| 摘要 |
PURPOSE:To exercise AGC by substituting a video signal with a reference white level signal at a transmission side, and detecting the peak of a TV signal at a reception side, and detecting and using the level of the reference white level signal invariably. CONSTITUTION:An analog switch 22 alternates a TV signal from a camera 1 and a standard white level signal 23 under the command of a switch controller 21 to substitute the video signal with the white level signal approximately once per tens or hundreds of lines. At a reception side, a signal from a transmission line 4 is amplified by an AGC amplifier 5, whose output is extracted partially by a branching circuit 24; and a detecting circuit 7 detects its peak value, and an error amplifier 8 adjusts the gain of the AGC amplifier 5 so as to coincide the detected value with a set value 9. |
