[opendtv] Re: Transition report
- From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Tue, 16 Jun 2009 14:37:16 -0400
John Shutt wrote:
> "Unfortunately" my rear end. Politicians didn't force VHF on any
> station. Those stations CHOSE VHF in order to preserve the low
> power bills that they've grown so accustomed to from decades of
> analog operation.
[ ... ]
> Too bad those VHF ATSC operators don't have the option of reducing
> their bitrates temporarily in order to increase receivability
> until those petitions are granted...
See, John, here's my problem with your pining about COFDM flexibility.
If a station is so interested in low power bills as to remain in low
VHF, which is a pain for their audience, they will also resist going
back to full spectral efficiency if they think they can remain at, say,
16-QAM. What do they care? What better way to get people to subscribe to
cable, than to make HDTV only available over cable? Not having that
extra knob (until M/H) creates an urgency that otherwise wouldn't exist.
Just trying for logical consistency here.
Anyway, in practice, the same problems *are* occurring now in COFDM
countries going through transition. The UK has the one great equalizer:
Freesat. Aside from that, when DTT coverage is found to be wanting, I
haven't seen any recent evidence of a reduction in modulation mode. (Not
that it couldn't be done, of course.)
> The FCC had ample opportunity to use the Digital Transition to
> level the playing field between major network VHFs and independent
> (or minor network) UHFs both in terms of coverage/power levels and
> operating costs. It was the major network stations that insisted
> that VHF remain part of the final plan, and to insist on being
> able to run 1 MW ERP on UHF to replicate their NTSC VHF coverage
> area.
To me, the problem with VHF, high VHF at least, is not so much that
stations decided to use it, but it's that some misguided recommendation
says that 12 dB less ERP than analog is fine. And even worse than that,
that stations up and down the East coast have adopted ERP levels between
14 and 18 dB less than their previous analog signal. That's silly.
Even if by some theoretical turn of math you can show parity at 12 dB
less than analog, how does that account for the digital cliff? A dark
screen is what happens when one forgets about signal margin.
Bert
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