| 摘要 |
PURPOSE:To reproduce a tape recording a sound signal on one channel or two with a simple circuit by detecting the presence or absence of an FM sound carrier during a vertical blanking period at reproduction. CONSTITUTION:A reproduced sound signal from a magnetic head 1 is amplified by a head amplifier 2 and a luminance FM signal from an HPF3 is demodulated by an FM demodulating circuit 5. A low frequency modulating chroma signal from an LPF6 is processed by a color reproducing processing circuit 7 to form a modulating chroma signal of carrier frequency. Further, an audio signal on the 1st and 2nd channels from BPF10, 13 is demodulated by FM demodulating circuits 11, 14 and an output of the circuit 11 is outputted to an output terminal 2. Further, an output of the circuit 14 is applied to a gate circuit 17, where the output is gated by a pulse in the vertical blanking period from a pulse generating circuit 20. Further, a detector 18 detects the presence or absence of the sound carrier and outputs a demodulating signal of the 2nd channel to an output terminal 16 by turning on a switch circuit 15, and eliminates the FM carrier in the 2nd channel in the luminance signal by turning on the trap circuit 4. |
