Abstract: A method for communication between and/or determination of the movement of at least two vehicles 2a, b, c travelling in succession by means of a communication arrangement 4, wherein the communication arrangement 4 has at least one first communication apparatus 3a for arrangement on a first vehicle 2a and at least one second communication apparatus 3b for arrangement on a second vehicle 2b, is proposed, in which a signal is transmitted via a transmission path between the communication apparatuses 3a, b, c, wherein a main transmission link H of the transmission path runs at least beneath the first and/or second vehicle 2a, b and/or in which the determination of movement is carried out on the basis of the propagation time and/or propagation time differences.

Abstract: This application relates to a method for selecting sources of illumination to jam, performed by an apparatus of selecting sources of illumination to jam for passive radar jamming. The method may include, predicting sources of illumination used by a virtual passive radar of interest disposed within a jamming range with respect to the location of a passive radar jammer. The method may also include selecting sources of illumination as candidates for jamming if the signal strength of a target reflection signal received by the virtual passive radar of interest from the sources of illumination is equal to or greater than an acceptable received signal strength. The method may further include picking out which sources of illumination to jam from the sources of illumination selected as candidates for jamming, based on how frequently the virtual passive radar of interest uses each of the selected candidates for jamming.

Abstract: The signal processing device includes an interference processing unit which generates an interferogram from a plurality of SAR images, a coherence calculation unit which calculates coherence of the SAR images, a singular point processing unit which performs an operation for resolving singular points in the interferogram, a phase unwrapping unit which executes a phase unwrapping process using operation result of the singular point processing unit, and an SBAS analysis unit which performs displacement analysis by SBAS, using processing result of the phase unwrapping unit.

Abstract: The present invention discloses a system and a method for detecting, localizing and categorizing radio frequency (RF) emitting sources. In operation presence of one or more RF sources are determined. Further, movement in the detected one or more RF sources is detected based on at least presence of spread power in spatial harmonics and visibility phase measurement. The frequencies of the radio waves at which the movement of one or more RF sources is detected are identified. A localization antenna subsystem is tuned to the identified frequencies one at a time to localize and identify the RF sources. Furthermore, the RF source is classified as an airborne source or ground-based source using radio interferometry imaging. Finally, on determination that the moving RF source is airborne, the interferometric images are further processed to confirm the type of airborne source.

Abstract: Systems, methods, computer-readable storage media, and apparatuses to provide active attack detection in autonomous vehicle networks. An apparatus may comprise a plurality of electronic control units communicably coupled by a network, and logic, at least a portion of which is implemented in hardware, the logic to: receive an indication from a first electronic control unit (ECU) of the plurality of ECUs specifying to transmit a first data frame via the network, determine, based on a message identifier (ID) of the first ECU, whether a transmit window for the first ECU is open, and permit the first ECU to transmit the first data frame via the network based on a determination that the transmit window for the first ECU is open.

Abstract: In an embodiment, a method of operating a radar includes: generating a set of chirps; transmitting the set of chirps; receiving chirps corresponding to the transmitted set of chirps; using a finite state machine (FSM) to apply a phase shift to each of the transmitted chirps or each of the received chirps based on a code; and demodulating the received chirps based on the code.

Abstract: In an embodiment, a method for tracking human targets includes: receiving radar signals using a radar sensor; generating a range-Doppler map based on the received radar signals; detecting a human target based on the range-Doppler map, where detecting the human target includes determining a range and a bounding box dimension of a bounding box bounding the detected human target, the bounding box at least partially surrounding the detected human target; and when the determined range is inside an expected region associated to a track, adding to the track a new detection point including the determined range and bounding box dimension, where the expected region is determined based on bounding box dimensions of detection points of the track.

Abstract: In accordance with an embodiment, a method of operating a radar system includes activating a transmitter to transmit a radar signal during a first time period, receiving a reflection of the radar signal from a radar antenna, downconverting the reflected radar signal, and digitally processing the downconverted reflected radar signal within a first frequency bandwidth using a first signal path. The method also includes deactivating the transmitter during a second time period, receiving a second signal from the radar antenna during the second time period, downconverting the second signal, measuring a power of the downconverted second signal within a second frequency bandwidth using a second signal path different from the first signal path, and determining an interference metric based on measuring the power.

