Research On Signal Processing System Of Acoustic Doppler Current Profiler

With the development of social economic and the emergence of new water problems,the monitoring of water flow velocity information has been widely used in water resources protection,development,utilization,flood control and drought resistance.The traditional method of water flow measurement is poor in real-time performance,cannot meet the requirements of modern hydrological monitoring.Acoustic Doppler Current Profiler(ADCP)with advanced automation technology can obtain water velocity information in real-time,and it has the characteristics of high accuracy,easy to use and simple operation.Based on the research of the acoustic processing system of ADCP,this paper designs ADCP signal processing units based on Field Programmable Gate Array(FPGA).The feasibility of the signal processing system is verified.The result shows that the system can measure flow velocity quickly and exactly.The main contents and achievements of the paper are summarized as follows:(1)After studying the Doppler effect of the sonar signal propagation in the water and the complex correlation frequency measurement principle,this paper proposes the computing units of the ADCP signal processing.The computing units have floating-point multiplier and Finite Impulse Response(FIR)digital filter with the advantages of fast processing capability and less resource utilization.The filter can be used for multi-channel parallel filtering,and can effectively filter out high-frequency useless signal.(2)After studying the working mechanism of ADCP,this paper proposes an FPGA-based design method combining hardware and software.The computational modules with high computational complexity and parallel processing are designed as custom IP cores.At the same time,process control,data scheduling and command communication and other functions are implemented in Xilinx MicroBlaze soft core.The internal parallel resources of FPGA are used to improve the processing speed effectively.(3)In the laboratory,we use simulated sonar signal to verify the complex correlation velocity measurement method.The calibration and accuracy test of the ADCP signal processing system is also verified in actual water.The result shows that the system can measure flow velocity quickly and exactly.