The Design Of The Ultrasonic Wind Measurement System Based On FPGA

With the development of science and technology, measuring wind speed and direction plays an increasingly important role in many areas. In this context, the rapid development of wind vector measuring instruments, measuring instruments and methods is growing wealth, which includes the rapid development of ultrasonic wind measurement method in recent years. Ultrasonic Anemometer compared with conventional mechanical anemometer, no moving parts, machinery loss, and without starting wind speed.When fixing the ultrasonic propagation distance in the air, there is a spread time delay between downwind and headwind, the time delay has a linear relationship with the measured wind speed. So this time delay has become a key factor in the wind speed measurement system, how to improve the measurement accuracy of this time delay has become the design key elements of this thesis. This paper studies lie in the time delay measurements and do the following tasks:1、In computing the time difference analysis, because the time delay is an important parameter for the characterization of signal propagation of sensors. In order to improve the precision of time delay estimation, this article proposes an algorithm based on bispectrum interpolation. The algorithm first calculates the characteristic spectrum function on the basis of the bispectrum of the two signals. The frequency domain interpolation is done on the characteristic spectrum function. By conducting the inverse Fourier transform and the maxima seeking method, the calculation formula for the time delay of the two signals is deduced. The simulation test results show that compared with the bispectrum-based time delay estimation method, the bispectrum interpolation-based time delay estimation method has improved greatly in terms of the estimation precision and temporal resolution. The algorithm has the advantages of high precision, small error and strong ability to suppress the correlative Gaussian noise. At the same,combined with device resources, integrated signal processing algorithms TDE.2、On the basis of the difference method of wind measurement system, using the FPGA which not only has high frequency sampling capability but also has the strong timing ability to control the send module,receive module and data processing, information transmission, etc. at last using the Verilog HDL and C language to achieve the high-precision ultrasonic velocity measurement system.