Abstract: A method for processing a received, modulated pulse (i.e. waveform) that requires predictive deconvolution to resolve a scatterer from noise and other scatterers includes receiving a return signal; obtaining L+(2M?1)(N?1) samples y of the return signal, where y(l)={tilde over (x)}T(l)s+v(l); applying RMMSE estimation to each successive N samples to obtain initial impulse response estimates [{circumflex over (x)}1{?(M?1)(N?1)}, . . . , {circumflex over (x)}1{?1}, {circumflex over (x)}1{0}, . . . , {circumflex over (x)}1{L?1}, {circumflex over (x)}1{L}, . . . , {circumflex over (x)}1{L?1+(M?1)(N?1)}]; computing power estimates {circumflex over (?)}1(l)=|{circumflex over (x)}1(l)|2 for l=?(M?1)(N?1), . . . , L?1+(M?1)(N?1); computing MMSE filters according to w(l)=?(l)(C(l)+R)?1s, where ?(l)=|x(l)|2 is the power of x(l), and R=E[v(l)vH(l)] is the noise covariance matrix; applying the MMSE filters to y to obtain [{circumflex over (x)}2{?(M?2)(N?1)}, . . . , {circumflex over (x)}2{?1}, {circumflex over (x)}2{0}, .

Abstract: A method of removing returns from rain in Doppler radar systems (and corresponding apparatus and computer software) comprising receiving a Doppler radar return signal, transforming the signal into a range versus frequency map, for a plurality of range cells, performing a fit over frequency, for the plurality of range cells, calculating a total energy, for the plurality of range cells, comparing the calculated total energy to a threshold value, and replacing the return signal for a range cell with another signal if for the plurality of range cells the comparing step is positive.

Abstract: A radar suppresses a dc component so as to improve the precision in processing a signal that belongs to a low-frequency band. The radar comprises a mixer that mixes a transmitted signal and a received signal, and an A/D converter that analog-to-digital converts an output signal of the mixer. The radar further includes: a removing unit that removes a dc voltage component by subtracting a predetermined removal voltage value from output data of the A/D converter; and an analyzing unit that Fourier-transforms data, which has the dc voltage component removed therefrom by the removing unit, so as to analyze the data.

Abstract: The invention concerns a passive radar receiver for a received orthogonal frequency division multiplex-type signal consisting of symbol frames each emitted on coded orthogonal carriers. After formatting the received signals into digital symbols (S1 S1), a filtering circuit (2) eliminates by subtraction or using a covariance matrix, in the symbol signal at least unwanted signals with null Doppler effect so as to apply a filtered signal (X?) including essentially signals backscattered by mobile targets to a Doppler-distance correlator (4).

Abstract: A radar is provided which transmits a radar wave whose frequency is so modulated as to rise, fall, and be kept constant cyclically. The radar uses beat signals produced by the radar wave and radar echoes received by two antennas to produce radar data on a target. When it is impossible to pair frequency peaks of the beat signals in a modulated frequency-rising and -falling ranges, the radar determines that the frequency peaks have arisen from different objects so that they overlap each other and uses frequency peaks of the beat signals in a constant modulated frequency range to acquire the radar data.

Abstract: A synthetic aperture radar (SAR) compensates for ionospheric distortions based upon measurement of the group delay, particularly when operating in the VHF/UHF band. The SAR is based upon a multi-input multi-output (MIMO) technique for estimating the effective ionospheric conditions, which is referred to as the group delay approach. The group delay approach is divided into a 1-dimensional (range) approach and a 2-dimensional (range and cross-range) approach. The group delay measures the effective or observed TEC, which is used to reduce the ionospheric distortion.

Abstract: A synthetic aperture radar (SAR) for a moveable platform includes an antenna, a radar transmitter and radar receiver cooperating with the antenna. A radar processor is connected to the radar transmitter and radar receiver to account for the Faraday rotation introduced by propagation through the ionosphere by estimating an individual ionospheric distortion for each received echo pulse based upon a measured Faraday rotation, and reducing the ionospheric distortion for each received echo pulse based upon the estimated individual ionospheric distortion associated therewith for providing a compensated echo pulse.

Abstract: In an object-detecting system using an FM-CW wave, points f1 to f4 corresponding to detection peaks of a reflected wave from a road-side object such as guardrail and points m1 and m2 corresponding to detection peaks of a reflected wave from a moving object such as a reflector of a preceding vehicle are indicated on two-dimensional coordinates along with the shape of a road ahead of a subject vehicle. Among the points f1 to f4, m1 and m2, the points f1 to f4 are determined as being provided by the reflected wave from the road-side object, and a distance from the subject vehicle to the object and a speed of the subject vehicle relative the object are calculated using the remaining points m1 and m2 excluding the points f1 to f4. Thus, only the moving object except the road-side object can be detected.

