ADCP Echo Signal Processing Based On The Most Value Algorithm

Acoustic Doppler Current Profiler(ADCP) is a kind of precise instruments used to measure water flow velocity. It is designed using Doppler effect of sound wave. The power spectrum estimation algorithm based on plural autocorrelation theory is the most common algorithm when designing ADCP. Correlation coefficient in time domain of the power spectrum estimation algorithm is selected by experience, reducing the degree of automation. Frequency domain of the power spectrum estimation algorithm needs a lot of calculations, so it is very complex. This paper researched plural autocorrelation theory and putted forward the most value altorithm, improving calculational efficiency.First, the properties of underwater acoustic and doppler effect of sound is introduced. Doppler effect formula in one dimensional space is given. A mathematical model of transmitting and receiveing sound waves is established. Formula to measure velocity of water flow in single transducer and coordinates of the three dimensional are derived.Second, since there is a cycle in phase angle of plural autocorrelation function, enumerative algorithm in conditional constraints is used in the theory of complex autocorrelation. There is most value of Doppler frequency shift in real case, the most value altorithm is putted forward. This altorithm gives the exact range of correlation coefficient. The relationship between periodical coefficient and correlation coefficient is given. Enumerative algorithm and the most value altorithm are discretized. Processes of those algorithms are given. The most value algorithm is proved to be right when simulated and analyzed in Matlab.At last, the influence of sampling point location on sampling frequency, transmission frequency and filter are demonstrated. The analog demodulation circuit, analog filter circuit and sampling circuit are designed. According to the principle of the most value algorithm the signal processing is given.