| 摘要 |
PURPOSE:To omit parts to make this circuit suitable for an IC by substituting a HPF and a shift register for the BPF for sub-channel signal separation. CONSTITUTION:FM-FM sound multiple signals are inputted to a HPF which is operated as a LPF for main channel signals and a HPF for sub-channel signals. Main channel signals are separated and are applied to L R signal selector switches SL1 and SL2. Sub-channel signals are applied to shift register SR. The shift register is driven by clocks obtained by subjecting chrominance subcarrier signals of 3.58M HZ, which are obtained in the TV receiver, to frequency division. The shift register is constituted by connecting flip flops in plural stages, and a desired delay time is obtained and pulse count detection is performed on a basis of the number of these stages. Demodulated sub-channel signals are applied to L R signal selector switches. |
