Study And Realization Of Power Line Spread Spectrum Receiving System

Power line carrier communication has been gradually developing in recent years.It uses the existing power line network as transmission media and is paid more andmore attention by its advantages, including less investment, convenient connection,wide coverage and so on. However, to some extent, the reliability of power linecarrier communication is affected by the transmission channel with stronginterference and noise. This paper researches a scheme of carrier communicationsystem which is suitable for the environment of power line by using spread spectrumcommunication technology. Moreover, it also studies and proves the former researchof power line carrier communication by means of appropriative Integrated Circuitdesign.This thesis mainly discusses the domestic channel characteristics and builds anapproximate power-line channel model, then analyzes spread spectrum technologyand studies an improved sliding correlation acquisition and digital matched filteralgorithm. Furthermore, the simulation model of spread spectrum communicationsystem is built in the environment of MATLAB/SIMULINK and the simulationresults are also analyzed. At last, the hardware development of this spread spectrumsystem is realized and the required function is obtained.This paper studies an improved sliding correlation algorithm. And compared withthe traditional sliding correlation algorithm, the new one has better acquisitionperformance in the low-voltage power line environment. Also, the best band is got bydiscussing the center frequency of band-pass filter in the new algorithm. At last, thedigital matched filter algorithm is studied.According to the theoretical research, the scheme of spread spectrumcommunication system has been determined, including using digital matched filteralgorithm as the synchronous acquisition method and Costas as the carrierdemodulation method. Then the spread spectrum system is simulated in theenvironment of MATLAB/SIMULINK and is proved in the theory.Based on the simulation above, the hardware development of this spread spectrum system has been implemented. Using the hardware description languageVHDL, some modules of the spread spectrum system are developed in theenvironment of ISE, such as sending module, synchronous acquisition module, carrierdemodulation module, judging module and so on. Then the hardware system is alsosimulated in the environment of Modelsim. And the simulation result shows that thisspread spectrum system accomplishes the preliminary communication function. Andsummary and prospect on this system are given at the end of this paper.