Fujitsu Corporation

Fujitsu Ten Limited

Hiroyuki Yatsuka

Satoshi Ishii

Yoshikazu Dooi

Tetsuo Seki

Koji Arai

Nobukazu Shima

Shigefumi Masuda

Masaki Hitotsuya

Kazuaki Hamada

Toshiyuki Morita

Yasuhiro Isogai

A radar apparatus comprises: a transmitter unit having a high-frequency oscillating unit whose oscillation frequency is variable, and a pulse amplitude modulating unit for amplitude-modulating a pulse of a transmission high-frequency signal output from the high-frequency oscillating unit with a first control pulse signal; a receiver unit having a gating unit for controlling ON/OFF of an input of a received high-frequency signal with a second control pulse signal; and a controlling and signal processing unit for controlling the transmitter unit and the receiver unit, and for switching a first operation mode for making the apparatus function as an FM-CW radar, and a second operation mode for making the apparatus function as a pulse radar.

Radar apparatus, radar apparatus controlling method

A pulse radar apparatus uses different frequencies, for example, frequencies one of which is a multiple or a submultiple of the other for a signal which becomes a reference of a control pulse for controlling a gate operation for a reception signal and a signal which becomes a base of generation of a transmission pulse. As a result, even if noise is caused by the gate operation, its influence can be removed in the processing of reception signals having different frequencies.

Pulse radar apparatus

An embodiment comprises a unit generating a control pulse signal by delaying a basic signal in generating a transmission pulse, and a unit performing a gate operation on a received signal using the control pulse signal. Another embodiment comprises a unit generating a control pulse signal by delaying a signal generated using a first basic signal, a second signal for phase modulation having a lower frequency than the first signal, and a pseudo-random signal generated at an intermediate frequency between the frequencies of the first and second signals, and a unit performing the gate operation.

A picture signal transmitting system using a CATV network sends a picture signal from a transmission path to subscribers by using a radio transmitter and receiver, and in the picture signal transmitting system, there is no physical wire connection from a tap off of the transmission path to subscribers. The picture signal transmitting system using a CATV network includes a CATV center, a first radio transmitter and receiver connected to said CATV center through a CATV transmission path, and provided near a subscriber's house for concurrently sending out a side band signal obtained by up-converting a picture signal of a frequency bandwidth including a plurality of channels with a local oscillation signal of which level is larger than that of said side band signal, and the local oscillation signal, and a second radio transmitter and receiver provided in the subscriber's house for separately receiving the picture signal and the local oscillation signal sent out from the first radio transmitter and receiver, and down-converting the frequency bandwidth of the received picture signal with the received local oscillation signal to an intermediate frequency bandwidth.

Picture signal transmitting system using CATV network in which the local oscillator is transmitted separately

The output of a voltage-controlled oscillator (VCO), after being passed through a resonator having a single-peak characteristic, is detected by a detector. The output of the detector is sampled and held at a time instant that the control input voltage to the VCO reaches a maximum and also at a time instant that it reaches a minimum, and the difference between them is fed back to the control input of the VCO. In this way, the center frequency of the VCO is controlled so that it becomes equal to the center frequency of the resonator. In the case of a VCO as an FM modulator in an FM-CW radar, the sample-and-hold timing is derived from a clock signal based on which a triangle wave is generated. In the case of a VCO as an FSK modulator, the sample-and-hold timing is obtained by detecting a 0 and a 1 in input data.

Automatic frequency control apparatus for stabilization of

A switching type FM-CW radar, the type of FM-CW radar improved to reduce FM-AM conversion noise, is further improved to reduce interference by radar waves from other vehicles and echo waves returned from them. A switching circuit is provided at the transmitter side, and its switching frequency is set at a different value for each individual vehicle. Furthermore, the switching frequency of an interfering wave is measured, in accordance with which the switching frequency of the switching circuit is changed.

FM-CW radar

Radar equipment for vehicles which sends out from a transmitting antenna a continuous wave signal modulated by a frequency modulator, receives a reflected wave by a receiving antenna and mixes it with one portion of the output from the frequency modulator by a mixer for output and in which the transmitting antenna and the receiving antenna are arranged in a V-letter form. A directional coupler is provided between the frequency modulator and the transmitting antenna for applying one portion of the output from the frequency modulator to a mixer of an in-line type and a coupling element are disposed between the receiving antenna and the directional coupler, and an impedance-adjustable dummy load is connected to a dummy terminal of the directional coupler.

Growing community of inventors

Kawasaki, Japan

Hiroyuki Yatsuka