Abstract: A radar device is described having means (10) for generating a carrier signal having a carrier frequency fT, means (12, 13, 15, 17) for generating pulses having a pulse repetition rate fPW, means (16) for splitting the carrier signal between a transmission branch and a reception branch, means (18, 19, 21, 27, 29) for delaying the pulses, means (24) for mixing the carrier signal in the reception branch with a reception signal and means (26) for integrating the mixed signal, whereby means (20, 23) for modulating the carrier signal in the transmission branch with the delayed pulses are provided and means for altering the delay in the pulses according to a predetermined code are provided. A method of suppressing interference with the functioning of a radar device is also described.

Abstract: An in-phase/quadrature component (IQ) mixer is configured to reject returns from a negative doppler shift swath in order to mitigate corruption of returns of a positive doppler shift swath. The mixer includes a sample delay element which produces a quadrature component from the in-phase component of an input signal. Further included are a plurality of mixer elements, a plurality of low pass filters, a plurality of decimators, and a plurality of all pass filters which act upon both the in-phase and quadrature components of the input signal. Also, a subtraction element is included which is configured to subtract the filtered and down sampled quadrature component from the filtered and down sampled in-phase component.

Abstract: Apparatus for processing a signal of a predetermined intermediate frequency (IF) to generate in-phase (I) and quadrature (Q) components thereof comprises: an analog-to digital converter circuit for sampling and digitizing the IF signal to generate digitized data samples thereof at a sampling rate that produces consecutive digitized data samples that are separated in phase by a substantially fixed phase angle 2&pgr;/n, where n is an integer greater than zero; first digital circuitry coupled to the analog-to digital converter circuit for demodulating the digitized data samples by multiplying every n consecutive digitized data samples with n respectively corresponding digital reference samples; and second digital circuitry coupled to the first digital circuitry for combining selected ones of the demodulated samples based on the substantially fixed phase angle to generate digital data samples of the I and Q components of the IF signal.

Abstract: An embodiment comprises a unit generating a control pulse signal by delaying a basic signal in generating a transmission pulse, and a unit performing a gate operation on a received signal using the control pulse signal. Another embodiment comprises a unit generating a control pulse signal by delaying a signal generated using a first basic signal, a second signal for phase modulation having a lower frequency than the first signal, and a pseudo-random signal generated at an intermediate frequency between the frequencies of the first and second signals, and a unit performing the gate operation.

Abstract: A method for measuring range and bearing of an object. At least a portion of a first signal is transmitted from a sensor. The transmitted signal is reflected from an object and received by the sensor. At least a portion of the first signal is applied a first mixer and a second mixer. The received signal is applied to the first mixer and the second mixer. A second signal is generated from the first mixer, and a third signal is generated from the second mixer when the portion of the first signal that was transmitted overlaps the reflected signal at least partially. Bearing angle, degree on or off boresight and object range may be determined from the second and third signals, or a combination thereof. Also disclosed is a sensor for object range and bearing measurement.

Abstract: A method, apparatus, and processing system for radar detection and tracking of a target using monopulse ratio processing comprising the following steps. First, receiving a signal comprised of a plurality of sum azimuth beams and difference azimuth beams. Then staggering the received signal. Next, filtering and localizing a clutter signal which is a portion of the received sum and azimuth beams. Then adaptively forming a sub-array sum azimuth beam and a sub-array difference azimuth beam from the filtered output to cancel the clutter. The adaptive beam forming including the determination of a sum and difference beam weight where the adaptive weight be equated to a product of the weight and the respective covariance matrices of the sum and difference beams, the product having no constraint points.

Abstract: To measure the absolute speed of a body 100 moving relative to the ground 33 using an onboard speed sensor 1, a radar wave is transmitted towards the ground by an antenna with a wide aperture angle. The wave reflected by a reflecting obstacle on the ground and the transmitted wave are mixed and the frequency content of the low frequency signal obtained is determined. The speed of the moving object and the height of the transmitter and receiver antennas above the ground can then be measured by adjusting a theoretical curve to the time-varying evolution of the Doppler frequency corresponding to the reflecting obstacle.