Abstract: An apparatus for frequency content separating an input signal is disclosed. The apparatus comprises a plurality of frequency splitting stages, each stage including one or more up-converter and down-converter pairs. An up-converter and down-converter pair serves (i) to receive a complex input signal representing an input bandwidth and (ii) to output a first complex output signal representing an upper portion of the input bandwidth and a second complex output signal representing a lower portion of the input bandwidth. The upper portion and the lower portion being contiguous and together representing the input bandwidth portion.

Abstract: A vehicle radar system extracts peak frequencies fbu and fbd of respective beat signals B1 to B9 representing the frequency difference between a transmission signal fs and a plurality of received signals fr1 to fr9. The phase difference of respective beat signals B1 to B9 at the peak frequencies fbu and fbd is converted into a frequency signal. In the case of reflection from a close range road surface or raindrops, the phase difference of each beat signal is irregular. The peak frequency intensity of a converted frequency signal is small. This system compares the peak frequency intensity of the converted frequency signal with predetermined criterion intensity. Then, the system identifies an objective with a close range road surface or raindrops when the peak frequency intensity of the converted frequency signal is not larger than the predetermined criterion intensity.

Abstract: A method that can locate the center of a target even when the target is a large vehicle, and that, when a plurality of beams are reflected, determines whether the reflected beams are from the same target or not, wherein, of peaks generated based on a radar signal reflected from the target, peaks whose frequencies are substantially the same and whose reception levels are not smaller than a predetermined value are selected and, when a plurality of such peaks are selected, a center angle between the angles of the leftmost and rightmost peaks is obtained, and the thus obtained center angle is taken as an angle representing the target. Further, the plurality of peaks are paired up to detect a distance, relative velocity, and displacement length for each of reflecting points on the target, and when the differences in these values are all within respectively predetermined values, the plurality of peaks are determined as being peaks representing the same target.

Abstract: A radar signal processing unit comprises a Fourier transform section 1 for executing Fourier transform of the received signal to a frequency signal, a frequency domain power calculation section 2 for calculating a power spectrum of electric power for each frequency from the frequency signal, an abnormal echo removal section 3 for determining the abnormal echo based on the power value of the power spectrum and outputting only the power spectrum not corresponding to the abnormal echo, an incoherent processing section 4 for performing incoherent integration of only the power spectrum not corresponding to the abnormal echo and averaging, and a signal detection section 5 for calculating the physical quantity of the atmosphere from the incoherent-integrated power spectrum.

Abstract: To provide a radar system mounted on a vehicle that reliably detects the reception of the interference wave with high-performance and inexpensively. There is provided a radar system mounted on a vehicle for detecting a target object, including a transmitter for transmitting an electromagnetic wave, a receiver for receiving the electromagnetic wave reflected by the target object, a signal processor for measuring a distance between a vehicle of his/her own and the target object and a relative velocity on the basis of the transmitting electromagnetic wave and the receiving electromagnetic wave, and an interference detector for suspending a transmit operation of the transmitter under a control of the signal processor to detect an interference signal from another external device.

Abstract: A chirp-based method and apparatus measures phase variation through a reference frequency transport cable for a phased array antenna. A chirp is injected into the a signal transport path from a remote transmit/receive portion of the antenna, so that the chirp is conveyed over the signal path, reflected from an upstream bandpass filter at a local transmit/receive portion of the antenna, and returned to a remote transmit portion of the antenna. Energy in the returned chirp is extracted by a downstream bandpass filter and correlated in a delay lock loop with energy in an auxiliary chirp signal, that is delayed relative to the injected chirp. The delay of the auxiliary chirp is adjusted to maximize the correlation output and provide an indication of the delay through the signal path.

Abstract: A synthetic aperture ladar system using a mode locked laser transmitter. The inventive system (12) includes a mode locked laser transmitter (22), a receiver (40) adapted to detect signals transmitted by said laser (22) and reflected by an object (32) and a signal processor (50) for analyzing the signals. The laser (22) is particularly novel as a synthetic aperture ladar transmitter inasmuch as it includes a mode locking mechanism (180). The mode locking mechanism (180) causes the laser to output energy at all modes within the gain profile in phase with one another. The result is a series of coherent pulses which may be used for synthetic aperture ladar applications. In a particular embodiment, the present teachings are implemented in a multifunctional laser which, in its operational mode, outputs a mode locked beam for synthetic aperture ladar.

