Underwater Acoustic Communication Based On FRFT Algorithm On FPGA

With the exploration development and utilization of marine resources, and theneeds of national defense development, people pay more attentions on the research ofacoustic communication technology. With the acoustic channel’s characteristics oftime-varying, frequency-changing, space-varying and severe multi-path interference,making the acoustic channel can use a lower frequency, and the bandwidth which canbe used is limited. With these features of underwater acoustic channel, we need to usesome communication algorithms to overcome these problems for better communication.Fractional Fourier transform can be understood as chirp-based decomposition of alinear FM signal (chirp).This paper used linear FM signal as a modulation signal, takingadvantage of a linear FM signal in the fractional Fourier transform domain of energyfocusing properties, can improve the system’s anti-noise, anti-multipath interference andfrequency selective fading ability.This paper first designed and implemented a hardware platform with a FPGA chipas a digital signal processor, then debugged and configured the hardware platform ofthe data path. Designed Ozaktas sampling-based algorithm module as the core withVHDL language, researched the algorithm of based on the U-domain modulationfractional Fourier communication and the algorithm of based on fractional Fourier forOFDM communications and implemented the VHDL modules. Finished the jointdebugging of sending and receiving communications modules based on the U-domainfractional Fourier modulation algorithms on the hardware platform, the requirement ofcommunication has realized successfully.