Procedure for the recognition and separation of useful echoes and interference in the received signal of distance sensors which operate according to the principle of pulse-echo.

PCT No. PCT/DE94/00249 Sec. 371 Date Sep. 5, 1995 Sec. 102(e) Date Sep. 5, 1995 PCT Filed Mar. 10, 1994 PCT Pub. No. WO94/22033 PCT Pub. Date Sep. 29, 1994In a first step, an individual echo is associated with each local maxima in the received ultrasonic signal. Subsequently, characteristic features such as time position, amplitude and form factor of each respective individual echo are detected numerically for the individual echo. In a second step, the mentioned features are subjected to a fuzzy evaluation. The features form the input variables of the evaluation. A multiple echo probability for each individual echo is available as the result. With this awareness, with the aid of the a priori knowledge and with the aid of the awareness of the history, it is possible, for example, to draw conclusions concerning the filling level of the bulk material in containers in which the surface of the bulk material is at times masked for the ultrasonic beam by the stirring apparatus.