Abstract: This invention relates to an object recognition apparatus. This apparatus comprises an antenna which emits transmission beams toward a plurality of directions; a receiving circuit which receives reflected signals of the transmission beams from predetermined directions; a distance and direction calculation circuit which calculates distance and direction to objects reflecting the transmission beams based on the transmission beams and the reflected signals; an object pattern storage unit which stores range direction patterns of reflected signals obtained in advance with respect to predetermined objects; an object recognition circuit which compares range direction patterns of the reflected signals received by the receiving circuit with respect to the predetermined directions, with the range direction patterns stored in the object pattern storage unit, and which recognize that a pair of reflected signals from two neighboring directions are signals reflected by the same object.

Abstract: A modulation signal generation circuit performs frequency modulation of a VCO with a triangular wave for operation as an FM-CW radar. A signal processing circuit gives a modulation signal for detection generated from the modulation signal generation circuit to the VCO. A high-frequency signal subjected to frequency modulation in the VCO is transmitted as a radio wave from a transmission antenna and is reflected on a target and the reflected radio wave is received at a reception antenna. The reception signal and the high-frequency signal are mixed by a mixer to provide a beat signal and frequency shift corresponding to a voltage V1 is detected from the frequency of the beat signal. If the voltage V1 of the modulation signal for detection is switched, the frequency shift corresponding to different voltage V1 can be provided and the frequency modulation characteristic can be detected.

Abstract: A security and tracking apparatus is provided, comprising at least two signaling units in communicating proximity, and means for identifying the location of the signaling units. In one embodiment, a security and tracking apparatus is provided, comprising at least two signaling units in communicating proximity, and means for identifying and automatically transmitting the location of the signaling units when the signaling units are separated by more than a preselected distance.

Abstract: A Fast Chirp Transform (FCT) for the digital processing of chirp signals and exemplary applications. The FCT is a generalization of a multidimensional Fast Fourier Transform. Phase coefficients for boundary intervals are calculated using phase functions describing the time dependent frequency characteristics of an input signal in the time domain. A multidimensional FFT is performed on the dot product of the phase coefficients and the input signal resulting in a multidimensional representation of the input signal in the frequency domain. The FCT and its inverse can be used to enhance the signal to noise ratio in applications involving chirp signals.

Abstract: A stationary object detection method for a scanning radar wherein, of peaks generated based on a radar signal reflected from a target, peaks having substantially the same frequency are grouped together, and a decision is made as to whether or not the frequency of the grouped peaks is equal to/higher than a predetermined value, and wherein if the peak frequency is equal to or higher than the predetermined value, then a decision is made as to whether or not the number of grouped peaks is equal to or greater than a predetermined number and, if the number of peaks is equal to or greater than the predetermined number, it is decided that the target is an overhead bridge candidate or an overhead bridge.

Abstract: A radar signal processing apparatus has a range gate for extracting range gate data sequences from a memory, a first frequency extraction section which extracts a beat frequency corresponding to a target by performing frequency analysis by FFT at a low computation load and with low frequency measurement accuracy on all range gate data sequences extracted by the range gate, a second frequency extraction section which extracts a beat frequency corresponding to the target by performing frequency analysis by FFT at a high computation load and with high frequency measurement accuracy only on the range gate data sequence from which a beat frequency has been extracted by the first frequency extraction section, and a distance and speed derivation section which obtains the relative distance and the relative speed of the target on the basis of the beat frequency extracted by the second frequency extraction section.

Abstract: A transmitted signal and a received signal are combined and the combination is expected to determine whether or not a target signal is present. Either the transmitted signal or the received signal is combined with an auxiliary signal containing a range of frequencies corresponding to an anticipated Doppler shift, so that an output of the combined transmitted and received signal will be present only if a target signal exhibiting a Doppler shift within the anticipated range is present. The auxiliary signal preferably comprises finite-duration signal portions of different types so as to provide a substantially uniform frequency response throughout the selected range.

Abstract: A method for processing squint-mapped synthetic aperture radar data of the present invention. The inventive method includes the steps of effecting range compression of the data; deskewing the data; performing a Fourier transform with respect to the deskewed data; providing a range migration interpolation of the transformed data; effecting a frequency remapping of the range interpolated data; and performing an inverse Fourier transform with respect to the deskewed data.

