Design of FM-DCSK Waveform for Underwater Covert Communication System

The bit energy of chaotic signal in underwater covert communication system is not stable, which will cause the estimation interference and the bit rate decline. Therefore, the frequency-modulated differential chaos shift keying (FMDCSK) covert communication system was proposed which was combined the FM modulation with the differential chaos shift keying (DCSK) system. The bit energy of signals remained stable by using FM modulation so that the BER performance can be improved. Meanwhile, the system was also combined with the modified DCSK system which uses a two-channel scheme, therefore it can improve the transmission efficiency. In this paper, the feasibility of FM-DCSK was analyzed first. Meanwhile, the Matlab simulation contrasted the two different systems of FM-DCSK and DCSK. The simulation results show that the relative performance in this proposed system can be worked well.