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

Abstract: Methods and apparatus compress data, comprising an In-phase (I) component and a Quadrature (Q) component. The compressed data may be saved into a memory or may be transmitted to a remote location for subsequent processing or storage. Statistical characteristics of the data are utilized to convert the data into a form that requires a reduced number of bits in accordance with the statistical characteristics. The data may be further compressed by transforming the data, as with a discrete cosine transform, and by modifying the transformed data in accordance with a quantization conversion table that is selected using a data type associated with the data. Additionally, a degree of redundancy may be removed from the processed data with an encoder. Subsequent processing of the compressed data may decompress the compressed data in order to approximate the original data by reversing the process for compressing the data with corresponding inverse operations.

Abstract: A coherent radar detection system (2) comprises a radar signal transmitter (4) and a correlation receiver (6). The transmitter (4) comprises a waveform generator which generates a signal at an intermediate frequency. The signal is divided into two divided signals by a coupler, and then the divided signals are mixed together in a mixer to generate an output signal which has a wider bandwidth than the intermediate frequency. The bandwidth can be increased further by repeating the coupler/mixer stage. The system generates very wide bandwidth signals coherently, allowing coherent processing in high resolution range gates.

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: Signal processing methods useful in single-antenna multiple-pass interferometric synthetic aperture radars. The signal processing methods compute an initial elevation estimate from the phase difference between a pair of images (A0, A1) with a relatively small elevation angle difference (i.e., a short interferometric baseline) and uses it to initialize the elevation estimation process for pairs of images (A0, A2) with longer interferometric baselines. The method may be used to process images that are coherent, or not necessarily mutually coherent. The outputs of the methods comprise a terrain elevation map that mitigates for atmospheric error and a turbulence map.

Abstract: The present invention relates to a process for the phase amplitude demodulation of a received radar signal and to an implementing device, the process consisting in sampling the intermediate frequency signal at a sampling frequency fe such that fe is equal to &agr;B, &agr; being a number greater than or equal to 2 and B being the width of the pass-band, the intermediate frequency fi and the sampling frequency being in a ratio such that fi=(k±¼)fe, k being an integer. Application to coherent detection radars.

Abstract: A pulse Doppler radar receiver is disclosed wherein monopulse sum and difference signals are time-multiplexed and passed through a single gain-controlled amplifier channel for normalization, the sum signal being processed to provide both a D.C. gain control signal for such channel and a reference signal for demodulating the difference signal.

Abstract: A system and a method for distance measurement utilizes a radio system. The distance is measured by determining the time it takes a pulse train to travel from a first radio transceiver to a second radio transceiver and then from the second radio transceiver back to the first radio transceiver. The actual measurement is a two step process. In the first step, the distance is measured in coarse resolution, and in the second step, the distance is measured in fine resolution. A first pulse train is transmitted using a transmit time base from the first radio transceiver. The first pulse train is received at a second radio transceiver. The second radio transceiver synchronizes its time base with the first pulse train before transmitting a second pulse train back to the first radio transceiver, which then synchronizes a receive time base with the second pulse train. The time delay between the transmit time base and the receive time base can then be determined.

Abstract: A ground penetrating radar includes a signal generator, a return signal processor, a gate and an antenna. The signal generator is a dual frequency synthesizer that generates a stepped frequency master signal and a tracking signal offset by an intermediate frequency. The return signal processor is a dual channel quadrature receiver that mixes down a return signal and a sample of the master signal to intermediate frequency using the tracking signal. The signal generator is pulsed by the gate and the return signal is gated at the same frequency. Hollow pyramidal antennas are also described that have an ultrawide band bowtie structure with antenna electronics located within one antenna element. A method of operating the radar is also described.

