant over the duration of a pulse. With such an arrangement, the constant phase shift across each pulse has no effect on the performance of intrapulse compression modulation and results in pulse to pulse phase shifts easily being accomplished with existing phase shifters.

Abstract: The present invention relates to a receiving/transmitting apparatus for radiating a predetermined signal and receiving a signal arriving as a response to the radiated signal, and to a radar equipment in which the receiving/transmitting apparatus is installed. In the receiving/transmitting apparatus and the radar equipment according to the present invention, high coherency is reliably achieved without any great enlargement in hardware scale. Therefore, it is possible to realize with high reliability improvement in performance and reliability as well as price reduction, downsizing, and running cost reduction in apparatuses and systems to which the present invention is applied.

Abstract: For optimizing the computing expenditures when using STAP filters in real-time systems, the determination of the filter coefficients and the filtering of radar source data of the distance Doppler matrices {right arrow over (X)}left and {right arrow over (X)}right of two adjacent reception channels are carried out in the frequency domain. On the basis of {right arrow over (X)}left and {right arrow over (X)}right, a distance Doppler matrix {right arrow over (Y)}clutterfree is created, at which the echoes of fixed targets are suppressed and the echoes of moving targets a coherently intensified.

Abstract: Radar apparatus in which output RF signals are modulated on an optical signal prior to transmission. Incoming optical echo signals are converted into RF signals using a detector. The original functionality of the radar apparatus is to a large extend retained, including the Doppler processing. The target radar cross section is determined by the wavelength of the optical signal.

Abstract: A radar tracking system extracts moving target content from a single radar pulse stream. The radar tracking system has a single phase center antenna for receiving the radar pulse stream. The tracking system further includes a signal processing system for converting the radar pulse stream into a plurality of SAR images. Each image has a corresponding moving target content and a corresponding clutter content. The tracking system also includes a targeting system for canceling identical clutter content between the images. The signal processing system includes a synthetic subaperture system for generating a plurality of synthetic subapertures and defining a common reference point. The common reference point has known slant ranges with respect to the plurality of synthetic subapertures. A deramping module uses a unique deramping function to compute a deramped signal for each synthetic subaperture based on the known slant ranges.

Abstract: A radar detection and imaging system provides for the simultaneous imaging of the stationary objects on the earth's surface and the detection and imaging of moving targets. The radar system includes at least one transmitting aperture and a plurality of receiving apertures that are simultaneously operated in a synthetic aperture radar (SAR) mode caused by the motion of the satellite or airborne platform on which they are mounted. Each receiving aperture is connected to its own coherent receiver and the digitized signals from all receivers are processed to image both stationary clutter and moving targets. The system employs space-time adaptive processing (STAP) algorithms to better compensate for channel mismatches, better suppress stationary clutter, and to suppress mainbeam jamming. Moving target detection and estimation modules are also included and are their performance is improved as a result of the STAP algorithms.

Abstract: A curve radius of a roadway is determined by measuring the difference in wheel speed of at least two vehicle wheels and the rate of yaw of the vehicle, and hence the curve radius, is determined therefrom. The wheel speeds are determined by measuring the time required for the wheel to rotate by a fixed rotational angle, based on a fixed number of pulses produced by a pulse transmitter which is part of an ABS or ASR system for the vehicle. The method provides considerably improved accuracy using simple, vehicle-contained components and various parameters can be taken into account simultaneously.

Abstract: A method for the detection of a target by a radar in the presence of noise, the detection being performed on M antenna rotations, comprises at least: a first step for the estimation of the Doppler frequency ({circumflex over (f)}) of the target; a detection step, the target being detected if an associated variable Z is greater than or equal to a predetermined threshold S, the variable Z being defined according to the following relationship: Z = MAX t ∈ D t , f ∈ D f ⁢ ( ∑

Abstract: In a radar system it is necessary to distinguish signals reflected from wanted targets such as aircraft from those reflected from fixed terrain features, known as clutter. The clutter signals can in some cases be significantly stronger than the wanted signals. One method for dealing with land clutter is the use of a high resolution clutter map. The area around the radar is considered to be divided into cells, and an array of background signal estimates is maintained for these cells. Whenever a signal is received by the radar, it is compared with the stored background level for the cell it occupies, and a detection is only reported if the signal exceeds the background by a pre-set threshold. Received signals are also used to modify the stored background levels so that the clutter map adapts to the reflections from clutter which are present over long periods. Clutter maps have so far only been used successfully for radars at fixed locations.

