Claims
- 1. A system for transmitting an enhanced television signal for reception by standard NTSC receivers comprising:
- means for forming a first signal during a portion of a television image filed containing information for providing an enhanced television image;
- means for controlling the level of said first signal so that said first signal does not exceed a peak-to-peak value of between +N and -N IRE units, and wherein N is an integer greater than zero;
- means for forming an NTSC compatible signal having a black level at +N IRE during another portion of said television image field while maintaining the video clamp level at zero IRE; and
- means for combining said first signal and said NTSC compatible signal into a signal suitable for transmission for reception by television receivers.
- 2. The system for transmitting an enhanced television signal of claim 1 wherein N is set at 15 IRE.
- 3. A method for transmitting an enhanced television signal for reception by standard NTSC receivers comprising the steps of:
- forming encoded signals during a portion of a television image field, said encoded signals containing information for providing an enhanced television image;
- controlling the amplitude level of said encoded signals to maintain a peak-to-peak value of +N and -N IRE, where N is an integer greater than zero;
- forming an NTSC signal having a black level during another portion of said television image field;
- setting the black level of said NTSC signal to a value equal to or higher than +N IRE while maintaining the video clamp level at zero IRE; and
- combining said encoded signals and said NTSC signals into a television signal suitable for transmission to television receivers.
CROSS REFERENCE TO RELATED APPLICATION
This application is a continuation in part of copending application Ser. No. 07/643,756, filed Jan. 22, 1991.
US Referenced Citations (1)
Number |
Name |
Date |
Kind |
5075773 |
Pullen et al. |
Dec 1991 |
|
Foreign Referenced Citations (1)
Number |
Date |
Country |
0007054 |
May 1991 |
WOX |
Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
643756 |
Jan 1991 |
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