Abstract: A system is disclosed for wirelessly detecting movement of a target. The system comprises a reference oscillator, a transmitter, a receiver, a demodulator, and a processor, wherein: the reference oscillator generates references frequencies for the transmitter, the receiver, and the demodulator; the transmitter generates a continuous-wave signal at a frequency based on the transmitter reference frequency and wirelessly transmits it to the target; the receiver wirelessly receives a reflected signal from the target having a phase angle corresponding to movement of the target and converts the reflected signal into an intermediate frequency signal based on the receiver reference frequency; the demodulator demodulates the intermediate frequency signal into an in-phase component and a quadrature component; and the processor converts the in-phase component and the quadrature component into a movement signal corresponding to movement of the target.

Abstract: A method of error handling in a slope monitoring system that generates slope movement data from interferometric signal processing of radar images of the slope monitoring system. The error handling occurs in two steps. The movement data is corrected for changes in atmospheric conditions and disturbances are identified. It is convenient to mask the regions identified as disturbed in the display of the corrected movement data. Typical disturbances include short term disturbances, such as trucks, and long term disturbances, such as vegetation.

Abstract: An apparatus includes a plurality of sensor modules that are disposed at spacings with respect to one another, each sensor module having a local oscillator device. The oscillator device generates an oscillator signal that is passed on to a transmit/receive device, and the oscillator signal is radiated. The transmit/receive device is set up such that it can receive signals reflected from the object. A phase detection device is coupled at one input to the oscillator device and at a second input to the transmit/receive device. Based on the oscillator signal and the received reflected signals, the phase detection device determines a phase signal. A control and signal-processing device determines, based on the spacings of the sensor modules with respect to one another and the phase signals, a direction of the object with respect to the sensor module.

Abstract: An electronic scanning radar device that detects an azimuth angle of a target based on a phase difference between a first pair of received waves received by a first pair of antennas separated by a prescribed distance, and combines the first pair of received waves and generates a first composite wave. The composite wave has a steep antenna pattern, for which the amount of level change is large for the amount of change in azimuth angle, and an azimuth angle judgment unit performs true/false judgment in which a detected azimuth angle is judged to be true when the level of the above first composite wave is equal to or above a reference value, and the azimuth angle is judged to be false when the level is below the reference value.

Abstract: A proposed spread spectrum signal receiver includes a radio front-end unit and a processing unit. The radio front-end unit, in turn, has an antenna, a digitizing circuit and a primary buffer unit. The antenna is adapted to receive radio signals (SHF) from a plurality of signal sources, and the digitizing circuit is adapted to downconvert and filter the received signals (SHF), and generate sample values (SBP-D) thereof. The primary buffer unit is adapted to temporarily store the sample values (SBP-D) from the digitizing circuit and allow the processing unit to read out a first set of stored sample values (SBP-D) contemporaneously with the storing of a second set of sample values (SBP-D) in the primary buffer unit. The processing unit is adapted to receive the sample values (SBP-D) from the primary buffer unit, and based thereon, produce position/time related data (DPT).

Abstract: A method and processor for resolving a processing radar return data to determine a mechanical angle to a target relative to a radar array having a right antenna, an ambiguous antenna, and a left antenna. An LA linear relationship determining, based upon a characteristic number of LA wraps relative to the mechanical angle. Likewise, determining a RA linear relationship determines a characteristic number of RA wraps and a RL linear relationship determines a characteristic number of RL wraps relative to the mechanical angle. All permutations of LA wraps, RA wraps, and RL wraps are listed, and for each permutation, a truth relationship is determined. A look up table is populated with permutations where the truth relationship is true.

Abstract: A system (200) and method (400) for determining the location of an object is provided. A plurality of radio transceivers (101,201,203,205) are disposed about a location of interest (221). One or more tags (102) are coupled to an object. The radio transceivers (101,201,203,205) transmit radio frequency signals (115,215,217,219) to the tag (102), which backscatters a return signal (116,216,218,220) having a unique identifier modulated therein due to a switch (108) switching between two or more loads (110,112) in accordance with a unique identification code (118). A location determination module (107) then determines the location of the tag (102) by using a course location estimate (502), a fine location estimate (503), or combinations thereof. A object modeling module (109) can create multidimensional models using the locations of the tags (102).