Abstract: An along-track alignment and formatting system (ATAFS) formats synthetic aperture radar (SAR) data to align and format signals from scatterers in a scene to achieve an ideal data format in the along-track dimension in which such ideal data format leads to improved image quality of an image based on the SAR data and/or reduced computational burden for generating an image based on the SAR data. Two aspects of the ATAFS include: 1) the division of data stabilization into two distinct steps; and 2) the along-track (or slow-time) migration of signal support of scatterers as a function of their along-track location. A suite of SAR image formation algorithms use the ATAFS in conjunction with conventional signal processing stages to transform input coherent signal data into a complex image with image quality and geometric accuracy commensurate with the inherent information content of the input data.

Abstract: A system-of-systems avionics architecture that is compatible with futuristic multi-function multi-platform sensor applications. The method and device of the invention is based on localized “adaptive” waveform and spectrum allocation for ultra-wideband radio frequency and microwave signals. The invention includes a plurality of system platforms with each platform comprising a common radio frequency front end for receiving ultra-wideband signals, a common radio frequency back end for transmitting ultra-wideband signals and a plurality of sensors for exchanging data between platforms.

Abstract: The distance and relative speed of an object remote from an observation point determined using a signal form which includes two signals having a predetermined spacing relative to each other. The two signals are transmitted for a certain time interval during which the frequency of the signals is modulated in a stepwise fashion. Additionally, the signal sections of the two signals are transmitted alternately for each step so that there is a predetermined frequency spacing between the signal sections being emitted consecutively.

Abstract: This invention relates to radar signal processing. In particular, this invention concerns signal processing of agile Pulse Repetition Time (PRT) sampled signal transmitted using spread spectrum technique. This invention solves, in particular, the incompatibility between Doppler processing and spread spectrum such providing an improved anti-jamming technique without narrowing the Doppler range. The method for deconvolution comprises combining the pulses with the same carrier in a burst, transforming the obtained signals from time to frequency domain, and deconvolving the obtained spectra. In a first embodiment of this invention, such a deconvolution method is adapted to irregular PRT sampled signal comprises an irregular samples to regular zero-padded samples conversion step between the combination and the transformation steps.

Abstract: A chirp-based arrangement derives a measure of phase variation through a reference frequency transport cable of a phased array antenna architecture, such as a spaceborne synthetic aperture radar system. A direct digital synthesized chirp signal is injected in an upstream direction into the transport cable from a downstream end thereof, so that the chirp signal is transmitted in an upstream direction, reflected from an upstream bandpass filter, and returned in a downstream direction. At each of a plurality of nodes that are distributed along the transport cable, the two chirp signals are extracted and frequency domain-processed to derive said measure of transport delay through the cable between the source of the reference frequency signal and each of the nodes.

Abstract: Methods and apparatus for detecting objects. In one embodiment, a person entering a secured or “Safe Zone™” is illuminated with low-power polarized radio waves. Differently polarized waves which are reflected back from the person are collected and measured. In a preferred embodiment, concealed weapons are detected by calculating the difference of a pair of differences (Delta A and B) of different polarized reflected energy (upper and lower curves in the two graphs) in the time domain, and by using signal processing methods and apparatus to improve the reliability of the detection process.

Abstract: Methods and systems are provided for characterizing an overhead line. A radar signal is propagated in a region that includes at least a portion of the overhead line and a reference object, which may, for example, be a ground surface, growth over a ground surface, or another overhead line. A reflected radar signal is received from the overhead line and the reference object. A determination is made of a geometric relationship between the overhead line and the reference object, such as by determining a minimal separation between the overhead line and the reference object.

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: Computation of the Extended Discrete Fourier Transform (XDFT) for N×N input data (corresponding to an N×N image) gives additional information about each point in the image. This additional information can be presented in the form of a polar plot of magnitude vs. phase. Parameters derived from this plot allow novel parametric images to be obtained, giving additional information beyond that obtained by a conventional Discrete Fourier Transform. The plots can be manipulated (e.g. smoothed), corresponding to a new method of image processing for this kind of data. Applications of this new method are as widespread as the use of conventional Fourier transform analysis. The analysis is more computationally intensive than the well-known Fast Fourier Transform algorithm, but the extra information obtained and image processing capabilities can more than compensate for this.

Abstract: Disclosed are systems, methods, devices, and apparatus to interrogate a clothed individual with electromagnetic radiation to determine if a concealed weapon is being carried. This determination includes establishing data corresponding to an image of the individual and processing data sets corresponding to a number of spatial frequency representations of different image portions to evaluate if the concealed weapon is present.

