Abstract: A distance and speed measuring method and a radar signal processing apparatus using the method are provided which are capable of obtaining highly reliable measurement results while reducing the number of false targets and undetectable targets, by obtaining the relative distance and the relative speed of each target based on the frequencies of a beat signal of up (or down) phase alone through the use of information in a time series direction of the frequencies of the beat signal of up (or down) phase.

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 distance and speed measuring method and a radar signal processing apparatus using the method are provided which are capable of obtaining highly reliable measurement results while reducing the number of false targets and undetectable targets, by obtaining the relative distance and the relative speed of each target based on the frequencies of a beat signal of up (or down) phase alone through the use of information in a time series direction of the frequencies of the beat signal of up (or down) phase.

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: 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: A radar system and method for observing weather phenomena which sets a weather model corresponding to weather conditions, determines the attenuation of a radio wave due to the atmosphere and particles based on the weather model, calculates a radar range using the attenuation of the radio wave, and determines radar system parameters based on the radar range.

Abstract: A radar data processing method of switching a continuous wave consisting of up phase and down phase into a transmission signal and a local signal in an interrupted manner and using a beat signal between the local signal and a reception signal. The method comprises the steps of setting a range of beat frequencies in up phase used for making a search for a combination and a range of beat frequencies in down phase used for making a search for a combination from beat frequencies corresponding to a distance range to be measured and a predetermined measurement speed range, and making a search for a combination for the same target for the beat frequencies in the up phase and the beat frequencies in the down phase only in the range.

Abstract: A vehicle ID radar system has a simple construction and obtains high identifying performance by making a general identification based on a plurality of responses. There are provided an antenna for obtaining a plurality of question signals from a base station radar unit, a receiver for processing the signals received from the antenna, a question code demodulator for demodulating question codes from the received signals, a question code decoder for decoding the question codes and reading responses respectively corresponding to the plurality of questions from a plurality of data bases, a response code generator for generating response signals, and a transmitter for modulating the response signals and supplying them to the antenna.

Abstract: A stabilizing method of a synthetic aperture radar and a position determining method by the radar. At least three repeaters are arranged in mutually different positions on the ground or the sea and a radio frequency signal having a predetermined frequency is transmitted from the radar mounted on a radar platform such as an aircraft to the repeaters. Each repeater frequency-modulates and amplifies the received signal to return the signal to the radar. The radar receives the signal returned from each repeater. The radar calculates a distance between the radar platform and each repeater on the basis of a time required for the transmitting and the receiving and phase information of the received signal. When the position of each repeater is known, by using the positions of the repeaters and the calculated distances, the position of the radar platform can be calculated. On the basis of the obtained position of the radar platform, a reference signal for phase compensation is generated.

Abstract: A radar signal processor for use in a pulse radar system. Reception signals are given from a range divide and output circuit to a plurality of integration point variable coherent integrators, each of which is allocated to a different range domain. The range domain is given to an integration point setting section provided corresponding to each integration point variable coherent integrator. The integration point setting section determines the number of coherent integration points based on the given range domain and sets it in the corresponding integration point variable coherent integrator. The signal resulting from coherent integration by the integration point variable coherent integrator is discriminated to frequencies, then supplied to any square detector for square detection for each frequency component. Square detection output is fed into a CFAR detector, which then makes its false alarm rate constant for a supply to a display, etc.

Abstract: A synthetic aperture radar system is mounted in a moving platform. The synthetic aperture radar system includes a multi-beam antenna having a plurality of reception beams different in direction from one another, the multi-beam antenna being adapted to receive radar echoes from objects. The width of each of the reception beams is selected such that the band width of a Doppler shift contained in the radar echo of a moving object is broader than that of a Doppler shift contained in the radar echo of a stationary object. The radar echo is pulse compressed to improve the range resolution before the frequency thereof is shifted such that the center frequency of the Doppler shift due to the velocity of the moving platform becomes zero. After the frequency shifting, the radar echo is filtered to separate the radar echoes of the moving and stationary objects from each other.

