Device for measuring distance with ultrasound

摘要

A device for the measurement of distance with ultrasound is provided in which a transmitter emits a pulse-type signal which is reflected and is converted into an electrical echo signal in a receiver. The distance between transmitter and receiver is determined by measuring the transit time between the emitted and the received signal. Since the level of the echo signal as a function of the emitted signal depends on the characteristics of the reflector and on the distance between transmitter and receiver, inaccuracies may occur in the evaluation of the echo signal and these are avoided by varying a switching threshold or by varying the amplification of the echo signal or by modifying the radiated signal as a function of the previously received echo signal.