수중음향통신시스템의 구현 및 실시간 시험

Abstract

This paper deals with an implementation and it's real-sea test of an nderwater acoustic communication system,which allows the system to reduce complexity and increase robustness in time variant underwater environments. For easy daptation to complicated and time-varying environments of the ocean, all-igital transmitter and receiver systems were implemented. For frame synchronization the CAZAC sequence was used, and QPSK modulation/ demodulation method with carrier frequency of 25kHz and a bandwidth of 5kHz were applied to generate 10kbps transmission rate including overhead. To improve transmission quality, we used several techniques and algorithms such as adaptive beamforming, adaptive equalizer, and convolution coding/Viterbi decoding. For the verification of the system performance, measurement of BER has been done in very shallow water with depth of 20m at JangMok, Geoje. During the experiment, image data were successfully transmitted up to about 9.6km.