Abstract: A method and apparatus for optimizing radar system performance is provided that is independent of any specific radar application. In one embodiment, an optimization system (110) includes an optimization engine (112) and various input modules including constraint module (114), a variable module (116) and an objectives module (118). The input modules provide information sufficient to define an optimization application under analysis. Based on these inputs, the optimization engine (112) identifies an appropriate optimization model and determines optimal radar system parameter values. In this manner, the optimization engine (112) need not be preprogrammed with knowledge of the application under consideration, and is applicable in a variety of context involving different radar system types.

Abstract: A radar system employing Doppler tolerant radar pulses such as linear FM or hyperbolic FM chirps includes a pulse compressor configured as a digital finite impulse response filter. In one embodiment, the radar returns are split into in-phase and quadrature phase components for manipulation in complex form within the filter.

Abstract: An Ultra Wideband (UWB) short-range radar system is used for the detection of targets in clutter. Examples of targets on the ground include human walkers, crawlers and runners, and vehicles. The UWB sensor can also be used to detect small approaching boats in different levels of sea clutter or airborne targets like hang gliders. One of the primary differences between this device and other UWB radar sensors is the manner in which the bias on the threshold detector is set as well as the logic circuitry used to find targets in clutter while maintaining a low false alarm rate. The processing is designed to detect targets in varying degrees of clutter automatically. There may be no front panel controls other than an ON-OFF switch. The system is lightweight, low-cost, and can be easily installed in minutes.

Abstract: A coherent, frequency agile pulse radar system in which each transmitted pulse is made up of subpulse pairs having frequencies of &ohgr;o±&Dgr;i forces a jammer to broadband jam the system in order to ensure jamming the actual operating frequency of the system. On reception, a separate receiver channel is utilized for the detection of each subpulse frequency. Within the processing system, the signal return for a subpulse having a frequency of &ohgr;o+&Dgr;l is multipled times the signal return for the subpulse having a frequency of &ohgr;o−&Dgr;l to provide a combined signal which is free of the offset frequencies. This combined signal is a standard coherent frequency agile pulse doppler radar signal with the exception that the carrier frequency and the doppler frequency are both doubled. Moving target indicating or doppler processing may be used.

Abstract: A slow speed pulse chase apparatus in a bistatic radar system, wherein the receive antenna follows the transmit pulse out in space. The receive beam comprises many parallel beams that overlap all the possible positions of the transmit pulse as it travels into space. Slow speed chase apparatus provides a small group of beams which are held in a fixed location as the transmit pulse travels by and then is jumped in one large step to continue to the next position to remain there until the transmit pulse travels by.

Abstract: A processing method or algorithm is for use with a monopulse radar system that provides accurate position information in a cross-range direction for ground moving targets detected using the monopulse radar system. The method corrects the phase of each detected moving target on an individual basis, and thus more accurately compensates for the phase error introduced into each target in a random fashion as a result of noise. The direction of angle correction is determined from clutter data. A gain correction factor includes a term for antenna effects to provide for a more accurate gain correction factor calculation.

Abstract: An MTI radar system transmits pulses with variable interpulse time periods and is structured with a lattice filter to process return signals to identify targets while substantially rejecting static and moving clutter. The MTI radar system also operates to reject adverse effects of transmitter instability in the processing of return signals. The MTI radar system is applied as an airport traffic control in which aircraft are detected as targets.

Abstract: A method and system for detecting moving objects using azimuth streaks in synthetic aperture radar (SAR) image data are disclosed. The method and system of the present invention are directed to processing amplitude data relating to a SAR image, the first amplitude data having at least first and second indications corresponding to at least a first object moving at a substantially constant linear velocity and clutter, respectively, to separate or filter at least the first indication from the second indication, reducing/altering a spatial frequency power of the clutter corresponding to the second indication relative to a first azimuth streak power of a first azimuth streak corresponding to the first indication, and thresholding a first amplitude of the first azimuth streak to detect the first azimuth streak.

Abstract: Radar detection of accelerating airborne targets in accordance with the present invention utilizing a sequence of velocity, acceleration matched filters. This system includes a transmitter generating a signal oscillating at a predetermined frequency controlled by modulator such that the transmitter repeatedly outputs short duration pulses. The output pulse frequency is passed to an antenna that radiates the energy into free space. Reflected electromagnetic wave energy is received by the antenna to produce a radar return signal that is processed to a receiver that includes a radio frequency amplifier having an output that is mixed with a local oscillator signal an applied to an IF amplifier. An output of the IF amplifier is mixed with the output of an IF oscillator where the mixed signal passes through a low pass filter to a pulse compression network. An output of the pulse compression network is input to a matched filter processor array having multiple outputs applied to an adaptive threshold detector.

