[opendtv] Re: News: TV Braces for the Apple Tablet

  • From: "Allen Le Roy Limberg" <allimberg@xxxxxxxxxxxx>
  • To: <opendtv@xxxxxxxxxxxxx>
  • Date: Sat, 30 Jan 2010 21:16:53 -0500

SFNs are not in the cards for 8-VSB because of the large base of legacy DTV
receivers that do not have adaptive channel equalization filters that can
handle the long echoes, especially long pre-echoes, that are encountered in
the zones where the coverage areas of transmitters overlap. So, at least for
now, SFNs are infeasible, not for technical reasons, but for business
reasons.  A government mandate for better adaptive channel equalization
filters would have to be in place for several years before SFNs could be
introduced without obsoleting most of the DTV receivers in the field.  Gap
filler transmitters will continue to be on a different channel than
big-stick transmitters insofar as 8-VSB is concerned.

Or so I am told.

Al

----- Original Message ----- 
From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
To: <opendtv@xxxxxxxxxxxxx>
Sent: Friday, January 29, 2010 6:31 PM
Subject: [opendtv] Re: News: TV Braces for the Apple Tablet


> Craig Birkmaier wrote:
>
> > The same can be said about broadcasting - and the big stick
> > model is horribly inefficient in terms of spectral reuse.
>
> Craig, you can keep repeating this same mantra year after decade, but it's
not more profound now than it was last century.
>
> The big stick model is not horribly inefficient at all, WHEN you have to
cover large market areas and leave no holes in coverage between markets. As
a matter of fact, I have shown you countless times how SFNs are used in
practice, in the few European cities that have SFNs. SFNs cover single
markets, and DO NOT appreciably change anything wrt spectrum reuse. The most
recent example being the two-tower SFNs used in Rome, for the UHF
transmitters, post analog shutoff. They might make reception a little easier
(were it not for the very low power), but in practice, that frequency is
tied up just as it would be with a big stick.
>
> I have shown where very wide area SFNs are a pain to run well. They
require very many towers and cause high probability of interference zones,
which will vary with weather and other atmospheric gliches.
>
> Big sticks, potentially supported by on-channel gap fillers or very low
power translators, are a PERFECTLY viable solution for broadcast TV coverage
in these parts.
>
> > Sorry Bert, but with IP Multicast, telco networks are far
> > more spectrally efficient than ATSC MHP for video delivery.
>
> You mean cellco? Guess what, Craig? Cellco networks are the big stick
model scaled down, and they are scaled down only because they have to
support the high count of two-way unicast links. Cellco nets are scaled down
translator nets, Craig, not SFNs. They are simply designed to a different
set of criteria, and they take a lot more manpower to keep running for a
given coverage area.
>
> > The reality Bert is that most people DO NOT want to watch the
> > stuff that broadcasters are delivering on their mobile
> > devices. Most of us are not watching this stuff at all.
>
> Whatever TV they are watching on mobile devices is more efficiently sent
using broadcast, Craig, even if that means using local storage. And I'm
sorry that you feel so compelled to tell us how no one watches broadcast TV,
when all the stats we see continue to contradict this.
>
> Bert
>
>
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