The Design Of DS-based Power Line Digital Communication System

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. At the same time, if we can apply the spread spectrum technique on power line, improve the quality of the power line carrier communication, make the better use of the existing power line resource, then we can resolve the channel-lacking problem and overcome complex channel character, bring direct and considerable social economic benefit.Based on these problems, this paper makes street lamp's intensive manage system for example and desigrs a communication system based on direct sequence spread spectrum modulation and demodulation technology on power line, and aims at the problems which emerged during tests brings forward resolvents. The actual tests and analyses show that the system has excellent performance , strong anti-interference capability , good reliability and high performance-price-ratio and can be used in such middle &. low speed data transmission occasions with higher demand of communication reliability as Distribution Automation, Automatic MeterReading System> Industry Control.This paper first analyzes the low-voltage power line channel character and establishes the corresponding channel model. And then introduces principles of DS technique, methods of implementation and discusses the feasibility and superiority of taking DS technique for the modulation plan of power line carrier communication in detail. Secondly, the hardware design & the software development are thoroughly discussed. The hardware design includes PL2101 and AT89C2051 power line node, assistant magnify control circuit. The software development comprises the compile of the microcontroller's assembly program and the compile of the communication program between the computer and the microcontroller. Subsequently, the paper aims at the problems what were emerged during tests brings forward resolvents. At last, the debugging and the program between the computer and microcontroller.