Research On The Technology Of Shortwave Broadband Streaming Media Transmission

HF communication plays a significant role in military communications. As an indispensable influential research field in HF communication, the transmission of digital voice signals is critical in military communications. The transmission technology of digital voice signals through HF 12 kHz channel with information rate at 600 bps is discussed in this thesis. The serial single-carrier modulation is adopted in HF communication system.The key technologies of HF broadband streaming media transmission system are studied in this thesis. First, the design scheme and the overall block diagram of HF broadband streaming media transmission system are given. And the transmitting procedure of streaming media waveform and the frame structure of transmission signal are discussed. Vocoder, CRC and waveform forming, which used in transmission systems, are also introduced.Then the direct sequence spread spectrum technology is described, focusing on the soft information extraction algorithm of spread spectrum system. Based on the existing Dual-Maxima algorithm, a modified soft information extraction algorithms is given. And simulation results show that the modified algorithm is about 1-2dB better than the Dual-Maxima algorithm.At last, Reed-Solomon codes used commonly as error-correction codes in practice is studied. The fundamental principle, the hard-decision decoding algorithm and chase decoding algorithm of Reed-Solomon codes are researched and simulated. And the performance differences between the hard-decision decoding algorithm and chase decoding algorithm is analyzed.