----- Original Message -----
From: "Dan Hearn" <dhearn@wwnw.net>
To: "Towertalk@Contesting.Com" <towertalk@contesting.com>
Sent: Monday, October 31, 2005 8:28 AM
Subject: [TowerTalk] Snow and rain attenuation
>I have been compelled to use dial up ISP service for some time. Recently a
> high speed RF link service has become available. It operates on 5.7ghz.
> The
> ISP transmitter is located on a mountain top at about 15 miles distance
> and
> I have line of sight to it. The operator has recently increased power and
> thinks an acceptable signal to my location is available. They are ready to
> test for this.
> I am concerned that our frequent snow and rain this winter might result
> in
> unreliable signal levels. The receiver end uses a dish and my experience
> with the Dish TV system is that less than an inch of snow on the reflector
> kills the signal. The ISP antennas on the mountain top are in a snow
> environment all winter for sure. They may have heaters on their antennas
> to
> solve this problem at that end.
> Has anyone had experience in a situation like this? Should I stick with
> my
> dial up?
>
> 73, Dan, N5AR
Assuming that your ISP is using proper radomes at the mountaintop headend,
then you are probably okay. You can probably get by with a coarse mesh
dish for wireless at 5.8 GHz (barbecue grill) since you don't care so much
about system temperature (you are going to be pointed at a 300 kelvin
target),
so snow collection on your antenna may not be too big a problem. The fact
that
you will be pointed close to the horizon instead of up toward the equatorial
plane
like your DBS antenna should help as well. Rain fade shouldn't be too bad at
5.8 GHz, but if it turns out that it is, you can just put up a bigger
receive antenna
to add margin to the link (doubling the diameter of your RX antenna will add
roughly 6dB to the link fade margin).
Also see if your wireless ISP will provide dial-backup. When I lived in
Pasadena, Ca my cable modem provider (Charter) used Earthlink as an ISP, so
you automatically got access to dial-backup when you subsribed to their
cable
modem service.
73 de Mike, W4EF............................................
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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