| 摘要 |
PURPOSE:To enable constant correct measurement at a time when a distance is measured for a long time and thereby to improve the precision of measurement, by renewing timely the waveform of the distortion of a beat wave signal for measuring a frequency. CONSTITUTION:When a change in phase of pi is caused in the beat wave signal S with the vertical motion of a substance 100, the maximum and minumum values of the signal S at the point of time of sampling based on a clock pulse 12 which is higher than the signal S are memorized 14 throughout an area of a time for measurement. The difference between the maximum and minimum values which are memorized is calculated 16 at the point of time when the change of pi is caused in the signal S, the waveform of the distortion caused in a microwave circuit 2 or by multiple reflection, etc. is memorized, the signal S is modified 4 in a substracting manner, and thereby a signal S' for measurement is obtained. And, the difference between the maximum and minimum values within a distance obtained from the signal S' and within the period wherein the change in phase of pi is caused in the signal S' are calculated 22-23, the deviation of the value of the difference thus obtained from a thoretical value 25 of the difference in distance which causes pi in the signal S' is calculated 24, and when the deviation exceeds a prescribed value 28, the waveform 14 of the distortion is renewed. |