Abstract: The invention is an improved clutter suppressor for MTI and pulse doppler radars operating so that the received clutter pulses are large enough to hard limit within the receiving system. It is especially useful for radars that use antenna beam scanning to perform tasks such as search, surveillance, and height finding because the combination of hard limiting with beam movement creates strong clutter residue at the output of a doppler filter. The invention can be implemented with either analog or digital technology, or with a digital processor and software.

Abstract: A computer-implemented process is disclosed for processing incoming target data from a focal plane or scanning radar to accomplish multiple Target Tracking. Inputs are pixel plane coordinates and intensity of target blips. The Intelligent Target Tracking Processor (ITTP) employs an optimal target tracking algorithm. An optimal observation-to-track assignment exists when all target blips in a new frame of target data are matched up with nearby tracks, such that the sum of all the distances from each target blip to its assigned track is minimized. An expert system is used to control overall processing flow and provide efficient allocation of computing resources. Target blips without near neighbors are allowed to go directly to a real track table of established tracks, if their coordinates match-up with projected tracking gates. Otherwise, target blips are tested sequentially against two-frame, three-frame, and four- or higher-frame discriminants, to reject blips not belonging to established tracks.

Abstract: A radar system includes a radar receiver that provides the amplitude and the angular position of a plurality of return signals. A computer forms a test function of amplitudes and angular positions of the plurality of return signals and compares the test function with a threshold value. Returns associated with a test function whose value is equal to or greater than the threshold value are determined to be targets, and those with lesser values are considered clutter.

Abstract: A method of processing radar returns derived from a new radar waveform. The method processes radar returns derived from transmitting the radar waveform to provide simultaneous matched processing and range profiling of different size objects in the presence of clutter. In the present method, radar returns are digitized and processed to produce pulse compressed radar returns having a predetermined (169:1) pulse compression ratio. A pulse to pulse fast Fourier transform on each RF step is performed on the pulse compressed radar returns. The Fourier transformed radar returns are then simultaneously processed by three processing channels, one each for ships, boats and submarines to provide detection of the different size objects. The waveform permits concurrent detection, discrimination, and high resolution range imaging of detected objects within a single dwell, using a single waveform. Thus, a radar search mode using the waveform integrates several search functions without increasing search frame time.

Abstract: The device for the elimination of intermediate frequency echoes from fixed targets carries out the cancellation of the echoes from the fixed targets by the storage, in the form of amplitude and phase samples, of the response to the first pulse of a burst reduced to video band, the synthesis on the basis of these samples of an intermediate frequency replica of the response to the first pulse of a burst and the subtraction of the synthesized replica from each of the subsequent pulses of the burst. It is of the double cancellation type, the preparation of the replica being done in two steps, a first rough-working step in which a rough replica is prepared and a second refining step in which the modelling error of the rough replica is taken into account.

Abstract: An MTI with no blind speeds which compensates for antenna scan modulation. his design includes circuitry for generating and transmitting consecutive first, second and third doppler-tolerant FM pulses, wherein the first and third FM pulses have a given dispersion characteristic, and the second FM pulse has a dispersion characteristic which is the complex conjugate of the first and third FM pulses. Circuitry is then provided for receiving and compressing the first, second, and third echos from the first, second, and third pulses, respectively. Finally, a processing circuit is used to effectively add the first and third echo pulses and to subtract twice the second echo pulse from this sum to effect the detection of the moving target.

Abstract: A detection system will detect targets against a fixed background if the target is of a type emitting a gaseous plume. The detection system directs electromagnetic energy, preferably radio frequency signals, toward the fixed background in an area of suspected target activity. The detection system has a receiver which detects reflected electromagnetic energy from the fixed background. The system will identify anomalous variations in range. The variations occur as a result of refraction of the electromagnetic energy wave passing through the gaseous exhaust stream. This indicates a probable target which is creating exhaust plume.

