Phased Array Doppler Velocity Algorithm

Modern instruments such as underwater acoustic technology,applied electronic technology,laser technology and remote sensing technology have become the mainstream of marine observation instruments.In order to understand the ocean,scientists found that the instrument must be allowed to enter a specific part of the ocean to complete the experiment.In recent years,the range of available ocean observation instruments has expanded to include manned underwater vehicles,underwater remotely controlled vehicles,unmanned underwater vehicles and underwater towing robots.Acoustic Doppler Current Profiler is installed on the underwater vehicle to assist underwater navigation positioning.Based on the application of Acoustic Doppler Current Profiler,this paper studies the velocity measurement technology of Phased Array Acoustic Doppler Current Profiler.The main contents of this paper include:1.Compare three target speed measurement methods,and focus on the process of measuring the water flow velocity using the Doppler velocity measurement method.The beamforming of the transmit signal of the phased array and the beamforming method of the received signal are analyzed.The phase shift values inserted between the array elements in the transmission process and the receiving process are obtained through theoretical analysis.The beam directivity of the transmitted signal and the received signal are simulated.2.Compare the correlation between Barker code and m sequence,and compare the advantages and disadvantages of the two coding sequences.The spectral characteristics and correlation characteristics of the repetitive coded signal are analyzed.The coding form and parameter selection rules are introduced.The formula of the layering and the relationship between signal pulse width and water depth are analyzed.The influence of signal pulse width and water depth is simulated.3.For the part of speed measurement algorithm,the discrete Fourier transform algorithm and the pulse pair algorithm are mainly studied.The basic formulas of these two algorithms are deduced,and the problem that the pulse pair algorithm has frequency-frequency ambiguity is obtained.Aiming at this problem of the pulse pair algorithm,the derivation process of two defuzzification algorithms is analyzed.Through the simulation,the accuracy of the pulse pairing algorithm and the error accumulation problem of the algorithm are studied after using the defuzzification algorithm.In order to solve the problem of error accumulation in the algorithm of de-fuzzy pulse pairing,this paper proposes a joint estimation algorithm combining discrete Fourier transform algorithm and pulse pair algorithm.The speed measurement accuracy of joint estimation algorithm is studied by simulation.