Simulation And System Implement Research Based On PLC Technology

Among various communication technologies employed nowadays, power line communications (PLC) gains more and more attention. Employing the power line as the communication media, PLC can take full advantage of the existing equipments and networks and possesses the advantages of repeated construction avoidance, the equipment simplicity, the prompt effect as well as the robustness to destroy. On the other hand, as the transmission media, power line exhibits unfavorable properties such as heavy load, severe noise and interference, serious channel fading and multipath delay and so on.First of all, the thesis analyzes and simulates the impedance, noise and signal attenuation characteristics of power line through MATLAB in detail, based on which, the noisy environment characteristics including the background and impulse noise, as well as the channel fading characteristics caused by signal attenuation and multipath propagation, are obtained. Further, the error rate performance of high data rate wideband PLC system using orthogonal frequency division multiplexing (OFDM) technique is simulated. In order to improve the system performance in the multipath fading channel, schemes involving channel estimation, frequency domain equalization and frequency diversity are introduced. Simulation results presented show that the multipath fading effects on PLC system are mitigated to some extent, which brings better error performance.Secondly, in the thesis, hand-writing input application and PLC technique are combined to implement a complete PLC-based hand-writing system. Transmitting hand-writing information through power line, the system can take full advantage of PLC technique to meet the specific needs of different users, including special environment, long distance, multipoint input and so on. Based on the integration of hardware platform and software program, the system can implement functions including hand-writing input information collection, encoding, modulation, demodulation, interface conversion, system control and so on. The final testing results presented indicate that the system is able to implement reliable hand-writing input and PLC transmission, and the design demand is achieved on the whole.In the end, a high data-rate wideband PLC modem based on INT5200 chip is designed. The modem consisting of Ethernet physical interface, INT5200 module, transient protecting module, power supply module, logic reset module and so on can be used for the construction of local area network (LAN) and the access to Internet. Detailed discussions on the circuit design are provided.