IMPLEMENTATION OF A POWER LINE COMMUNICATIONS MODEM BASED ON OFDM

摘要

Implementation of a Power Line Communications Modem based on OFDM The aim of present invention is to implement a power Line Communication (PLC) modem on a platform consisting of a DSP and an FPGA MATLAB/SIMULINK model based on Orthogonal Frequency Division Multiplexing (OFDM). Since more than 50 years, the electricity grid is used for primitive signaling (e.g. switching of streetlights etc). The recent advent of powerful digital signal processors made a higher bandwidth power line communication (PLC) possible. The electricity distribution grid can provide a solution for the so-called last mile problem. Domestic applications such as automatic switching and alarm switching, metering i.e. measurement of energy consumption measurements and broadcasting tariff information as well as demand side management require a small bandwidth and that will be our prime interest. he purpose of the PLC modem is to transmit digital data over the power line in the analog form. A similar modem is required at the receiver side to convert the analog data received again into digital format. A parallel line is used to transfer data from PC to the DSP. The DSP containing PCB is located besides the FPGA daughter board. The DSP is connected to the FPGA which is connected to the AD or DA converters through a flat cable. The front end is connected to the power line through a transformer, which attenuates 50 Hz frequencies of the power mains. This modem configuration is implemented in three parts. Firstly a MATLAB/SIMULINK model is developed employing OFDM (Orthogonal Frequency Division Multiplexing) to divide the available spectrum into small bands employing an appropriate channel model. In the second part, VHDL code is developed to interface chip for AD and DA converter. Finally, the PLC modems is implemented on the DSP and an FPGA board for both transmitter and receiver sides as shown in the following figure