| 摘要 |
PURPOSE:To enable automatic gain control without giving interference to PCM- FDM signal, by picking up the pilot signal in PCM-FDM signal and suppressing the transmission level variance with this signal. CONSTITUTION:When a pilot signal in PCM-FDM signal is varied during transmission, the pilot signal picked up with a pilot filter 13 is rectified at a rectifying circuit 14, and a DC component is varied through an LPF15. This variable DC component controls the gain of an automatic control amplifier 11 and the variance of transmission level is suppressed. Thus, when PCM-FDM signal is located to the bands of a plurality of basic supergroups and transmitted, automatic gain control can be made without giving interference to PCM-FDM signal to make easy the long distance transmission. |
