On Mon, 2003-01-20 at 15:04, Tim Pozar wrote:
> On Sun, Jan 19, 2003 at 11:49:01PM -0800, Greg DesBrisay wrote:
> > Sure, I do this all the time. 
> > GPS units work great (as long as you're outdoors and you're not
> > surrounded by too many tall buildings).
> > Just about any brand works fine.
> > Most of my experience has been with Garmin gear, and older Trimble gear.
> > 
> > What exactly are you trying to accomplish?
> > 
> > If all you want to do is determine if your link is unobstructed, then
> > eyeballing your link may be the most effective thing, given that your
> > potential link is only two miles long.
> > 
> > For longer links, for links with obstructions, or for links that you
> > want to document, you can use the lat/lon measurements you get along
> > with a topographic map (or topo-map software like Topo-USA from
> > Delorme--cheap and good in my experience) to figure out if you've got
> > enough clearance over hills, etc.. (It takes a bit more work to account
> > for the height of buildings or trees along the path.)
> 
> And it doesn't take into account refraction and curvature of the earth.

That's absolutely right.  You have do curvature and Fresnel-zone
clearance calculations by hand with simple topo-map software.  I have a
spreadsheet handy that I use for that.  There's nicer propagation
analysis software that does all that for you of course.

Greg DesBrisay


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