Endress U. Hauser Gmbh U. Co.

Bernhard Michalski

Jurgen Lau

Wolfram Berger

An ultrasonic echo sounding apparatus disposed at a measuring location transmits ultrasonic pulses in successive transmission periods. The echo pulses received after reflection at a target are converted to electrical envelope signals which represent the envelope curves of the echo pulses. The envelope signals are transmitted via a connecting line to an evaluation apparatus disposed at an evaluation station remote from the measuring location. In the evaluation apparatus the envelope signals are evaluated for determining the target distance from the travel time of the ultrasonic pulses. The transmission of envelope signals results in the advantage that the information contained in the pulse shape of the echo pulses is available in the evaluation station, although it is not necessary to transmit signals having the high frequency of the ultrasonic pulses via the connecting line. Preferably, the envelope signals are transmitted in a first section of each transmission period, and low-frequency signals which are generated at the measuring location and are characteristic of parameters necessary for the evaluation of the envelope signals are transmitted in a second section of each transmission period. It is also possible to transmit control signals from the evaluation station to the measuring location during the second section of every transmission period.

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Schopfheim, Germany

Bernhard Michalski