| 摘要 |
PURPOSE:To realize an FM demodulation of a wide-band signal with no distortion, by applying the output of an amplitude limiter to a frequency discriminator via a filter that prevents a signal having a double frequency band to an input signal. CONSTITUTION:A signal received an FM demodulation by a video signal is supplied through an input terminal 1 to an intermediate frequency amplifier 3 via a band-pass filter 2 to be led to an amplitude limiter 4. The upper and lower parts of a signal wave are clipped, and the output of the limiter containing a higher harmonic component is supplied to a filter 9 that prevents the 2nd higher harmonic component. The output of the filter 9 is supplied to a frequency discriminator 6 and then extracted through an output terminal 8 in the form of a video signal component after passing through a low-pass filter 7. The components higher than the 3rd higher harmonic wave of the output of the limiter 4 are sufficiently away from the signal frequency and accordingly suppressed enough through a resonance circuit within the discriminator 6. |
