| 摘要 |
PURPOSE:To reduce the effect of noise and jitter, by changing the circuit constant in response to the level of noise component at a part where no video information of a composite video signal exists. CONSTITUTION:Noise component existing at a part (e.g., horizontal synchronizing part) where video information of a composite video signal does not exist is detected at a noise gate 10 and a noise detection circuit 11, and a voltage almost proportional to the level of the noise component is outputted. This voltage is stored in a level hold circuit 12 and the stored voltage is applied to a chroma reproducing circuit, a synchronizing deflection circuit and a noise cancelling circuit as a control signal. |
