Bridge buildings ~10 miles apart

Looking to perhaps setup a bridge between 2 buildings. Have
successfully setup a 10Mbps bridge between corporate and a sales office
about a half-mile away, so I have a little experience. BUT, looking to
link another site with corporate HQ. This building is roughly 10 miles
away and I am thinking about using Proxim TeraBridge 5845 which can
supposedly go to ~40 miles. But, how do I ascertain LOS existence? From
up on the roof I think I could probably see the other building, but
what type of equipment (without spending 10 grand on the final product)
cna I use to deduce LOS quality? Anyone done something similiar ot this?

On 6 Mar 2006 11:10:41 -0800, (E-Mail Removed) wrote:

>Looking to perhaps setup a bridge between 2 buildings. Have
>successfully setup a 10Mbps bridge between corporate and a sales office
>about a half-mile away, so I have a little experience. BUT, looking to
>link another site with corporate HQ. This building is roughly 10 miles
>away and I am thinking about using Proxim TeraBridge 5845 which can
>supposedly go to ~40 miles.

See:
| http://en.wikibooks.org/wiki/FAQ_for...k_Calculations
for how to do link calculations. Run the numbers and don't believe
the 40 miles claims.

>But, how do I ascertain LOS existence? From
>up on the roof I think I could probably see the other building, but
>what type of equipment (without spending 10 grand on the final product)
>cna I use to deduce LOS quality? Anyone done something similiar ot this?

I use a program called Topo! for doing path profiles. Find the
*EXACT* latitude, longitude, and probable antenna height above the
ground. I just print the path profile, which shows all the
intervening hills, mark points at both ends of the path for the
radios, and draw a straight line. If you hit the ground or any hills,
it won't work.
http://maps.nationalgeographic.com/topo/

A better way is to use Radio Mobile for the path calcs:
http://www.cplus.org/rmw/english1.html
Note the 2nd photo (labelled link):
http://www.cplus.org/rmw/rme.html
Be sure to use the SRTM data and not the DEM data. When I have time,
or want an exact calculation, I use this method.

At 10 miles, the Fresnel Zone at 5.7GHz will be 48ft around the line
of sight at midpoint. You'll need about 38ft clearance to all
obstructions including the ground. Also, don't foget about the
curvature of the earth.
http://www.terabeam.com/support/calc...esnel-zone.php

There are a number of excellent calculators at:
http://www.qsl.net/n9zia/

Also:
http://my.athenet.net/~multiplx/cgi-...eless.main.cgi

If you're stuck, yell.

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558 (E-Mail Removed)
# http://802.11junk.com (E-Mail Removed)
# http://www.LearnByDestroying.com AE6KS

Thanks so much for the thorough reply....