"Leonard Erickson" wrote to "Phil Marlowe" (04 Jul 03  02:37:08)
 --- on the topic of "RECEPTION, TV"

 -=> Quoting Phil Marlowe to Mike Ross <=-

 PM> The reception I got from the U.S. in winter
 PM> was as sharp and crisp as the local channel 12,
 PM> ie excellent. Now I can't even bring up a blurry
 PM> picture -- just a blank screen.
 PM>
 PM> I'm guessing but I don't think height and location
 PM> would be a factor, since they haven't changed? And
 PM> different TV sets in different rooms all worked
 PM> equally well -- in the winter.

 LE> Height *can* be a factor. See below.

 PM> This summer thing is definitely a puzzle. I wonder
 PM> if the stations themselves are aware of it?


I just read something about the signal in winter can be some 6db
stronger simply due to the lower radiation angle (wave front goes lower
instead of off into space over your head). That's a big difference. Say
you have a viewable 30db s/n and the signal drops by 6db in summer then
you'll be receiving practically nothing watchable. So that explains it!


 LE> I and a friend are studying for a ham ticket. Yes, temp & humdity
 LE> *can* make a difference. With the right combo., you can get a
"duct"
 LE> that caries the signal places it wouldn't otherwise go.

I caught AM 720Khz Pasto, (Bolivia?) one afternoon. It's a mountain city up
around 7,000ft. The weather conditions were just perfect for ducting!


 LE> Basicly, under the right atmospheric conditions, you can get a signal
 LE> to bend around the curve of the earth.

That's the idea of lowering the radiation angle so it curves just so.


 LE> So to get the signal when conditions *aren't* right, you need to have
 LE> an antenna high enough to be in "line of sight" of the station's
 LE> antenna.

 LE> How far away are these stations? Any idea where their *transmitters*
 LE> are?

About 80 miles apart more or less. The transponders are up in the
Adairondacks and Blue Mountains of Vermont in various high spots. Am
drawing a blank on which mountains right now though around Mt.Pellier,
Saranac Lake, Plattsburg, Burlington, Lake Champlain area, etc. We
receive a pretty good signal in Montreal proper.

 Mike
 ****

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