Abstract: A signal discrimination device using a neural network for discriminating input signals such as radar reception signals includes an adaptive code generator means for generating codes for representing the discrimination categories. The distances between the codes for closely related categories are smaller than the distances between the codes for remotely related categories. During the learning stage, the neural network is trained to output the codes for respective inputs. The discrimination result judgment means determines the categories by comparing the outputs of the neural network and the codes for the respective categories.

Abstract: A pulsed Doppler radar system comprises a transmitter for generating and transmitting a pulse signal having expanded frequency bandwidth, an antenna apparatus for sending the output of the transmitter to a target and for receiving a signal which was sent by the transmitter and reflected by the target, a receiver for processing the received signal to obtain a complex video signal, a pulse compressing circuit including a pulse Doppler processor responsive to the complex video signal for detecting a relative speed of the target and a storage device for storing a reference signal which includes a compensation factor by which an influence of the Doppler effect is compensated in accordance with the speed of the target.

Abstract: A pulsed doppler radar system having an improved detection probability, comprising an antenna unit, a transmitter for transmitting a signal through the antenna unit, a receiver for receiving a signal reflected by a target through the antenna unit to provide a reception signal. A processing unit which receives the reception signal from the receiver determines, in accordance with a range of the target and a signal-to-noise ratio and bandwidth of the reception signal, an optimum integration number which maximizes the detection probability and performs coherent integration on the reception signal by the number of times equal to the determined optimum integration number thereby outputting a signal having a predetermined level. Such a signal is fed to a display and an image of the target is displayed on a display.

Abstract: A multistatic radar system is provided in which a transmitter radiating high-frequency radio waves is mounted on a flying object adapted to be launched into the sky, whereby the range of the radar system is improved.

Abstract: A radar system having a phased array antenna for transmission and a digital beam forming antenna for reception for observing a plurality of targets by transmitting transmission pulses to the respective targets comprises a subtraction control circuit, a transmission timing control circuit and a transmission beam direction control circuit. The substraction control circuit calculates a required number of transmission pulses (beams) to be transmitted for each of transmission cycles in accordance with detected Doppler frequencies of the targets, so as not to cause ambiguity on the detected Doppler frequencies, and determines a beam direction for each of transmission beams. The timing control circuit and beam direction control circuit control transmission timing and direction of the beams.

Abstract: A synthetic aperture radar system wherein a plurality of beams is formed for receiving echo signals and the spectra of the received signals are synthesized in an azimuth compression unit to improve the cross-range resolution.

Abstract: A radar system having improved interference resistance. A transmitting section includes an oscillator capable of switching the oscillation frequency, and a transmitting antenna connected to said oscillator and capable of transmitting electric waves having specified transmitting frequencies transmitted in different directions in a specified order to enable a desired range to be scanned. The oscillator and the transmitting antenna are designed to operate so that every time one scanning is completed or every time the transmitting direction is changed during each scanning period, the transmitting frequency may be changed. The receiver can simultaneously form a plurality of beams in the scanning range, convert the received signals to digital signals, and output signals indicating the frequencies and arrival directions of the received signals. The operating mode of the transmitting section may be altered in accordance with the frequency and arrival direction of the received waves.

Abstract: The receiving apparatus of a spotlight mapping radar system is provided with a digital beamforming antenna capable of converting the echo signals received by a plurality of antenna elements into corresponding digital signals and processing them by DFT and forming a plurality of reception beams oriented in different directions at the same time to enhance the cross-range resolution without reducing the distance measurement capability and the measurable range. Pulse compressors, azimuth compressors, display buffers and reference signal generators are provided respectively for each of the outputs of the digital beamforming antenna for outputting the plurality of reception beams. An output picture synthesizing apparatus synthesizes signals representing the picture information from the respective display buffers and outputs the synthesized signals to a display to display thereon the synthesized picture of an object to be observed.

Abstract: A multiple-beam antenna system capable of forming a plurality of beams at one time in different directions. The antenna system has a plurality of element antennas arranged in a predetermined configuration. A signal received by each element antenna is converted to a digital signal which in turn is subjected to a Fourier transform. The Fourier-transformed receiving signal is multiplied with a Fourier-transformed weighting function. The resultant product is subjected to an inverse Fourier transform to be used for calculating an antenna radiation pattern. A holographic multiple-beam antenna is also disclosed.