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 system is provided for generating multiple frequencies in a specified frequency band, with a specified step size between frequencies, in which the spectral purity of the frequencies is assured. The switching speed between frequencies is very fast, limited only by the speed of the switches used. In one embodiment, only five tones are generated as the base for the rest of the synthesis, in which the relationship of the five tones is f0+/−⅛f0 and +/−{fraction (1/16)}f0. The subject system may be utilized in air defense systems for generating the transmit channels to be able to permit a missile seeker to transmit a signal at the appropriate frequency. In one embodiment, spectral purity is achieved by providing a number of stages of up converting, expanding, and dividing down of an input signal.

Abstract: An FM-CW radar apparatus permits proper pairing between beat frequencies in an up interval and beat frequencies in a down interval and comprises a peak extracting section for extracting level peaks at each scanning angle of beat frequencies, each beat frequency being a frequency difference between a received wave and a transmitted wave, in each of a modulation frequency increasing interval and a modulation frequency decreasing interval; a grouping section for grouping level peaks of approximately equal beat frequencies adjacent in a scanning direction to create level peak groups having respective typical scanning angles, for either of the increasing-interval level peaks and decreasing-interval level peaks thus extracted; a pairing section for pairing a level peak group in the increasing interval with a level peak group in the decreasing interval where the level peak groups have an equal typical scanning angle; and a calculating section for calculating target information from beat frequencies of the increasing

Abstract: A modulation signal generating section produces a modulation signal for controlling an oscillation frequency of a voltage-controlled oscillator. The modulation signal generating section comprises a triangular wave oscillator producing a linear modulation component of a triangular waveform which varies the modulation frequency linearly, a sine wave oscillator producing a cyclic modulation component of a sine waveform which varies the modulation frequency cyclically, and a signal adder producing the modulation signal by adding the linear modulation component and the cyclic modulation component. A transmitting signal frequency modulated by the modulation signal is mixed with a received signal and produces a beat signal comprising a fundamental wave component of a beat frequency and harmonic components.

Abstract: A digital signal processor (DSP) traffic radar utilizing pulses from the patrol vehicle's electronic speedometer to steer the DSP's search of Doppler return information for the patrol vehicle's radar return signal, to improve target identification and minimize inaccuracies. In moving mode, when the patrol vehicle comes to a stop, no pulses are received by the DSP and therefore the patrol speed is set to zero, eliminating false association with other moving targets.

Abstract: A Doppler-based radar system used to determine the speed of a selected moving target includes an array of selectable filters and related method for determining the speed of the selected moving 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. This allows the speed of the target vehicles traveling in the same lane and in the same direction as the patrol vehicle to be monitored without manual assistance from the operator. The radar system is further adapted in a stationary mode of operation to determine the speed of a selected moving target independent of the location of the patrol vehicle. This is accomplished by selectively filtering either all approaching or receding targets depending upon the traffic scenario.

Abstract: In a method and device for frequency-modulated continuous-wave radar detection with removal of ambiguity between the distance and the speed, the radar sends out at least alternately two parallel and discontinuous frequency modulation ramps that are slightly offset by a frequency variation (.DELTA.F), the frequency switching from one ramp to the other at the end of a given duration (Tf), the distance from a detected target being estimated as a function of the difference in phase (.DELTA..phi.) between a received signal (S.sub.1 (t)) corresponding to the first ramp and a received signal (S.sub.2 (t)) corresponding to the second ramp, the speed of the target being obtained from the estimated distance and the ambiguity straight line associated with the target. The disclosed method and device can be applied especially to radars for automobiles.

Abstract: In the particular embodiment disclosed in the specification, a CW radar process for measurement of distances and relative speeds between a vehicle and one or more obstructions including transmitting a sequence of constant-frequency radar signal bursts which follow one another without any time interval during four successive measurements. In the first measurement, the radar signal bursts are of sequentially increasing frequency and in the second measurement they are of sequentially decreasing frequency while in the third measurement they have the same frequency and in the fourth measurement the burst frequencies follow a coded pattern. Demodulation of the signals which are reflected by obstructions is carried out by mixing them with the transmitted signals using only one single-channel mixer providing an output signal which is not the signal of a phase curve but of an amplitude curve.

Abstract: Receivers 14 and 16 comprise mixers 14b and 16b for mixing reception signals of receiver antennas 14a and 16a with a transmission signal to generate beat signals B1 and B2, respectively. Signal processing section 20 performs the Fourier transformation of beat signals B1 and B2 supplied from receivers 14 and 16 to obtain the phases of beat signals B1 and B2 and then obtain the azimuth based on the difference of these phases.

Abstract: To measure the speed of a body (1) moving relative to the ground (2) by means of a broad-band Doppler radar (3) fixed to the moving body, two incident radar waves are transmitted successively towards the ground at instants that are close together, and the corresponding reflected waves are picked up, the frequency of at least the first incident wave being time-varying, the signals representative of the first incident and reflected waves are multiplied together, a spectrum is determined for the low frequency component of the product of said two signals, the same operations are performed for second incident and reflected waves, then two peaks that correspond with a certain amount of frequency shift in the two spectra are identified, and the speed of the moving body is determined as a function of the frequencies of these two singular points and as a function of the height of the radar relative to the ground.

