[BC] Analogue is better for many viewers

[Ron Youvan]

> I haven't studied 8VSB extensively. Is there any sort of fall-back system
> in it? For example, if noise prevents the detection of 8 RF levels (3 bits
> per baud), drop to 4 RF levels (2 bits per baud), or 2 RF levels (1 bit per
> baud). Ideally with the lower bit rate, people would still get a picture,
> just lower resolution. So... under 8VSB, does the receiver ALWAYS need
> sufficient SNR to decode 3 bits per baud, or can it fall back and still
> give usable video?

   No, and there are is no "picture" to receive just a jumble of lots of kinds of data blocks in a 
serial stream, the receiver must put each block in the correct buffer in the correct order for the 
play-out processes to use them.
   A high noise level results in an incorrect detection of the RF level instead of missing something.

   We also have the idea that a lot of error correction is a substitute for a signal that is 
stronger than the noise, which is something that is 100% correct only on paper.
   The three high channel VHF stations in Tampa have dropped from 100, 50 and 25 kW TPO to about 6 
kW TPO and I (and everyone that I have asked) can only get the nearest two.

-- 
Ron KA4INM