Abstract: An adaptive waveform radar system transmits a selected waveform of a family of related waveforms and either phase shifts or bit shifts the radar return signal for correlating with the other waveforms of the family. In some embodiments, phase shifting may be performed to null an unwanted target or clutter, while bit shifting may be performed to enhance a desired target, although the scope of the invention is not limited in this respect. In some embodiments, the bits of the return signal may be either phase shifted or bit shifted to match a bit of each one of the other waveforms of the family prior to correlation.

Abstract: A measuring apparatus for measuring a distance from an object to be measured has, a transmitting means for alternately modulating amplitudes of a first continuous wave having a first frequency and a second continuous wave having a second frequency for transmitting a transmission signal as a carrier wave using an AM signal. The AM signal is produced by an AM producing circuit for modulating the amplitudes. The transmission signal is reflected as a reflection signal by the object to be measured and received by a receiving circuit. A first distance calculating circuit calculates the distance using a phase difference between the first and second continuous waves. A second distance calculating circuit is used for demodulating the receipt signal, detecting a phase difference, and calculating a distance from the object to be measured using the detected phase difference. A determining circuit determines a final distance measurement based on the above calculations.

Abstract: In an FM-CW radar system, a frequency modulating said modulating wave output from said modulating signal generator has a frequency variation skew with respect to a time axis (modulation skew), and the radar system includes a means for varying the modulation skew by controlling the modulation frequency amplitude or modulation period of the modulating signal. The radar system further includes a means for discriminating a signal component varying in response to the variation of the modulation skew, thereby discriminating a signal related to a target object from other signals. In the case of an FM-CW radar system that performs transmission and/or reception by time division ON-OFF control the radar system includes a means for discriminating a signal which, when the frequency used to perform the ON OFF control is varied, varies in response to the variation of the frequency, thereby discriminating a signal related to a target object from other signals.

Abstract: A radar system having a beamless emission signature is described. In one implementation, the radar system includes a transmission system and a receiver system. The transmission system is configured to transmit a pattern comprising a plurality of radar signals having different frequencies simultaneously. The receiver system is configured to receive a reflection of the pattern and combine the plurality of radar signals into a composite waveform forming an image of a target.

Abstract: In a radio wave radar system using a two-frequency CW modulation method, it is possible to detect a distance between a host vehicle and a forward vehicle and to realize a stable ACC following travel, even in a condition in which the relative speed is 0. By combining the two-frequency CW modulation method with the frequency pulse CW modulation method, that is, by using combination with the two-frequency CW method when the relative speed occurs and the frequency pulse CW method when the relative speed is close to 0, even if the relative speed is 0, the IF signal obtained from the reflected wave from the forward vehicle can be generated to detect the existence of the ACC target vehicle, so that it is possible to realize a stable ACC following travel.

Abstract: A radar system and method use a radar FMCW chirp having variable chirp characteristics.

Abstract: The invention relates to remote distance measurement by means of a transmitted noise modulated probing signal (E), whereby at least one of a distance (Y(t)) and a velocity (V(t)) in relation to a signal transceiver (200) is determined. The probing of signal (E) is generated on basis of at least one first noise signal (x1(t), x2(t)). The transmitted signal (E) is presumed to be reflected to the signal transceiver (200) via at least one signal reflecting object in the form of an information carrying signal (e). This signal thus constitutes a delayed and possibly doppler shifted version of the transmitted signal (E). Moreover, according to the invention, a second noise signal (x2(t)) is added either to the probing signal (E) before it is transmitted or to the information carrying signal (e) before information pertaining to the reflecting object is derived there from.

Abstract: In an automotive radio wave radar, a center frequency of a transmitted wave is shifted at a certain cycle, and position information of an obstacle detected at three or more center frequencies is subjected to decision by majority to determine whether detection results of the obstacle are erroneous with the occurrence of jamming. If any of the detection results is determined to be abnormal, the abnormal result is discarded. An automotive radio wave radar is realized which can correctly perform the obstacle detection even in the event of jamming without causing erroneous obstacle detection or omission of the detection.

