| 摘要 |
<p>PURPOSE:To remove errors in the return time of reflected electromagnetic waves due to variation in the delay time of a trigger signal by a method wherein fluctuation in the delay time of the trigger signal sent to a transmitter or a receiver is corrected by using a received waveform. CONSTITUTION:By preliminary measurement, reflected electromagnetic waves Vb by electromagnetic waves Va radiated from a transmitting antenna 13 are first received by a receiving antenna 16, N amplitude values which have been sampled by a sampler 15 within a definite time are taken into a waveform analyzer 17, the value at which the amplitude is first changed from a positive value to a negative value above the noise level is detected, and the value is stored in a storage device 18 as a reference value. When an object W is measured, a measured waveform is taken into the analyzer 17 in the same manner as in the preliminary measurement, the value at which the amplitude is first changed from a positive value to a negative value is detected, and the detected value is compared with a received waveform (a reference value) at the preliminary measurement. When the difference is caused by this comparison, it is judged that a change in the delay time is caused, the change is fed back to a delay device 14, the delay time is made definite or the delay time is made definite by changing the display phase, and the error in the return time is removed.</p> |
