Cliff wrote:
Compare that to 1920 X 1080 at 30p or 60i. The video bandwidth now is 31 MHz, and all you need to decode this essentially error free in a 6 MHz channel is 15 dB of C/N, give or take a few fractions of a dB. And this is very predictable, from what my STB's signal monitor tells me.Bert, please provide us all a comprehensive list of the HDTV monitors and/or TVsets that in their specifications state that they are truly capable of 31 mHz video bandwidth. I'll even accept -3dB at 31 mHz.
What does that have to do with it, Cliff? I didn't ask for the same real-world-hardware examples of NTSC receivers either. I didn't ask what sets actually make use of the full 4.2 MHz video bandwidth.
What we are comparing is the potential of the standards, and how close they come to the Shannon limit.
I could have used the digital domain as the comparison. If you compare the quality of 704 X 480i equivalent in NTSC with 704 X 408i in digital, with A-VSB and MPEG-2 compression you can receive such a stteam with 1.something dB of C/N, for image quality that in analog would require 40 dB of C/N. (Note: I had to use A-VSB because I had to reduce the bit rate in the 8-VSB channel to the bit rate required to carry only one channel of SDTV. Compare apples with apples.)
There's no question that doing this stuff in digital gets you closer to the Shannon limit, as of today anyway. Although I'm also positive that better analog techniques *can* be developed.
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