The Research Of Underwater Acoustic Digital Radio Transmission System Base On DSP

Digital, broadband is the focus of today’s wireless communication, newtechnologies continue to emerge that the traditional design method has been eliminated.In recent years, with develop of modern marine science and technology. Especially forocean exploration method continuous improvement, the sonobuoy system as animportant survey method develops from analog signal to digital signal. The analogsignal is used to transmit the data by traditional underwater acoustic data transmitter.This method can not realize the intelligent control. It particularly susceptible to oceannoise and other interference factors in the sea surface communication channel. It alsoseriously affect the sea detection accuracy can not meet the demand for air detectionaccuracy. Along with the development of wireless communication technology and thepopularity of the DSP development, digital modulation method weakened thedisruption of the underwater acoustic data in the wireless transmission to a certainextent，in order to meet the rising air detection accuracy requirements.According to the theory of software wireless and the characteristics of sea surfacecommunication channel, a digital upconverter frequency modulation structure oftransmitter system which is suitable for buoy system is researched in this paper. Baseon the characteristics of buoy, the system modulation mode and the modulatorstructure are discussed, and through the comparison of several modulation schemes,finally the GMSK modulation is selected as the baseband modulation mode. At thesame time, the mode of waveform storage and orthogonal modulation is selected as theoutput mode of system modulation, which can digital achieve the GMSK modulation,this method can avoid complex filter design and implementation, and can producebaseband pulse shape and modulated signals with any characteristics, not only savingcomputing resources, and reduces the time delay of the system. The data compressionmethod of the underwater acoustic signal is analyzed according to the characteristicsof underwater acoustic signal processing, and the CVSD coding in waveform coding is selected, and its encoding algorithm is discussed. Use the combination of FPGA andDSP when designing the system hardware, and design a reliable underwater acousticdigital wireless data buys transmitting circuit. The hardware includes DSP circuit,FPGA circuit, I/O modulation circuit, frequency conversion circuit and peripheralinterface circuit. At the same time the hardware interface is configured in DSPdevelopment environment, provides an efficient DSP signal transmission andprocessing flow, to achieve the real time transmission and processing of signal.Simulation results show that the system can realize the wireless transmission of theunderwater acoustic data. The research of this paper provides a practical project andreference basis.