Research On The Digital Multi-Channel Receiving Method With A Wide Dynamic Range

In the field of signal processing at hydroacoustics,the signal processor mainly completes the amplification of the acoustic signal after the acoustic transducer of the acoustic transducer,the automatic gain control,the frequency selective filtering function,and provides the normalized signal as the back-end digital signal processor for calculation and analysis.At present,the signal preprocessing method based on analog operational amplifier basically meets the current design requirements of various types of mines and projects.In recent years,the advent of large-scale arrays has put forward higher requirements on underwater acoustic signal preprocessing.However,it is very difficult to design further on the basis of the original analog pre-processing technology.This article digitally redesigns the traditional analog receive technology due to the high performance of high-speed analog-to-digital converters and FPGAs in data acquisition and processing.In this paper,AD7763,which is high-speed,high-precision,large dynamic range and serial interface,and Xilinx’s Zynq-7000 expandable processing platform are used for the research of receiver technology which is digital,multi-channel and wide dynamic range.4-channel prototype is designed with low-noise preamp function,4-channel AD synchronous acquisition and storage capabilities and digital beamforming,and the system should have a larger dynamic range.This article mainly introduces the following aspects of work:1)In combination with the design requirements of this topic,select AD7763 as the analog digital conversion chip,select the Zynq chip as the control acquisition processor.The design of 4-channel AD principle prototype hardware includes the selection of suitable low-noise preamplifier circuit,the design of power supply circuit of AD chip,differential driver circuit and acquisition circuit.Combining the working principle of AD chip and the expansion of Zynq development board sport features,to complete the AD board clock line settings,address line settings,control signal settings and communication interface settings.2)The design of 4-channel AD prototype software is designed to realize synchronous acquisition and control of 4-channel AD with FPGA,and store the data in FIFO.The design content includes the clock,configuration register,serial data read,multi-channel AD shared serial bus data read and FIFO memory according to AD chip work flow,and finish the program design and function simulation of the above modules.3)To study the related theory of digital beamforming,grasp the mathematic principle and realization method of beamforming,the 4-channel principle prototype is equivalent to linearray,realize the beam in the specified direction and complete the simulation,make the system have the function of beamforming.4)The system is debugged and functional verification,the dynamic range of the test system,the acquisition performance of a single channel and the multi-channel synchronous acquisition performance,analyze the source of error and propose improved methods.