| 摘要 |
PURPOSE:To miniaturize a modulator without using a lead filter by holding frequency precision in a stereophonic broadcast and bilingual broadcast by dividing two frequencies from a reference oscillator into prescribed frequencies by a low- frequency oscillator. CONSTITUTION:To reference oscillator 7 of oscillator 1 for a TV sound-multiplex control signal subcarrier, switch 8 changing frequencies of oscillator 7 is connected and through the switching of switch 8, oscillations are changed over from predetermined frequencies f1 and f2 to frequencies 2N1f1 and 2N2f2. Oscillation frequencies 2N1f1 and 2N2f2 from oscillator 7 are applied to frequency-division-ratio change- over part 9 of low-frequency oscillator 5 and through the switching of switch 10, frequencies 2N1f1 and 2N2f2 are divided by N1 and N2 respectively; and the output is applied to frequency-having part 11, which generates an output with a duty ratio of 50%. The output of frequency division part 11 is applied to modulator 6 via LPF12 and oscillation frequencies 2N1f1 and 2N2f2 from oscillator 7 are modulated to miniaturize the modulator. |