Abstract: Circuitry and technique for improving the analysis of a signal, such as radar return, by eliminating the effects of frequency variations of the carrier and thereby stabilizing the modulation spectrum. This is accomplished by tracking the carrier frequency and using it as a reference signal for translating the carrier frequency in the radar return to zero frequency.

Abstract: In a radar, a coupler extracts a part of a transmission signal as a local signal and a mixer mixes a reception signal from a circulator and the local signal so as to output an intermediate frequency signal which is the frequency difference between the transmission signal and the reception signal. An IF-amplifying circuit amplifies the intermediate frequency signal and an AD converter converts the signal to digital data. A DC-removing unit removes a DC component by subtracting the average from the data and an FFT operation unit performs fast Fourier transform so that the distance to a target and the relative velocity of the target are calculated based on a peak included in the frequency spectrum.

Abstract: Apparatus and methods are disclosed for detecting anomalies in microwave penetrable material that may be used for locating plastic mines or pipes underneath the ground. A transmitter is positioned at a plurality of different positions above the ground. A microwave signal is transmitted that is stepped over a plurality of frequencies. At each position, a plurality of reflections are received corresponding to each of the plurality of frequencies that were transmitted. A complex target vector may be produced at each position that contains complex values corresponding to magnitude, phase, and time delay for each of the plurality of reflections received at that location. A complex reference data vector may be produced, either based on predetermined values or based on data from the received plurality of reflections. A comparison is made between the complex target vector and the complex reference data vector to produce a channel vector.

Abstract: A method and apparatus for measuring the parameters of atmospheric turbulent flows utilizes the Doppler shifted frequencies of received radar signals backscattered from sound generated aerodynamically by atmospheric turbulent flows. Doppler frequency bandwidths of the received backscattered signals are used to estimate the atmospheric flow turbulence and the mean frequency within a bandwidth is processed to estimate its radial flow velocity. Total flow velocity and the flow velocity angle with respect to the antenna boresight of the atmospheric turbulent flow may be estimated by estimating the radial flow velocity at two radial positions and processing these radial velocities. Processing of the Doppler data is initiated when the total signal power within the Doppler frequency band exceeds a predetermined power level.

Abstract: In a radar, a frequency-modulated transmission signal whose frequency varies in time is generated. The gain-frequency characteristics of an IF signal which represents a beat signal between the transmission signal and a reception signal has its peak at or below one half of the sampling frequency of an AD converter. The gain-frequency characteristics of an IF amplifier circuit is determined so that the gain increases as the frequency increases at or below the frequency corresponding to the peak, the ratio of change in the gain relative to change in the frequency becomes smaller at short distances for which a saturation of a mixer is caused, and the gain is reduced at DC and in the vicinity of DC.

Abstract: This invention concerns a procedure for the elimination of interferences, such as pulses and linear chirps, in a radar unit of the FMCW type. According to the procedure, the useable signal in the form of a beat signal, is subjected to time-frequency division of the type STFT for division of the signal into narrow-band frequency bands. Interference is detected and eliminated in each frequency band, after which the time signal freed from interference and its Discrete Fourier Transform, DFT, are calculated from the time-frequency division in narrow-band frequency bands.

Abstract: A radio direction finding system for a low signal quality transmission signal performs a Fast Fourier Transform (FFT) on an entire received RF band into a number of FFT bins, each serving as an IF filter. The contents of each FFT bin are demodulated to decode a frequency signature from the encoded RF signal. A signal-to-noise ratio comparator receives the FFT baseband samples and determines the signal level from the known frequency signature. The FFT baseband buffer with the greatest SNR corresponding to a particular FFT frequency bin is outputted as a direction finding metric.

Abstract: An antenna section radiates a pulse beam and receives its reflected wave, and a signal processing section observes a rain or cloud occurring region within a covered area based on a signal intensity of the reflected wave. In this case, to obtain wind direction and velocity information for the rain or cloud occurring region, the signal processing section observes Rayleigh scattering-induced Doppler echo components in that region to calculate the wind direction and velocity from a result of the observation. To obtain the wind direction and velocity information for a region other than the rain or cloud occurring area, the beam formed by the antenna section is directed toward the region to be observed so that the signal processing section can observe Bragg scattering-induced echo components based on a received signal of the reflected wave to calculate the wind direction and velocity from a result of the observation.

