Liquid flowmeter including doppler signal processing, and method

Abstract

A liquid flowmeter and method for determining the velocity of flow of fluid in a conduit, including a sensor adapted for mounting in the bottom of the conduit, and including acoustic energy transmitting and receiving devices, an in-phase reflected Doppler energy signal detector connected with the receiving device, an anti-alias low pass filter for producing from the in-phase reflected energy a filtered signal, a digital-to-analog converter for digitalizing the in-phase signal to produce a sampled array, an accumulator for storing a first number (M) of mean zeroed power spectra from the sampled array, a zeroing device for zeroing a second number (K) of the initial samples of the power spectra, thereby to produce a first modified spectra, a median filter of rank R for filtering the first modified spectra to produce a second modified spectra, a limiting device for limiting the second modified spectra to produce samples limited to the upper portion of a range of amplitudes, thereby to produce a third modified spectra, a device for determining the high-frequency edge of the third modified spectra, a first converting device operable when the third modified spectra have a wide band width for producing as a multiple of the high-frequency edge an estimate of mean fluid velocity, and a second converting device operable when the third modified spectra have a narrow band width for producing as a function of the spectral peak an estimate of mean fluid velocity.