Notch Elimination by Halfway Termination of Powerline and Matched Coupling Method

On the powerline communication method, there is a problem of the notch frequencies of the powerline. The notch frequency is a frequency with very low impedance. It is generated by a reflection at the end of powerline. Data transmission is obstacle at the notch frequencies. Notch frequencies are unpredictable because they depend on the length of powerline and the length of powerline varies with user's circumstance. In the preceding technology, this problem was avoided with putting a matched terminator at the end of the powerline or using matched adaptive filter to avoid communication at notch frequencies. However, the terminator is not easily set up because it is difficult to find the end of the powerline in the practical situations. Matched filter needs high computational effort to find the optimum filter parameters. In this paper, it is presented that an improvement of frequency characteristics was observed in an experiment when the terminator was put on the halfway of the powerline. Further, a matched coupling circuit is proposed which enables communication through powerline between the two terminators put on the halfway of a powerline. In this method, terminators can be put on any places where two terminators sandwich communication sites. Hence, it would be much more applicable to most of practical situations where powerlines are covered by wall.