AUTOMATIC GAIN CONTROL SYSTEM FOR FREQUENCY MODULATION

摘要

The gain is controlled by transfering the reference voltage of a level comparator (4) of a gain voltage detector (3) according to the variation of the input level which is greater than the certain level so that the dynamic region of the gain control is extended in the VTR. The controller comprises an automatic gain control amplifier (1) controlling the input image signal to the certain level, a buffer (2) shifting the reproduced wave to the multiple terminals to repeat the gain control, a transfer circuit (6) changing the reference voltage level of the detector (3) according to the compared output of the comparator (4), and a reference voltage generator (5) supplying the reference voltage which level is changed by the circuit (6).