Power-line Research And Design Of Direct Sequence Spread Spectrum Carrier Communication Module

Exchanging data through low -voltage powerline is a leading edge technology started in early 1990s . Because of its large latent markets and its wide applications, it is called "the undigged gold mountain". In terms of the difficulties of transcription of consumption of water, power and gas, this paper set up the goal of designing the powline carrier communication interface. This interface is the key part for remote transcription system based on powerline carrier technology.From the aspects of the channel characteristics of low-voltage powline, this paper analyzes the difficulties of communication through powerline . Signal attenuates sharply on powerline, noise is too high , impedence match is hard, and these characteristics are also time- varying, which contribute to the difficulty of powerlie communication and the design of the interface. After studying the powerline carrier technology domestic and overseas, this paper employs DSSS technology to overcome the attenuation and noise. 2FSK is used then to furtherly reduce the influence of noise. At the same time , several filters are adopted in hardware circuits. The reception chip MC13135 with high gain is used to promote the capability of anti-attenuation of the interface . The coupling part between hardware circuits and powerline consists of piezo-resistor,filter capacitances and coupling transformer so as to protect the interface and filt the voltage surge. ES16 is used to receive and send the signal of spread spectrum, and demodulate the received signal with software . Fault tolerant and two methods of falt check are employed here. Three kinds of experiments are done, including remote-data reading, effective distance of communication, and anti-interference as well.The results show that the designation of the communication interface is successful and reliable. At last, its further research is presented.