Abstract: A fine grained multi-planar clutter rejection processor (10) for correlating multiple sets of data. The processor (10) maps each set of data onto a plurality of arrays (28-34). The data includes target data which is correlated between sets and clutter which is uncorrelated between sets of data. The system also includes a means for shifting (40) the positions of the second and subsequent arrays in a pattern which is larger for each successive array. In addition, a correlation identification unit (78) identifies the coordinate locations in the first array (28) which contain data points and which also contain data points in subsequent arrays in their shifted positions. In this way, data points identified in this manner are correlated and the remaining data points can be discarded as clutter. The processor (10) system is able to handle a very large number of data points per scan (over 100,000) over a high number of scans (such as eight).

Abstract: The invention improves the radar detection capabilities for moving targets by censoring clutter and noise after it is outputted from a doppler processor. It effects the resulting clutter and noise suppression of doppler radars through use of thresholders that function in operative association, one principally for noise and the other principally for clutter.

Abstract: An improved MTI radar system including a signal expander/compressor for providing palindromic P2 phase-coded upswept and downswept expanded signals that are alternately transmitted by a radar transmitter. The echos from the upswept and downswept signals are received by a receiver, compressed in the signal expander/compressor and inputted to an MTI subtractor. Since the autocorrelation sidelobes of the palindromic phase coded echos are real, the echos from stationary clutter are completely cancelled so that the system is capable of detecting weak echos from moving targets.

Abstract: The present invention relates to a signal processing apparatus for use in radars, which can detect a target from a receive signal by digital processing. An A-D converter samples the receive signal by a clock signal A, and quantizes the sampled value. A clock accelerator generates a clock signal B having a frequency which is N times a frequency of the clock signal A. A signal latch holds an output from the A-D converter for an N clock period of the clock signal B. A digital low-pass filter performs low-pass filtering processing with respect to an output from the signal latch with the clock signal B as an operating clock. As a result, an output from the digital low-pass filter includes a more approximate value of the maximum value in the receive signals. Therefore, it is possible to provide improved accuracy of the target detection by a target detector.

Abstract: An MTI radar based on a comparison of the Doppler shifts of the original signal and a phase-reversed signal using pulse compression wherein the received signal is phase detected for in-phase and quadrature components relative to the IF. A Doppler-corrected pulse compressor produces a magnitude signal for the Doppler shift of the received signal from the sequence of in-phase and quadrature components. Another Doppler-corrected pulse compressor produces a magnitude signal for the Doppler shift of the received signal from the conjugates of the sequence of in-phase and quadrature components. The magnitude signal of the same Doppler shift of the two compressors are compared and the difference is the output of the MTI.

Abstract: A target tracking system (10) comprises sensors (12) which provide data corresponding to a region of interest, the data being time dependent and consisting of amplitudes, ranges and angles. A window (202) is placed around data of interest, the size of the window being determined based on target size, assumed speed and acceleration characteristic, and the window is thereafter broken down into a plurality of smaller windows (208), thereby forming a grid having a nodal point (210) at each corner of the smaller windows. The data within the window is stored in a matrix, and background noise is thereafter minimized by filtering the data past a threshold value (215). The filtered data is analyzed to determine its distance weighted contribution at each nodal point (219), and the weighted distances are summed for each nodal point resulting in a nodal point magnitude for each of the nodal points (220).

Abstract: A pulse-compression, MTI, doppler-radar system for determining target velty information from a single target-return pulse is improved by the addition of a pulse-compression filter consisting of at least two pulse compressors and by the addition of a phase-comparison processor. The pulse compressors simultaneously pulse-compress separate portions of the single target-return pulse. The phase-comparison processor then determines the phase difference between the compressed pulses to obtain the target velocity information.

Abstract: A method of detecting a target signal at a target signal level below the level of clutter in the return signals of a radar receiver. The receiver i.f. signals are correlated by multiplying delayed i.f. signals with undelayed i.f. signals. The correlated signals are filtered and then decomposed into their spectral component frequencies. The spectral components are compared, in turn, with individual thresholds. The individual thresholds are formed by summing the weighted values of selected ones of the spectral components, the selection being such that the spectral component being compared with a threshold is not used in forming that threshold. A target output signal is generated whenever any one of the spectral components exceeds the level of the threshold against which it is compared. In a second embodiment, in-phase and quadrature correlator signals are formed by the use of two correlators and two delay lines having different delay times that provide a 90 degree phase difference.

Abstract: A pulse-compression, MTI, doppler-radar system for determining target velty information from a single, frequency-coded uncompressed target-return pulse includes a coded modulator, two pulse compressors, and a phase-comparison processor. The coded modulator generates for transmission an uncompressed pulse with the first and second halves of the pulse coded with the even and odd harmonic sidebands of a pulse repetition frequency, respectively. The first and second halves of the pulse returning from the target are pulse compressed simultaneously by the two pulse compressors. The phase comparison processor then determines the phase difference between the compressed pulses to obtain the target velocity information.

