| 摘要 |
PURPOSE:To minimize attenuation or the signal level by using one specific phase of a three-phase commercial frequency as a carrier for transmission and controlling the end point of transmission command data, which is sent to the transmission equipment in each substation, to the phase other than the zero-cross point of this specific phase. CONSTITUTION:One specific phase of the three-phase commercial frequency on the side of a transmission equipment 1 passes an LPF 3 and is superposed on the MODEM carrier of a communication line 4 and is transmitted to the side of a center device 2. On the side of the center device 2, the commercial frequency of the specific phase and the MODEM carrier are divided by an LPF 5 and an HPF 6 respectively and are inputted to a transmission/reception circuit 7. The center device 2 transmits command data to the transmission equipment 1 in each substation at the timing based on the phase of the commercial frequency of this specific phase by the control of a controller 8. The transmission equipment 1 generates a carrier based on the commercial frequency of the specific phase, which is transmitted to the center device, by multiplication or frequency division after multiplication in a multiplying circuit 9 and a frequency dividing circuit 10 and receives command data from the center device to modulate the carrier. |
