Abstract: A following distance measuring communication system comprising a transmitter and a receiver which are mounted on the front part of a following automotive vehicle, a time measuring unit connected to the transmitter and the receiver provided on the following automobile, and an answering transmitter-receiver unit mounted on the rear part of a preceeding vehicle. A pulse modulated signal is transmitted from the transmitter on the following vehicle, and this signal is received by the answering transmitter-receiver unit on the preceeding vehicle. At the instant that the signal is received, the answering transmitter-receiver unit on the preceeding vehicle generates a reply signal which is in turn received by the receiver on the following vehicle. The time required for this process is measured by the time measuring unit connected to the following vehicle receiver to determine the distance between the following vehicle and the preceeding vehicle.

Abstract: A vehicle mounted obstacle detecting radar is disclosed. An electromagnetic wave radiated from the radar apparatus is received by a first antenna mounted on the ground and passed through a transmission line to a second antenna mounted on the ground and radiated thereby to a monitor area. A response electromagnetic wave from an obstacle within the monitor area is received by the second antenna and passed through the transmission line to the first antenna and received by the radar apparatus. When the transmission channel is arranged along a curved road, an obstacle in the curved road can be detected.

Abstract: An ultrasonic wave transmitter/receiver wherein an ultrasonic wave transducer is connected to a radiating ultrasonic wave carrier frequency oscillator through a switching means during transmission, while the ultrasonic wave transducer is connected to an operational amplifier and a band pass filter through the switching means during reception, comprises an impedance conversion circuit at an input of the operational amplifier to form a band pass amplifier of a low input impedance. By this arrangement, a receiving sensitivity near an antiresonance frequency of the transducer is reduced to lower the receiving sensitivity for noise, but without sacrificing an echo receiving sensitivity thereof, and a stable receiving operation is assured for possible change in a characteristic of the transducer.

Abstract: There is provided a collision predicting operation system comprising a radar circuit whereby a reflected wave which has been radiated from an oscillator and encountered and reflected from a target is received and caused to interfere with the radiated wave to generate a doppler signal, an oscillator circuit group for generating a periodic wave synchronized with the doppler signal when the amplitude of the doppler signal is higher than a predetermined value and its frequency is within a predetermined range, means for changing the oscillation frequency of the oscillator in synchronization with the periodic wave, and means for detecting the polarity and the amount of change of the phase of the doppler signal changed by the frequency modulating means.

Abstract: A pulse radar system which is designed for installation on a vehicle. A control pulse generating circuit is triggered by the trailing edge of a transmitting pulse to generate a pulse train consisting of 8 time-divided pulses which in turn are supplied to a distributor. Simultaneously, the echo of the transmitted pulse is demodulated and the resulting signal is applied to the distributor so that depending on which one of the 8 divided pulses corresponds to the applied demodulated signal, the distance to the target is displayed on the corresponding indicator.

Abstract: There is provided a relative distance indicating speedometer for a vehicle comprising relative distance detecting means for measuring the relative distance of a vehicle carrying the speedometer with respect to an object such as the vehicle in front, and relative distance indicating means for indicating the measured relative distance in accordance with the output signal of the relative distance detecting means. The relative distance indicating means are arranged in the speedometer which indicates the speed of the vehicle, and therefore the apparatus of this invention is inexpensive to manufacture and simple in construction.