Abstract: A wave-form generator drives a number of microwave generating devices each operating at different frequency bands. The output of each microwave generator is connected to its own transmission channel of limited bandwidth which contains all the non-linear components necessary for transmission such as an amplifier, T/R switch, rotary joint and beam switch. These individual channels are finally combined onto a common wideband channel which contains only substantially linear components such as a single waveguide and the antenna itself. Because of the isolation between channels there is little or no opportunity for the generation of harmonics or intermodulation distortions which would otherwise occur in a transmitter capable of operating over a very wide bandwidth.

Abstract: A method for processing pulsed-Doppler radar signals to detect a target includes transmitting radar signals from a radar system according to a predetermined frequency technique including signals having frequency diversity, receiving signals within a frequency band, including a target return signal having a frequency indicative of the velocity of the target, and transforming the target return signal using a Fourier Transform having a variable frequency scale.

Abstract: A method for processing pulsed-Doppler radar signals to detect a target includes transmitting radar signals from a radar system according to a predetermined frequency technique including signals having frequency diversity, receiving signals within a frequency band, including a target return signal having a frequency indicative of the velocity of the target, and transforming the target return signal using a Fourier Transform having a variable frequency scale.

Abstract: A signal from CW radar is received, and the received power detected by the CW radar's swinging in all directions is averaged in each direction. Then, the maximum value and the minimum value of the received power are detected for each direction, and the difference between the maximum value and the minimum value is computed. An average power value of obtained power is also computed. On a 2-dimensional plane on which the difference between the maximum value and the minimum value and the average power value are used for coordinate axes, slice processing is performed using a threshold indicated by a line graph or a curve.

Abstract: From a transmitter (18) and a transmission antenna (10), a first frequency signal having a fixed frequency is transmitted for a predetermined time or more, a second frequency signal having a certain frequency difference from the first frequency signal is transmitted for a predetermined time or more, and a third frequency signal having a frequency difference twice the frequency distance from the first frequency signal is transmitted for a predetermined time or more. Reflected waves from objects under measurement at the respective transmission frequencies are supplied to a reception antenna (11), a mixer (12), an analog circuit unit (13), an A/D converter (14), an FFT (15) and a signal processing unit (16).

Abstract: An FM-CW radar processing system pairs up peaks obtained by fast-Fourier transforming a beat signal occurring on an up portion and a down portion of a triangular-shaped FM-CW wave, calculates a distance or relative velocity with respect to a target object based on the peak signal in the up portion and the peak signal in the down portion obtained by the pairing, and compares the distance or relative velocity, obtained after changing the modulating signal for the FM-CW wave, with the distance or relative velocity obtained before changing the modulating signal. If the distance or relative velocity differs before and after changing the modulating signal, the pairing is judged to be mispairing.

Abstract: As to a beat signal of a received wave, for instance, a plurality of FFT-based frequency spectra of every FM rise zone are accumulated in an accumulation unit. A judgment unit judges a valley section from the plurality of frequency spectra accumulated. A peak frequency extraction unit acquires, as beat frequencies of different targets, respective beat frequencies of peak sections located at both sides of the valley sections judged.

Abstract: A method and an apparatus for multiple object detection by automotive FMCW radars provides distance and relative velocity information. A two chirp frequency sweep with small slope difference is utilized and, since the difference is small, the distance information can be obtained by automatically eliminating the Doppler frequency. Therefore, the distance and the relative velocity information for each of multiple objects can be calculated without ambiguity.

Abstract: The invention relates to a process for determining the relative velocity in the radial direction between two moving objects, using linear frequency modulation with continuous frequency sweeps. A problem in such processes lies in being clearly able. to determine the phase difference. According to the invention, a clear determination is realized by varying the period. length for successive frequency sweeps and using the difference in period length and corresponding phase change in determining the volocity.

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: A method and apparatus for detecting the presence of objects in a vehicle operator's blind spots. The apparatus comprises a side-facing Doppler radar system using continuous wave (CW) transmission with frequency modulation (FM) operation from a frequency modulation switching technique. The radar system determines the presence, range and closing rate of detected targets. The radar system detects targets even when operated in adverse weather conditions and will not generate false warnings due to rain clutter caused by wet roads and other wet surroundings. The radar system uses ranging techniques to reject false targets that are detected outside of a predetermined target detection zone. In accordance with the present invention, the radar system indicates that a target is detected if and only if any part of the target is within the detection zone and it: (1) remains in front of the antenna for at least TH1 seconds; (2) is at a range between Range.sub.min and Range.sub.

