Design Of ADCP System Based On OMAP

At present, Acoustic Doppler Current Profilers(ADCP) is an extremely advanced measuring equipment in the river flow measurement. Along with the equipment appearance and widespread using, they have brought great convenience to related hydrologists and water conservancy departments. In the meantime, they also make the velocity measurement of unstable flow and the flow influenced by tidal possible. In recent years, our country has made great progress in the real-time dynamic ADCP system, high speed, longevity storage, remote monitoring and networking aspects.This paper is based on the specific needs of the actual project, using the open multimedia application plant(OMAP) to design and implement the ADCP measurement system. The system is with the characteristics of memory interface and high- speed, high processing capacity. It consists of OMAP-L138 dual- core processor(ARM+DSP) and ultrasonic sensor signal circuit.The paper describes the hardware design and software development of ADCP measurement system in detail. The design in hardware circuit consists of two parts. Firstly, the hardware circuit design of ultrasonic signal transmitter module, including the circuit of periodic signal generating and signal power amplifier. Secondly, the hardware circuit design of ultrasonic signal receiving module, including the signal amplification circuit, the band-pass filter circuit, mixer, low- pass filter circuit and the A/D analog conversion circuit. However, the software development includes the ARM core and DSP core based on the main control unit of OMAP-L138, also gives a brief introduction of the communication mechanism between ARM core and DSP core.Finally, in dealing with the Doppler echo signal, the thesis mainly introduced the periodogram and the improved cycle diagram method(Welch method). It also studied that using the bandpass filter with multiple analytic modulation spectrum analysis could improve the frequency resolution of the echo signal when the frequency of the echo signal relatively dense, then get the corresponding echo signal frequency, finally the velocity of the fluid and flow rate could be obtained.