Cbs Corporation

Other

John P Rossi

Abraham A Goldberg

Renville H McMann, Jr

Marvin A Stern

In the generation of NTSC color television signals, the luminance signal and the color difference signals are pre-filtered along the vertical picture axis. Full bandwidth luminance is pre-filtered by combining, with appropriate coefficients, signals from three adjacent television lines, and, additionally, a vertical detail signal is generated by combining the same three adjacent television lines, with difference coefficients, and low pass filtering the resultant signal. A desired adjustable level of the vertical detail signal is added back into the pre-filtered full bandwidth luminance signal to partially or fully cancel the effect at the lower frequencies of pre-filtering the luminance signal. Time multiplexed color difference signals at baseband are prefiltered by combining with appropriate coefficients, the signals from three adjacent television lines. The prefiltering operation is translated to the conventional NTSC chrominance band by the color modulation process. The processed chrominance signal is added to the processed luminance signal to obtain an NTSC color television signal.

System for filtering color television signals utilizing comb filtering

The high frequencies of the red, blue and green color television signals, with appropriate individual gain levels, are combined in a mixer having non-additive and additive characteristics, with the standard high frequency luminance signal to obtain a correction signal that is the greatest of the four when all have the same polarity, or in the event any of the four signals has opposite polarity with the others a correction signal that is equal to a linear combination of the two opposite polarity, highest level signals. This correction signal is used to compensate for the violation of the constant luminance principle of a luminance signal that was generated by linear matrixing of gamma corrected color signals. The compensation signal is combined with the luminance signal using a mixer similar to that used to generate the correction signal.

System for compensating for the violation of the constant luminance

A television system for broadcasting high definition television on two channels of a direct broadcast satellite, a first of which carries a compatible 525-line picture. A second channel carries an augmentation signal, which in conjunction with the signal from the first channel, produces at a receiver tuned to both channels a 1050-line high definition television picture with a 5:3 aspect ratio. Time multiplex component signals and processing are employed, and high fidelity sound is provided by digital audio signals transmitted in time sequence with the video. There may be as many as five sound channels so as to provide three-channel stereophonic audio and various combinations of data and sound channels.

Two channel compatible high definition television broadcast system

Method and apparatus for detecting and significantly correcting bit errors in a pulse code modulated television signal which recognizes the unique spectral characteristics of isolated bit errors in a digital bit stream, which generate spectral energy outside the frequency band of the video signal, and utilizes that energy to detect and correct errors without the use of overhead bits.

Method and apparatus for digital television error correction without

A sub-Nyquist sampled PCM NTSC color television signal is obtained directly from a PCM encoded color television signal sampled at four times the color subcarrier frequency by selecting every other sample in each line of the 4F.sub.sc sampled television signal and introducing a one 4F.sub.sc sample displacement every two sequential television lines. A sub-Nyquist sampled signal may also be obtained from an NTSC color television signal having a color subcarrier frequency F.sub.sc by generating a sampling signal having a frequency of 2F.sub.sc, the sampling phase of which shifts by 180.degree. every alternate time sequential television line, and sampling the NTSC color television signal in response to the sampling signal. Whichever of these two techniques is used to obtain the sub-Nyquist samples, the 4F.sub.sc samples can be reconstructed when comb filters are used to remove alias components. The process of converting 4F.sub.sc encoded signals to sub-Nyquist and back to 4F.sub.sc can be repeated without impairing picture quality beyond that introduced during the first conversion-reconversion process.

Method and apparatus for PCM-encoding NTSC color television at

The disclosed system for correcting excessive horizontal blanking of color television signals, separates the luminance and chrominance components of the television signal, separately expands or stretches the luminance and chrominance components, corrects the error in the color subcarrier caused by expansion of the chrominance component, and combines the expanded luminance and chrominance components. The system may be implemented in either the analog domain or the digital domain, the latter being preferred because the circuits are less critical and the quality of performance is substantially constant.

Horizontal blanking corrector for television signals

A system for reducing noise in a television signal utilizing integration and including a storage device for storing a television signal, and a summing device for adding a fractional amplitude portion of the signal stored in the storage device to a fractional amplitude portion of an incoming video signal, and operative automatically to change the fractional amplitude portion of the stored signal fed to the summing device as a function of the difference between stored and present signals, thereby to change the integration time constant of the system to accommodate for motion between the incoming signal and the stored frames, is improved by eliminating from the noise-reduced output signal troublesome transients caused by not changing at the appropriate time the fractional amplitude portion of the stored signals fed back to the summing device. This problem is overcome by generating in response to the difference between the incoming and stored video signals a gating waveform during the existence of which an increased portion of incoming video is coupled to the output of the system, delaying the incoming and stored video signals by an arbitrary amount sufficient to ensure that the onset of the gating waveform occurs sufficiently in advance of the delayed incoming and stored video signals as to be anticipatory of the delayed arriving and stored signals, and delaying the turn off or termination of the gating waveform thereby to delay the return to a condition of coupling a lower value of the fractional amplitude portion of the incoming video signal than occurred during the gating waveform.

System utilizing integration and motion evaluation for reducing noise in

NTSC television signals are digitally encoded at sub-Nyquist rates by placing the alias components into those parts of the spectrum not normally occupied by the luminance or chrominance components of the video signal. In a system described, the sampling frequency, f.sub.s, is exactly 2f.sub.sc + 1/4f.sub.h or 2f.sub.sc - 1/4f.sub.h, where f.sub.sc is the NTSC color subcarrier frequency and f.sub.h is the line-scan frequency. Most of the alias signals in the thus encoded signal are removed from the baseband video by comb filtering between f.sub.s - f.sub.y and f.sub.v, where f.sub.v is the baseband video bandwidth.

A comb filter system for the separation of the luminance and chrominance components of an NTSC color television signal which analyzes the video signal on the television lines and detects luminance or color transistions in the vertical direction, and in response to the presence of one or both of such transitions, automatically either modifies or removes the comb filter, to minimize transient distortions in the reconstructed television picture. The system can be implemented in either the analog domain or the digital domain.

Comb filter for television signals having adaptive features

An apparatus and method for digitally encoding an NTSC color television signal in a manner that facilitates comb filtering of the digitally encoded signal. In accordance with the invention there is provided a means for generating a first sampling signal having a characteristic frequency of three times the NTSC color subcarrier signal. Another means is provided for generating a second sampling signal having the same characteristic frequency, this second sampling signal having its sampling reference points interspersed equally in time between the sampling reference points of the first sampling signal. Enabling means, responsive to the NTSC color television signal, are provided for alternately enabling the first and second sampling signals during successive horizontal scanlines of the television signal. Further provided is a means, responsive to the enabled sampling signal, for sampling the television signal. Finally, means are provided for converting the sampled television signal into digital form. In a preferred embodiment of the invention, the first and second sampling signals are opposite phases of a square wave at 10.74 MHz.

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Stamford, CT, United States of America

John P Rossi