编码激励带宽对超声气体流量测量性能的影响

对比研究了四种不同带宽线性调频信号激励下,超声流量测量系统的性能。超声换能器为Senscomp中心频率125kHz,带宽10kHz的收发型压电换能器。信号产生、数据采集和时序控制由FPGA设计的专用电路实现。对接收信号进行脉冲压缩处理后,测得流速与横河1.0精度等级的涡街流量计比对,计算标准偏差和读数误差。结果表明,在B=20kHz的线性调频信号激励下,流速测量的误差和标准偏差最小;B=10kHz时,带宽与换能器带宽匹配,系统流速测量性能次之;B=5kHz时和B=50kHz时,流速测量性能最差。

Impact of coded excitation bandwidth on the performances of the ultrasonic gas flow metering system

This work compared the performance of ultrasonic gas flow metering systems with four different kinds of linear frequency modulation（LFM）signal in bandwidth.Senscomp 10 kHz bandwidth piezoelectric transceiver operating at 125 kHz center frequency was used in all measurements.The application-specific circuit was designed with FPGA for signal generating,data sampling and timing control.The receiving signals were compressed to calculate the flow rate which could be compared with the reference provided by the Yokogawa vortex flow meter（reading err ±1.0%）.Then the standard deviation and reading errors were given.The result shows that,when the bandwidth of the LFM excitation signal is 20 kHz,the system has the smallest flow rate standard deviation as well as the reading error.When it is 10 kHz,which matches the transducer bandwidth,the performance of the system gets worse.When it is 5 kHz or 50 kHz,the system has the worst performance.