针对超声波测量技术存在难以准确捕捉回波前沿起点的问题,设计基于宽频带、高接收灵敏度的静电换能器的超声测温系统,配合脉冲高压偏置驱动电路,得到前沿明显且易捕捉的回波信号;设计石英玻璃超声波传递通道,采用阈值检测法和钳位电路设计防误触发回波处理电路,提高系统的稳定性;选用高主频单片机STM32F407准确测量超声波传递时间,再以分段线性插值法对系统测温值进行标定。在恒温箱10~58℃的温度范围内将系统测温数据与高精度测温计TSIC506的测温值对比,实验结果表明系统可实现精准测温。
To solve the problem that the ultrasonic technology can hardly capture the start point of echo leading edge, an ultrasonic thermometry system based on an electrostatic transducer with wide band and high receive sensitivity is designed. With a pulse high voltage drive circuit, it captures an easily captured echo signal with obvious leading edge. An ultrasonic wave transmission path with quartz glass material is designed and threshold detection method and clamping circuit are used to design a mlss-trigger prevention echo processing circuit to improve the system's stability. A high frequency MCU of STM32F407 is selected to measure the ultrasonic transmission time accurately and the piecewise linear interpolation method is used to calibrate the value of system thermometry. By contrasting the measured value of the system with the measured value of high- precision temperature measuring meter TSIC506 in a Calorstat with temperature range of 10-58℃, the results show that the system can measure the temperature accurately.