基于正交解调算法的介质声速实验研究

Experimental Study on Ultrasonic Velocity of Medium Through Quadrature Demodulation

为了实现塑料管道容器中的超声波介质传播速度测量,研究一种基于正交解调算法的介质声速测量方法。为了验证方法的性能,对算法进行软件仿真分析,并搭建基于STM32单片机的声速测量系统进行实际测量。该方法使用正交解调算法获取数字化的超声信号包络,并使用包络上升沿拟合法得到超声波在固定传播路径上的飞行时间。运用简单的距离-时间转换公式就能达到测量超声波在介质中传输速度的目的。通过对实测数据的分析表明,测量的飞行时间存在一定的系统误差,需对测量系统进行校准。该系统能够满足塑料管道容器中的介质声速测量要求。

Presents a study on ultrasonic velocity of medium through quadrature demodulation in order to realize the measurement of ultrasonic medium propagation speed in plastic pipe container.Some numerical tests are conducted on simulated signals and an experiment system based on STM32 single-chip microcomputer is used for real tests.The method applies a quadrature demodulation scheme to get the envelope of the digitized ultrasonic signal,and locate its TOF on a fixed distance by a method based on fitting the rising edge of the envelop.The purpose of measuring the ultrasonic velocity of medium can be achieved by using a simple distance-time conversion formula.The analysis of the measured data shows that there is a certain systematic error in the measured TOF,and the measurement system needs to be calibrated. The system is capable of meeting the sound velocity measurement requirements of media in plastic pipe containers.