DETECTION METHOD OF ZERO-POINT SHIFT IN ULTRASONIC FLOWMETER

摘要

PURPOSE: To find a zero-point shift in terms of a circuit quickly and with high accuracy by a method wherein individual received waveforms in the forward direction and the reverse direction are corrected in advance on the basis of individual crest values in a forward-flow mode and the mode is then changed over to a reverse-flow mode. ;CONSTITUTION: A received-wave correction circuit 3 corrects received waveforms by a correction signal from a control part 5. That is to say, in a forward-flow mode, individual received waveforms in the forward direction and the reverse direction are corrected in such a way that their crest values of waves for time detection coincide. A time difference related to a forward-flow value is found by the individual corrected waves for time detection. The individual received waveforms, in the forward direction and the reverse direction, which can be obtained by changing over the relationship between individual wave transmitter- receivers 11, 12 in terms of a circuit are corrected in advance on the basis of individual maximum crest values in the forward-flow mode in such a way that the crest values of the waves for time detection coincide. After that, the mode is changed over to a reverse-flow mode, and a time difference related to a reverse flow value is found. On the basis of the respective time differences, the forward-flow value and the reverse-flow value are found. A zero-point shift is found as the mean value of the forward-flow value and the reverse-flow value.;COPYRIGHT: (C)1994,JPO&Japio