Mitsubishi Denki Kabushiki Kaisha

Tetsuo Kirimoto

Michimasa Kondo

Takahiko Fujisaka

Yoshimasa Ohashi

Kohei Nomoto

Yoshimasa Ohhashi

Yoshimasa Oh-Hashi

Masashi Mitsumoto

Yasuhiro Harasawa

Takashi Hotta

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. The beat frequencies of targets in the modulating frequency ascent and descent periods are used to form a combination seeking table, from which a component other than the reference beat frequencies of either the moving targets or the stationary targets are removed. The distances and speeds of the targets are calculated based upon the beat frequency components from the combination seeking means.

Method for measuring distances/speeds of plural targets and radar apparatus, capable of discriminating moving targets from stationary targets

An unwanted signal suppression device is disclosed for suppressing unwanted signals in input signals containing desired and unwanted signals. The input signals are divided into segments in the time domain. The device includes a unit for detecting the segment having maximum power, a unit for computing reflection coefficients on the basis of the segments except the detected power segment, and a lattice filter for suppressing the unwanted signals by using the computed reflection coefficients. A second device includes a reflection coefficient computing unit, a median filter and a lattice filter. A third device includes a unit for estimating unwanted signals frequency, a filter for computing filter weights on the basis of the estimated frequency and filter coefficients and for applying the computed weights to the input signals so as to suppress the unwanted signals.

Unwanted signal suppression device

A sequential type Fuzzy backward reasoning device is disclosed, which is capable of performing computation progressively every time a feature quantity is observed to update reasoning, and of performing the reasoning even if the order of observations is arbitrary, by providing means for performing the sequential reasoning instead of batch type reasoning means, and feedback means for feeding back a reasoned result. Additionally, a target recognition device is disclosed, which is capable of computing the reliability of a recognized result on a target and outputting the same as a numerical value, by obtaining another recognition information even if there is not obtained any information concerning the target, using said sequential type Fuzzy backward reasoning device.

Fuzzy backward reasoning device

A sequential type Fuzzy backward reasoning device is disclosed, which is capable of performing computation progressing every time a feature quantity is observed to update reasoning and of performing the reasoning even if the order of observations is arbitrary, by providing means for performing sequential reasoning instead of batch type reasoning means, and feedback means for feeding back a reasoned result. Additionally, a target recognition device is disclosed which is capable of computing as a numerical value the reliable degree of a recognized result on a target by obtaining another recognizing information even if there is not obtained any information concerning the target, using said sequential type Fuzzy backward reasoning device.

An apparatus, usable in a radar system, for generating a multi-value orthogonal sequence includes a multi-element M-sequence generator and a component substituting device. The M-sequence generator comprises a shift register including delay elements, multipliers for multiplying signals output from the respective delay elements by feedback factors, and adders for adding the multiplied signals from the multipliers to provide the result to the delay element initially arranged in the shift register whereby a multi-element M-sequence is generated from the delay element finally arranged therein. The substituting device comprises a microcomputer and substitutes each component of the M-sequence with one of complex-numbers, Z.sub.o, Z.sub.i, . . . Z.sub.q-1 in such a manner that when the component is 0, it is substituted with Z.sub.o .noteq.0, and when it is .epsilon..sup.i (i=1, 2, . . . q-1), it is substituted with z.sub.i, where the set of Z.sub.o, Z.sub.i, . . . Z.sub.q-1 are the solution of the following simultaneous algebraic equations: ##EQU1## where mod.sub.q-1 (.multidot.) represents a calculation of modulo (q-1) and is expressed as q-1 when the result is 0, * represents a complex conjugate, and r=1, 2, . . ., q-2.

Orthogonal sequence generator and radar system incorporating the

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.

Radar system

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.

Digital beam forming radar system

An apparatus for generating orthogonal sequences is disclosed which includes an M-sequence generator for providing a signal of M-sequence of which the component takes 0 or 1 and the period is N, and substitution means connected to the output of the M-sequence generator for substituting the component of the M-sequence. The substitution means substitute the component with A.sub.0 e.sup.j.phi..sbsp.0 when the value of the component is 0 and with A.sub.1 e.sup.j.phi..sbsp.1 when it is 1, where each of A.sub.0 and A.sub.1 is a positive real number, and the substitution is performed so that a trigonometric function f.sub.1 (.phi..sub.1 -.phi..sub.0) having a phase of (.phi..sub.1 -.phi..sub.0) is a ratio of two functions f.sub.2 (A.sub.1 /A.sub.0) which is a quadratic function of A.sub.1 /A.sub.0 with a coefficient of a linear function of N and f.sub.3 (A.sub.1 /A.sub.0) which is a linear function of A.sub.1 /A.sub.0 with a coefficient of a linear function of N, whereby the orthogonal sequence is generated from the substitution means.

Apparatus for generating orthogonal sequences

An auto-tuning controller includes a fuzzy resonator for the adjustment of control parameters used in the development of a control variable for controlling the operation of a system to be controlled. A characteristic variable extractor is provided which is responsive to an error signal representative of a difference between a reference value and a controlled variable value output by the system to produce a characteristic variable indicative of the operational state of the system. Based upon this characteristic variable, a fuzzy resonator adjusts the control parameters in accordance with predetermined reasoning rules stored in a reasoning rule memory.

Auto-tuning controller using fuzzy reasoning to obtain optimum control

A radar system for finding the location of a second flying object from a first flying object, comprises a nondirectional antenna for radiating a first radio wave from the first flying object, a second nondirectional antenna provided on the second flying object to receive the first radio wave and to radiate a second radio wave generated by modulating the received first radio wave and an array antenna provided on the first flying object to receive the second radio wave. The respective amplitudes of the signals given by the antenna elements of the array antenna are compared individually with a specified level and an operation for determining the direction of arrival of the second radio wave is executed using the signals given by all the antenna elements when either of the amplitudes of the signals given by the antenna elements is greater than the specified level.

A tracking radar system which includes a variable frequency oscillator for supplying to a vertical antenna array an oscillation frequency which is changed for each of a number of pulses transmitted from the antenna array. The antenna array transmits an electric wave toward a target at a low altitude and receives an echo from the target. An electronic computer estimates an elevation angle of the target from the echo received by the antenna array according to array aperture sampling technique for each pulse. An averaging circuit averages those estimated elevation angles of the target to provide its elevation angle. Alternatively, the oscillation frequency may change for each of finite time intervals.

Growing community of inventors

Kanagawa, Japan

Tetsuo Kirimoto