[opendtv] Re: Broadband DTV interferers

  • From: Craig Birkmaier <craig@xxxxxxxxx>
  • To: opendtv@xxxxxxxxxxxxx
  • Date: Mon, 28 Jan 2008 14:18:04 -0500

At 12:44 PM -0500 1/28/08, Manfredi, Albert E wrote:
This is what you said:

 In some rural market you might be able to use virtually all of the
 channels allocated to TV broadcasting, as there would not be any
 markets close enough to interfere with.

Sounds like you think rural areas should have no meaningful TV coverage
to me. How else could you use "virtually all the channels?"

Give it a break Bert. This is moronic. If there are no interfering signals you can use all of the channels available in any market, perhaps with a few taboo channels excluded. You don;t even need to checkerboard if you multiplex a bunch of channels through a single antenna.

I was talking about geographically isolated markets, which often encompass large areas with small populations. All you need to do is look at one of those images of the U.S. continent at night to see where the people are...

As the Masked Engineer likes to point out, the "Salt Lake City market" extends into five states:


The Salt lake City market has 20 full power stations and almost 600 translators in Utah alone.

Some markets are isolated, some are not. Thus the infrastructure to cover a market and the frequencies that may be used in adjacent markets will vary widely. That's the beauty of using a mix of transmission types based on the best way to assure that everyone in a designated market area can receive FTA broadcasts.

 In fact, you have provided a perfect example...

 Cliff lives in the Philladelphia market, yet he has great
 difficulty receiving the Philly stations because of terrain
 blocking issues. He would be PROPERLY served via the SFN that
 covers Philadelphia.

No, Craig, not SFNs. Cliff lives 35 miles south of Phila. To have an SFN
tower over the top of the hill, you would need a dense mesh of towers
throughout the area, because 35 miles is way too long a distance between
towers of a real SFN. A much better idea is to locate a low-powered
on-channel repeater or translator tower on the hill, aiming its signal
downward and to the South.

OK. I get it. You are playing semantic games again. Yes, to serve Cliff there would be an on-channel repeater rebroadcasting the signal it is picking up from the mains closer to Philly.

This is still an SFN Bert. At least by every definition I have ever seen...

 Stop trying to confuse the issues for the sake of argument.

I gave you the specifics about channel reuse up and down the East Coast,
rather than vague arguments about "hundreds of miles." I gave you
specifics about large area SFNs and their drawbacks. To me, vague
assertions about how wonderful SFNs would be constitute "gratuitous
negativism." And can only delay progress.

You did no such thing. You simply explained where the big stick transmitters are today.

There is no reason that these markets cannot be served by a mix of medium powered transmittwers ringing the core market, and repeaters to cover the areas that are terrain blocked or too far from the mains to get decent reception. That said, there are some unique issues in the NE (and Southern California) that are related to tunneling across large bodies of water. This problem is exacerbated by the use of high powered transmitters...


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