| 摘要 |
PURPOSE:To improve the capacity of a line correlating circuit to improve the quality of reproduced pictures by delaying a reproduced frequency modulation signal with a glass delay line by one period after converting it to a high band by the output signal from an oscillator and extending equivalently the signal pass band width of this glass delay line. CONSTITUTION:The frequency modulation signal (reproduced FM signal) reproduced by a video head 9 is amplified by a preamplifier 10 and is controlled to a certain level by an automatic gain control circuit 11. The reproduced FM signal subjected to band conversion is peaked by an SAW filter 14, whose group delay characteristic and amplitude characteristic can be selected independently, and passes an inversion preventing circuit consisting of a high band limiter 15, a low band amplifier 16, and a mixer 17 and passes a changeover switch 18 and is demodulated to a video signal A by an FM demodulator 1. Simultaneously, the reproduced FM signal delayed by a 1H delay line 19 is demodulated to a video signal B by an FM demodulator 2. In this embodiment, the wide-band glass delay line is used as the 1H delay line 19.
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