The authors are developing the technology of total distribution automation for performing load control, line switch control and automatic meter-reading by using ripple control (outbound signal in middle-tension voltage), current answer-back signal (inbound signal in middle-tension voltage) and phase pulse signal (two-way communication signal in low-tension voltage distribution line). This paper covers the waveform-detecting method which has been developed as the sending and receiving technology by phase pulse signal. It also shows that, by application of the waveform detecting method, more than 99.9% of total communication performance is secured.