| 摘要 |
PURPOSE:To decrease the trouble of measurement and the waste of time and to improve the measuring accuracy by providing a band pass filter, a band stop filter circuit, a filter setting circuit, a desired frequency counter circuit and a signal propriety deciding a circuit so as to pass a desired frequency component of an input signal selectively. CONSTITUTION:A beat signal of a laser doppler velocity meter (LVD) probe output passing through a filter circuit is led to a waveform shaping circuit 6, the detected envelope waveform is subject to waveform shaping and led to a counter circuit 7 to count a beat signal envelope waveform. The beat signal through the filter circuit is led simultaneously to the signal propriety discriminating circuit 8, which discriminates the propriety of the input beat signal based on the counted value of the number of waves from the counter circuit 7 at each prescribed count time under the control of a count time setting circuit 9. When it is decided that the signal is good by the circuit 8, a wave number count data is extracted as the result of measurement of the LDV probe 1 and led to a filter setting circuit 11 as a filter circuit pass band control data to set the pass band of the filter circuit. |