Abstract: A series of police doppler single mode radars and a multimode police doppler radar, all with direction sensing capability are disclosed. A duadrature 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: The invention concerns a passive radar receiver with an array of antennas for a OFDM received signal comprising frames of symbols each emitted on coded orthogonal carriers. After formatting received signals into digital symbols, dummy signals from dummy OFDM emitters at different distances from and in different directions relative to the receiver are generated and added to the signals picked up by the antennas. The modified received signals are filtered by means of inverse covariance matrices in order to eliminate at least unwanted zero Doppler effect signals and to provide an isotropic reception diagram without blind sector of direct path being generated and by detecting mobile targets along the direct path.

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 and with changing range gates in each of the antenna beams the coverage of the detection zone can be varied.

Abstract: A radar is provided which transmits a radar wave whose frequency is so modulated as to rise, fall, and be kept constant cyclically. The radar uses beat signals produced by the radar wave and radar echoes received by two antennas to produce radar data on a target. When it is impossible to pair frequency peaks of the beat signals in a modulated frequency-rising and -falling ranges, the radar determines that the frequency peaks have arisen from different objects so that they overlap each other and uses frequency peaks of the beat signals in a constant modulated frequency range to acquire the radar data.

Abstract: Disclosed is a radar apparatus equipped with a function for detecting an abnormality of modulation width. Distance rt2 at time t2 is calculated from the values of the distance Rt1 and the relative velocity Vt1 measured at time t1 and the elapsed time t2−t1, and the difference relative to the actual measured value Rt2 is compared with a threshold value C1. If the difference relative to the actual measured value exceeds the threshold value C1, the modulation width is judged to be abnormal.

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: 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, apparatus, and computer readable medium are provided for creating a quantitative, three-dimensional representation of a surface of a human subject. Data representing a physical appearance of a human subject is gathered using inverse synthetic aperture radar. A source signal is directed toward the human subject as the target rotates through a range of motion and a return signal is collected. The returned signal is transformed into a quantitative representation of the surface data. The quantitative representation can be added to an archive or can be checked against an archive to determine if the human target is indexed in the archive.

Abstract: Disclosed is a radar apparatus equipped with a function for detecting an abnormality of noise floor level. An abnormality of noise floor level is detected by measuring the level in a region not lower than 60 kHz when FM modulation is stopped or modulation width is made infinitely small by instruction from a CPU to a modulating signal generator.

Abstract: In an object-detecting system using an FM-CW wave, points f1 to f4 corresponding to detection peaks of a reflected wave from a road-side object such as guardrail and points m1 and m2 corresponding to detection peaks of a reflected wave from a moving object such as a reflector of a preceding vehicle are indicated on two-dimensional coordinates along with the shape of a road ahead of a subject vehicle. Among the points f1 to f4, m1 and m2, the points f1 to f4 are determined as being provided by the reflected wave from the road-side object, and a distance from the subject vehicle to the object and a speed of the subject vehicle relative the object are calculated using the remaining points m1 and m2 excluding the points f1 to f4. Thus, only the moving object except the road-side object can be detected.

Abstract: Disclosed is a radar apparatus equipped with a function for detecting an FM-AM conversion noise peak. When the direction of radiation is swept, any peak whose level remains substantially unchanged is judged to be a peak due to FM-AM conversion noise. Further, when FM modulation is stopped, any peak appearing in a region not lower than 50 kHz is judged to be a noise peak.

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 and with changing range gates in each of the antenna beams the coverage of the detection zone can be varied.

Abstract: Disclosed is a radar apparatus which receives a transmitted signal reflected from an object by switching between a plurality of antennas, wherein the plurality of antennas are divided into a plurality of groups, and at least one of the plurality of antennas contained in each of the groups is a common antenna.

Abstract: This invention relates to radar signal processing. In particular, this invention concerns Doppler processing and clutter filtering on irregular Pulse Repetition Time (PRT) sampled signal. This invention solves the above-mentioned drawbacks, in particular solving the velocity ambiguity and filtering any type of clutter, providing a deconvolution method which filter any kind of clutter even varying clutter like sea clutter, rain clutter . . .

Abstract: In a radar apparatus for automobiles for transmitting a radio wave, receiving a radio wave reflected from an object and measuring a rate of the object, a digital signal processor has at least two operation modes, a normal operation mode and a low energy consumption mode, and has a function of switching between the operation modes of the digital signal processor in accordance with a signal supplied from a counter (judgement unit) for judging whether a received signal satisfies predetermined conditions. The radar apparatus can reduce consumption power when necessary.

