At&t Bell Laboratories

American Telephone & Telegraph Co., At&t Bell Laboratories

Melih Pazarci

Theodore S Rzeszewski

Joseph L LoCicero

A television (TV) system having provision for automatically compensating for signal distortion which would cause artifacts at the point where high- and low-resolution portions of an extended aspect ratio, high-definition TV display are joined together. Compensation parameters are calculated at the TV receiver in response to a known test pattern transmitted during the vertical retrace interval of the TV display and then accessed and utilized to compensate received active display signals. The compensation parameters are calculated by first converting Y, I, and Q signals for the test pattern into digital samples and then processing these digital samples in a digital signal processor unit. After the compensation parameters have been calculated by the digital signal processor, they are stored in a memory. The received active display signals are compensated by accessing the stored compensation parameters during the active display time. Each accessed compensation parameter is converted to an analog signal and is multiplied with received Y, I, and Q edge signals and combined with the center signals to compensate for distortions. In addition, the stored parameters are also averaged over a period of time to stop transient conditions from affecting the stored value of a compensation parameter.

Recombination of low- and high-resolution segments of an extended aspect

A television (TV) system having a compatible high-definition signal receivable at conventional resolution by conventional TV receivers without auxiliary apparatus with carrier modulated high-definition luminance information being transmitted in a continuous spectrum spanning two conventional TV channels, carrier modulated quadrature amplitude modulated (QAM) high-frequency chrominance information being transmitted in the luminance spectrum and carrier modulated QAM low-frequency chrominance information being transmitted outside luminance spectrum. A decoder recovers the high-definition luminance information by demodulating the transmitted signal. The chrominance information is recovered from the transmitted signal by first notch filtering the transmitted high-definition signal to remove energy existing between the two sidebands of the QAM high-frequency chrominance information, and then, demodulating at the carrier frequency. The demodulating at the carrier frequency results in the QAM high- and low-frequency chrominance information forming a continuous spectrum that is then bandpass filtered. The high-definition I and Q chrominance signals are then recovered from the bandpass filtered chrominance information by a QAM demodulator. The QAM demodulation of the latter results in continuous high-definition I and Q chrominance signals.

Economical high-definition television using a modulated-signal

A television (TV) system having a fully compatible high-definition signal with extended aspect ratio information receivable at conventional resolution by conventional TV receivers without auxiliary apparatus with one TV channel carrying the conventional TV signal while high-frequency luminance and chrominance information plus extended aspect ratio information are provided in a second TV channel. The television system uses a video camera that produces the Y, I, and Q video signals with a bandwidth of 9.4 megahertz (MHz). These, Y, I, and Q signals have already been line decimated to 525 lines per frame with a scan rate of the standard 15.7 kiloherts (kHz). The resulting 63.5 microseconds line scan time comprises 42 microseconds of center information and 10.5 microseconds of edge information with 11 microseconds being allowed for the blanking and synchronization interval. The low-frequency center luminance and chrominance information is first time expanded and inserted into the first channel, and the high-frequency center chrominance and luminance information is time expanded and inserted into the second channel. The extended aspect ratio chrominance and luminance information is contained within the edge information and is transmitted during the horizontal retrace interval in the second TV channel.

Compatible high-definition television with extended aspect ratio

A television system having a fully compatible high-definition signal with extended aspect ratio information receivable at conventional resolution by conventional TV receivers without auxiliary apparatus with one TV channel carrying the conventional TV signal while high-frequency luminance and chrominance information plus extended aspect ratio information are provided in a second TV channel. The extended aspect ratio information including luminance and chrominance information is transmitted during the horizontal retrace interval of the second TV channel. The extended aspect ratio chrominance information comprises I.sub.e and Q.sub.e segments which are transmitted during alternate horizontal retrace intervals. Since the segments are alternately transmitted, a storage mechanism is provided so that a segment received during a previous horizontal retrace interval can be reused during the present horizontal retrace interval for displaying the complete chrominance edge information.

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Chicago, IL, United States of America

Melih Pazarci