| 摘要 |
<p>PURPOSE: To attain a device which can work in real time, has low rate of failure warning, and provides cost reduction by fitting a low-pass filter or a high-pass filter whose limited frequency is above or below the spectrum region of a Doppler signal at two channels respectively. CONSTITUTION: In the signal evaluation circuit which notifies an operator of an object which has approached in a prescribed distance from a device and can use the identical phase (I) and the quadrate (Q) of a Doppler signal as a signal, I-channel of two channels involves a low-pass filter TP and Q channel involves a high-pass filter HP. The limited frequency of the low-pass filter TP is below the spectrum region of the Doppler signal, and the limited frequency of the high-pass filter HP is above the spectrum region of the Doppler signal. The cutoff frequencies of them are outside the spectral region of the Doppler signal. Therefore, a roughly constant phase difference of 90 deg. is generated respectively within the range of usage, and an exact phase converting number of zero-point passage of I and Q between a prescribed number of the zero-point passage is calculated using a phase difference.</p> |
