JPS54128762A - Flow speed and rate meter - Google Patents

Abstract

PURPOSE: To meter the flow speed or the like at an excellent S/N ratio without preventing the flow of a fluid to be metered by differentiating the detected output of a flow speed or the like, which is detected with the use of ultrasonic or electromagentic wave transmitting and receiving elements arranged equidistantly so that the unnecessary components are offset whereas the necessary components are emphasized.

CONSTITUTION: Ultrasonic wave received signals, which have their phases modulation in accordance with the flow speed through a pipe 1, are detected by ultrasonic transmitting and receiving elements 21 to 28 and 31 to 38 which are arranged equidistantly at a right angle with respect to the pipe 1. These detected signals are differentially applied to a phase difference demodulating circuits 51 to 54 so that the demodulated signals have their perpendicular speed components of the fluid of a period of d/N(N:0, 1, 2 and so on) offset by the spacial filter effects resulting from the elements 21 to 28 and 31 to 38 and have their perpendicular speed components of a period of d/(N + 1/2) emphasized. Thus, at the trough of the spectrum of the modulated signals, the perpendicular speed components are offset, whereas at the crese of the same the components are emphasized so that the components corresponding to the flow speed or rate are taken up by a signal processing circuit 7 through an adding circuit 60 without prohibiting the flow of the flow. Thus, it is possible to accomplish the metering operation at an excellent S/N ratio.

COPYRIGHT: (C)1979,JPO&Japio