 Adaptive PAL - or NTSC - comb filter |
| In an illustrated preferred embodiment according to the principles of the invention, when ... |
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| Video signal processor for removing a separated signal component from an input video signal |
| Accordingly, it is an object of the present invention to eliminate the above-described problems in ... |
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| Optical reading device for reading an information carrier with motion effect facilities |
| The invention can be used for obtaining an automatic stop at the desired frame irrespective of the ... |
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| Movement detection circuit for a PAL television signal |
| What is claimed is: 1. A movement detection circuit for a PAL television signal containing a ... |
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| Phase-lock-loop lock indicator circuit |
| OF THE INVENTION Referring to FIG. 1, a block diagram illustrating a phase-lock-loop including the ... |
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| Digital phase-locked loop circuit |
| Accordingly, it is an object of the present invention to provide a new and improved digital PLL ... |
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| Chroma lock detector |
| A chroma lock detector circuit monitors charge pump control signals within a phase-lock loop to ... |
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| Fax processor |
| Accordingly, it is the general purpose and object of the present invention to provide an autonomous ... |
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Method and system for interference suppression in a color television system
| Details |
Inventors: Hausdorfer, Michael;
Assignee: Robert Bosch GmbH (Stuttgart, DE)
Primary Examiner: Masinick; Michael A.
Assistant Examiner:
Attorney, Agent or Firm: Frishauf, Holtz, Goodman & Woodward
To improve TV image reproduction, and to suppress interference in the luminance channel of a color TV decoder, a controlled portion of the amplitude of a part of a TV signal, which part is within the frequency range of the chroma subcarrier, is subtracted from the TV signal. The portion of the luminance signal which is within the frequency range of the chroma subcarrier is rectified to derive a control signal and the amplitude of the controlled portion which is subtracted is controlled as a function of the controlled signal. Non-linearities of reproduction by the TV tube and of human perception can be compensated within the circuit which includes, for example, a matrix, and a non-linear signal transfer channel, or derived from the TV tube itself. |
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DETAILED DESCRIPTION FIG.
1 collectively, illustrates the system which is known in accordance with the prior art.
In FIG.
1a, a decoder is shown at 5 which is customary in color TV receivers.
FIG.
1b illustrates the frequency distribution of a chroma carrier trap, or filter, which can be included within the luminance channel of the circuit of FIG.
1a.
An input terminal 1 receives the color video signal which is then conducted through a time delay line 2 to a chroma subcarrier trap or filter 3, and then applied to a matrix 4, which decodes the signals and provides the red (R), green (G), and blue (B) output signals to a color TV tube.
Amplifiers, buffers and other circuits well known in the art are not necessary to an understanding of the present invention have been omitted from the diagram.
The delay circuit 2 is used to match the coursing time of the luminance signal to that of the chroma signal, or, rather, to the color difference signals.
The input signal is additionally applied to a color signal decoder 5 which demodulates the color signal on its carrier and provides the two output signals R-Y and B-Y, for application to the matrix 4.
The output signals from the matrix 4 are suitably amplified and then applied, for example, to the cathodes of the image reproduction tube.
The filter or chroma carrier trap is, essentially, a band block filter, tuned to the chroma carrier frequency.
The frequency distribution of the signal as it passes through the circuit 3 is shown in FIG.
1b.
Components of the luminance signal which contribute to the sharpness of the received image are within the range of the chroma carrier.
These components substantially increase the sharpness of the signal and, hence, by including the circuit 3 within the channel from the input terminal 1 to the matrix, the sharpness of the reproduced image is impaired.
FIGS.
2a and 2b, which correspond to FIGS.
1a, 1b, illustrate the system of the present invention.
Input terminal 1 again receives the TV signal, which is delayed in delay line 2, provided to match the coursing time of the signals to the remaining circuit, and having the same function as in the system of FIG
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TV Signal 
