REFERENCE LEVEL ADJUSTING DEVICE OF VIDEO SIGNAL

摘要

PURPOSE:To reduce the fluctuation of the gain of an FM modulator by controlling a transmission frequency and a gain by the 1st and 2nd error signal obtained by comparing two signal components of a video recording signal with different reference frequency respectively. CONSTITUTION:The N-channel of video signals S31-S3N are transmitted to frequency-gain automatic adjusting circuits 121-12N via a serial-parallel converter 11 from a video signal S1 incoming from a camera 3. The video signal S31 of the 1st channel is given to an FM modulating circuit 16 via a gain control circuit 15, this FM modulation output is transmitted as a recording signal S21 of the 1st phase and applied to an automatic frequency adjusting circuit 17 and an automatic gain adjusting circuit 18. The carrier frequency of the 1st phase recording signal S21 is adjusted automatically by an output of the automatic frequency adjusting circuit 17, the output of the automatic gain adjusting circuit 18 is fed back to the gain control circuit 15 so as to adjust automatically the level of the 1st phase recording signal S21.