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 receiver includes an RF bridge and a processor coupled to the RF bridge to receive an information signal from the RF bridge. The processor includes a clock source and a processor front end. The processor front end includes first and second frequency sources, a processor down converter and an analog to digital converter. The first frequency source generates a reference signal based on a signal from the clock source. The reference signal is coupled to the RF bridge. The second frequency source generates a first local oscillator signal based on the signal from the clock source. The processor down converter heterodynes the first local oscillator signal and the information signal. The analog to digital converter is coupled to the processor down converter and provides a digitized down converted signal.

Abstract: A radar device has a plurality of receiving antennas which receive, as a reception wave, a radar wave sent in a predetermined reference direction and reflected by a target; a phase difference detection unit which detects a first phase difference of the reception wave received by a first receiving antenna pair that is spaced by a first gap, and a second phase difference of the reception wave received by a second receiving antenna pair that is spaced by a second gap smaller than the first gap; and an angle detection unit which performs a first process of determining, as a detection angle, an angle of the target relative to the reference direction being a mutually coincident angle from among a plurality of first angles corresponding to the first phase difference and a plurality of second angles corresponding to the second phase difference. The radar device allows expanding an angle detection range without reducing the resolution of the angle corresponding to the second phase difference.

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

Abstract: A method to compensate for variances in signal path delays for a plurality of radar return processing channels is described. The method comprises providing a signal in the signal path between an antenna and a corresponding receiver of each radar return processing channel, receiving a reflection of the provided signal from each antenna at the corresponding receiver, measuring phase variances between the reflected signals processed by each receiver, and adjusting compensation algorithms for each radar return processing channel based on the measured phase variances.

Abstract: A transmitter for transmitting signals to targets and a receiver for receiving signals reflected from targets are included. The transmitter outputs CW signals for detecting direction and velocity of the target. The receiver performs: a function of receiving signals reflected from targets with a plurality of receiving antennas at the same time as transmitting from the transmitter, and performing spectral analysis with respect to receiving signals to thereby classify them by velocity component; a function of correlating signals of the receiving antenna systems; a function of integrating the signals correlation-processed; and a function of obtaining phase fronts of signals made incident on an antenna face from the phase differences of signals between receiving antennas, and performing two-dimensional FFT to the outputs to thereby measure the direction and velocity of the target.

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

Abstract: A system for generating a pseudomonopulse tracking error includes an antenna system (401) that generates a sum antenna beam and a difference antenna beam. The sum antenna beam has a pattern with a peak gain on the boresight axis, and the difference antenna beam has a pattern that is circularly symmetric and forms a null about the boresight axis. The difference antenna beam has a relative phase that varies 360 degrees around the boresight axis. A differential phase dispersion is provided as between the sum and difference RF channels (405, 407) to providing a rotating scanning plane (702).

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

Abstract: A method for determining a mechanical angle to a radar target utilizing a multiple antenna radar altimeter is described. The method comprises receiving radar return signals at the multiple antennas, populating an ambiguity resolution matrix with the electrical phase angle computations, selecting a mechanical angle from the ambiguity resolution matrix that results in a least amount of variance from the electrical phase angle computations, and using at least one other variance calculation to determine a quality associated with the selected mechanical angle.

Abstract: A method and apparatus for use in determining the range in a single time sample from a platform to a target are disclosed. The method includes receiving radiation emanating from the target at two points on the platform in a common time sample; detecting the received radiation and generating a signal representative thereof; and processing the signal. The signal is processed to determine a respective angle to target from two points on the platform by using a correlation between received signal amplitude and respective angle; and determine the range from the platform to the target from the respective angles and the separation distance between said two points in a single signal-to-noise sufficient sample. The apparatus includes a plurality of optical channels through which the apparatus can receive radiation emanating from the target, the optical channels and a plurality of electronics.

Abstract: An interferometer arrangement includes an antenna array that receives radiation from a plane wave emitted by a transmitter, the radiation being incident on the array at an angle (?). The array includes a plurality of antennas that provide output signals to a switching unit. The switching unit selects pairs of signals and passes them to a processor for processing. The processor is configured to produce an output signal that unambiguously indicates the value of the angle (?).

