Echo energy integral based signal processing method for ultrasonic gas flow meter

Abstract

Ultrasonic gas flow meter possesses unique measurement advantages, and is especially suitable for natural gas measurement of large diameter gas pipelines. It is very important to obtain the accurate transit-time of ultrasonic signal for ensuring the measurement accuracy of ultrasonic gas flow meter. However, it is difficult to find stable feature points for determining the transit-time in ultrasonic gas flow meter signal processing. Aiming at this problem, the echo energy gradient is analyzed from the point of the echo energy integral in this paper, an echo energy integral based signal processing method is proposed, and corresponding parameter selection is put forward. First of all, the FCE (fixed cumulative energy) value is set as a standard, and the area of the EES (echo energy signal) rising section is integrated, that is, the echo energy in this period of time is accumulated. When the cumulative energy value exceeds the FCE value, the end position of the FCE value is taken as the feature point. Then the ultrasonic transit-time is obtained, and the gas flow rate is calculated. This digital signal processing method is implemented in real-time in the digital system with the FPGA (Field Programmable Gate Array) and the DSP (Digital Signal Processor) as the double cores, and the gas flow calibration experiments are conducted to verify the effectiveness of the proposed digital signal processing method.