Abstract: A multi-stage processing system receives data from signals that indicate information related to scatterers, such as signals from a Doppler scanning system. The multi-stage processing system tracks allowed processing time for the data. The multi-stage processing system performs a first stage of processing for the data to generate first estimates of spectral moments for the signals. The multi-stage processing system performs additional stages of processing for the data as the allowed processing time permits and stops the additional stages of processing for the data when the allowed processing time expires. The additional stages of processing may comprise generating second estimates for at least some of the spectral moments. The additional stages of processing may use methods having increasing complexity and accuracy.

Abstract: An electronic warfare radio receiver of the monobit type wherein the signal processing circuitry, including a bandpass filter array, analog to digital converter circuit and Fourier transformation circuit, are located in a plurality of parallel-disposed but isolated receiver channels. The parallel disposed receiver channels limit interference between received signals and enable the customary processing of two simultaneous input signals of differing signal strength in each receiver channel; this increases the number of simultaneous input signals processable by a factor equaling the number of receiver channels used. Single chip embodiment of the receiver is disclosed thereby tending to compensate for the added complexity of the channelized processing. Signals falling in digital filter overlap regions are addressed by the invention.

Abstract: This FM-CW radar apparatus comprises a transmitter section, a receiver section, and a signal processing section. The transmitter section transmits a frequency-modulated continuous wave as a transmitted wave. The receiver section receives a radio wave resulting from reflection of the transmitted wave at a target, as a received wave, by a receiving antenna comprising an array of antenna elements, generates a beat signal which is a difference of the transmitted wave and the received wave in each of channels of the respective antenna elements, and converts this beat signal to a digital beat signal by A/D conversion. The signal processing section executes a digital beamforming operation with the digital beat signals and detects the target from the result of the operation.

Abstract: A complex frequency shift keyed homodyned diplexed radar system and method that can accurately determine the range of one or more targets where the targets have little or no velocity relative to the radar system. The system and method generates a FSK electromagnetic wave that is reflected off the one or more targets and converted into a delayed or phase shifted baseband signal and undelayed baseband signal where the delayed and an undelayed baseband signal may be analyzed to determine the range of the one or more targets.

Abstract: A radio altimeter using a linear oscillator to send out a continuous wave that is frequency modulated linearly between two boundary values sends the antenna installation an incident signal, collects the signal reflected by the installation and examines it. This incident signal may be that of the linear oscillator. For the reception antenna installation, this means providing for a rerouting in order to direct a small part of the signal of the oscillator to this installation. In the case of the transmission antenna installation it is enough to provide for a rerouting that injects the signal reflected by this installation into the reception channel. Application to all the FM/CW radio altimeters.

Abstract: A radar signal processing method and system for detecting target objects of unknown acceleration and having low SNRs which reduces the computational burdens and provides a more efficient way of performing the operation of non-coherent integration. Radar signal processing is conducted according to a predetermined scheme in which partially processed received signal data is selectively stored and reused, reducing redundant processing. The radar system receives return signals frequency shifted from a predetermined frequency scheme by unknown amounts. The received signals are coherently integrated transforming them into frequency domain templates which are non-coherently arranged into an array matrix. The data of the frequency domain templates are processed to form presums which are stored for use in forming higher level presums and for forming acceleration bins. Once the acceleration bins have been formed, they are analyzed to detect the presence of target object return signals.

Abstract: Method of obtaining a gain function by means of an array of antennae and a weighting of the signals received or to be transmitted by vectors ({overscore (b)}) of complex coefficients, referred to as weighting vectors, according to which, a reference gain function being given, the said reference gain function is projected orthogonally onto the sub-space of the gain function generated by the said weighting vectors of the space of the gain functions, provided in advance with a norm, and a weighting vector generating the reference gain function thus projected is chosen as the optimum weighting vector.

Abstract: A Doppler-based radar system and related method are provided for determining the direction and speed of at least one selected target traveling in the same lane as a moving patrol vehicle supporting the radar system independent of the direction of the target relative to the platform. The radar system includes an oscillator to generate a signal, an antenna to transmit the signal toward the at least one target and to receive a return signal reflected from the at least one target, a turnstile in communication with the antenna for receiving the return signal and forming processing signals which are different in phase, and circuitry for determining the direction of the at least one target relative to the platform. In particular, samples of the processing signals are transformed into the frequency domain and cross-correlated forming cross-correlation components.

