| 摘要 |
PURPOSE:To decrease noise effectively without degrading the vertical relative resolution with a simple circuit by inputting an input signal to a feedback type comb line filter, and varying the characteristic of the said filter in response to the frequency by means of one piece filter. CONSTITUTION:From a video signal entered in an input terminal 1, the noise components are extracted by the feedback type comb line filter 2. And the said components are subtracted from the input signal by a subtractor 3 to output a signal whose noise is decreased to an output terminal 4. For instance, the input signal supplied from the terminal 1 is added with the output of a one-H delay circuit 25 by an adder 21 and then inputted to the filter circuit 22. The output of the circuit 22 is again added with the input signal by an adder 24, and the result is made an input to the circuit 25. a subtractor 26 subtracts the output component from the input of the circuit 25. And the resulting signal is limited of its pulse width by a pulse-width limiter 27 to single out the noise components by eliminating such components that has no vertical correlation. Therefore, such part that has no vertical correlation is outputted as it is. But from such part that has vertical correlation, the higher noise components that are easily noticeable is reduced effectively.
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