[opendtv] Re: "It can't be done"
- From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Thu, 28 Dec 2006 19:02:47 -0500
Mark Aitken wrote:
> Impressive? We'll see. Perhaps... but just a nit...since when did
> the NE corridor not include Boston (as just one example)?
>
> Craig Birkmaier wrote:
>>
>> As a starting point, I did a bit of research yesterday into some
>> basic OFDM design constraints. The best resource I found is a pdf
>> White paper published by MediaFlo, the Qualcom subsidiary that is
>> building out an OFDM-based mobile TV infrastructure in recovered
>> 700Mhz spectrum.Here is the link:
>>
>> http://www.qualcomm.com/mediaflo/news/pdf/MediaFLO_SFN_Whitepaper.pdf
>>
>> The paper is highly informative, and includes several maps
>> detailing how the network will be built in several areas of the
>> country. One interesting take away is that it will take only 30
>> transmission sites to completely cover the NE corridor,
Indeed. If Craig had done his homework, he would have noticed that his
definition of "completely cover the NE corridor" was actually limited to
partial coverage, with no sharp contours, of only a narrow strip between
Wash DC and NYC, with a few islands of coverage in other nearby
communities to the east and west of I-95 and US 1. And that's partial
coverage, even of the narrow corridor, such that there are large gaps
between Baltimore and Philadelphia, and certainly to the east and west
as well.
But this entire area is populated. There is no wilderness here. What
about, say, Front Royal, VA? What about Cumberland MD? What about
Harper's Ferry, VA? What about the MD Eastern Shore? What about all the
homes between these small communities and the big cities? They can use
DBS.
And, as mentioned before, this involved the use of towers as tall as 300
meters, and 50 KW ERP. Earth scorchers, by his definition.
In short, no magic going on here. The simpler design for broadcasters is
to use a mix of fewer, more powerful sticks, gap fillers, translators,
and no need for synchronization.
Bert
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