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

  • From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
  • To: "opendtv@xxxxxxxxxxxxx" <opendtv@xxxxxxxxxxxxx>
  • Date: Sun, 31 Jan 2010 17:11:33 -0600

Al Limberg wrote:

> 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.

That sounds right, things being as they are. Matter of fact, a few years back, 
wasn't there a question whether the FCC should mandate ATSC receiver 
performance minima?

As I recall, a lot of people on this list opposed such an idea, saying that the 
FCC could pick out numbers from the air, that bear no resemblance to what is 
technically feasible. Instead I was in favor. Why? Simple. The FCC is the 
spectrum manager. How can a spectrum manager expect to do a reasonable job of 
assigning spectrum to achieve certain coverage criteria, if that spectrum 
manager has no idea of receiver performance? It doesn't make sense.

And yet, aren't SFNs being set up anyway? I think there's one in the NYC area. 
With the main tower in NJ, IIRC. Or is that still in the experimental phase?

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