High-speed Underwater Acoustic Communication Technology Research Based On Sound Card

With the development of the ocean exploration and the information industry, therequirements of the underwater acoustic communication systems with high-speed andhigh-reliability are growing day after day. Based on the development trend of modernunderwater acoustic communication, to realize the high-speed, high-capacity andhigh-reliability communication is becoming a research hot in underwater acousticcommunication. Because of the bad transmission characteristics of the marineunderwater acoustic channel, the realization of the high-speed and reliable informationtransmission in the ocean has become a challenging issue. In this article, theapplication of the PSK modulation in the high-speed underwater acousticcommunication technology is deeply studied, based on the core of the computer soundcard, the starting point of the research of the high-speed and high-reliabilityunderwater acoustic communication. In addition to this, the method of thesynchronous coherent demodulation based on the software phase-locked is designedcombined with the characteristics of the underwater acoustic channel in marineenvironment.Firstly, the basic characteristics of the ocean water and the basic performance ofthe water acoustic channel are analyzed briefly. The coherent communication andnon-coherent communication in underwater acoustic communications are compared.Then, based on the analysis of the underwater acoustic channel, the advantage of thecoherent communication in underwater acoustic communications is introduced. Andthe application of the PSK modulation in the high-speed and high-reliabilityunderwater acoustic communications is researched deeply.Secondly, the basic features of the sound card is introduced. With the example ofAC97 sound card, the linking standards and the reduction of the sound card areanalyzed. The collection and preservation of the audio signals with the core of thesound card are analyzed carefully. Besides, the endpoint detection of the collectedaudio signals is processed using voice activity detection, and the test results are achieved.Thirdly, through the research of the synchronous technology and based on theCosta ring, the demodulation of the BPSK signal is accomplished using the softwarephase-locked loop. The demodulation process is showed out.Finally, the analogical experiment of the underwater acoustic communications isrealized with the MATLAB and VC++ as the software platform, with the core of thesound card and microphones. The experiment results verify the feasibility of the PSKmodulation and the phase-locked loop in the high-speed and high-reliabilityunderwater acoustic communications.