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

Abstract: The present invention relates to a CW radar method for measuring distances between and relative speeds of a vehicle and one or more obstacles. The present invention further provides that the transmission (s(t)) can be composed of at least four consecutive chirps (A, B, C, D), each having different slopes. The intersection points of all lines in the distance-relative speed diagram from two chirps (A, B) can be calculated from all the ascertained frequency positions K1,n and K2,p. To validate those intersection points, one may observe whether a peak exists in the Fourier spectrum of a third chirp C at a frequency position K3,q, whose assigned line intersects a surrounding area of the intersection point in the distance-relative speed diagram.

Abstract: The present invention discriminates between moving targets and stationary targets in order to measure distances and speeds of the targets without producing a false target. The invention transmits signals whose modulating frequencies ascend or descend to a target, and receives signals reflected from this target. A frequency spectrum of a beat signal of each target is detected during a modulating frequency ascent period and a modulating frequency descent period. The frequency spectrum of the modulating frequency ascent period and the frequency spectrum of the modulating frequency descent period are used to set a reference spectrum. The reference beat frequencies of either the moving targets or the stationary targets are detected based upon the reference spectrum.

Abstract: A motion detector based on the Doppler principle contains a microwave module for emitting a microwave signal containing at least two frequencies into a room under surveillance and for receiving the radiation reflected from the latter. An evaluation stage is connected to the microwave module and generates first and second Doppler signals from the received radiation. The first and second Doppler signals have a phase difference which is proportional to the distance of an object reflecting the microwave signal. The phase difference is determined by an integral transformation. In addition, the relative size of an object and the direction of travel of an object reflecting the microwave signal can be determined by the evaluation stage.

Abstract: A method for filtering clutter from a first digital input image is disclosed. Generally, the method includes the steps of applying at least first and second transforms to first digital image data corresponding to the first digital input image, performing an appropriate filtering operation to retain, in first and second transform domains, at least a portion of the transform indications corresponding or at least correlatable to a structure or target in the first digital input image, applying to the remaining transform indications inverse first and second transforms, and processing the filtered first digital input data to produce a single filtered image and/or image data, whereby the target or structure in the first digital input image formerly obscured by the clutter is detectable/recognizable.

Abstract: A radar detection process includes computing a derivative of an FFT output signal to detect an object within a specified detection zone. In one embodiment, a zero crossing in the second derivative of the FFT output signal indicates the presence of an object. The range of the object is determined as a function of the frequency at which the zero crossing occurs. Also described is a detection table containing indicators of the presence or absence of an object within a respective radar beam and processing cycle. At least two such indicators are combined in order to detect the presence of an object within the detection zone.

Abstract: The invention relates to a radar distance measuring device. An especially linear frequency-modulated high frequency signal is emitted via an antenna and mixed with an echo signal reflected by a target object whose distance is to be determined. The distance of said target object can then be calculated by analyzing the frequency of the mix result. The aim of the invention is to improve the distance resolution or increase the accuracy of measurement. To this end, a first frequency analysis is first carried out to obtain a rough analysis result. Said rough analysis result is used to control a filtering device which then restricts the mix result in its time range to a segment around the frequency of the target object. A discrete Fourier transformation is then carried out for this segment in order to produce an analysis result with a more refined scanning step than the first frequency analysis.

Abstract: A radar system mounted on a vehicle is capable of properly measuring an angle even when a linearity is impaired without increasing a scale of hardware and a load on signal processing, and exhibiting a high performance at a low cost.

Abstract: A method of detecting foreign bodies in a medium with a radar having a transceiver, and including emitting a radar wave through a wall surface into the medium with the transceiver, detecting a radar signal reflected in the medium, pre-processing the reflected radar signal and subjecting the pre-processed radar signal to evaluation and assessment, determining a characteristic of a foreign body at a stationary position of the transceiver with an algorithm which is based on a pre-processed, digitalized receivable signal, which characteristic permits to recognize differences between a shape of the reflected radar signal and stored comparison values, and conducting a comparison assessment of the shape differences of the reflected signal against predetermined threshold values.

