| 摘要 |
The circuit automatically tracks the frequency of the beat noise in a television receiver, and eliminates the beat noise by varing the filtering frequency. The circuit comprises a frequency discriminator (11), connected between a video detector (4) and a video processor (5) to detect the beat frequency and provide a frequency variable filter (12) with the voltage relating to the beat frequency, the frequency variable filter (12) for converting the filtering frequency into the beat frequency, and a delay circuit (13) to delay the output of the video detector for the delay time in the frequency discriminator and the frequency variable filter.
|
