| 摘要 |
<p>In a process for measuring distances by means of pulse transit times, in particular by the pulse-echo transit time method (working by echos) or by the pulse-reflex transit time method working by transponder, using waves having a given velocity of propagation, in particular ultrasound waves, a pulse packet of given length and frequency is generated, transmitted, and received as an echo or a reflex after a time-interval depending on the transit time. The positions of a plurality of received pulse packets (echos or transponder reflexes) on the time axis are compared; for this purpose the positions of a certain number of pulse packets on the time axis must be comparable within a given tolerance. The mean value of the results obtained is calculated. The individual measurements must be made in the fastest possible sequence, because the arrival of a response pulse (pulse packet) triggers a new measurement which, if a response pulse is not received, is limited to a maximum time-interval corresponding to the maximum possible measurement range.</p> |