Abstract: Disclosed are a method and a device for the removal of ambiguity in distance. The method computes the distance of the targets detected by the radar using several estimation functions (21, 22, 23). When the estimation functions give substantially the same result, the targets are defined as being in the field of non-ambiguous distances and when the estimation functions give different results, the targets are defined as being in the domain of ambiguous distances. Application especially to frequency-shift keying, continuous-wave radar for automobile traffic control.

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: Disclosed is a device for the reduction of noise in a radar receiver. The noise to be reduced being governed by a 1/F.sup.k relationship and the radar carrying out an encoding of the transmission in at least two frequencies, the device comprises at least the following means: firstly, means for routing the signals received to at least two channels so that, when a target is illuminated by a transmission at the first code frequency (F.sub.1), the corresponding received signal (S.sub.1) is sampled and routed to a first channel and then, when the target is illuminated by the second code frequency (F.sub.2), the corresponding received signal (S.sub.2) is sampled and routed to a second channel; and secondly, means for the linear combination of the signal (S.sub.1) present in the first channel and the signal (S.sub.2) present in the second channel, the linear combination synthesizing a filtering of the noise.

Abstract: A multibeam FM radar system has an FM radar module for transmitting beams of FM signals whose frequencies linearly vary in rising and falling periods, in respective different directions with adjacent ones of the beams overlapping each other, receiving echo signals from a given beam, and mixing the FM signals and the echo signals into beat signals corresponding to said given beam. The multibeam FM radar system also has a main radar circuit including a central processing unit for identifying pairs of beat frequencies in the beat signals corresponding to said given beam, and processing the pairs of the frequencies to calculate distances up to and/or relative speeds with respect to objects within said given beam which have produced the echo signals, while comparing the frequencies within said identified pairs of beat frequencies to beat frequencies within a beam adjacent to said given beam to produce a detected result corresponding to an object producing echo signals within said given beam.

Abstract: An FM radar apparatus detects a distance to and/or a speed of a target not only from peak frequencies of beat signals in respective frequency rise and fall regions but also by reusing the peak frequency in the preceding frequency rise or fall region. As a result, it becomes possible to obtain target data at twice the conventional pitch and hence to detect the target more finely and minutely.

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: Coherent, frequency multiplexed radar is a new generic type of continuous wave radar architecture wherein contiguous pulses of discrete frequency segmented signals are serially transmitted from an antenna, and after reflection from radar targets, signals from the same antenna are coherently processed in a parallel manner to provide correlated measurements of target's pulse compressed range and radial velocity. Simultaneously transmitted and received signals are separated by frequency multiplexing.

Abstract: A radar system having a transmitter for transmitting a series of radio frequency (RF) pulses with sequential, incrementally changing carrier frequencies. A receiver receives energy from multiple scattering points of an object reflecting such transmitted RF pulses. The received energy from each one of such scattering points includes a series of radio frequency (RF) pulses corresponding to the transmitted pulses delayed in time, .tau., from the transmitted pulses an amount proportional to the range to such scattering point and shifted in frequency from the carrier frequency an amount proportional to the velocity of such scattering point. The receiver includes a heterodyning section, responsive to a range tracking error signal, .epsilon..sub.R, and a velocity tracking error signal, .DELTA..sub.VEL, for producing a series of pulsed signals for each one of the scattering points. Each one of the pulsed signals for any given scatterer sequentially changes in phase, .phi., at a rate, .DELTA..phi./.DELTA.

Abstract: A continuous wave Doppler radar system having a transmitter module and a receiver module is provided for automotive vehicles. Each module includes an antenna system, including a horn, a lens, and a waveguide system, which is attached to a monolithic microwave integrated circuit (MMIC) chip that provides all necessary electronic functions. Each MMIC chip may be attached to a metal base heat sink, which may be conveniently connected to a base plate heat sink that holds the entire radar assembly. The transmitter module includes a voltage controlled oscillator (VCO) that generates a VCO frequency signal which is amplified and switched sequentially to three multiplier chains for transmission in three different directions. Each transmit signal is taken off the MMIC chip by a dielectric waveguide and directed to the antenna system. The receiver module includes three receivers that are selected sequentially to provide a beam azimuth scanning function.