Abstract: There is provided a radar apparatus wherein a local signal having a coherent sine wave is modulated to generate a composite signal of two signals modulated by different modulation functions. The composite signal is transmitted as a transmission signal, and a reception signal associated with the transmitted signal is separated into two signal components modulated by the different modulation functions. A difference between the two signal components is found, thereby removing a reflection signal from a static clutter and extracting a signal component which has been frequency-deviated by a moving target. Thus, the moving target is displayed. The transmission frequency can be quickly changed without losing the function of detecting the moving target.

Abstract: A radar apparatus provided with transmitter means (1), rotating antenna means (2) and receiver means (3) for the transmission per burst and the processing in a video processor of radar echo signals. The video processor includes moving target detection unit (4) provided with a doppler filter bank, for instance an FFT processor, and slow moving target detection unit (6), provided with coherent clutter maps, one map for each radar transmitter frequency used. The coherent clutter maps are also used for reducing the clutter strength of radar echo signals which are applied to the moving target detection unit (4), by subtracting the coherent clutter strengths stored in the clutter maps from the radar echo signals.

Abstract: A covert radar response system suitable for use with an illuminating coherent radar system having a moving target indicator subsystem shifts the phase and/or frequency of a retroreflected beam to transmit a message to the illuminating system that is not detectable by other observers in the vicinity.

Abstract: A method for distinguishing between a target and clutter analyzes frequency components of returned wave energy to detect target energy characterized by being present in a narrow range of frequencies, by increasing in the range over time, or by remaining substantially in the range over time. The method utilizes time sequential spectra of the returned energy. The spectra may be signals from a plurality of band pass filters or may be a spectrogram. The energy in adjacent band pass signals and spectra frequencies are correlated to detect energy in a narrow range of frequencies. Differences in successive spectra are integrated to detect increasing energy in a range of frequencies. An energy peak detected in a narrow range by correlation is integrated to detect that the peak remains in the range.

Abstract: While the computation of high resolution radar images based on higher order tatistics is position insensitive, velocity estimation may be based on the ratios of values of a trispectral slice and a cross-trispectral slice computed as quadruple products of complex valued signals developed by coherent radar. Signal-to-noise ratio is improved by either averaging over a plurality of bursts during computation of both the trispectral slice and the cross-trispectral slice or averaging of values of ratios of trispectral slice and cross-trispectral slice values at particular frequencies or wavenumbers, or both.

Abstract: A digital pulse compression apparatus comprises a plurality of doppler correction circuits for carrying out doppler correction in the time domain or the frequency domain and for carrying out pulse compression, and a maximum amplitude selecting means for selecting and outputting the maximum amplitude signal out of the compressed signals obtained from the doppler correction circuit at the rate of range bin period. The present invention can supply a pulse compression apparatus having a stable compression performance, even if a doppler frequency of the input signal is not known.

Abstract: A maximum likelihood estimator and range-only-initialization target detection method employed to detect and resolve targets in a multislope linear frequency modulated waveform radar. The method resolves a large number of target returns without a large amount of signal processing and without creating a significant number of false alarms, or ghosts. The method simultaneously estimates range and doppler for each target. The method rejects undesired long-range targets that fold into target regions, and processes target regions of interest around a nearest target to reduce signal processing throughput requirements. Using a K out of N detection rule, the method detects targets that compete with mainlobe rain clutter, mainlobe ground clutter, and receiver leakage. The method simultaneously estimates target parameters and optimally resolves any number of targets.

Abstract: An AWTSS is shown to be made up of an improved synthetic aperture radar (SAR) for generating radar maps with various degrees of resolution required for navigation of an aircraft and detection of ground targets in the presence of electronic countermeasures and clutter. The SAR consists, in effect, of four frequency-agile radars sharing quadrants of a single array antenna mounted within a radome on a "four axis" gimbal with a sidelobe cancelling subarray mounted at the phase center of each quadrant. Motions sensors are also mounted on the single array antenna to provide signals for compensating for vibration and stored compensating signals are used to compensate for radome-induced errors. In addition, a signal processor is shown which is selectively operable to generate radar maps of any one of a number of desired degrees of resolution, such processor being adapted to operate in the presence of clutter or jamming signals.

