Research And Simulation Analysis Of Broadband Acoustic Doppler Velocity Log’s Algorithm

As human’s continuous research about wireless communication technology,the research of positioning and navigation equipment is from land(radar and satellite)to underwater sonar.Acoustic Doppler Velocity Log(DVL),it is the most widely autonomous navigation device that used for the underwater body and ship application so far.In Acoustic Doppler Velocity Log system,velocity algorithm is the key content that needs to study,and accuracy of velocity is the key factors in velocity measurement.Based on the background of “Acoustic Doppler Velocity Log system” during the practice,the aim of this project is develop a small self-contained Doppler Velocity Log with competitive,low-power,wide dynamic range,high data rate,appearance and software interface that the users can accept.A lot of literatures show that broadband signal have better performance than narrowband signal in velocity measurement,so based on the previous studies,this thesis uses the broadband signal as the emission signal,and studies and analyzes from the perspective of time delay.Based on the work principle of Doppler Velocity Log in velocity measurement,and combines with the actual project needs,this thesis derives the formula of doppler frequency shift and velocity on Janus;studies the main technical parameters of the transceivers which used on Doppler Velocity Log;analyzes possible factors which affect velocity error,and gives the method that can improve the precision of velocity measurement respectively.Then,this thesis studies the advantages and disadvantages of continuous sound pulse signal,single frequency rectangular pulse signal,single frequency rectangular pulse-to-pulse signal,the linear frequency modulation pulse signal and pulse-encoded signal,and chooses the pulse-encoded signal as the transmission signal of this system,and designs the wave;establishes the undersea echo model in a better way,and verifies the rationality and correctness of the model by simulation and analysis.Last,this thesis has a deep research on algorithm of velocity measurement.By comparison with Zero-crossing detection algorithm,FFT algorithm and Multiple correlation algorithm,this thesis chooses pulse-to-pulse algorithm which suitable for pseudo-random coding signal,and analyzes algorithm’s details.This thesis gives the program of velocity calculation,and simulates and analyzes the algorithm of velocity measurement with MATLAB.Based on the pulse-to-pulse algorithm,this thesis simulates and analyzes velocity performance on different conditions.Based on the above work,velocity accuracy reaches the development program’s requirement of Acoustic Doppler Velocity Log.