| 摘要 |
PURPOSE:To integrate a device highly and reduce its size and weight, and to improve the utilization efficiency of a radio wave by using a single fixed oscilator as a common oscillation source for both transmission and reception and performing simultaneous transmitting and receiving operation. CONSTITUTION:A fixed oscillator and heterodyne detector 1, a low-pass filter 2, a rectifying circuit 4, a switching circuit 5, a low frequency oscillator 6, a driving oscillator 7, buzzer Bz, a light emitting element D2, etc., are provided. Then, a carrier from the fixed oscillator of the detector 1 is transmitted from an antenna through an oscilator and high frequency transformer, a carrier from the opposite device arrives from the antenna at the same time and is inputted to the detector 1 to perform heterodyne detection. Then, a low frequency signal based upon the carrier frequency and the reference frequency of the fixed oscillator is extracted and a high frequency component and a nearby disturbing wave are removed by the filter 2; and the signal is made into DC by the circuit 4 and level-converted by the circuit 5. Further, the output of the oscillator 7 is intermitted through the oscillator 6 and then while the buzzer B2 is put in sounding operation intermittently, the element D1 is allowed to flash intermittently, so that the approach of the opposite body into a specific distance range is known.
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