[Cu-wireless] fwd: [isp-wireless] Re: Fw: Rain Fade stats for 2.4 and 5.8 gig

[pfolk at gargtech.com]

Some good info on rain, etc, from isp-wireless,
Peter

----- Forwarded message from "Forrest W. Christian" <forrestc at imach.com> -----

Date: Tue, 5 Nov 2002 02:26:13 -0700 (MST)
To: isp-wireless at isp-wireless.com

On Mon, 4 Nov 2002, Don Briggs wrote:

> Any one out there have a definision of rain figure stats for the 2.4 to 5.8
> gig range

Generally, you don't need to worry about rain fade until you get around
10Ghz.  However If you really *must* know.  Try FCC OET bulletin 70:

http://www.fcc.gov/Bureaus/Engineering_Technology/Documents/bulletins/oet70/oet70a.pdf

This includes everything you ever wanted to know about propogation up in
the Ghz bands, including such bizzare stuff as oxygen and water
absorption, sky noise, and similar.

If you *really* want to engineer a link for rainfade, it even includes a
climate map to determine your average rainfall, etc. so you can determine
availability figures.

In my neck of the woods, I can get 5 nines of reliability (<5 mins/year)
(only counting rain fade) with a link margin of only 1/10th of a db per km
at 5.8.  At 2.4 we're talking less than 1/100th of a db per km.  In the
wettest parts of the country it is closer to .6db/km at 5.8, so if you
live in florida, you *might* want to take that into consideration.

Just for reference, the five nines rainfade for that 70 mile redline link
we've been hearing about in Idaho would only be about 12db.  And that's
assuming that all 70 miles is experiencing that heavy of a rain, which
isn't likely.

- Forrest W. Christian (forrestc at imach.com) AC7DE
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----- End forwarded message -----

Peter

--
Peter Folk                                          Volo Wireless Internet
email: pfolk at gargtech.com                      Gargoyle Technologies, Inc.
ph: 217 367-VOLO
fax: 866 841-0233                                            www.volo.net