The Research And Realization Of Long-distance Data Communication Demodulation By Software

The Communicate technique melts into the computer and the digital signal technique took place revolutionary variety. Communicate technique computer technique combining with digital signal technique is a sign of modern Communications. At the time of the communicate technique to develop quickly,the HF communication also developing fast. The HF communicate distance is far, and it have strong ability of anti-ruin and self-determination, and low cost. These advantages making HF communication become an important tool in long-distance communications. In recent years, people adopt multi- kind measures to counteract eclipse and multi pathway, such as kinds of coding technique, mistake control technique, modulate and demodulate technique, equipoise and expand frequency technique, and these measures effectively boost up the communications ability of the HF communicate system, and lowered the mistake code rate effectively. That is ,the HF communication can be an important manner to transmit the data signal of.This text mainly based on the characteristics of HF channel, choosing several technicals of communication. and study deeply. Analyzing and emulating the choose showed its feasibility,then using the software ,and establish the system to solve the demodulate of long-distance data signal.The system can carry digital processing quickly and precision, and it can offer some kinds method of solution for signal processing. Here studys two kinds of modulating ways, including 4 FTSK and the Raised cosine. The error control encode chooses the linearity grouping code, and adopt the technique of interleaver and deinterleaver which could solute abrupt false. In the HF demodulation system of raised cosine modulation , time -domain equalization, spread spectrum and despread spectrum are widely used . Based on computer simulation , using software...