Abstract: Aspects of the disclosure relate generally to detecting road weather conditions. Vehicle sensors including a laser, precipitation sensors, and/or camera may be used to detect information such as the brightness of the road, variations in the brightness of the road, brightness of the world, current precipitation, as well as the detected height of the road. Information received from other sources such as networked based weather information (forecasts, radar, precipitation reports, etc.) may also be considered. The combination of the received and detected information may be used to estimate the probability of precipitation such as water, snow or ice in the roadway. This information may then be used to maneuver an autonomous vehicle (for steering, accelerating, or braking) or identify dangerous situations.

Abstract: The relative position of one vehicle vs. another vehicle, both driving in a vehicular environment, is determined using vehicular communications based on the IEEE 802.11 standard. The relative position determination is performed in a measuring vehicle using data provided by a measured vehicle through IEEE 802.11 communications carried through beacons as well as GPS or other location data and local map information.

Abstract: Parallel compression is performed on an input data stream by processing circuitry. The processing circuitry includes hashing circuitry, match engines, pipeline circuitry and a match selector. The hashing circuitry identifies multiple locations in one or more history buffers for searching for a target data in the input data stream. The match engines perform multiple searches in parallel for the target data in the one or more history buffers. The pipeline circuitry performs pipelined searches for multiple sequential target data in the input data stream in consecutive clock cycles. Then the match selector selects a result from the multiple searches and pipelined searches to compress the input data stream.

Abstract: Aspects of this invention are directed to the substantially improved detection and geolocation accuracy of targets (stationary or moving) by using the coherent data received at multiple airborne sensors. Further aspects are directed to aligning the (unknown) time-delayed and Doppler-shifted signals received at the multiple sensors relative to an arbitrary reference sensor, which depend on the unknown target position. This results in the target position and velocity vectors being simultaneously estimated and the detection peak enhanced by obtaining near coherent gain. Still further aspects are directed to the coherent generalized likelihood ratio test (GLRT) and the minimum variance distortionless response (MVDR) statistic for multistatic radar systems, conditioned on estimation of certain parameters that render the system coherent. Analytical and computer simulation results are presented to show substantially enhanced detection and geolocation of moving targets in clutter.

Abstract: The relative position of one vehicle vs. another vehicle, both driving in a vehicular environment, is determined using vehicular communications based on the IEEE 802.11 standard. The relative position determination is performed in a measuring vehicle using data provided by a measured vehicle through IEEE 802.11 communications carried through beacons as well as GPS or other location data and local map information.

Abstract: Systems and methods to determine motion parameters of physical objects using radio frequency identification (RFID) tags attached to the objects. In one embodiment, a method implemented in a radio frequency identification (RFID) system includes determining a motion parameter of the RFID tag based on detecting a Doppler frequency shift in a radio frequency signal received from the RFID tag.

Abstract: A moving object detection system is provided with an existence detection part, an integrating part and an existence judgment part. Based on first and second detection signals, the existence detection part calculates a rotation angle of each transition factor that is obtained from the first and second detection signals and rotates around the origin in a two-dimensional coordinate system. The existence detection part is configured so that the rotation angle becomes less than 90 degrees. The integrating part integrates each rotation angle to obtain an integrated angle. The existence judgment part judges whether or not a moving object approaching or leaving a receiver of the device exists in a detection area based on the integrated angle and a threshold angle.

Abstract: A method for measuring certain parameters of the impulse response of a propagation channel involving emitters and reflectors that are fixed or mobile, and for detecting and determining the parameters regarding the position and kinematics of the emitters and reflectors, or for auto-locating the reception system implementing the invention, in a system comprising N sensors receiving signals from the emitters or from the reflection on the reflectors. The method determines an ambiguity function which couples the spatial analysis and the delay-distance/Doppler-kinematic analysis, and determines at least one sufficient statistic ?(l,m,K) corresponding to the correlation between the known signal s(kTe) corresponding to the complex envelope of the signal emitted and the output of a filter w(l,m) where l corresponds to a temporal assumption and m corresponds to a frequency assumption.

Abstract: Certain embodiments of the present disclosure propose methods and systems for classifying the Doppler spread based on the output of the frequency-tracking loop (FTL) discriminator in WiMAX systems to improve the performance of the channel estimation. The Doppler spread may be classified as low, medium or high based on the statistics of the output of the discriminator in the fine-tracking mode.

