Improving Accuracy of the Arrival Time Determining of a Flowmeter Acoustic Signals by the Correlation Method

Abstract

The paper notes some important aspects of the digital signal processing methods applications to reduce the achieved measurement error of the acoustic signals propagation time. As an example, it's proposed the consideration of the correlation method processing of the received probing signals of an ultrasonic time-of-flight liquid flowmeter. The indicated method is based on the calculation of discretized cross-correlation functions. This article is the actual continuation of the previous publication within the topic under discussion. It was shown, the main features that should be taken into account when choosing discretized signal values sequences for the correct calculation of correlation functions, were discussed. In article speaks of individual limitations that are imposed on the analyzed signals in order to obtain adequate results of calculating discretized correlation functions. Earlier, a special algorithm was developed to reduce the possible error in determining the required time intervals using a special "window", which selects individual signals samples, in fact, truncates the signals. The formulated theoretical arguments were veryfied and supplemented by mathematical calculations and modeling in the MatLab software package.