超声波流量计通过超声波在流动的流体中传播载上流体流速信息，再通过简便、可靠的信号处理方法，就把这个流速信息转换成流量信息。超声波流量计与以往传统的流量计相比，具有所要求的费用低，安装简便，不会改变流体的流动状态，不产生附加阻力，适合大管径大流量的测量等优点，是一种非常理想的节能型流量计。然而，由于超声波流量计只是在近几十年才出现的一种新型仪表，还有很多地方不完善，没有得到普遍的应用，因而在科学技术迅速发展的今天，非常值得去进行研究，这便是本课题选题的一大因素。 本文就是针对目前流量测量中存在的问题而设计的一种超声波相关流量测量系统，而且本文的特点是把数字信号处理器引入其中，使得测量系统的性能大大提高。主要研究工作有：首先从互相关理论出发，推导出利用FFT运算和IFFT运算计算两信号互相关函数的数字离散化公式，并在MATLAB中编程验证了其正确性；其次在此基础上设计了整个系统的硬件电路，其中硬件系统以TI公司的DSP芯片TMS320VC5402为核心，由于DSP芯片的信号处理速度快，就确保了本系统高的测量精度，硬件包括超声波信号的产生与功率放大、信号接收与放大，数据采集、存储、显示和DSP处理器系统；然后根据系统的硬件电路，又在CCS环境下编写了系统的软件程序，软件包括DDS子程序、A/D转换子程序、基2FFT子程序和主程序；考虑到现场情况，还对系统软、硬件进行了抗干扰设计。 通过实验室模拟，证明了该系统是一个低成本、高效能的设计，具有较高的理论研究和实际应用价值，并且本方案是可行的。

Both industrial production and scientific experimentation cannot go away with realization and control of flow.The ultrasonic flowmeter’s operating theory is that when ultrasonic pass the liquid，it carries out the signal reflecting the liquid’s flow velocity，and then，the signal will be used to compute the flow. Due to its advantage in accuracy，turndown ratio and no excess pressure drop，the current market for ultrasonic flowmeter technology is growing rapidly in flow measurement. However，the ultrasonic flowmeter develops just some ten years，and has not run in all fields it can be, so it provides many distinct and difficult challenges. That is one reason why this thesis chooses the topic. The system of ultrasonic correlation flowmeter has been designed aiming at solving the current problems. Performance of flowmeter is improved because of using the DSP. At first discrete formula for computing correlation function of two signals has been deduced by using FFT transform and IFFT transform from correlation theory and correctness is validated by virtue of program in MATLAB. Secondly, hardware has been designed, whose core is DSP chip of TMS320VC5402 on the basis of forward formula. High precision is guaranteed because of quick velocity of signal processing of DSP chip. Hardware includes generating and amplifying of ultrasonic，receiving and amplification of signal，data acquisition，Memory, display and DSP; Thirdly software is programmed in CCS according to the hardware. Software includes subprograms of direct digital frequency synthesis，subprogram of analog to digital converter，subprogram of FFT, subprogram of display and main program. Finally Considering the other factors, anti-jamming has been added to the system of hardware and software. By imitating in the laboratory, it is proved that this system is a low cost and high efficiency one, and it’s valuable for theory and application study and it is feasible.