Distance measurement using sound transition time measurement involves using counter with variable clock length inversely dependent on temp. in working temp. range and on speed of sound

摘要

The method involves starting a counter by transmitting a sound pulse and reading the counter on receiving an echo pulse, whereby the number of pulses counted is a measure of the sound transition time and hence a measure of the distance to the measurement object. To increase the measurement accuracy the temp. dependency of the transition time or the speed of sound is compensated by using a counter with a variable clock length inversely dependent on temp. in the working temp. range as well as on the speed of sound. An Independent claim is also included for an arrangement for implementing the method.