Underwater Acoustic Communication of FH-MFSK Method with Multiple Orthogonal Properties

In this paper, we propose an underwater acoustic communication of FH-MFSK(Frequency-Hopped Multiple Frequency Shift Keying) system with multiple orthogonal property. Generally, the processing of FSK(Frequency Shift Keying) method is simple, but it is vulnerable to ISI (Inter-Symbol Interference) caused by multipath transmission. In this paper, the orthogonal codes are generated with the same number of transmitting symbols, and these codes are corresponding to multiple frequencies. We used m-sequence to generate multiple orthogonal codes. We compared the performance of proposed method with conventional MFSK method via the experiment. As a result, we confirmed that the proposed method shows 6 similar to 10 % lower error rate at 100 bps than conventional method.