| With the rapid development of power undertaking of our country, the traditional ways of meter reading can not satisfy the demand of the market any more. Based on the vast collecting and consulting the concerned information of the remote meter reading system of home and abroad and going deep into the consumers and power consumption administrative departments to investigate and research widely, a remote meter reading system adopting carrier communication technology of the low-voltage power line(PLC) had been proposed in this paper. It had network structure of three layers, i.e. the computer administrative system, concentrator and carrier meter. And the functions and characteristics of the whole system together with its every component had been analyzed.Because high attenuation, high noise and high distortion exist in the low-voltage power lines of our country, special communication technology must be adopted. Firstly, the transmission characteristic when high-frequency signal was transmitted through power lines was analyzed. Secondly, the application of spread spectrum communication technology to carrier communication of the power line was emphatically discussed. Thirdly, the interior principle of the special MODEM IC PL3105 adopting direct sequence spread spectrum communication technology was deeply studied. Based on this, PL3105 was selected to realize the reliable data transmission between the concentrator of the long-distance meter reading system and the terminal signal carrier ammeter.Being the heart of the automatic meter reading system, the concentrator connected the computer with the terminal carrier meter. The hardware and software system of the concentrator were emphatically designed according to the main functions and the demands for performance targets of the concentrator stated in the power trade standard of PRC. It was mainly composed of MCU,external expanded RAM, clock module, watchdog module, the computer communication interface circuit and the PLC communication circuit together with its peripheral circuits.During the design of the software, the communication protocols between the concentrator and the computer as well as the concentrator and the carrier meter were first established. Then the software of every functional module was designed. The program was designed according to the principle of modularization so that it could be easy to program, debug, modify and check errors.In addition, communication distance is the key of carrier communication of the power line. The software relay technology i.e. the carrier meters were relayed each other was designed in this paper so that the concentrator could automatically seek for relays. The relay link could be adjusted continuously and had the function of self-study. The restrictions of the relays as well as coding principles were also proposed in order to improve the efficiency of relay seeking.Finally, the concentrator based on carrier communication technology of the low-voltage power line designed in this paper wasconnected with the carrier meters as well as the computer administrative system designed by other cooperatives into an integrated remote meter reading system. After a great deal of experiments were carried on, the system passed the checkout and test of the national power industrial devices and instruments quality examination center on April 5th 2005 (the report number is PD2005003) at last. The report results indicate that the concentrator designed in this paper has perfect functions of data collection, processing, storage, setting and communication, and each performance target achieves the correlative standard stated by our country.
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