Two-channel compatible HDTV system
AssigneeZenith Electronics Corporation
InventorWayne E. Bretl
Life of this patent
Estimating the term…
Abstract
A video signal is produced as a 37.8 MHz bandwidth high resolution signal. The system then derives a compatible NTSC signal from that signal and transmits the NTSC signal on one channel and an enhancement signal is transmitted on a second channel. The enhancement signal is produced by storing the 37.8 MHz signal, scanning it at a lower frame rate, and folding it so that the original information is retained within a normal channel width. In an HDTV receiver, the two channels are received and the signals are decoded separately then, using dot interlace techniques, combined to produce the HDTV signal having three times the horizontal and vertical resolution of a standard NTSC signal.
Claims30
A system for transmitting visual and audio signals and comprising:
- means for producing a set of visual signals representing a scene to be reproduced by a video receiver and having an aspect ratio compatible with a pre-existing color television broadcast system;
- means for producing audio signals representing information in the audio frequency range;
- first processing means for processing said set of visual signals and said audio signals to produce a first channel signal which is essentially compatible with a pre-existing color television system and includes synchronizing signals and a first set of horizontal lines;
- and
- second processing means for processing said set of visual signals to produce a second channel signal which includes and extends the spatial frequency response of said first channel signal and includes a second set of horizontal lines having three times as many lines as the first channel signal, said second set of horizontal lines being transmitted at a scanning rate which is substantially lower than the scanning rate of the pre-existing system, and said second processing means includes means for producing three output signals in response to the chroma and luminance of said scene and means for removing high diagonal spatial frequencies from each of said three output signals.
A system for transmitting high definition television signals and comprising:
- camera means for producing wide bandwidth video signals having an aspect ratio compatible with a pre-existing color television broadcast system and having very high resolution at the normal frame rate of said pre-existing system;
- first encoder means for producing from said video signals a first modulator signal which is essentially the standard signal of said pre-existing system;
- first transmitter means for transmitting said first modulator signal on a first channel;
- means for producing from said video signals a high resolution signal which has a bandwidth several times wider than the bandwidth of said pre-existing system;
- frame storage means for storing said high resolution signal;
- means for retrieving said stored signal at a rate substantially lower than the scanning rate of said camera means and subsampling said retrieved signal to provide a folded second modulator signal occupying a bandwidth no wider than the bandwidth of said pre-existing system;
- and
- second transmitter means for transmitting said second modulator signal.
A receiver for utilizing television signals occupying first and second channels and having three times the resolution of a pre-existing color television system in two dimensions, the signal in the second channel being derived by scanning at three times the rate of said pre-existing system and being subsampled to reduce the bandwidth of the scanned signal, the reduced bandwidth signal containing all information of the scanned signal, the receiver comprising:
- first means for receiving and decoding said first channel television signal to provide the normal signal of said pre-existing system at the standard frame rate of that system;
- second means for receiving and decoding said second channel television signal to provide a resolution enhancement signal at a reduced frame rate;
- combining means for combining said normal signal and said enhancement signal to provide a high definition television signal;
- and
- display means for utilizing said television signals to create a video display.
A high definition television system comprising;
- transmission means including;
- means for producing a set of signals representing a scene to be reproduced by a video receiver;
- means for producing audio signals representing information in the audio frequency range;
- first processing means for processing said set of visual signals and said audio signals to produce a first channel signal which is essentially compatible with a pre-existing color television system and includes a first set of horizontal lines;
- first transmitting means for transmitting said first channel signal;
- second processing means for processing said set of visual signals to produce a second channel signal complementary to said first channel signal and including a second set of horizontal lines having three times as many lines as the first channel signal, said second set of horizontal lines being produced at a scanning rate which is substantially lower than the scanning rate of said pre-existing system signal, said second processing means including means for producing three output signals in response to the chroma and luminance of said scene, and means for removing high diagonal spatial frequencies from each of said output signals;
- second transmitting means for transmitting
- said second channel signal;
- and receiving means including;
- first means for receiving and decoding said first channel television signals to provide the normal signal of said pre-existing system and having the standard frame rate thereof;
- second means for receiving and decoding said second channel television signals to provide resolution enhancement signals at a reduced frame rate;
- combining means for combining said normal signal and said resolution enhancement signals to provide high definition television signals;
- and
- display means for utilizing said television signals to create a video display.
Dependencies are inferred from the claim text.