Power Line Communication System Design Based On FPGA

PLC is a power line to transmit information and provide communication services technology, is one of the last one kilometer technical solutions for the information highway. PLC can use the existing power line network without additional wiring and can be deployed quickly. Transmission of information can be used powerful, reliable encryption method. Since the advantages of PLC are obvious, so the power line communication in the field of communications research is a hot topic. This project uses existing power line network for save the cost of establishing a communications network.FPGA can be programmed repeatedly and reused. FPGA integration based on look-up table is very high. It can complete very complicated temporal logic and function of combinational logic circuit, so this project adopts FPGA as the hardware platform.Digital frequency modulation and demodulation transport symbol by carrier frequency information. The multi-band frequency shift keying(MFSK) modulation and demodulation is one of the representatives of the digital frequency modulation and demodulation. MFSK communication equipment is not complicated, but also be easier to implement. MFSK can save hardware resources. This way of anti-jamming and anti-fading is excellent. Frequency modulation technique widely used in the field of communication especially is suitable for communication rate of communication system is not high. Therefore, the PLC system uses MFSK modulation and demodulation techniques. Anti-jamming and anti-fading ability of the system can meet the project requirements.In this dissertation, the key is to design the transmitter and receiver scheme. When alarm signal is detected in the transmitter, alarm signal and address information are combined into two symbols. These two symbols are mapped four symbols via RS(4,2) coding that later two symbols are redundant symbols, with error detection and correction. These four symbols into the frequency generator, it is mapped into seven frequencies, which a symbol requires seven frequencies. Digital signal output from the transmitter, via D/A conversion, is coupled to the power line. Modulated signal via the coupler and A/D conversion, enter the receiver. First, modulated signal is down-conversion, and then via IIR filter, high frequency information is filtered out and low-frequency information is sent to eight demodulators. Each channel signal is multiplied by the sine and cosine of the same frequency, through IIR filter, and then signal is squared and. At this point, only the amplitude information is generated. The sampling decider makes use of amplitude information to judge and obtain symbol information. Via RS decoding error detection and correction, the alarm signal is output and the alarm signal transmission completes.In this dissertation, the design of PLC system based on FPGA and MFSK achieves the design goals. This system can be applied not only to automatic meter reading system of the water table and gas, but also to medical care, underground communications, automatic alarms and other fields. PLC system technology has great advantages and prospects.