| 摘要 |
PURPOSE:To switch a system without debasing its frequency control capacity, at a low cost, by using a simple quartz oscillator for a color signal processing circuit, and switching the PAL system and the NTSC system by turning on or off this oscillator. CONSTITUTION:When recording, outputs of a 40fh oscillating circuit 5 controlled by a horizontal synchronizing signal fh applied to a terminal 4, and a changeover switch 6 are added by a converter 3, and only the sum frequency passes through a BPF 2, is supplied to a converter 1, and the input signal is converted to a low band. When inputting the switch 6, an (fsc+fh/8) oscillator 8 and a voltage control type quartz fsc oscillator 8 are selected in case of the PAL system and the NTSC system, respectively. A phase comparing circuit 10 is switched by a changeover switch 9 so as to control the oscillator 8 and a circuit system of the circuit 5, when recording and reproducing respectively. When reproducing, outputs of the circuit 5 and the switch 6 are added by the converter 3, only the sum frequency passes through the BPF 2, and is converted to its original frequency fsc by the converter 1. In this case, the oscillator 8 is made to run freely. |