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: This invention concerns a procedure for the elimination of interferences, such as pulses and linear chirps, in a radar unit of the FMCW type According to the procedure, the useable signal in the form of a beat signal, is subjected to time-frequency division of the type STFT for division of the signal into narrow-band frequency bands. Interference is detected and eliminated in each frequency band, after which the time signal freed from interference and its Discrete Fourier Transform, DFT, are calculated from the time-frequency division in narrow-band frequency bands.

Abstract: An antenna section radiates a pulse beam and receives its reflected wave, and a signal processing section observes a rain or cloud occurring region within a covered area based on a signal intensity of the reflected wave. In this case, to obtain wind direction and velocity information for the rain or cloud occurring region, the signal processing section observes Rayleigh scattering-induced Doppler echo components in that region to calculate the wind direction and velocity from a result of the observation. To obtain the wind direction and velocity information for a region other than the rain or cloud occurring area, the beam formed by the antenna section is directed toward the region to be observed so that the signal processing section can observe Bragg scattering-induced echo components based on a received signal of the reflected wave to calculate the wind direction and velocity from a result of the observation.

Abstract: A radar apparatus is provided which is designed to form digital beams using beat signals each of which is produced by one of a plurality of receivers and analyze the frequency of the beat signals in units of the beams for obtaining data such as the distance to, relative speed, and azimuth of a target. The apparatus performs the complex Fourier Transform twice on beat signals in time series and space series along the array of receiving antennas to derive results of the frequency analysis in units of the beams, thereby resulting in simplified structure and decrease in operation load of the apparatus.

Abstract: Disclosed is a radar system capable of obviating a problem that a sufficient improvement of an S/N ratio could not be obtained in the prior art, and comprising a transmitter/receiver for detecting a phase of a receiving signal reflected from an observation target, an A/D converter for converting the receiving signal into a digital signal, a range gate for extracting the receiving signal having a time corresponding to the predetermined pulse width, a data dividing unit for dividing the receiving signals in to two groups of data, an FFT unit for fast-Fourier-transforming one group of data of the two groups of data, an FFT unit for fast-Fourier-transforming the other group of data, a complex conjugating unit for taking a complex conjugate of an output of the FFT unit, a complex multiplying unit for performing a complex multiplication for the every same Doppler frequency component with respect to an output of the former FFT unit and an output of the complex conjugating unit, and a complex adder for executing a co

Abstract: An FM-CW radar is provided which may be employed in anti-collision systems or cruise control systems installed in moving objects such as automotive vehicles. The radar analyzes a beat signal in frequency to produce peak frequency components in a modulated frequency-rising range wherein the frequency of a frequency-modulated radar wave transmitted from the radar increases and a modulated frequency-falling range wherein the frequency of the radar wave decreases. If one of peak frequency pairs, each of which is made up of each of the peak frequency components in the modulated frequency-rising range and one of the peak frequency components in the modulated frequency-falling range, lies within a given lower frequency range, the radar identifies the one of the peak frequency pairs as radar data arising from a moving object appearing suddenly in a radar detection zone.

Abstract: Apparatus and methods for processing RF signals are disclosed. A method according to the invention includes receiving a set of time domain energy samples representing signal energy present in an RF spectrum, transforming the set of time domain energy samples into a set of frequency domain power samples, determining from the set of frequency domain power samples whether a signal of interest is present in the RF spectrum, and forwarding to a follow on system a subset of the set of frequency domain power samples, wherein the subset corresponds to the signal of interest. Transforming the time domain samples can include dividing the set of time domain energy samples into a plurality of N windows, each of which is associated with a predefined window period, and performing an FFT on each said window to generate a set of K frequency bins, wherein each frequency bin has a value based on energy present in a predefined frequency band during the corresponding window period.

Abstract: The present invention relates to multi-function, multi-channel digital receiver architecture for performing three distinct receiver functions including simultaneous intrapulse analysis, direction finding and LPI signal detection; for determining parameters of incoming signals, comprising a plurality of receiver channels, each channel including a respective antenna for receiving the signal; a down-converter for converting the signal to an intermediate frequency (IF) signal; and an analog-to-digital converter operatively coupled to receive the IF signal and to provide a digital signal at a sampling rate, the digital signal being indicative of the amplitude and phase of the received signal in the channel, and a digital processor operatively coupled to receiving the digital signals from each of the plurality of channels for determining the amplitude and phase intrapulse profiles; by combining the amplitude and phase intrapulse profiles from all of the plurality of channels to provide both intrapulse and conventio

