Noise eliminating circuit for video television signal

Claim 2

A noise eliminating circuit for video television signals having synchronous denoting signals comprising: a. a low pass filter through which a substantially low frequency band component of said video television signals is passed; b. a high pass filter through which a substantially high frequency band component of said video television signals is passed; c. a signal clipping circuit connected to said high pass filter by which black peak signals over a predetermined black signal level are clipped from said high frequency band component; and d. a mixer for combining the output signals of said low pass filter and said signal clipping circuit.

Claim 3

A noise eliminating circuit according to claim 1, wherein said synchronous denoting signals are horizontal synchronous signals in horizontal blanking periods of said video television signals and said clipping circuit clips a negative going overshoot pulse in said horizontal blanking periods.

Claim 4

A noise eliminating circuit according to claim 1, wherein said clipping circuit includes means for variably controlling the clipping level thereof.

Claim 5

A noise eliminating circuit according to claim 3, wherein the high frequency component of the output of said mixer is improved so as to achieve an aperture correction of said signals.

Claim 6

A noise eliminating circuit according to claim 1 further comprising a noise limiter which is connected between said high pass filter and said clipping circuit.

Claim 7

A noise eliminating circuit for a demodulated video signal which includes blanking intervals with a synchronizing signal in each blanking interval and an overshoot noise directed toward the black level side of the video signal at the front porch of each blanking interval, said circuit comprising: low pass filter means for separating a low frequency band component from said video signal; high pass filter means for separating a high frequency band component from said video signal; clipping circuit means receiving said high frequency band component and clipping from the latter black peak signals exceeding a predetermined black signal level so as to substantially remove said overshoot noise; and mixing means combining said low frequency band component with the output of said clipping circuit means so as to reconstitute therefrom a video signal devoid of said overshoot noise.

Claim 8

A noise eliminating circuit for a demodulated video signal which includes blanking intervals with a synchronizing signal in each blanking interval and an overshoot noise directed toward the black level side of the video signal at the front porch of each blanking interval, said circuit comprising: low pass filter means for separating a low frequency band component from said video signal; high pass filter means for separating a high frequency band component from said video signal; clipping circuit means receiving said high frequency band component and clipping from the latter black peak signals exceeding a predetermined black signal level so as to substantially remove said overshoot noise; and mixing means combining said low frequency band component with the output of said clipping circuit means so as to reconstitute therefrom a video signal devoid of said overshoot noise.

Claim 9

A noise eliminating circuit according to claim 6; in which said clipping circuit means includes adjustable means for varying the clipping level thereof, said low pass filter provides said low frequency band component with a curved characteristic at said front porch of each blanking interval, and said clipping level is selected by said adjustable means so that a vestige of said overshoot noise remains in said output of the clipping circuit means to cancel said curved characteristic and provide the reconstituted video signal from said mixing means with a flat characteristic at said front porch.

Claim 10

A noise eliminating circuit according to claim 7; in which said high pass filter provides said high frequency band component with overshoot noises directed toward the white level which are unaffected by said clipping circuit means and therefore included in said reconstituted video signal during each picture period between successive blanking intervals for accentuating the contours of a picture produced from said reconstituted video signal.