Abstract: Systems and methods to determine motion parameters of physical objects using radio frequency identification (RFID) tags attached to the objects. In one embodiment, a method implemented in a radio frequency identification (RFID) system includes determining a motion parameter of the RFID tag based on detecting a Doppler frequency shift in a radio frequency signal received from the RFID tag.

Abstract: A signal generation system suitable for use in a radar system comprises a local oscillator (LO) and an intermediate frequency (IF) oscillator, wherein the IF oscillator is a Direct Digital Synthesizer (DDS), and the LO is a free running oscillator not itself locked to another oscillator but which acts as a clock reference for the DDS and is the highest frequency oscillator in the system. The LO may also act as a reference for a receive chain digitizer. The invention exploits phase noise advantages of a free running oscillator at some distance from the carrier whilst maintaining coherency with other system components. The system typically finds application in FMCW radars.

Abstract: A method is provided for coordinating detection of emitted signals by a receiver with transmission of signals by a transmitter, wherein the receiver and the transmitter are located on the same platform. The receiver scans a surrounding environment to detect emitted signals in multiple frequency ranges while the transmitter transmits signals in a predetermined frequency range. The receiver may employ dwells which may be defined as receiver configurations. A dwell, when executed, may be used to detect signals in a certain frequency range. If a frequency range of the dwell conflicts with the frequency range of transmitter signals, which may result in interference of transmitter signals with detection of emitted signals, execution of the dwell may be delayed. If the frequency range of the dwell is such that transmitter signals do not interfere with execution of the dwell, the dwell can be executed.

Abstract: A method for rapid convergence of radar target state includes the steps of using range acceleration to estimate perpendicular velocity and jump-starting a Cartesian state filter with the estimated perpendicular velocity. The improved estimate in the Cartesian state filter allows improved coasting of the range-state.

Abstract: Aspects of this invention are directed to the substantially improved detection and geolocation accuracy of targets (stationary or moving) by using the coherent data received at multiple airborne sensors. Further aspects are directed to aligning the (unknown) time-delayed and Doppler-shifted signals received at the multiple sensors relative to an arbitrary reference sensor, which depend on the unknown target position. This results in the target position and velocity vectors being simultaneously estimated and the detection peak enhanced by obtaining near coherent gain. Still further aspects are directed to the coherent generalized likelihood ratio test (GLRT) and the minimum variance distortionless response (MVDR) statistic for multistatic radar systems, conditioned on estimation of certain parameters that render the system coherent. Analytical and computer simulation results are presented to show substantially enhanced detection and geolocation of moving targets in clutter.

Abstract: A method for interleaved pulsed-Doppler processing. Radar energy management and associated processing techniques take advantage of spatial degrees of freedom available on modern, short range, wide angle, volume search ESA radar systems. The method creates an advantage in Doppler resolution when compared to currently utilized Doppler processing techniques. An Electronically Scanned Array (ESA) radar system includes one or more processors that may be programmed to read and execute instructional commands including transmit a plurality of synchronized, coherent pulsed transmit beams having substantially repeatable gain and phase pattern characteristics; electronically steer the plurality of transmit beams in a respective, sequential plurality of spatially diverse directions in a temporally-interleaved manner; sequentially collect a respective plurality of receive beams in a respective plurality of time vs.

Abstract: A method and apparatus for estimating a satellite signal parameter in a satellite positioning system receiver is described. In an example, a plurality of correlation results between a satellite signal and a reference signal is generated and stored in a memory. At least one satellite signal parameter is estimated from the plurality of correlation results using a co-processor integrated within the satellite positioning system receiver. As the coprocessor estimates the parameter, new correlation results are added to the memory. The at least one satellite signal parameter is then provided to the processor.

Abstract: A wireless communication device uses a time-invariant delay-Doppler channel response estimate for received signal demodulation. The device provides coherent signal demodulation by accounting for frequency and time selectivity in a land-based mobile communication environment, which arise mainly because of delay and Doppler shifts, respectively. In one embodiment, the wireless communication device includes a channel estimator that estimates channel response in a wireless communication network by estimating a delay-Doppler response of a wireless communication channel to obtain a delay-Doppler channel response estimate and converting the delay-Doppler channel response estimate to a time-varying channel response estimate, e.g., a time-varying frequency or impulse response. The delay-Doppler response may be estimated in a continuous or discrete domain.

