Research And Design Of The Phased Array Acoustic Doppler Current Profiling System

PAADCP is short for Phased Array Acoustic Doppler Velocity Profiler which is a new type of flow velocity measuring apparatus based on phased array technology.It is one of the most indispensable underwater acoustic equipment to ocean exploration and environmental monitoring.Compared with the conventional ADCP with piston transducer,PAADCP not only smaller in size and have lower operating frequency which makes the measuring range larger and the precision higher,but also do not need complex sound velocity compensation.To analyze the PAADCP system,we carry on related simulation,design and debugging from three aspects: the composition of planar array transducer,the principle of Doppler flow velocity measuring algorithm and the composition of the transmission and receiving system.The major content of this thesis as follows:Firstly,we make a simple introduction to the research background and the development course of PAADCP.Then expound its working principle and illustrate the advantages of PAADCP to the conventional ADCP with piston transducer.In addition,we give the overall design block diagram of PAADCP system.Secondly,several kinds of traditional time-frequency analysis algorithm have been introduced in this paper because of the importance of Doppler flow velocity measuring algorithm in ADCP system.And then we analyze the advantages and disadvantages of them.After this,we propose a new time-frequency analysis algorithm based on Nonlinear Mode Decomposition(NMD)and Adaptive Optimal Kernel(AOK).Then we prove its advantages through simulation and comparing with the results of several algorithms mentioned above.In addition,this thesis introduces a method to extract the instantaneous frequency from the time-frequency representation figure.Then construct the underwater acoustic echo signal model and prove the feasibility of the time-frequency analysis algorithm through the echo signal generated by the model.Fourthly,we expound the working principle of phased array and introduce a kind of planar array structure which can be used in PAADCP system.Then verify its phased directivity through simulation.Finally,the circuits of transmission and receiving system which is correspond with the planar array mentioned above were designed and debugged.It contains transmitter,receiver and transmit receive switch.Meanwhile,the structure,parameters and performance of the main chips in the system were analyzed.And the testing results were also presented.