Abstract: A method of recognizing a radar target comprises producing a sequence of Doppler spectra of radar returns form a scene and producing therefrom a sequence of Doppler feature vectors for a target in the scene. Hidden Markov modelling (HMM) is then used to identify the sequence of Doppler feature vectors as indicating a member of a particular class of targets. HMM is used to identify the sequence of Doppler feature vectors by assigning to each feature vector an occurrence probability by selecting a probability distribution or state from a set thereof associated with a class of targets, multiplying the occurrence probabilities together to obtain an overall probability, repeating for other probability distributions in the set to determine a combination of probability distributions giving highest overall probability for that class of target, then repeating for at least one other class of targets and selecting the target class as being that which yields the highest overall occurrence probability.

Abstract: An access control system for an object, particularly a motor vehicle, comprises at least one base station with a transceiver device that transmits a wideband modulated interrogation signal, at least one transponder that has a modulation device, in order to modulate an auxiliary carrier signal, the frequency of which is changed between an infinite number of frequency positions, onto an interrogation signal received at a distance from the base station and reflect it as a code-modulated response signal, and an evaluation device that is connected after the transceiver device and that evaluates the response signal in sidebands of the changed frequency positions, with respect code and distance.

Abstract: Disclosed is a transmit-receive FM-CW radar apparatus which switches between transmission and reception by time division control, wherein amplifiers capable of controlling gain are provided in a transmitter signal path and a receiver signal path, respectively, and wherein the gain in the leading edge portion of a receive timing interval or the gain in the trailing edge portion of a transmit timing interval is suppressed by controlling the gain of the amplifier provided in the receiver signal path or the gain of the amplifier provided in the transmitter signal path, respectively.

Abstract: Disclosed is a Doppler shifted radar apparatus for correct target identification with respect to surveillance of moving vehicles. More particularly, an improved radar detection system using two or more continuously transmitted frequencies is used. The multiple frequencies are directed toward target vehicles whereby the phase difference of the two or more reflected Doppler signals is calculated and subsequently used to accurately determine a target range, thereby displaying the closest vehicle and closest vehicle speed. Vehicle speed is determined with use of the standard Doppler frequency shift. The next closest and/or next faster vehicle speed can also be easily determined.

Abstract: An FM-CW radar system comprises a modulating signal generating means for changing a modulating signal to be applied to a FM-CW wave, a calculating means for calculating a distance or relative velocity with respect to a target object by performing processing for detection by fast-Fourier transforming a beat signal occurring between a transmitted signal and a received signal, and a control means for determining a detection range based on the calculated distance, and for performing control to change the modulating signal, wherein the modulating signal is changed by changing one parameter selected from among a modulation frequency, a triangular wave frequency, and a transmit wave center frequency. The detection range is set to a distance obtained by adding a prescribed distance to the shortest distance detected, or to a distance obtained by subtracting a prescribed distance from the distance of a fixed object.

Abstract: A vehicle radar system extracts peak frequencies fbu and fbd of respective beat signals B1 to B9 representing the frequency difference between a transmission signal fs and a plurality of received signals fr1 to fr9. The phase difference of respective beat signals B1 to B9 at the peak frequencies fbu and fbd is converted into a frequency signal. In the case of reflection from a close range road surface or raindrops, the phase difference of each beat signal is irregular. The peak frequency intensity of a converted frequency signal is small. This system compares the peak frequency intensity of the converted frequency signal with predetermined criterion intensity. Then, the system identifies an objective with a close range road surface or raindrops when the peak frequency intensity of the converted frequency signal is not larger than the predetermined criterion intensity.

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: A method and system are disclosed for detecting objects of interest in a target area using ultra wide band (UWB) RF signals. A transmitter and antenna array generate ultra wide band RF impulsive signals that are used to probe a target area that may include an object of interest. An antenna and a signal processor receive return signals from the target area and process the return signal to generate a set of coordinates. The coordinates of the processed return signals are compared to coordinates of known objects in a pre-existing database to determine whether there is a match between the return signal and a known object. When there is an indication of a match, the existence of the known object is displayed to an operator of the system.

Abstract: A method of terrain mapping and/or obstacle detection for aircraft, comprising:

Abstract: Disclosed is a radar apparatus equipped with a function for detecting an abnormality of modulation width. Distance rt2 at time t2 is calculated from the values of the distance Rt1 and the relative velocity Vt1 measured at time t1 and the elapsed time t2−t1, and the difference relative to the actual measured value Rt2 is compared with a threshold value C1. If the difference relative to the actual measured value exceeds the threshold value C1, the modulation width is judged to be abnormal.