| 摘要 |
PURPOSE:To enable to reduce the deviation of gain control between a plurality of channels, by level detection for the reference channel signal only and constituting the AGC loop at each channel. CONSTITUTION:The reference channel signal S component branched 7 is modulated 8, it is superimposed on the ERROR signals E1, E2 at the mixers 9a, 9b and it is branched into the reference channel signal and ERROR signal via the high frequency amplifiers 1a, 1b, mixers 2a, 2b, and gain variable amplifiers 3a, 3b, for level detection 4a, 4b, and after the reference channel level detection signal is in DC amplification at 5a, 5b, it is added at 10a, 10 b with the reference channel gain control signal A being the ERROR channel gain control signals B1, B2, to constitute the AGC loops 11a, 11b to control the gain of the amplifiers 3a, 3b, and the level of the reference channel signal component at the input terminal of the detectors 4a, 4b is kept at a given level according to the branching of the level branch unit 7. Thus, the deviation of gain control between a plurality of channels can be reduced. |