Abstract: A method for calculating a center frequency and a bandwidth for a radar doppler filter is herein described. The center frequency and bandwidth are calculated to provide radar performance over varying terrain and aircraft altitude, pitch, and roll. The method includes receiving an antenna mounting angle, a slant range, and velocity vectors in body coordinates, calculating a range swath doppler velocity, a track and phase swath bandwidth, and a phase swath doppler velocity. The method continues by calculating a range swath center frequency based on the range swath doppler velocity, calculating a phase swath center frequency based on the phase swath doppler velocity, and calculating a level and verify swath bandwidth based upon the track and phase swath bandwidth.

Abstract: A method for resolving radar range ambiguities is disclosed, where the radar is modulated with a phase code which comprises a number of chips. The method includes acquiring a radar return within a verify gate, the verify gate being aligned with one chip of the phase code, determining an amplitude of the return, stepping the gate outbound to a next chip of the code, acquiring a return, and determining if the return has an amplitude greater than a threshold based on the original return. The verify gate is repeatedly stepped outbound to determine if a chip can be found which has an amplitude in excess of the threshold or until returns from all chips within the phase code have been acquired. If such a position is found, search logic of the radar is moved outbound to the chip position which had the highest amplitude return, if not the original chip position and the entire process begins again.

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: This invention relates to a system and method for suppressing external interference in radar data provided by a plurality of sensors from a main sensor array, the data being pre-processed. The noise suppression system includes a first processing module and a second processing module. The first processing module receives the radar data and produces matched radar data while the second processing module receives the radar data and produces mis-matched radar data. The system further includes a beamformer that is in communication with the first processing module and an adaptive beamformer that is in communication with the second processing module and the beamformer. The beamformer receives the matched radar data and produces beamformed matched radar data.

Abstract: A filter, includes a first order band pass filter configured to process non-zero amplitude gated radar return samples and process a portion of received zero amplitude return samples. The filter also calculates past filter outputs based on filter outputs generated during previous non-zero gated radar return samples.

Abstract: An in-phase/quadrature component (IQ) mixer is configured to reject returns from a negative doppler shift swath in order to mitigate corruption of returns of a positive doppler shift swath. The mixer includes a sample delay element which produces a quadrature component from the in-phase component of an input signal. Further included are a plurality of mixer elements, a plurality of low pass filters, a plurality of decimators, and a plurality of all pass filters which act upon both the in-phase and quadrature components of the input signal. Also, a subtraction element is included which is configured to subtract the filtered and down sampled quadrature component from the filtered and down sampled in-phase component.

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: A series of police doppler single mode radars and a multimode police doppler radar, all with direction sensing capability are disclosed. A quadrature front end which mixes received RF with a local oscillator to generate two channels of doppler signals, one channel being shifted by an integer multiple of 90 degrees in phase relative to the other by shifting either the RF or the local oscillator signal being fed to one mixer but not the other. The two doppler signals are digitized and the samples are processed by a digital signal processor programmed to find one or more selected target speeds. Single modes disclosed are: stationary strongest target; stationary, fastest target; stationary, strongest and fastest targets; moving, strongest, opposite lane; moving, strongest, same lane; moving, fastest, opposite lane; moving, fastest and strongest, opposite lane; moving, fastest, same lane; moving fastest and strongest, same lane.

Abstract: A method (100) for coherent change subtraction of mission and reference synthetic aperture radar (SAR) data (20′,20″) is provided. The method (100) forms (102) mission and reference images (22′,22″) from the mission and reference SAR data (20′,20″), registers (122) the mission and reference images (22′,22″) on a common plane to form registered mission and reference images (24′,24″), and forms (124) the registered mission and reference images (24′,24″) into at least one patch (26) containing mission and reference data (28′,28″). The method (100) then processes (126) each patch (26) by removing (130) linear phase terms (34) from the mission data (28′), trimming (142) non-overlapping spectra of the mission and reference data (28′,28″), and balancing (144) phases and amplitudes of the mission data (28′).

