[opendtv] Re: Charles Rhodes on SFNs
- From: Tom Barry <trbarry@xxxxxxxxxxx>
- To: opendtv@xxxxxxxxxxxxx
- Date: Fri, 25 Jun 2010 10:03:19 -0400
Craig Birkmaier wrote:
> At 3:46 PM -0500 6/23/10, Manfredi, Albert E wrote:
>>
>> 1. Unless you deploy a Boston-to-Richmond regionwide SFN, you still
>> cannot reuse the same frequencies in these different markets. The
>> case today is that the same channels ARE used, in every other market
>> up the coast, using the intevening market as the interference zone.
>
> Not exactly. Many frequencies - especially VHF channels - need much
> wider protection, as in hundreds of miles.
>
> With SFNs the potential for interference is much more limited and YES,
> you can checkerboard frequencies from market to market, which means
> that every market can have about half of the available channels, as I
> have noted for years. That's plenty of spectrum in each market to
> offer equal or better services than exist today.
>
> Regards
> Craig
How do they typically do it, lay out the areas for frequency use? Is a
simple black & white checkerboard pattern sufficient? Like:
B W B W B W ...
W B W B W B ...
B W B W B W ...
W B W B W B ...
It seems that would allow half the frequencies but maybe have too much
overlap at the corners of the checkerboard squares. Or do they need
something more like the Red/Green/Blue pixel pattern of old color tv's.
Like:
R G B R G B R G ...
B R G B R G B R ...
R G B R G B R G ...
B R G B R G B R ...
R G B R G B R G ...
That allows only 1/3 of the frequencies. Does TV even have a standard
target pattern or did it just evolve?
- Tom
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