Design And Implementation Of Underwater Acoustic Communication Modulation And Demodulation System Based On FPGA

As people on the Marine exploration, underwater acoustic communication technology is more and more attention. In this paper, the design of underwater acoustic communication modulation demodulation system based on FPGA is a one-way low speed underwater acoustic communication system. The purpose of the design is to verify the feasibility of the hardware platform and the design proposal,and to lay a foundation for the system optimization and upgrade of the late.The system include a power amplifier, small signal amplifier, the FPGA digital processing system, also include software algorithms for signal demodulation, to complete the acoustics communication system design.One of the main work of my design is the realization of the hardware platform of underwater acoustic communication system.Including the power amplifier, small signal amplifier circuit. Power amplifier is the most important part of the transmitter in underwater acoustic communication. This paper describes an efficient class D power amplifier design and implementation method. Chose a integrates triangular wave generation, signal comparator, MOSFET drive circuit and protection function driver chip, connecting two MOSFET which designed for class D power amplifier, to make up the high efficiency and low distortion power amplifier. Small signal amplifier circuit at the receiving end is through an op-amp chip of multistage amplifier circuit, and amplifier circuit first level and the last level of the bandpass filter filter out noise.Second main work of this paper is on the basis of the hardware circuit to finish the FPGA demodulation system design. FSK modulation method was adopted, although the transmission rate is low, but has a good anti-jamming capability, and easy to implement and debug. FFT demodulation for the demodulation part, used the FPGA has been designed FFT IP core, can accurately and fast finish FFT work. At the receiving end this design uses the autocorrelation algorithm to realize the signal detection, and finish the synchronization signal to overcome interference.