| 摘要 |
PURPOSE:To make accurate adjustment with simple constitution by extracting at least an audio IF signal and an AFT signal from the output of a phase comparator. CONSTITUTION:The output signal of a limiter 8 is supplied to a pi/2 phase shifter 17 to generate a signal pi/2 out of phase with a video carrier, and the signal from the limiter 8 and that from this phase shifter 17 are supplied to a multiplier 19. At the output terminal 11 of the multiplier 19, a signal having a suppressed video signal component appears, and this signal is supplied to a 4.5 MC tuning circuit which is not shown in the figure to extract an audio intermediate frequency SIF signal. The signal appearing at the output terminal 11 is supplied to an LPF13 and an AFT signal is supplied to a local oscillator 4. Consequently, a BPF, a limiter, etc., are used in common to simplify circuit constitution, and adjustment points are less, so the adjustment is easy, thereby making the accurate adjustment. |
