单通道时差法超声流量计研发(硬件部分)【毕业论文】.doc

- PAGE I - 本科毕业设计 （20 届） 单通道时差法超声流量计研发(硬件部分) 所在学院 专业班级 电气工程及其自动化 学生姓名 学号 指导教师 职称 完成日期 年 月 PAGE I 摘　要 【摘要】超声流量计拥有测量方式简单、对水质要求低、压力损失小、计量精度高可靠性好、无接触测量等优点，具有广阔的应用前景。本课题基于时差法测量原理研发一个单通道时差法超声流量计，整个硬件系统由单片机、计时芯片、超声波收发切换、信号处理和液晶显示等模块构成。根据时差法超声流量计的测量原理，可知其测量精度与超声波传播时间的准确测量有着密切关系，因此选用高精度的计时芯片TDC-GP2来测量时间。同时，为了获得可靠的Stop信号，对从接收换能器接收的信号进行信号处理，包括信号的放大、带通滤波以及Stop信号选取，其中Stop信号选取是利用阈值比较和过零比较相结合的电路模块来完成的。最后，通过实验调试，实际获取的Stop信号符合预期的设计，确保了测量的精度，系统各模块都能正常工作，符合设计要求。 【关键词】时差法；超声波流量计；信号处理。 Abstract 【ABSTRACT】The ultrasonic flow-meter has the advantages as simple measurement, low demand on water quality, low pressure loss, high accuracy and reliability, non-contact measurement, etc., has a broad application prospect. Based on the principle of time-difference measurement ,research and development a single channel time-difference ultrasonic flow-meter, the hardware system includes SCM, timing chips, switch the ultrasonic transceiver, signal processing and LCD modules. According to the principle of time-difference ultrasonic flow-meter measurement, we can see that its measurement precision has a close relationship to the accurate measurement of ultrasonic propagation time, so we choose the High-precision timing chip TDC-GP2 to measure the time. Meanwhile, in order to obtain reliable Stop signals, processing the signal received from the receiver signal transducer, including signal amplification, band-pass filter and Stop signal selection ,and the circuit module of Stop signal selection constituted by the combination of threshold comparison and zero-crossing comparison. Finally, through the experimental commissioning, the actual received Stop signal in line with expectations designed , Guaranteed the measurement accuracy, every system module can work, meet the design requirements 【KEYWORDS】time-difference method；ultrasonic flow-meter；signal processing. 目　录 TOC \o 1-3 \h \z \u HYPERL