[mythtv-users] DTV: It Has Begun
allen.p.edwards at gmail.com
Tue Sep 9 15:16:07 UTC 2008
On Tue, Sep 9, 2008 at 6:29 AM, Brian Wood <beww at beww.org> wrote:
> Allen Edwards wrote:
> > At some point, the government realizes that they could cram all the
> > stations into less spectrum with the new format and sell off the parts
> > that were better used by other services. I think that came later.
> It's not really "cramming" them into less spectrum, it was the idea of
> moving everyone to UHF, where there is more space (there are more big
> numbers than smaller ones). The actual bandwidth used stayed the same,
> though you could argue it is being used more efficiently.
Well, they can get more stations in the same total BW but you have to be
thinking big picture. Each station has the same BW but the band plan is
tighter. With analog TV, if you put a station on a channel, you can't use
some rather large number of other channels. One source I saw said that
assigning channel 30 blocked 19 other channels. That seems excessive but
they are putting DTV stations right next to each other.
Whatever the details, what is certain is that you can get more DTV stations
in the same number of available channel slots because you don't have to
leave so many empty.
When you expand this problem to different geographies, the DTV advantage is
even greater. They can "cram" more stations across the geography than they
could with analog TV because these digital stations just
don't interfere with each other nearly as much. If they
require directional antennas, the geographical reuse is even better. I am
not sure if that is a requirement or not.
That is what I was talking about in terms of cramming. They can cram more
6MHz channels in the overall BW allocated to TV. Analog TV was very
inefficient because of the adjacent channel and other requirements. DTV
doesn't have that problem.
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