Patent ID: 8156792
Filing Date: 2012-04-17
Classification: G01F

Abstract:
1. A method for ascertaining and/or monitoring a process variable, comprising the steps of: feeding a time-limited exciting signal, which is described by at least one desired quantity, or by a desired signal form, to a first piezoelectric element or to a first polarized zone of the first piezoelectric element; registering a response signal, which is described by at least one actual quantity, or actual signal form, corresponding to the desired quantity, or desired signal form, by a second piezoelectric element or a second polarized zone of the second piezoelectric element; comparing the actual quantity, or the actual signal form, of the response signal and the desired quantity, or desired signal form, of the response signal with one another; modifying the exciting signal, in the case of a deviation of the actual quantity, or actual signal form, of the response signal from the desired quantity, or desired signal form, of the response signal that the actual quantity, or actual signal form, of an ultrasonic measuring signal transmitted from the first piezoelectric element, or from the first polarized zone of the first piezoelectric element, is at least approximately equal to the desired quantity, or the desired signal form, of the response signal; and ascertaining the process variable on the basis of the ultrasonic measuring signal, which is describable by the defined, desired quantity, or the defined, desired signal form, via a sound-entrainment method or an echo method, wherein: the two piezoelectric elements are coupled together via a coupling element; and the two piezoelectric elements are arranged adjacent to one another.