Direct Sequence Spread Spectrum Underwater Acoustic Communication Based on Differential Correlation Detector

Taking advantage of the spread processing gain, direct-sequence spread-spectrum (DSSS) underwater acoustic (UWA) communication system can be carried out at low signal levels, which is the preferred method for high quality UWA communication and remote UWA communication. However, phase fluctuation caused by complex marine environment and Doppler affect seriously affects the performance of spread spectrum system, leading to the spread processing gain reduction. Differential correlation detector (DCD) that is suitable for the receiver of a direct-sequence system is proposed in this paper, whose outputs is got from conjugate multiplication of adjacent spreading symbols. This method is insensitive to the phase fluctuations and multipath interference. Good performance is achieved for a signal-to-noise ratio (SNR) as low as -10 dB based on at-sea data.