Abstract: A mixer used in a millimeter-wave band and a microwave band capable of achieving loss reduction, a radar module, and a communication apparatus incorporating the mixer and having high efficiency. The mixer includes two electrodes formed on one main surface of a dielectric substrate and another electrode formed on another main surface thereof such that non-electrode portions on both main surfaces are opposed to each other via the dielectric substrate. Additionally, a diode is connected bridging a slit between the two electrodes on one main surface to constitute a circuit board. The circuit board and a dielectric strip are arranged between upper and lower conductive plates.

Abstract: A system for functional testing in a continuous-wave radar having a transmitter circuit for generating radar transmit signals, a transmit/receive antenna coupled by way of a circulator with the transmitter circuit, and a receiver circuit whose input is coupled with the transmit/receiver antenna by way of the circulator, for processing radar echo signals of a target object received at the transmit/receive antenna. The circulator relays the transmit signals generated by the transmitter circuit to the transmit/receive antenna, and splits off echo signals of the target object received from the transmit/receive antenna to the input of the receiver circuit. An RPC circuit coupled between the output and the input of the receiver circuit suppresses those portions of the transmit signals that are split off from the transmitter circuit and/or reflected from the transmit/receive antenna directly into the receiver circuit.

Abstract: A sensor front end is disclosed that is able to discriminate objects based on their range from the sensor. The sensor includes an antenna that transmits a sensor signal and, if an object is present receives a reflected signal therefrom. A pulsed oscillator provides a pulsed first signal having a first frequency and phase, and wherein the pulsed oscillator provides the pulsed first signal for a predetermined pulse duration and with a predetermined pulse repetition frequency. The pulsed oscillator provides the pulsed first signal to a first input port of a dual mode mixer that is further coupled to the antenna via a second port. The dual mode mixer transmits a portion of the pulsed first signal from the first input port to the second port and thus to the antenna to be transmitted as the sensor signal. In addition, the dual mode mixer uses a portion of the first signal to mix with the received reflected signal. The dual mode mixer then provides a mixed signal as an output at a third port.

Abstract: A radar-plow drillstring steering system comprises a steering plow and a measurements-while-drilling instrument for mounting just behind the drill bit and downhole motor of a drill rod. The instrument includes a radar system connected to upward-looking and downward-looking horn antennas and a dielectric-constant sensor. The steering plow includes four pressure pads radially distributed around the outside surface and their associated servo motors. A coordinated control of the pressure pads allows the steering plow to push the drillstring and drill bit up-down-left-right. The antennas and sensor are embedded in respective ones of the pressure pads and are used to electronically and non-invasively probe a coal seam to locate its upper and lower boundary layers. The dielectric-constant sensor provides corrective data for the up and down distance measurements. Such measurements and data are radio communicated to the surface for tomographic processing and user display.

Abstract: A system and method for detecting a target. The inventive method includes the steps of receiving a complex return signal of an electromagnetic pulse having a real and an imaginary component; extracting from the imaginary component information representative of the phase component of the return signal; and utilizing the phase component to detect the target. Specifically, the phase components are those found from the complex range-Doppler map. More specific embodiments further include the steps of determining a power spectral density of the phase component of the return signal; performing a cross-correlation of power spectral density of the phase component of the return signal between different antenna-subarray (quadrant channels); and averaging the cross-correlated power spectral density of the low frequency components. In an alternative embodiment, the cross-correlation is performed on the phase component of the range-Doppler map directly.

Abstract: A radar receiver is shown wherein the frequency of a first local oscillator is changed to bring an intermediate frequency signal representative of a moving target into frequency coincidence with a signal from a reference oscillator of fixed frequency.

