| 摘要 |
PURPOSE:To perform accurate reception at all times, by detecting a signal level most suited to the accurate reception of information at a reception side and transmitting the information at a transmission side prior to the transmission of the information. CONSTITUTION:A central processing device 1 given with a transmission instruction (t) drives a check data generating means 5 of a transmission level and a timer 6 prior to the transmission of information. A check signal from the means 5 is modulated at 7 and the amplitude is adjusted at 8 via a level adjusting means 11 and transmitted to the reception side from a coupler 9 via power lines l1 and l2. The level of a check signal is detected at 20 from a coupler 17 via a high-pass filter 18 and an amplifier 19 and its detection signal is discriminated 22. At the transmission side, if no response signal is transmitted from the reception side even with a prescribed time of the timer 6 elapsed, it is judged as insufficient level of the check signal and a signal to increase the level of the check signal from the device 1 to the means 11 is outputted. |