Abstract: A technique for estimating maximum Doppler frequency of a wireless signal in a wireless communication system, wherein the method comprises receiving a wireless signal; determining an impulse response of the received wireless signal; determining an auto-correlation function (ACF) value of the impulse response of the received wireless signal; determining a power spectrum density of said received wireless signal based on the ACF value; and selecting an algorithm for performing demodulation of the received wireless signal by utilizing the determined power spectrum density.

Abstract: Systems and methods for Doppler beam sharpening in a radar altimeter are provided. In one embodiment, a method comprises receiving a return signal at a radar altimeter receiver and applying a first gate to the return signal to select at least a first component of the return signal. Spectral analysis is performed on the first component of the return signal to generate a plurality of frequency bins, wherein each frequency bin is centered around a different frequency across a Doppler shift frequency spectrum for the first component of the return signal. The method further comprises tracking the first component of the return signal, selecting a first frequency bin of the plurality of frequency bins based on the Doppler shift frequency of the first component of the return signal, and outputting a portion of the first component of the return signal falling within the first frequency bin for further processing.

Abstract: Electronically steered radar systems such as frequency scanning radars are particularly suitable for detecting and monitoring slow moving, ground-based targets. So-called crawler radar systems are intended for detection of targets that deliberately attempt to avoid detection by keeping low and by moving slowly. Disclosed is a radar system which includes an electronically steered antenna and a receiver arranged to process signals received from a target located at a distance from the radar system so as to identify a Doppler frequency associated with the target. The antenna stares at, rather than glides past, the target surrounding clutter. This means that the spectral spreading of static ground clutter associated with mechanical radar systems can be eliminated, overcoming one of the shortcomings of mechanical radar systems that would otherwise render a crawler radar system unsuitable for Doppler processing.

Abstract: A radar system includes: a transmission antenna outputting transmission signals having multiple frequencies; multiple reception antennas receiving reflected waves of the transmission signals, reflected from an object; a mixer mixing the transmission signals with reception signals received by the reception antennas to generate beat signals; and a signal processing unit detecting Doppler frequency by analyzing frequencies of the beat signals, detecting phase information of the Doppler frequency for each of combinations of the reception antennas and the transmission signal frequencies, constructing a matrix having the pieces of phase information arranged in a predetermined order with respect to the reception antennas and the frequencies of the transmission signals, obtaining a correlation matrix from the matrix and its complex conjugate transposed matrix, and estimating at least one of a distance, direction and relative velocity of the object based on the correlation matrix.

Abstract: A radiofrequency signal is converted to an intermediate frequency signal by a tuner, which is amplified by a variable gain amplifier. The so-amplified signal is converted into a digital signal by an ADC, which is supplied to an FFT, where it is separated into signals set every carrier, followed by being supplied to equalizers different in characteristic. The digital signal outputted from the ADC is further supplied to a level converting circuit from which a control signal is generated. The control signal is supplied to a DAC and a Doppler frequency detector. The DAC generates a gain control signal and supplies the same to the variable gain amplifier. The Doppler frequency detector outputs a frequency component of the control signal as a Doppler detection signal. The Doppler detection signal is compared with a threshold value by a comparator. A selector selects one of signals outputted from the equalizers, in accordance with a select signal indicative of the result of comparison.

Abstract: An apparatus and method for receiving electromagnetic waves using photonics includes a transmission unit transmitting electromagnetic waves in intervals; a time delay unit coupled to the transmission unit and controlling the transmission unit to transmit the electromagnetic waves in the intervals; an antenna receiving the electromagnetic waves reflected from the target; an interferoceiver coupled to the antenna and receiving the electromagnetic waves from the antenna, the interferoceiver comprising an optical recirculation loop to produce replica electromagnetic waves; and a computer identifying the target from the reflected electromagnetic waves.