Abstract: Radar systems use time delay measurements between a transmitted signal and its echo to calculate range to a target. Ranges that change with time cause a Doppler offset in phase and frequency of the echo. Consequently, the closing velocity between target and radar can be measured by measuring the Doppler offset of the echo. The closing velocity is also known as radial velocity, or line-of-sight velocity. Doppler frequency is measured in a pulse-Doppler radar as a linear phase shift over a set of radar pulses during some Coherent Processing Interval (CPI). An Interferometric Moving Target Indicator (MTI) radar can be used to measure the tangential velocity component of a moving target. Multiple baselines, along with the conventional radial velocity measurement, allow estimating the true 3-D velocity of a target.

Abstract: A new differential technique and system for imaging dynamic (fast moving) surface waves using Dynamic Interferometric Synthetic Aperture Radar (InSAR) is introduced. This differential technique and system can sample the fast-moving surface displacement waves from a plurality of moving platform positions in either a repeat-pass single-antenna or a single-pass mode having a single-antenna dual-phase receiver or having dual physically separate antennas, and reconstruct a plurality of phase differentials from a plurality of platform positions to produce a series of desired interferometric images of the fast moving waves.

Abstract: A multi-antenna, multi-pass IFSAR mode utilizing data driven alignment of multiple independent passes can combine the scaling accuracy of a two-antenna, one-pass IFSAR mode with the height-noise performance of a one-antenna, two-pass IFSAR mode. A two-antenna, two-pass IFSAR mode can accurately estimate the larger antenna baseline from the data itself and reduce height-noise, allowing for more accurate information about target ground position locations and heights. The two-antenna, two-pass IFSAR mode can use coarser IFSAR data to estimate the larger antenna baseline. Multi-pass IFSAR can be extended to more than two (2) passes, thereby allowing true three-dimensional radar imaging from stand-off aircraft and satellite platforms.

Abstract: Signals-of-interest are identified by distinguishing such signals from signals constituting environmental or internal receiver noise. A received signal is rapidly sampled in order to set a dynamic, system threshold. Signals above the threshold constitute signals-of-interest.

Abstract: A system and method provide for the collection of interferometric synthetic aperture radar (IFSAR) data. In the system, a first space vehicle configured for emitting electro-magnetic energy and collecting the reflection from a region of interest (ROI), may be directed along a first orbital track. The collected image data may be stored and later provided to a ground station for image and interferometric processing. A second space vehicle may also be configured for emission and collection of electro-magnetic energy reflected from the plurality of ROI's. The second space vehicle is positioned in an aligned orbit with respect to the first space vehicle where the separation between the vehicles is known. In order to minimize decorrelation of the ROI during image processing, the lead and trail satellite are configured to substantially simultaneously emit electromagnetic pulses image data collection.

Abstract: A method for processing radar return data to determine a physical angle, in aircraft body coordinates to a target, is disclosed. The radar return data includes a phase difference between radar return data received at an ambiguous radar channel and a left radar channel, a phase difference between radar return data received at a right radar channel and an ambiguous radar channel, and a phase difference between radar return data received at a right radar channel and a left radar channel. The method includes adjusting a phase bias for the three phase differences, resolving phase ambiguities between the three phase differences to provide a signal, and filtering the signal to provide a physical angle to the target in aircraft body coordinates.

Abstract: A noise generator for generating multi-octave, high-level, millimeter- and submillimeter-wave noise is disclosed. According to one embodiment of the invention, the noise generator includes: a microwave noise source; a microwave power-amplifier chain; a level-set attenuator; a frequency multiplier; and a transmission structure. The output of the generator has a high-intensity noise power spectrum over a frequency range from about 60 GHz to about 1 THz. This type of noise is particularly suited and has sufficient power for testing and calibrating millimeter- and submillimeter-wave components, devices, and circuits; material evaluation and characterization; and for use as a broadband millimeter- and submillimeter-wave noise source for a Fourier Transform Spectrometer.

Abstract: A system employs null angle measurements developed in response to the detection of radiation, such as jamming, along with the positions at which the null angles are measured, to determine the location of the radiation source through reverse triangulation.

