Power Line Communication Method Analysis Based On Chaos Spread Spectrum And Wavelet Denoise

The Power Line Communication (PLC) is a kind of rising communication mode differing from traditional communication such as telecommunication, telephone, radio communication, etc. Along with the pace of global networking quickening, information networking and control automation have become the pressing requirements of every industry for improving efficiency and realizing modernization. So it has very wide application prospect. Power line carrier communication technology adopts power line as communication medium and possesses the merits of making full use of resources on hand, easy construction, low comprehensive cost, being unrestricted by environmental conditions. But power line is characteristic of violent change in amplitude-frequency peculiarity, narrow effective band, complex channel character, which needs higher comprehensive characteristics.The spread spectrum (SS) communication system has stronger ability of resisting jamming, narrow band, and multi-path interference than that of the conservation communication system. And because of its lower transmitting power spectrum, it also has the characteristics of low probability intercept and multiple access secure communication. Though, in the existing spread sequences system, the m and Gold sequences are used widely, which are generated by the longest linear shift register, they all have the limitation of length and number in some sense. The discovery of chaotic dynamic system broad the way of study of PN sequence.This dissertation first analyzes the power line channel character and establishes the corresponding channel model, and then discusses the advantage of DSSS technology to use in power line communication. Subsequently, this dissertation introduces the chaotic digital spread spectrum sequence's production method, the characteristic and the application performance, proposes a new method to generate chaotic sequences based on delay interlude, analysis the new sequences'characteristics and proves the good performances of the new sequences to be use in power line communication spread spectrum. Uses the Matlab and Simulink set up a chaos spread spectrum communications system model, to the commonly chaotic sequence spread spectrum system, the proposed new chaotic sequence spread spectrum system and the Gold sequence spread spectrum system carried on the error rate simulation computation, compared with the different spread spectrum sequence ability of resisting jamming, narrow band, and multi-path interference performance fit and unfit quality, proves the superiority performance of the proposed method in this paper. In order to enhance the system's ability of anti-noise, proposes a de-noise method of association new threshold with translation invariant wavelet, to use this method de-noise the power line signals. This method decomposes the power line signals with noise, then in different scales chooses new thresholds and shift, in the end reconstruct the power line signals. Simulation results indicate this method can improve the signal ratio noise and minish the error. Uses the Matlab and Simulink set up a chaos spread spectrum communications system model, to the chaotic sequence spread spectrum system with noise, the new wavelet de-noising chaotic sequence spread spectrum system and the traditional wavelet de-noising chaotic sequence spread spectrum system carried on the error rate simulation computation, proves the dominance of error rate in chaotic spread spectrum system with wavelet de-noise.