Abstract: Systems and methods of improving sampling of WLAN packet information to improve estimates of Doppler frequency of a WLAN positioning device. A device estimates the position of itself. The device includes a WLAN radio module for receiving WLAN signals transmitted by WLAN APs in range of said device, extraction logic for extracting information from said received WLAN signals to identify the WLAN APs, and logic to cooperate with a WLAN-based positioning system to estimate the position of the device based at least in part on the extracted information identifying the WLAN APs in the range of said device. The WLAN radio module includes logic for measuring multiple received signal strength indicator (RSSI) values for sufficiently long WLAN packets to increase the sampled rate of RSSI of WLAN packets from WLAN APs and to thereby improve an estimate of the Doppler frequency of said device.

Abstract: Disclosed is a channel estimator and a method for changing a coefficient of an IIR filter depending on a moving speed of a mobile communication terminal. In the channel estimator, a coefficient changing unit receives I and Q signals from a current base station, and selects a coefficient of the IIR filter optimized depending on the moving speed of the current mobile communication terminal. The coefficient changing unit sets the selected coefficient of the IIR filter to the IIR filter of the channel estimator. Accordingly, it is possible to prevent the performance degradation of the channel estimator caused by the speed of the mobile communication terminal.

Abstract: In the context of array sensors such as radar, sonar, and communications receiver arrays, the present invention exploits the geometry phase components of radiated wavefronts associated with the signals of interest in order to reduce the bandwidth requirements for DOA and beamforming processing. Additionally, geometry phase is exploited in order to effectively increase the resolution of an array without changing the size of its physical footprint or the number of array elements. Other embodiments of the invention include the use of virtual array elements for increase in effective array size.

Abstract: Radar for detecting and tracking short range airborne targets using a non-scanning beam to illuminate the entire search space, and processing the return signals from a plurality of spaced apart receive antennas. Target angle in one plane may be determined by coherent processing of the returns from the plurality of receive antennas. Spacing the receive antennas apart in three dimensions allows determining of two angles, such as azimuth and elevation. Processing of the returns may be coherent or noncoherent, or returns may be processed both coherently and noncoherently. Programmability of the processing algorithms and parameters provide flexibility in applications, as well as flexibility based on such things as the target type and its range. Exemplary applications are disclosed.

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: Methods and systems for estimating and correcting airborne radar antenna pointing errors. The methods and systems include predicting expected received power from at least one scattering source using terrain elevation information, transmitting a radar signal to the at least one scattering source, measuring received power from the at least one scattering source, determining an antenna pointing error based on the predicted and measured received power, and adjusting an antenna angle, an input value, or other components based on the determined antenna pointing error. The methods and systems also include a radar processing and control unit for predicting expected received power from at least one scattering source using a model of the radar power measurement process that includes terrain elevation information, for measuring received power from the at least one scattering source, and for determining antenna pointing error based on the predicted and measured received power.

Abstract: The present invention relates to a detector device and, more particularly, to a detector device comprising a self-diagnosis means for monitoring the correct performance or otherwise of the device. During testing, the device, which normally operates using the Doppler shift principle, is arranged to influence the phase and/or amplitude of the received signal in response to an applied test signal. The received signal may be a Doppler shifted version of a transmitted signal. Combining the phase and/or amplitude shifted version of the received signal and the signal from the local oscillator produces an IF signal that is indicative of the phase and/or amplitude shift. If the device is operating correctly, that signal should have a predetermined range of characteristics. If the self-diagnosis means determines that the produced signal falls outside of the predetermined range of characteristics, an alarm is raised to alert, for example, maintenance personnel to the problem.

Abstract: A system and methods for multistep target detection and parameter estimation which utilizes slices and/or projections of the cross-ambiguity function of the transmitted and received signals of a sensor system is disclosed. The system and methods of the present invention offer a computationally efficient means of detecting targets while achieving a high probability of detection and a reduced false alarm rate. Detection and parameter estimation of targets is accomplished by generating hypotheses and then validating the generated hypotheses. The hypotheses are generated using slices and/or projections of cross-ambiguity functions of transmitted signals and reflections received from the targets without the need to compute the entire cross-ambiguity function. After hypotheses are generated they are validated by determining the amplitude of a cross-ambiguity function at the coordinates of the hypotheses and comparing the amplitude to a predetermined threshold.

