基于相关法的超声波流量测量的发射设计

Design of the Ultrasonic Flow Measurement Based on the Correlation Method

针对传统相关法的超声波流量测量过程中计算结果不能准确的反映信号时间差的缺点,采用改进的相关法,使用FPGA(现场可编程门阵列)发出占空比调制的驱动脉冲,使超声波探头在需要的一定周期内发射出幅度调制的波形,克服等振幅周期信号在做相关后时间差判断不准的情况。通过实验可以证明,控制激励探头的脉冲信号的占空比,可以改变发射波形的幅值特性,从而得到适合相关运算的波形,达到预期的测量效果。

Due to the traditional correlation method of ultrasonic flow measurement results may not accurately reflect the signal time difference,an improved correlation method is used. Using duty cycle modulated drive pulse emitted by FPGA（ field programmable gate array）,ultrasonic probe can emit a waveform with modulating amplitude in a certain period,and avoid the constant amplitude periodic signals in the correlation processing time on the situation of inaccurate judgment. Through the experiments,by controlling the duty cycle of exciting probe pulse signal,the amplitude characteristics of emission waveform can be changed,thus the waveform suitable to do correlation operation can be acquired and achieve the expected effects of measurement.