Abstract: A method of and apparatus for passively determining agile-frequency-emitter location and computer-readable medium bearing instructions therefor. Unless a specified accuracy threshold is met or exceeded, phase, frequency, and baseline position are measured during a single receiver dwell and processed. An array of gains and phase difference ambiguity integers for all phase difference measurements are computed. An emitter DOA unit vector or COS(AOA) is estimated and an LBI phase difference is predicted. If the rank of the set of baseline-frequency product differences is greater than 1, each DOA unit vector is projected and scaled by the measured frequency corresponding to the baseline measurement. Otherwise, if the rank is 1, the product of the COS(AOA) and baseline length is formed and scaled by the measured frequency.

Abstract: Methods and apparatus are disclosed for measuring position and motion of a “marker” antenna (14), disposed on a subject (12) at a physical location to be tracked. Relative distance of the marker antenna (14) from receiving antennas (18) is measured by phase differences of its microwave signals (40) at the receiving antennas (18) for at least two successive marker positions. Alternatively, actual distances (104, 106) are calculated by choosing a source position (102) and iterating the distances (104, 106) until the calculated phase differences match those measured. Four to six receiving antennas (18) are positioned at edges of a volume (16) where activity is conducted. Each received signal (40) is amplified and down-converted in a mixer (44). A single reference oscillator (46) feeds all the mixers (42) to preserve phase relationships of the received signals. Received signals (40) are digitized and presented to a multi-channel digital tuner (50).

Abstract: A method for testing a radar system utilizing flight test radar data is described. The method includes time synchronizing measured radar data with a GPS based time marker, storing at least a portion of the time synchronized radar data, storing the GPS data, processing the stored GPS data to correspond with a physical position of an antenna which received the radar data, providing a radar model, and comparing the processed radar model data to the stored radar data.

Abstract: The height of a radar target above a horizontal plane at a location within the horizontal plane is measured using a synthetic aperture radar (SAR). The synthetic aperture radar is mounted on a moving platform. The moving platform moves along a continuous climbing path with respect to the horizontal plane acquiring a plurality of SAR arrays of radar return information. Monopulse , Interferometric SAR (IF-SAR), and shadow length height measurements are fused to refine the target height measurement. Monopulse and IFSAR are combined to resolve target height ambiguities. The SAR arrays are separated vertically, at separate heights with respect to the target, and acquired sequentially in time, as a single pass.

Abstract: A method for reducing effects of terrain return fading due to summation of out of phase radar returns in determining locations of radar targets is described. The method comprises determining an interferometric angle, &PHgr;, to a radar target based on at least one radar return and filtering the interferometric angle, &PHgr;, by adjusting an effect of terrain features contributing to the interferometric angle, &PHgr;, proportionally to a degree of radar return fading resulting from the terrain features of the radar targets. A corrected interferometric angle, &PHgr;out., is then provided, based at least in part on the filtering.

Abstract: A system is provided for reducing the time that a ship must be maintained on station to collect calibration data by reducing the frequencies at which calibration data is to be collected. Since it is impractical to consider calibrating over elevation angle and polarization on the full-scale ship, an accurate scale model and test facility are utilized, with surface wave data being collected from the ship before model-based data can be utilized. In the subject system, the number of calibration frequencies used aboard ship is dramatically reduced by as much as 80%, thus reducing the time the ship must be on station when doing a calibration run. In one embodiment, the shipboard surface wave data for one elevation and one polarization is combined with surface wave and sky wave data from the scale model to generate an array manifold or database used in subsequent direction finding activities.

Abstract: A system and method for detecting and tracking a target object, including the calculation of the target object's altitude, is disclosed. During the processing of signals received by a receiver, the system selectively calculates the altitude of the target object from signals modified by an interference effect pattern formed by the signals broadcast by a transmitter, or from the calculation of geometric shapes associated with three or more transmitters and determining the intersection point of those shapes.

Abstract: A phase processor is disclosed which is configured to receive processed radar return data from a left radar channel, a right radar channel, and an ambiguous radar channel. The phase processor comprises a plurality of phase detectors each with an input and a reference input. The phase detectors are configured to determine a phase difference between radar return data received at the input and radar return data received at the reference input.