Abstract: A radar device is described having means (12) for generating a first code, means (18) for modulating a transmission signal in a transmitting branch using the first code, means (32) for delaying the first code, means (20) for modulating a signal in a receiving branch using the delayed first code, and means for mixing a reference signal with a reception signal, multiple receiving channels (111, 112, . . . 11k) being provided, the receiving channels (111, 112, . . . 11k) having means (1201, 1202, . . . 120k) for generating additional codes (C1, C2, . . . Ck), the receiving channels (111, 112, . . . 11k) having means (131, 132, . . . 13k) for demodulating using the respective additional codes (C1, C2, . . . Ck), and means (15) being provided for modulating the transmission signal using at least one of the additional codes (C1, C2, . . . Ck). A method which may be implemented advantageously using the radar device described is also described.

Abstract: A radar device includes elements (10) for generating a carrier signal having a carrier frequency fT, elements (12, 14) for generating pulses with a pulse repetition frequency fPW, elements (16) for distributing the carrier signal to a transmission branch and a receiving branch, elements (20) for modulate the carrier signal in the transmission path using the undelayed pulses, elements (22) for modulating the carrier signal in the receiving branch using the delayed pulses and for generating a reference signal, elements (24) for mixing the reference signal in the receiving branch with a received signal and elements (26) for integrating the mixed signal. Elements (28, 30) are provided for binary phase shift keying (BPSK) modulation of the carrier signal and elements (32) are provided for switching the polarity of the received signal. A method for suppressing interference in a radar device is also described.

Abstract: A system for generating a false target radar image for countering wideband synthetic aperture and inverse synthetic aperture imaging radar systems to prevent a selected target from being detected by such radar systems comprises a receiver system for producing a digital signal that represents an incident radar signal. A phase sampling circuit is connected to the receiver for sampling the digital signal and providing phase sample data. An image synthesizer circuit is connected to the phase sampling circuit and arranged to receive the phase sample data therefrom. The digital image synthesizer circuit is arranged to process the phase sample data to form a false target signal, which is input to a signal transmitter system arranged to transmit the synthesized false target signal so that it can be received by a radar system.

Abstract: In order to magnetically shield the transmission line which connects the external connector mounted on the outer housing with the internal circuit and also to make it possible to freely mount the external connector without being limited by the position of the internal circuit, an outer housing 60 consists of an outer housing main body 61 and a shielding layer 62 applied to the inner-periphery surface of the outer housing 60. An transmission line 73 extends from the internal circuit through the outer-periphery side of the shielding layer 62 of the outer housing 60 along the shielding layer 62 to the desired position, where the external connector 70 is placed.

Abstract: A continuous signal of a radio frequency source is connected to an antenna using at least one mixer to generate and analyze radar pulses. To generate a radar pulse, the at least one mixer is briefly placed into a state of low throughput loss. After the radar pulse is generated and transmitted, the at least one mixer is switched over to a receive mode to analyze a mixed signal formed by a receive signal, in particular at least one radar pulse reflected by an object, and the continuous signal of the radio frequency source.

Abstract: A high-definition radar imaging system and method receives image data and adaptively processes the image the data to provide a high resolution image. The imaging technique employs adaptive processing using a constrained minimum variance method to iteratively compute the high-definition image. The high-definition image I is expressed in range and cross-range as I(r,c)=min&ohgr;HR&ohgr;, where &ohgr; is a weighting vector and R is a covariance matrix of the image data. A solution for I(r,c) is approximated by i) forming Y=[x1 . . . xK]T/{square root over (K)} where x1 . . .

Abstract: A method of removing RFI from a SAR by comparing two SAR images on a pixel by pixel basis and selecting the pixel with the lower magnitude to form a composite image. One SAR image is the conventional image produced by the SAR. The other image is created from phase-history data which has been filtered to have the frequency bands containing the RFI removed.

