| The wind speed measurement used in meteorological observation, wind power field, sea voyage, railway bridge monitoring, military, city and forest fire protection and other occasions. Compared with the traditional mechanical anemometer, the ultrasonic anemometer has the advantages of no mechanical friction, almost no initial wind speed limit, etc. Ultrasonic wind speed instrument will become the mainstream of wind velocity measurement.Based on the principle of time difference method, this paper uses digital signal processing technology to find the starting point of the receiving signal to accurately measure the propagation time of ultrasonic signal. The received acoustic signal is processed by digital filter without delay, and the average method is used to find out the sine signal of each period. The hypothesis test is performed by the real signal and the ratio of the residual square sum of the fitting signal and the reverse signal, and then the signal starting point is determined.Due to the signal processing is more complex, the system uses high performance ARM11 chip S3C6410. And designed minimum system control board, as well as having four signal conditioning acquisition board, including a signal transmitting circuit, receiving conditioning circuit, analog-digital conversion circuits and power supply circuits.Combined with wind speed measurement principle and digital processing method, system software based on Windows CE 6.0 operating system for the development of data acquisition stream driver and application. Through the preparation of the underlying driver and application calls API function, the use of PWM’s S3C6410 function and its high speed processing capacity to achieve high-speed analog digital converter real-time data reading. In the opposite direction, the propagation time of the ultrasonic signal is completed, and the value of the wind speed is calculated, and finally, the measured wind speed is displayed in real time. |
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