Abstract: A radar apparatus for detecting a distance/velocity has a transmitting system for transmitting a signal which is frequency-modulated with a modulating signal having a predetermined recurrence frequency, a receiving system for receiving a reflected wave signal, which is the modulated transmission signal transmitted from the transmitting system and reflected by an object, and which mixes the reflected wave signal and the modulated transmission signal from the transmitting system so as to detect a beat wave signal of the reflected wave signal and the modulated transmission signal.

Abstract: A police radar utilizing digital data transmission from the antenna unit to a separately housed counting and display unit. The antenna has a double balanced mixer to suppress even order harmonics. The counting and display unit has a computer programmed to perform digital signal processing on the digital data received from the antenna to improve the quality and accuracy of calculated speeds for patrol speed, strongest target speed and fastest target speed. Fastest target speed can be displayed simultaneously with strongest target speed. Signal processing techniques are used to suppress false signals caused by double and triple bounce, harmonics, intermodulation products, video display terminal interference, etc.

Abstract: In a method for measuring the distance and the velocity of objects employing electromagnetic waves, the frequency of an emitted signal is modulated. The signals received during one rise and one drop in the frequency of the emitted signal are mixed with the emitted signal. The intermediate-frequency signals resulting from the mixing are then spectrally analyzed. The distance and the velocity of at least one object are calculated from the frequency of the spectral lines of the intermediate-frequency signals during at least one rise and at least one drop in the frequency of the emitted signal.

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

Abstract: A method for resolving range and doppler target ambiguities when the target has substantial range or has a high relative velocity in which a first signal is generated and a second signal is also generated which is coherent with the first signal but at a slightly different frequency such that there exists a difference in frequency between these two signals of .DELTA.f.sub.t. The first and second signals are converted into a dual-frequency pulsed signal, amplified, and the dual-frequency pulsed signal is transmitted towards a target. A reflected dual-frequency signal is received from the target, amplified, and changed to an intermediate dual-frequency signal. The intermediate dual-frequency signal is amplified, with extracting of a shifted difference frequency .DELTA.f.sub.r from the amplified intermediate dual-frequency signal done by a non-linear detector. The final step is generating two quadrature signals from the difference frequency .DELTA.f.sub.t and the shifted difference frequency .DELTA.f.sub.

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

Abstract: A radar generates first and second mutually complementary binary code sequences. The autocorrelation functions of the first and second pulse sequences are selected so that, in the sum of their autocorrelation functions, the main lobes add, and the sidelobes are of equal amplitude and opposite polarity, and therefore cancel. The radar sequentially transmits dispersed pulses in which the chips are phase modulated with the two codes. The received pulses are applied uncompressed to the input of a Doppler filter bank, which filters them into various Doppler channels, each representative of a particular radial velocity of the target. Within each channel, the received signals modulated by the first code are matched-filtered by a filter matched to the first code, to produce a first time-compressed pulse, and those modulated by the second code are matched-filtered by a filter matched to the second code, to produce a second time compressed pulse.

Abstract: Method and apparatus for improving detection ranges of a pulsed radar sys wherein electromagnetic return signal data in range cell order is doppler filtered, digitized and stored in doppler memory channels over multiple scans of an azimuth. The digital doppler data in each doppler memory channel is scan-to-scan integrated over a predetermined number of scans to produce target displays for each possible velocity. The target displays are stored in a velocity memory, which is partitioned into velocity channels, each velocity channel corresponding to one possible velocity. A selector selects the target display having the largest total magnitude as a display signal. The scan-to-scan integrated target displays are not subject to collapsing losses since only target signals plus noise signals will be stored in the doppler memory channel corresponding to the target's velocity.

Abstract: Apparatus and methods for combining incoherent signals having different carrier frequencies but a common modulation to obtain a coherent summation of the modulations of such signals are described. The apparatus comprises adaptive means of changing the carrier frequencies and corresponding phases of various signals to a common carrier frequency and a common phase, thus enabling the coherent summation of the common modulation and enhancing, thereby, the level of received information content. When the incoherent signals are transponder-signals, radiated from an object or platform in response to a modulated interrogating signal, and are obtained by different frequency offsets from the interrogating signal carrier frequency, the particular offset frequencies being unique to that object or platform, the ability combining of modulations coherently provides a means of unique identification of the object or platform.

Abstract: A velocity reference system uses a Doppler shift between transmitted and received wave energy to determine the relative speed between the system and a surface or element. Other systems employing Doppler shifts for detecting velocity suffer from poor measurement accuracy. Cross talk between channels of systems having multiple transmitters and receivers produces measurement errors. Additionally, errant movement generates measurement errors since the sensors cannot distinguish such errant movement from forward velocity. Two sensing units directed towards one another, and preferably towards the same location on the surface, effectively eliminates random vehicle movement. Furthermore, transmitting different frequencies from the two sensing units reduces cross talk between the two channels. Vehicle applications require a system capable of minimizing errant movement and environmental noise.