Abstract Aiming at the problem that it is difficult to find the stable feature point in the signal processing of ultrasonic gas flowmeters,from the angle of the energy of the echo signal,the change rule of the echo signal energy is studied.The middle part of the rising segment of the contour of the echo energy signal is relatively stable,and the slope of the envelope of the middle part is the largest,which is approximately a straight line.A signal processing method based on echo energy peak point fitting is proposed.That is,firstly,the adjacent peak points of the rising segment of the echo energy signal are connected and the slope of each connected line is obtained,then four connected lines with larger slope are selected as the characteristic straight lines,and the right end points corresponding to the four characteristic straight lines are taken as the characteristic peak points to fit a straight line.Finally,the intersection point between the fitted straight line and x-axis is taken as the feature point,so as to calculate the ultrasonic propagation time.This signal processing method is implemented on the dual core system based on FPGA and DSP,and the calibration test is executed in the qualified testing institution.The results show that: the dual-channel ultrasonic gas flowmeter system based on the signal processing method of echo energy peak fitting achieves the 1.0-level accuracy,and the flow measurement range is 30~1200m3/h.
MA Jie,XU Ke-jun,JIANG Zhen, et al. A signal processing method of ultrasonic gas flowmeter based on peak point fitting of ultrasonic echo energy[J]. Acta Metrologica Sinica, 2022, 43(5): 597-602.
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2022, Vol. 43 
