Research And Implementation Of The Low-voltage Power Line Communication Systems Based On OFDM

Low-Voltage Power Line Communication is a new way of communication to achieve signal transmission by the existing low voltage power line. Due to the huge power line network, there needn’t new lines for data transmission, as using the low power line, so it has a low cost, wide coverage and some other advantages. With the advances in signal processing and modulation technologies, the transmission rate of PLC system has gone from a few Kbps to several Mbps development. Currently, PLC has entered the high-speed era, and it has get a lot of attention in the era of smart home as well as get Internet by power line. Orthogonal Frequency Division Multiplexing (OFDM) is a multi-carrier modulation technique. It uses a plurality of mutually orthogonal sub-carriers for data transmission, and OFDM not only has high spectral efficiency, but also has a strong anti-multipath interference.This paper analyzes the basic principle of low-voltage power line communication system at first. The carrier system is divided into three parts of power line modem module, coupling/power amplifier modules and power line channel. The power line is mainly used to transmit electricity energy in the low-power network. The changing load in power line will make the channel environment to be very harsh when sending high-frequency signals. So, we will analysis the impedance, attenuation and noise characteristics. Beside, analysis OFDM technology principle and mathematical expressions, the guard interval and the cyclic prefix, also we will do some simulation analysis in MATLAB.Then, design a rail-to-rail output operational amplifier using the resources of the internship company. The operational amplifier is used to enlarge the signal power, when it was processed by the OFDM chip. The area of low power carrier equipment will be reduced when the operational amplifier chip will be used. Finally, complete the power amplifier module production, and combined with the existing power line carrier system platform for signal transmission. From observing the distance of the signal transmission as adding the power amplifier module or not, we know the module can improve the effectiveness and the distance in communication process.