Signal processing method based on connection fitting of echo peak point with a large slope for ultrasonic gas flow meter.

Ultrasonic gas flow meters are especially suitable for measurement in pipelines with large diameters. However, on the one hand, it is difficult to find a stable feature point to calculate the duration of propagation of the ultrasonic signal, through which we can obtain the real-time flow rate of the gas, and on the other hand, the computation incurred by signal processing methods to this end is burdensome and affects the real-time performance of the flow meter. To solve these problems, this study examines the characteristics of the stability of the echo signal and patterns of variation in the echo contour at different flow rates of gas. We found that peak points of the middle part of the rising segment of the echo signal were relatively stable, and the slope of the envelope of this part was always relatively large but constant, which indicates that peak points in this part were approximately distributed along a straight line. This finding is used to develop a signal processing method based on the connection fitting of the echo peak point with a large slope. This method is easy to implement, incurs a small amount of calculation, and has strong anti-interference ability. Moreover, it can guide research on signal processing methods and the stability of the echo signal. The proposed method was implemented on a dual-core hardware system, and the results of calibration show that it can attain 1.0-level accuracy over a measurable range of 30 m/h-1100 m/h.