The Application Of High-speed And Real-time Tecnologies In Underwater Acoustic Communication On OFDM

The purpose of the underwater acoustic communication system lies in dependably transmitting the signal from the source to the end through ocean acoustic channel at high speed. Narrow bandwidth and strong interference introduced by multipath are the main obstacle of the underwater signal's credible and high-speed transmission. Thus projects of high speed and fidelity underwater signal transmissions, the designing and realizing of OFDM system become a hotspot in the fields of academic circles.Employing the DSP technology, we can carry out the real-time FFT algorithm, which is the kernel in OFDM technology. With the developing of DSP and VLSI technology, OFDM develops rapidly and becomes one of the promising high-speed signal transmission technology in practical applications.In this paper, for the merits of high frequency spectrum utility factor and parallel transmitting of multi-carriers, OFDM, which is combined with channel coding, is introduced into the underwater acoustic communication to combat the frequency-selective fades and ISI in the underwater acoustic channel, and it finally achieve high speed data transmission. In this paper, computer simulation is first accomplished. Then the proper parameters are chosen to realize a simple communication system according to the results of the simulation. The system is based on TI TMS320C64x+, in which there are transmitting part and receiving part. Corresponding functional modules are used, including scrambling and descrambling, coding and decoding of the channel, modulation and demodulation, channel estimation and so on. We are able to achieve a reasonable real-time high-speed underwater acoustic communication system. The system can carry out a test in the channel cistern of HEU, and achieve the communication effects.