| 摘要 |
PURPOSE:To prevent a video FM modulated signal component from leaking into a video signal by multiplying the carrier frequency of an FM-modulated signal by four. CONSTITUTION:The video FM-modulated signal is inputted from a terminal A to a transversal filter 1 and a full-band passing filter 2, and then FM-modulated signal which are 90 deg. out of phase relatively are obtained over the entire frequency range. Outputs of those filters 1 and 2 are supplied to limiter circuits 3 and 4 and full-wave differentiation circuits 5 and 6. Consequently, both differentiation circuits 5 and 6 output a compressional wave of plses of doubled carrier frequency. Their compressional waves are added together by an adding circuit 7 to obtain a compressional wave of pulses of four-fold carrier frequency, which is supplied to an integration circuit 8. Thus, the carrier frequency is multiplied by four, so the video FM-modulated signal component is prevented from leaking into the video signal. |
