| 摘要 |
<p>PROBLEM TO BE SOLVED: To receive response wave from a transponder for Doppler signal loaded on each of a plurality of moving bodies by sending wave as signal delayed for the third specific time with the same waveform as electromagnetic wave or acoustic wave received as output signal from a transmitter. SOLUTION: A transmitter receiver 20 for Doppler measurement radiates wave with a specific frequency, pulse width t0 and repeating period T in all direction in the air. A transponder 10 for Doppler signal loaded on a moving body receives only wave with center frequency of specific frequency F and in frequency zone having zone widthΔF in the front and back, which is transmitted in the air, with a reception antenna 11 and supplies it to an amplifier 15 via a reception switch 18. After elapsing the first specific time t1 since the first reception signal is obtained at the output terminal of the reception antenna 11, the switch 18 opens the circuit between the output terminal of the reception antenna 11 and input terminal of the amplifier 15 for predetermined second specific time t2 . A delay circuit 16 delays the input signal from the amplifier 15 for the third specific time t3 and supplies the delayed signal to a transmitter 17.</p> |
