| 摘要 |
PURPOSE:To realize a simple and cheap angle correction operating system for the radio wave flow speed meter, by using a reversible counter circuit and a gate circuit as a correction operating means related to the angle of depression and the argument by which the speed of a river, a waterway, and so on is obtained. CONSTITUTION:The radio wave of frequency f is incident from antenna 1 onto the flowing water surface at angle of depression theta and argument phi. When the Doppler deviation frequency of the reflection wave and the propagation speed of the radio wave in air are denoted as fd and C, speed V is given by expression (2). Antenna angle sensor 24 outputs a voltage proportional to (costheta)X(cosphi) to obtain V/F converter output (d). The radio wave of frequency f and the reflection wave of frequency f+fd are compared with each other by mixer 6 to detect deviation frequency fd. Signal (c) including fd and signal (f) which has the frequency proportional to (costheta)X(cosphi) and is selected in respect to time are input, and division of the most right side in expression (5) is performed by reversible counter 21, and signal (e) including quotient T is output through zero detector 22 from R.S flip- flop 23. Reference oscillator 26 outputs signal fs of expression (6). T and fs are multiplied by gate circuit 27, thereby obtaining the display signal of speed V as shown in expression (7). |
