Application Features of the Correlation Measurement Method in Ultrasonic Liquid Flowmeters at a Low Sampling Rate of Signals

The proposed article is considered to the correlation method analysis for measuring informative parameters - the propagation times of ultrasonic probing signals in flowmeters, taking into account individual features. The article investigates the sources of propagation time measurement error, determines the requirements for the probing signals shape and algorithms for their digital processing. The method consists in determining the maximum's position of the cross-correlation function for the probing signals. The flow measurement accuracy is primarily characterized by the fractional part of the propagation time's difference estimation. This is realized by the correlation function interpolation in its main maximum region. An interpolation error occurs, when the peak's position determining. Reducing the time shift calculating error is achieved using correct signal truncation.