Abstract: Methods and apparatus for local oscillator generation are provided. In a method embodiment, a method of signal processing includes splitting a signal having a first frequency into at least a first portion and a second portion. The method also includes generating a second signal having a second frequency at a predetermined frequency difference from the first frequency by optically modulating the first portion. In addition, the method includes generating a third signal having a frequency component at a frequency that is approximately the same as the predetermined frequency difference from the first frequency by combining the second portion with the second signal.

Abstract: Pulsed or mutual interference in a pulse radar system is ameliorated by a process that includes a pulse-Doppler filter, some frequency bins of which correlate with clutter. Pulsed interference is identified, and the corresponding column vectors of a pulse-Doppler-filter-equivalent matrix are identified. The row values of the corresponding interference-affected column vectors that correlate with clutter are nulled. The vectors are orthogonalized, and then converted to measurement and correction signal vectors for application to the pulse-Doppler received signals. Vector dot products of the measurement signal vectors with the received signals are calculated, to produce pulsed interference measurements that are nominally free of clutter. The pulsed interference measurements are combined with the correction signals which are then subtracted from the received signals to produce signals that are nominally free of pulsed interference.

Abstract: Disclosed is an adaptive channel estimator for improving a performance of a general channel estimator in a mobile communication system, and a method for controlling the same. The adaptive channel estimator further detects a noise level of a channel and a channel speed, and implements an optimum noise elimination filter on the basis of the detected noise level and channel speed. A comparison between mapping degrees predetermined by the detected noise level and channel speed allows an optimum noise elimination filter to be implemented, If such a channel estimator is implemented, then optimum packet data transmission is available for not only a low-speed channel but also a high-speed channel. A channel compensation caused by a difference between a spreading factor (SF) of a pilot channel and a spreading factor (SF) of a data channel can be compensated on the condition that a slope compensator executed by a SF ratio is controlled by a filter coefficient controller.

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 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: A method for determining an angle for each of two RF signals at different frequencies and offset from each other. The average angle of a composite signal is obtained from the two RF signals over a frequency difference period by averaging the frequency difference period. The average angle of the composite signal is the dominant signal's angle. The smaller signal's angle is then calculated from the dominant signal's angle, an angle centroid, and the signal voltages for the two RF signals.

Abstract: A method for determining an angle for each of two RF signals at different frequencies and offset from each other. The average angle of a composite signal is obtained from the two RF signals over a frequency difference period by averaging the frequency difference period. The average angle of the composite signal is the dominant signal's angle. The smaller signal's angle is then calculated from the dominant signal's angle, an angle centroid, and the signal voltages for the two RF signals.

Abstract: The present invention relates to active sensor applications, and more particularly is directed to efficient systems and methods for detection and tracking of one or more targets. The invention provides a method for receiving signals reflected from one or more targets, processing the received signals and the transmitted signal to compute two or more slices of the cross ambiguity function associated with the signals, and estimating the signal delay and the Doppler shit associated with the targets from the computed slices.

Abstract: A method for maintaining a position of a hovering vehicle that incorporates a radar altimeter is described. The method includes receiving signals at the radar altimeter based on a change of horizontal direction, operating the radar altimeter to generate a Doppler frequency spectrum based on the received signals, and determining a change in vehicle direction and velocity which will reduce a width of the Doppler frequency spectrum of the received signals. A radar altimeter which generates the Doppler frequency spectrum is also described.

Abstract: System and method for detection and tracking of targets, which in a preferred embodiment is based on the use of fractional Fourier transformation of time-domain signals to compute projections of the auto and cross ambiguity functions along arbitrary line segments. The efficient computational algorithms of the preferred embodiment are used to detect the position and estimate the velocity of signals, such as those encountered by active or passive sensor systems. Various applications of the proposed algorithm in the analysis of time-frequency domain signals are also disclosed.

Abstract: A system and method is provided for detecting emitter signals and for determining a scan strategy for a receiver system that receives such emitter signals. A rule-based system is provided for determining how emitters should be detected by a detection system. Rules may be used to prioritize certain emitters with respect to other emitters. The rules may also specify parameters for emitter modes, such as probability of intercept, turn-on range, detect-by range, tolerance, tolerance direction, scan periods, and other parameters. The rules may be used to compute the revisit time for the receiver. Multiple sets of rules may be created and a scan strategy may be computed based upon the selected rule set.