Abstract: A method and bistatic synthetic aperture radar (SAR) imaging system generate an image of a target area without knowledge of the position or velocity of the illuminator. The system includes an illuminator to illuminate a target area with a null-monopulse radiation pattern interleaved with a sum radiation pattern. The illuminator adjusts the phase terms of the sum radiation pattern to maintain a static electromagnetic field pattern at the target area. A receiver receives the radiation patterns reflected from the target area and generates phase compensation terms by correlating a measured electromagnetic vector field with the known static electromagnetic vector field. The phase compensation terms are used to generate an image of the target area.

Abstract: The present invention relates to a radar system having means (12) for producing a code, means (18) for modulating a transmission signal in a transmit branch, using the code, means (32) for delaying the code, means (20) for modulating a signal in a receive branch, using the delayed code, and means (26) for mixing a reference signal with a receiving signal, the modulation of one of the signals being performed by an amplitude modulation (ASK; “amplitude shift keying”) and the modulation of the other signal by a phase modulation (PSK; “phase shift keying”). Furthermore, a radar system is proposed in which blanking of phase transitions is provided. The present invention also relates to methods which may advantageously be carried out, using the radar systems according to the present invention.

Abstract: The present invention is a radar system for detecting the presence of obstacles. The radar system includes at least one transmitting antenna and at least one receiving antenna. The transmitting antenna receives an input signal and transmits an electromagnetic wave. The electromagnetic wave reflects off an obstacle back to the receiving antenna. The receiving antenna captures the reflected electromagnetic wave and produces an output signal. The output signal is then combined with the input signal in a quadrature mixer. The resulting in-phase (I) and quadrature (Q) signals may be further processed and then transmitted to a processing system. The processing system uses a suitable algorithm, e.g., a back projection algorithm, to estimate the type and location of obstacles that reflected the electromagnetic wave. In an exemplary embodiment, the algorithm is adapted to discriminate between different sizes and locations of obstacles in order to determine if there is a hazard.

Abstract: A system and method for efficient phase error correction in range migration algorithm (RMA) for synthetic aperture radar (SAR) systems implemented by making proper shifts for each position dependent phase history so that phase correction can readily be performed using the aligned phase history data during batch processing. In its simplest form, the invention (44) is comprised of two main parts. First (60), alignment of the phase error profile is achieved by proper phase adjustment in the spatial (or image) domain using a quadratic phase function. Second (62), the common phase error can be corrected using autofocus algorithms. Two alternative embodiments of the invention are described. The first embodiment (44a) adds padded zeros to the range compressed data in order to avoid the wrap around effect introduced by the FFT (Fast Fourier Transform). This embodiment requires a third step (64): the target dependent signal support needs to be shifted back to the initial position after phase correction.

Abstract: A system and method for sensing phase errors in a multiple receiver array use three non-collinear transmitters transmitting first, second, and third signals to a target and receiving corresponding signals reflected from the target using the multiple receiver array. In one embodiment, each transmitter transmits a characteristic signal which can be distinguished from each other by the receivers. In one embodiment, each transmitter transmits a slightly different monotone frequency that is preferably outside any imaging bandwidth. The sheared products computed from heterodyne measurements at the receivers in the array based on the reflected signals from the three transmitters are used to determine and correct for the combined transmitter/receiver phase errors at each of the receivers in the array.

Abstract: A sensor front end is disclosed that is able to discriminate objects based on their range from the sensor. The sensor includes an antenna that transmits a sensor signal and, if an object is present receives a reflected signal therefrom. A pulsed oscillator provides a pulsed first signal having a first frequency and phase, and wherein the pulsed oscillator provides the pulsed first signal for a predetermined pulse duration and with a predetermined pulse repetition frequency. The pulsed oscillator provides the pulsed first signal to a first input port of a dual mode mixer that is further coupled to the antenna via a second port. The dual mode mixer transmits a portion of the pulsed first signal from the first input port to the second port and thus to the antenna to be transmitted as the sensor signal. In addition, the dual mode mixer uses a portion of the first signal to mix with the received reflected signal. The dual mode mixer then provides a mixed signal as an output at a third port.

