| 摘要 |
PURPOSE:To generate a stable hue by causing an X-tal VCO (voltage control type crystal oscillator) to free-run with the carrier wave frequency to obtain a reference signal and by controlling the VCO, which oscillates with 160fH (horizontal frequency), by the output of phase comparison between the reference signal above and the reproduced burst signal. CONSTITUTION:At a reproducing time, switches SWs 3, 20, 30 and 31 are switched to positions opposite to recording positions. By switching of SW 30, X-tal VCO 22 free-runs with the carrier wave frequency, and the output becomes a reference signal. The output of VCO 22 and the burst signal in the output signal of 1HDL (delay line) filter 10 are compared in phase with each other, and VCO 14 is controlled by this output. Here, when the output frequency of four-phase logic circuit 17 is denoted as fr, the output frequency of BPF 19 becomes (fsc+fr) (however, fsc is the carrier wave frequency), and the carrier wave frequency of the output signal of BPF 9 becomes (fsc+fr+40fH). Since this frequency is so controlled that it may be the reference signal, fr=40fH is true, and VCO 14 becomes 160fH. |
