| 摘要 |
PURPOSE:To obtain a chrominance signal processing circuit where color noise produced at a weak electric field is made unremarkable by detecting an electric field intensity of a received radio wave and decreasing the saturation of a chrominance signal when the electric field intensity is decreased to a prescribed value or lower. CONSTITUTION:When a filter voltage of an ACC circuit given to an input terminal 9 is smaller than an output voltage of a DC power supply 11 (strong electric field), since a base and an emitter of a transistor (TR)8 are biased reversely, the TR8 is nonconductive. As a result, the gain of the 2nd amplifier 3 is controlled only by a color saturation signal from a color saturation adjusting terminal 5. On the other hand, when the filter voltage of the ACC circuit is larger than the output voltage of the DC power supply 11 (weak electrid field), the TR8 is conductive, a potential of the gain control terminal 5 of the 2nd amplfier 3 is decreased and the gain of the 2nd amplifier 3 is decreased. Thus, the safuration of the chrominance signal is decreased so as to make the color noise on the screen unremarkable. |