Abstract: Dual path detection processing in which a low SNR signal processor detects signals over a limited range of low acceleration values and a high SNR signal processor detects signals over a wider range of acceleration values. The low SNR signal processor uses acceleration bins formed from a noncoherent FFT array to detect low SNR signals of far away objects which tend to have lower angular acceleration. Because close proximity target objects tend to have higher SNR return signals, it is not necessary to rely on acceleration bins formed from an FFT array for signal detection. Close proximity targets with high SNR can often be detected in individual coherently integrated FFT templates, despite the likelihood of large acceleration uncertainty from higher angular acceleration rates.

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

Abstract: The computation system of the present invention comprises an improved method of moment estimation for devices which measure spectra as a function of range or time. The preferred embodiment of this system is illustrated as part of an automated meteorological monitoring system for the accurate real time detection of meteorological phenomena, such as winds, wind shear and turbulence. This automated meteorological monitoring system uses a standard weather radar transmitter to scan a predetermined volume of space with a stream of radar pulses to determine the characteristics of meteorological phenomena that are extant in the predetermined volume. The computation system of the present invention utilizes novel signal processing algorithms in the improved method of moment estimation to excise the valid data from the returns echoes, which are corrupted by the presence of contaminating signals.

Abstract: An electronic counter-measure receiver can be colocated with a threat simulator radar, which transmits a radar signal. As a pulsed-Doppler signal, this transmitted radar signal is sampled as a reference signal by the receiver to determine quadrature, coherent matched filter coefficients. A return signal is received and processed with the reference signal as quadrature signal components with the quadrature, coherent matched filter coefficients within a matched filter. The return signal is processed as a first intermediate frequency via a mixer and local oscillator and a second quadrature intermediate frequency via a digital local oscillator and mixer. A fast Fourier transform is performed to determine Doppler information. In a continuous wave transmission for sampling arbitrary but unevenly spaced in time pulses are generated from a pulse generator source internal to the receiver.

Abstract: A broadband radio receiver of the type usable in receiving and identifying the pulsed signals of radar transmitters in an electronic warfare environment. The receiver includes signal presence detecting apparatus in the form of a time domain signal detection apparatus usable in maintaining complex signal processing portions of the receiver, such as its fast Fourier transform generation circuit, in quiescent low energy dissipating status until needed to perform signal analysis. Such energy conservation enables use of the receiver in energy limited remote or space received environments. Energy conserving “clockless logic” or “null convention logic” is preferably used in embodying greater energy dissipating portions of the receiver.

Abstract: A radar apparatus is provided which includes a transmitter, a receiver, and a signal processor. The transmitter produces a transmit signal which is so modulated in frequency as to change with time cyclically and transmits the transmit signal as a radar wave. The receiver selectively establishes communication with one of receiving antennas and changes the communications with the receiving antennas in sequence in a cycle shorter than a cycle of a change in the frequency of the transmit signal to supply a series of signal components of input signals produced by the receiving antennas. The receiver mixes the series of signal components with a local signal having the same frequency as that of the transmit signal to produce a beat signal. The signal processor samples the beat signal to analyze frequency components thereof to determine the distance to, relative speed and azimuth of a target.

Abstract: A timing and control method and apparatus (111) for performing precise range rate aiding includes a range gate delay means (114) for generating an estimate of the range gate delay (135) each pulse repetition interval as a function of the initial range (134) and velocity (133) provided by a processor (104). The range gate delay (135) is converted into a coarse delay (138) defining the integral number of clock cycles preceding the range gate, and a fine delay (139) for positioning a range gate to within a fraction of a clock cycle. Fine temporal control is achieved using programmable delay lines (117) and (118), which retard various control signals, including the system clock signal (131), in accordance with the fine delay (139). A modified signal (126) then drives a counter means (119) which outputs a signal (128) that defines an analog-to-digital sampling window beginning at the elapse of the range gate delay (135).

Abstract: A method in which a sensor system with a frequency-modulated signal source an a delay line for generating a time-delay reference signal is implemented. Phase errors are compensated by correcting the modulation (pre-equalization derived from the reference signal. Signals with a long running time are measured and additionally compensated by a computational, subsequent elimination (post-equalization). A high-pass filter is provided to that end.