| 摘要 |
PURPOSE:To decrease data transmission time and also to improve the utilizing efficiency of a line by using plural carrier frequencies from a transmitter, applying different data processing to the carrier of different frequency, superimposing the processed result to a power frequency, allowing the receiver to detect the carrier at each frequency to attain data processing. CONSTITUTION:Transmitted data is prepared, a zero cross point is detected by the input of a zero cross point detection signal from a zero cross detection section 235 successively, the period at each bit is taken, the falling of the signal is detected and then after 3ms is elapsed, the carrier is controlled to be transmitted for, e.g., 4ms by controlling oscillators OS1, OS2 until no transmitted data exist. The carrier transmitted from a transmitter 23 and a receiver 24 is transmitted while being superimposed on the center of each cycle of the AC frequency. Thus, the receiver 23 and the transmitter 24 receiving the signal in this way detect the zero cross point from the power supply waveform only and generate one pulse zero cross detection signal surely. |