Abstract: A FM-CW radar device is provided for frequency-modulating a high frequency signal with a modulation signal, transmitting the modulated high frequency signal, receiving a signal reflected by a target object and frequency-modulating the reflection signal with a signal generated by a local oscillator signal source provided by branching a portion of the transmitting signal. A modulator is disposed between a radar transmitting section and a transmitting antenna. The modulator modulates the transmitting signal with a second frequency which is far lower than the radar transmitting frequency and twice as much as the sum or the difference of a Doppler frequency generated by a relative propagation velocity and a beat frequency generated by a propagation delay time. A first frequency converter frequency modulates the received signal reflected by the target object with the local oscillator.

Abstract: A Doppler control circuit for a CW or pulse Doppler radar system for monitoring not only the phase shift between echo signals from several targets but also the amplitude difference between several targets and to further tune the radar to a particular target among one or more targets from which echo signals return. The control circuit can be used in state of the art CW or pulse Doppler type radar systems. In a further system, a continuously generated radar signal is repeatedly transmitted at different frequencies in time division fashion to define a succession of transmit and receive frames. The receive frames are divided into a plurality of time interval windows with selected windows being used to detect received signals at the different frequencies. The remaining windows can be used for subsystems of the radar system.

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: A novel range based acquisition system includes a receiver for receiving PN encoded signals coupled to a novel range based variable dwell correlator which detects and acquires uniquely timed received transmitter PN encoded signals employing different search dwell times for each of the estimated ranges from which the receiver transmitted PN encoded signals are being propagated so as to enhance the speed of acquisition of said PN encoded signals.

Abstract: A microwave range detector system for determining the range of a moving object in a monitored area includes: a microwave antenna for focusing microwave energy in the area to be monitored; means for selectively generating microwave signals at a first microwave frequency and at a second microwave frequency for transmission by the antenna; microwave detector means, responsive to the microwave signal at the first microwave frequency and the return signal at the first microwave frequency from a target in the monitored area, for generating a pair of Doppler frequency signals with a fixed-phase relationshp, and responsive to the microwave signals at the first and second microwave frequencies and to the return signals at the first and second microwave frequencies, respectively, from a target in a monitored area, for generating a pair of Doppler frequency signals with a variable-phase relationship; direction decoder means, responsive to the Doppler frequency signals with the fixed-phase relationship, for determining w

Abstract: A coherent pulse radar system capable of eliminating a signal associated with a multiple time around path or capable of removing range ambiguity of this multiple time around signal. The radar system includes a device for changing phases of transmitted pulses, for phase detecting received radar pulses with respect to transmitted pulses associated with the present and preceding reception period, and for integrating phase detected signals in a coherent manner.

Abstract: A method of measuring the distance between two objects and/or the speed of one object in relation to the other, the objects incorporating respectively a transmitter-receiver unit and a transponder or reflector, in which method a phase comparison is made between a signal transmitted by the transmitter-receiver unit and a signal received in the transmitter-receiver unit and transmitted from the transponder or reflector. In accordance with the invention the transmitter-receiver unit is caused to transmit signals of microwave frequency, preferably about 2450 MHz, this transmission comprising the transmission of a first signal having a first frequency, the transmission of at least one second signal having a higher or lower frequency, and the transmission of a third signal having the same frequency as the first mentioned signal, wherewith the phase differences .phi.

Abstract: A multiple parameter doppler radar system transmits a radar signal which is alternated between a first and second frequency toward a target. The doppler shifted signals reflected from the target are received and processed to derive a pair of doppler signals related respectively to the first and second frequency signals. The frequency of one of the doppler signals is measured and scaled to a target speed. The phase magnitude between the two doppler signals is measured and scaled to a target range. The phase lead/lag relationship of the two doppler signals is detected to determine if the target is moving toward or away from the radar system. The components of the system are controlled by a microprocessor which is programmed to perform quality determinations on the data derived from the signals to assess the reliability of the data even in a multiple target environment prior to displaying the parameters of target motion.