Abstract: For interferometric and/or tomographic remote sensing by means of synthetic aperture radar (SAR) one to N receiver satellites and/or transmitter satellites and/or transceiver satellites with a horizontal across-track shift the same or differing in amplitude form a configuration of satellites orbiting at the same altitude and same velocity. Furthermore, a horizontal along-track separation, constant irrespective of the orbital position, is adjustable between the individual receiver satellites. In this arrangement one or more receiver satellites orbiting at the same altitude and with the same velocity are provided with a horizontal across-track shift varying over the orbit such that the maximum of the horizontal across-track shift occurs over a different orbital position for each satellite, the maxima of the horizontal across-track shifts are positioned so that the baselines are optimized for across-track interferometry.

Abstract: A system for reducing multi-path reflections from adjacent metal objects which cause distortion in an IFSAR includes a reflective cone extending between the top of the IFSAR and the skin of its aircraft, and a reflective shroud surrounding the IFSAR. Each of these components may be coated with radar absorbing material.

Abstract: A method for processing radar return data to determine a physical angle, in aircraft body coordinates to a target, is disclosed. The radar return data includes a phase difference between radar return data received at an ambiguous radar channel and a left radar channel, a phase difference between radar return data received at a right radar channel and an ambiguous radar channel, and a phase difference between radar return data received at a right radar channel and a left radar channel. The method includes adjusting a phase bias for the three phase differences, resolving phase ambiguities between the three phase differences to provide a signal, and filtering the signal to provide a physical angle to the target in aircraft body coordinates.

Abstract: A method for determining a position of a doppler radar target in aircraft body coordinates is described. The method includes calculating values for doppler circle equations, in doppler coordinates, based upon a range to the target, a vehicle velocity, and a center frequency and bandwidth of a doppler swath filter. Further, an interferometric circle in body coordinates is calculated based upon a range to the target, and an interferometric angle. The doppler circle equations are transformed into body coordinates utilizing received pitch, roll and yaw information. Finally, an intersection of the interferometric circle equations with the transformed doppler circle equations is calculated, the intersection being the position of the target in body coordinates.

Abstract: A HF radar uses the same antenna array (414, 424, 424′, 424′) for both transmission (TX) and reception (RX). Each radiating element of the array may be driven by its own local transmitter and may have its own local receiver, both being connected to a central processor via fiber optic cables conveying digital data to the local transmitter relating to element energization in the TX mode and data representing signals received by the radiating elements in the RX mode. Each antenna element may have its own TX/RX unit, or a single TX/RX unit may serve two or more radiating elements. Each radiating element may comprise a skeletal pyramidal dipole mounted at ground level.

Abstract: This present invention advantageously eliminates the critical deficiencies of current multipath interferometer processing demonstrated in field testing. In particular the present invention substantially improves AOA estimation accuracy and reliability when utilizing super resolution algorithms. The present invention also overcomes the data-gap drawback of data editing methods, especially for emitters at low elevations. The present invention does this by detecting phase processing errors and substituting correct AOA estimates for the corrupt ones. In the preferred implementation, the detection and substitution time extends only slightly the super resolution or data editing processing time. By thus requiring little additional processing time, the present invention allows the interferometer to output accurate angle estimates at the receiver's emitter-revisit rate for all emitter-array geometries and signal polarizations.

Abstract: A method for resolving interferometric ambiguities for an interferometer system with antenna elements employs multiple interferometric elements within the baseline. The overall accuracy of the interferometer system results from the interferometric elements with the longest baseline dimension; the remaining interferometric elements provide a means to correctly resolve ambiguities. According to the method, the baseline locations of additional elements are determined by using an integer fractional location. By so doing, the ambiguities of the overall baseline correspond to a limited number of ambiguities of the fractional baseline so that many of the ambiguities of the overall baseline can be eliminated. According to a preferred method, baseline values are selected to obtain a high probability of correct ambiguity resolution with a minimum number of additional interferometric elements. In this way, the design complexity is reduced.

Abstract: Disclosed is a method of associating a single pulse from an agile emitter with previously detected pulses from that emitter in a time interval less than the pulse repetition interval (PRI) of the radar. Ambiguous phases from the previously detected pulses from the same agile emitter are stored. A single cos(aoa) from a subset of the stored ambiguous phases is estimated. A new ambiguous phase &phgr;m at frequency fm, is detected. This frequency is different from at least one of the frequencies associated with the phases in the stored set. The phase measurement is made between two antennas spatially separated by distance d. A set of differenced phases is formed and corresponding differenced frequencies from the stored set, with at least one member of this set being the difference of the new ambiguous phase and frequency with one of the stored phases and its associated frequency.

