| PLC refers to the data transmission and information exchange over power line. PLC technology develops rapidly along with the development of modulation, data transmission and signal processing technology. It now adopts multi-carrier modulation instead of traditional single-carrier modulation. And transmission rate has significantly increased. At present, the PLC has entered the era of high speed and because of its advantages of no re-wiring and low cost, it has been studying in many areas such as smart home networking, broadband access and so on. Orthogonal Frequency Division Multiplexing (OFDM) is the key modulation technology of the high-speed, low-voltage power line communication. It is a multi-carrier modulation technique and also a kind of multiplexing using a number of mutually orthogonal subcarriers to transmit information. OFDM not only greatly improves the spectrum efficiency, but also effectively overcomes the frequency selective fading and multi-path delay in low-voltage power line channel and achieves high-speed and reliable data communication.This paper introduces the conception of PLC and its development situation, studys the basic characteristics of power line channel, analyses the trait of power line channel as communication media, establishes a useful channel model and briefly introduces the agreement of physical layer and media access control layer in the power line network communication protocol HomePlug 1.0. Then,it gives the principle of OFDM modulation and demodulation techniques, establishes a low-voltage power line communication system based on OFDM techniques with simulation software.The power line channel estimation methods have been given. At last, this paper describes the design process of low-voltage power line modem by using Intellon Corpration PLC chip--INT5500, focuses on different parts of the modem system hardware design, PCB layout cabling, system configuration process, analyzes the prototype performance, and gives scheme to improve the design. |
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