Abstract: A Doppler radar apparatus includes a first oscillator for generating a first sweep signal to repeatedly sweep a predetermined frequency range periodically; a second oscillator for generating a second sweep signal having sweep properties identical to those of the first sweep signal, the second oscillator 41b starting sweep before the first oscillator finishes frequency sweep; a power combiner for combining the first and second sweep signals to generate a transmission signal; a switch for receiving, as inputs, the first and second sweep signals, and switching an output between the first and second sweep signals synchronously with the timing when sweep with each of the first and second sweep signals is terminated; and a mixer for mixing a reception signal coming from a part of the transmission signal reflected in a target and received, and an output signal from the switch with each other to produce an output signal from the mixer.

Abstract: A system and method for calibrating a phase array antenna using a near-field probe and focused null and a signal coherent with the beam received or transmitted at the null location of the probe. In the transmit mode, a base-band phase comparator circuit is established by locating the first probe at the angular location of the null and the first probe measures the field at the null while an offset phase reference probe, or second probe, measures the field at one of the sum peaks of the difference lobes as the reference. In the transmit mode, the method uses the pattern characteristics of the difference pattern to allow direct measurement of the phase reference by the second probe that is located at one of the sum peaks of the difference pattern. In the receive mode, the signal source provides the reference and the second probe is not necessary.

Abstract: The present invention relates to a radar device and, particularly, to a radar device mounted on a vehicle to be used for a collision alarm and the like. The invention provides a radar device that has a unit for removing the FMAM noise without lowering the signal detection sensitivity. The radar device transmits a frequency modulation signal by switching the frequency modulation signal with a first switching signal, receives a signal reflected from a target object, switches the reception signal with a second switching signal, mixes the switched reception signal with the transmission signal, and further mixes the mixed signals with a third switching signal thereby to obtain a beat signal. The radar device obtains a distance to the target object and a relative speed of the target object from the beat signal.

Abstract: A method, apparatus, and processing system for radar detection and tracking of a target using monopulse ratio processing comprising the following steps. First, receiving a signal comprised of a plurality of sum azimuth beams and difference azimuth beams. Then staggering the received signal. Next, filtering and localizing a clutter signal which is a portion of the received sum and azimuth beams. Then adaptively forming a sub-array sum azimuth beam and a sub-array difference azimuth beam from the filtered output to cancel the clutter. The adaptive beam forming including the determination of a sum and difference beam weight where the adaptive weight be equated to a product of the weight and the respective covariance matrices of the sum and difference beams, the product having no constraint points.

Abstract: A vehicle speed sensing system includes an RF transceiver coupled to an antenna for transmitting an RF signal towards the terrain over which the vehicle moves and for receiving a reflected Doppler signal therefrom. The transceiver generates a time-domain in-phase reference signal I and a time-domain quadrature signal Q which is offset in phase by 90 degrees from the reference signal I. A digital signal processor which receives the I and Q signals, and uses a complex fast Fourier transform routine to convert the time domain I and Q signals to frequency domain values I(f) and Q(f). The digital signal processor further processes the I(f) and Q(f) values and generates a speed a direction signal which is unaffected by vehicle vibrations.

Abstract: A drillstring radar comprises a measurements-while-drilling instrument for mounting just behind the drill bit and downhole motor of a drill rod. The instrument includes a radar system connected to upward-looking and downward-looking horn antennas. These are used to electronically probe the interface of a coal seam with its upper and lower boundary layers. A dielectric constant sensor is included to provide corrective data for the up and down distance measurements. Such measurements and data are radio communicated to the surface for tomographic processing and user display. The instrument also includes a navigation processor and drill bit steering controls. The radio communication uses the drillstring as a transmission line and F1/F2 repeaters can be placed along very long runs to maintain good instrument-to-surface communication.