| 摘要 |
<p>PURPOSE:To make the constitution of the title detector simple and to achieve the cost reduction and miniaturization thereof by sampling and holding a receiving Doppler signal on the basis of a sampling signal having frequency twice that of a commercial AC power supply. CONSTITUTION:A received reflected wave is mixed with local oscillation frequency by a microwave receiver 5 and a pulse train signal modulated in amplitude by a Doppler signal, that is, a Doppler signal pulse is outputted. The Doppler signal pulse is sampled and held on the basis of the sampling signal from a pulse generator 1 by a sample hold circuit 6 to be demodulated as the Doppler signal and unnecessary frequency is removed by a band-pass filter 8. The band-pass filter 8 is constituted so as to obstruct OHz and facHz and to pass the frequency between OHz, facHz to the utmost. Therefore, the passage of a noise component band being an integral multiple of commercial AC frequency can be obstructed and this detector can be made inexpensive and small- size.</p> |