Abstract: An over-the-horizon, synthetic aperture radar (OTHSAR) system (10) is disclosed. The OTHSAR system is used to locate moving objects (14) at long distances in response to modulated high-frequency radiation reflected by the objects and distinguishes the objects from stationary clutter (16) that also reflects the radiation. Specifically, a central processor (26) synthesizes information received from an antenna (18) and receiver (22) over an interval of time t.sub.s to enhance azimuth resolution. Although ambiguous Doppler information is likely to be received from the moving object and the stationary clutter, the antenna is selected to have a real antenna beam that resolves the ambiguous data, ensuring that conflicting clutter data is eliminated.

Abstract: A method and apparatus for detecting an object of interest against a cluttered background scene. In a first preferred embodiment the sensor tracking the scene is movable on a platform such that each frame of the video representation of the scene is aligned, i.e., appears at the same place in sensor coordinates. A current video frame of the scene is stored in a first frame storage device (14) and a previous video frame of the scene is stored in a second frame storage device (20). The frames are then subtracted by means of an invertor (24)and a frame adder (28) to remove most of the background clutter. The subtracted image is put through a first leakage reducing filter, preferably a minimum difference processor filter (32). The current video frame in the first frame storage device (14) is put through a second leakage-reducing filter, preferably minimum difference processor filter (36).

Abstract: A pulsed doppler radar system having an improved detection probability, comprising an antenna unit, a transmitter for transmitting a signal through the antenna unit, a receiver for receiving a signal reflected by a target through the antenna unit to provide a reception signal. A processing unit which receives the reception signal from the receiver determines, in accordance with a range of the target and a signal-to-noise ratio and bandwidth of the reception signal, an optimum integration number which maximizes the detection probability and performs coherent integration on the reception signal by the number of times equal to the determined optimum integration number thereby outputting a signal having a predetermined level. Such a signal is fed to a display and an image of the target is displayed on a display.

Abstract: A radar system that enhances the display of moving targets by using negative scan-to-scan correlation to determine which pixels will be displayed at the brightest level. More specifically, a bit image stores a multi-bit scan-to-scan correlated history for each pixel on a display screen, and when new video data is received on a scan, the bit image memory is modified in accordance therewith. A pixel is enhanced to the brightest level only if a return is received from a spacial location from which returns were not received on previous scans. Thus, a target that moves to a new location is displayed at the brightest level because it doesn't correlate with returns from prior scans.

Abstract: Moving target indication unit provided with a doppler filter bank (1) with n output channels A.sub.i (i=0, 1, 2, . . . , n-1), several threshold circuits (24.i) connected to the output channels, a detection and registration unit (7, 14, 18, 23) provided with means (7, 14, 18) for the determination and registration, per azimuth cell, of a parameter for the amount of clutter in an azimuth cell. The said means are further suitable for determining, based on the output signals of the filter bank (1), k (k.gtoreq.2) parameters per azimuth cell and processing per azimuth cell the combination of k parameters to obtain n threshold values, used to set the n threshold circuits.

Abstract: A system for discriminating between signals received on the mainbeam of an antenna system and signals received on the sidelobe of the antenna system. The system utilizes a main antenna and multiple auxiliary antennas. The signals received on the main antenna are coincident on one or more of the auxiliary antennas. The auxillary antenna signals are multiplexed separated for single channel processing. The main antenna signal is compared with each of the multiplexed auxiliary antenna signals. The result of these comparisons are used to determine whether the signal received on the main antenna was received on a mainbeam or a sidelobe.

Abstract: A doppler determination system uses an amplitude comparison of odd and even MTI functions derived from the same signal returns in an MTI radar system to determine the doppler frequency of a target return. The system determines the ratio of the amplitudes of the return of a single canceller circuit with a delay of 2/PRF and the amplitude of the return of a double canceller with two delays of 1/PRF. The ratio is then employed to estimate the doppler frequency of the return. The respective amplitudes of the two MTI circuits are also processed in a 3-dimensional radar application to provide estimates of the target radar cross-section and elevation angle, and with PRF switching to determine the target unambiguous range rate.

Abstract: A space-time adaptive filter system is provided for eliminating unwanted signals from a radar or communication system. The filter system receives a main channel and several auxiliary channels wherein the target signal is not correlated between the various signal channels. Correlated noise components are eliminated by decorrelating the signals. The adaptive filter includes a Gram-Schmidt processor for sequentially decorrelating the auxiliary signals from the main signal. Each decorrelation element of the Gram-Schmidt processor comprises a transverse orthonormal ladder filter.