Research Of The Underwater Acoustic Spread Spectrum Communication System

In all communication channels, underwater acoustic channel is the most complex, and its fading, multipath effect, time-variation effect making many classic communication technologies can not be directly applied to underwater acoustic channel. Spread spectrum communication in the current military and civil has extensive application. At the present time, in the many underwater acoustic communication systems, spread spectrum communication of is catholic concern. This paper discusses the system.In the transmitting terminal, spread spectrum communication modulate the base band signal by PN code(its rate is far higher than the base band signal)to make the signal into the very low power spectral density broadband signal. In the receiving terminal, the system related to method uses to make the broadband signal into the base band signal. These features can make the signal stronger anti-jamming performance, good hidden and strong confidentiality, and so on.In this paper, a spread spectrum communication system—the minimum frequency shift keying (MSK), which is a continuous phase modulation techniques, and which can eliminate the phase mutation is used. First, this paper analyzes the fundamental principle of the MSK signal, the phase path diagram and the power spectral, then, configures the model framework, for the consideration of complex system, and use phase comparison to implement the difference demodulation. The synchronous modules use the slip correlator having stepping, with introducing many of the current commonly used synchronous modules. Finally, from the consideration of reception and synchronous, this paper gives the system simulation and performance analysis, and calculates the error rate of demodulation and synchronous, and gives the capture time of slip correlator which can prove to save the capture time.Analysis shows that this MSK spread spectrum communication system in the underwater acoustic channel is feasible.