Abstract: A satellite architecture and method for microwave interferometry radiating incrementally accumulating holography, used to create a high-gain, narrow-bandwidth actively-illuminated interferometric bistatic SAR whose VLBI has a baseline between its two bistatic apertures, each on a different satellite, that is considerably longer than the FOV, in contrast to prior art bistatic SAR where the interferometer baseline is shorter than the FOV. Three, six, and twelve satellite configurations are formed of VLA satellite VLBI triads, each satellite of the triad being in its own nominally circular orbit in an orbital plane mutually orthogonal to the others of the triad. VLBI pairs are formed by pairwise groupings of satellites in each VLA triad, with the third satellite being used as a control satellite to receive both Michelson interferometric data for phase closure and Fizeau interferometric imaging data that is recorded on a holographic disc, preserving phase.

Abstract: This disclosure describes an electronic support measures (ESM) system for estimating the angle of arrival of a signal which impinges on an array of antennas configured in a straight line. The antennas in the array are spaced such that the distances from the interior antennas to one of the end antennas—in terms of units of a reference length &xgr;—are relatively prime. The system does not require a priori knowledge of the signal radio frequency. In order to enhance the computational efficiency and ability of the system, a Diophantine processing algorithm is utilized. The set of antenna spacings is selected based upon minimizing the probability that this algorithm produces an ambiguity error in the estimated angle of arrival. The computational efficiency of the system is improved relative to current systems, as it requires only N2 real multiplications, where N+1 is the number of antennas in the array.

Abstract: A direction-finding method for determining an incident angle of a high-frequency electromagnetic signal in a system including at least two receiving antennas spaced apart by a known distance. the antenna output signals of the at least two receiving antennas are converted, together (in accordance with a multiplexing procedure) or individually, into the frequency domain through a Fourier transformation, followed by a conversion into an IF range and an A/D conversion. In this range, the phase difference between the output signals is determined and the signal frequency of the incident wave is determined through a phase-sequence analysis. The incident angle of the incident wave is determined from the phase difference and the signal frequency.

Abstract: For a radar device arranged above a reflecting surface, a method is suggested for estimating the height of an object above the surface. This method does not require a refined angle resolution for the radar antenna and is based solely on the processing of signals. The invention makes use of the appearance of an interference pattern for the radiation field of the radar antenna, which normally is viewed as a disadvantage, by evaluating the intensity modulation of a signal received from an object moving in radial direction to the radar device within the surveillance range. Together with the measured distance to the object, this is used to estimate a value for the height of the object above the road surface.

Abstract: A method and apparatus for determining the azimuth and elevation angles of a signal from an emitter is provided. An antenna array receives the signal. The antenna array includes one or more pairs of antenna elements of like polarization mounted diametrically opposite each other in a ring. A switch receives the received signal from the antenna pairs. The switch outputs a processor-selectable number of signals. A radio frequency converter downconverts a processor-selectable number of signals. The converter outputs the downconverted signals. An intermediate frequency processor measures phase differences across the antenna pair baselines for the downconverted signals. The intermediate frequency processor outputs the measured frequency and phase difference data. An ambiguity resolution processor selects antenna pairs by controlling the switch. The ambiguity resolution processor receives the measured frequency and phase difference data from the intermediate frequency processor.

Abstract: A radio wave receiving apparatus including a signal processing circuit which performs on Fourier transform with respect to an azimuth of an electric field signal outputted from an antenna receiving circuit. The Fourier transform is also performed with respect to an azimuth of the antenna pattern of an antenna. The Fourier transform signal derived from the electric field signal is then divided by the antenna pattern Fourier transform signal. A low-pass filter subjects the divided signal to low-pass filtering. The band of the output signal of the low-pass filter is extended into that beyond the cut-off frequency of the low-pass filter by using extrapolation. The band-extended signal is subjected to Fourier inverse transform with respect to azimuth, the signal after the Fourier inverse transform being outputted as a final antenna output.

Abstract: A means for identifying a particular range and Doppler shift signal in the field of view of a moving radar antenna which determines azimuth angle to this range-Doppler signal relative to the antenna by determining the phase difference between said signal as processed through two channels each fed by antennas displaced in a horizontal direction with respect to the axis of the antenna system.