The Application Research Of Low-voltage Power Line Carrier Communication Technology

With the development of communication technology, more attention has been paid to PLC (Power Line Communication). Using existing power lines to achieve data communication has many advantages, including decreasing the building cost of communication network, predigesting the communication equipment, taking effect quickly, hard to be destroyed, keeping in step with the building of power electric system and so on. It can realize the transmission of data, audio and video while transmitting the power. It also can provide telemonitoring and long-distance meter reading. After compared with several methods using in PLC, this paper selects FH (Frequency Hopping) in order to make the communication more reliable. FH has the anti-disturbance, anti-noise and anti-attenuation characteristics, lower bit error rate and multi-user function. As the power line is a hostile environment for carrier signals, these advantages make FH to be the suitable method to be used in low-voltage power line carrier communication. A bi-computer communication system based on FH is developed in this paper and it will be the model for further researching.Power line is not suitable for transmitting signals. Serious disturbance and attenuation exist in it. On the basis of the early research findings, together with the measure system, this paper deeply discusses the impedance, attenuation, noise and disturbance characteristics of the power line and give several communication policies. The theory, advantages, implement method and characteristics of FH are deeply discussed and the system schematic diagram is gotten. The entire hardware system includes the interface circuits between SCM (Single Chip Micyoco) and PC, SCM control circuits, power supply circuits, modem circuits and power lines coupling circuits. The paper emphasizes the hopping frequency generator and the achievement of synchronization. The hopping frequency generator is made up of crystal oscillator, frequency selecting unit and frequency dividing unit. And it use SCM to control the hopping of frequency. SCMs are programmed in order to achieve the synchronization communication. The entire software system includes the serial communication between SCM and PC, the...