| 摘要 |
PURPOSE:To form a high quality of FM signal for recording a required component by using DC components of a video signal, input amplifier for changing gain, voltage controlled oscillator for generating a carrier, frequency divider, and a digital AFC, etc. CONSTITUTION:Constant current proportional to an FM video signal to be controlled constantly its deviation by a volume 3 and its pedestal frequency by an AFC output and inputted through an input amplifier 2 is generated from a constant current source 5. An FM signal having frequency of twice the frequency of a carrier signal reduced at its linear distortion is outputted from a voltage controlled oscillator consisting of a capacitor 6, voltage comparator 7, switching circuit 8, etc. and reducing a delay part and a finely symmetrical signal is outputted from a 1/2 frequency divider 9. On the other hand, a digital AFC consisting of a gate circuit 13 to which said output is inputted, a pedestal frequency setting switch 16, a counter 14, a latch circuit, etc. generates an AFC output to be controlled uniformly with the set pedestal frequency even if temperature or the like is changed. |
