[opendtv] Re: Italian mobile TV provider has signals covered
- From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Thu, 29 Jun 2006 16:16:01 -0400
Al Limberg wrote:
> I think John Shutt is correct, particularly with regard
> to E-VSB. A 1/2 or 3/4 reduction in code rate is just
> too high. E-VSB and A-VSB are not backward compatible,
> since no part of them is usefully received by legacy
> receivers. Legacy receivers merely tolerate their
> presence.
Al, I never disagreed with that part. I was disagreeing with "ATSC never
will work in mobile applications without help from A-VSB or E-VSB." It
sounds too much like "8-VSB will never work with indoor antennas because
it was 'designed for' 35' towers." Surprise. It works.
> The problem with E-VSB and A-VSB is that they steal data
> space from 8VSB and no part of them is usefully received
> by legacy receivers.
Well, sure, and the same can be said for DVB-H. E-VSB isn't so bad if
it's used for very low bitrates, though. Like a robust audio channel. If
you create a robust 128 Kb/s audio stream, you're still left with more
than 19 Mb/s for the rest. Not so bad.
Part of John's persistent negativism comes from the fact that up-to-date
ATSC receivers are hardly ever demoed or tested. TPV, for example, never
tests the built-in receivers, in a way good audio magazines used to do
with FM and AM tuners back in the day of Audio.
I'd like to know, for example, whatever came of the Samsung Gemini chip,
and why the Samsung SIR-T451 is still being sold, after two years,
instead of an up-to-date STB with the Gemini chip. It's been just about
a year since it was tested by the CRC. Are they following the same
strategy as LG, who got out of the STB business as soon as they had a
truly viable solution?
That demod has respectable dynamic echo specs.
If Motorola managed mobile reception with 8-VSB, to at least 60 mph or
so, years and years ago, with at best a 2nd gen demod, why should
"common wisdom" dictate that this is such a herculean feat?
Bert
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