The Research And DSP Realization Of MC-MFSK In The Underwater Acoustic Communication

Once, Multiple Frequency Shift Keying (MFSK) and Frequency Hopping communication systems were the first selection as the underwater acoustic communication device for their robust performance and easy implementation. But, the decent performance with low frequency spectrum utilization limited their application in ever-increasing communication demand. It was mainly due to the limited communication bandwidth and time-vary and space-vary nature of the underwater acoustic communication channel. However, the developing of the communication technology, the Multi-Carrier Modulation technology and Orthogonal Frequency Division Multiplexing, for their higher using rate of frequency spectrum and stronger capability of mufti-route-interrupt resistance and the frequency choice decline, were widely used in the land wireless communication field now.Software radio was a new system structure in wireless communication that was put forward nowadays, which took hardware as a base platform for wireless communication and depended on software as much as possible to realize its function.Therefore, this paper mainly focused on the combination of MFSK system and Multi-Carrier Modulation technology with the Software Radio technology, and presents Multi-Carrier MFSK (MC-MFSK) transceiver scheme based on Software Radio platform. Meanwhile, the communication system based on Software Radio was researched in theory. Performance of the system was analyzed and evaluated in several aspects through simulation. On the basis of the system, frequency hopping Multi-user system was discussed primarily.In the DSP software design, accordance with underwater acoustic channel, a method of synchronization frame detection based on FFT was put forward in terms of Sliding Correlation theory. This method can avoid hard real time implementation of traditional synchronization frame correlation detection algorithm in the DSP platform.In addition, a method of synchronization frame detection based on FFT was put forward in terms of Sliding Correlation theory. It, taking advantage of the enfficient art of computation of FFT, settled the problem that routine correlation algorithm difficult to real-time implementation based on DSP.A new simple Doppler compensation method taken into account the characteristics of MC-MFSK system was proposed. The method complement the Doppler compensation using interpolation or decimation based on FFT in the demodulation of information without increasing calculations of the system, which was suited for hardware implementation such as DSP.At last, the performance of communication receiver system based on the MC-MFSK and FH-MC-MFSK was proved through the trial in the tank.