Power Line Communication System Design Based On MFSK

The progress of science and technology promote the rapid development of communication. In the information age of today’s society, the transmission of information and communication is the foundation of other information technology. Power line communication is a communication method using the ubiquityous power line to transmit data. Because of the universality of the power line,it do not need to set up a new line to communicate but directly uses existing power lines to transmit information. Build a communication network without new spending and can easily plug and play features are more and more attentionDigital communication is the important method and means of information transmission.Digital frequency modulation is a modulation method are commonly used in digital communication. Binary frequency shift keying(2FSK) method which can be asynchronous transmission is simple, easy to implement and demodulation do not need to restore local carrier. anti-noise and anti-fading performance of the method is also strong. Therefore, 2FSK modulation technology has been widely used in the communications industry, and is primarily suitable for low, medium speed data transmission. MFSK is a promotion of 2FSK system, under the same symbol transmission rate, MFSK information transmission rate is higher than 2FSK information transmission rate, which improve the effectiveness of the system.This paper firstly describes the concept of power line communication, introduces the development of it at home and abroad, and gives a brief introduction of FPGA technology, digital modulation technology and the filter theory. Then the paper gives related technical principles involved in this paper a necessary theoretical analysis, ready to related theory basis for system design. On this basis, the paper discusses the detailed design of the power line communication system,including the transmitter and receiver modules implementation principle.after that the paper make the transmitter and receiver floating point and fixed-point simulate to determine the fixed factor by MATLAB. In the end we built FPGA hardware platform, and the system is developed to run on the board, and tested the actual hardware debugging environment.The key of this paper is the design of modulation and demodulation algorithm. When an alarm signal is generated, an alarm signal together with the device address information begin to frame. A binary signal after RS coding, 8FSK modulation, DA converter couple to the DC power line to transmit. Signal received by the receiver through the AD conversion, digital down conversion, IIR low-pass filter and into 8 demodulator. In each demodulates the signals are multiplied by sine and cosine carriers, and passed IIR low-pass filter, square sum and square root. Then the 8 demodulator demodulates the signal and send it into a sampling decision device to obtain a signal frame. Finally warning signal is obtained by RS decoding.In this paper, the design of modulation and demodulation system based on MFSK achieve the design goals. The system can also be used in smart home and smart medical field, you can take advantage of the power line to achieve household appliances control and the real-time monitoring of residents’ health.