[time-nuts] GPS receivers and poor sky visibility.....

Scott Mace smace at intt.net
Tue Jun 10 04:09:30 UTC 2008


I'm using a HP58504a antenna that's mounted just at the roof line in a _heavily_
wooded lot (two story house).  The feed line is about 120ft of LMR-400
connected to a symmetricom 4port splitter.  I use belden 7806R for the short
runs from the splitter to the receivers.  I see 4-6 satellites on the
Z3801A and anything from 6-12 on the Fury.  Trees have never been a problem.
I even had the antenna at ground level for a while in the back yard with
much of the western and northern view blocked by the house and trees and
was able to track at least 3-4 satellites on the z3801a.  Isn't the southern
view the most important if you are in the northern hemisphere at higher latitudes?

	Scott

Michael Baker wrote:
> Hello, All--
> 
> Jim Robbins reported poor GPS performance because his GPS 
> antenna has a limited clear view of the sky.  
> 
> Hmmmmmm....  Jim-- might you have some sort of antenna or
> feed line problem?  My house is in the middle of a relatively
> small yard in the center of a VERY HEAVILY wooded 6 acre
> lot.   My Thunderbolt antenna has an extremely limited
> clear view of the open sky and at no direction is it better than
> 40 degrees above the horizon. My T-bolt typically indicates good
> signals from at least 6 or 7 birds with signal levels of
> 8.0 to over 12.0.  As an experiment, I switched it over to
> an antenna INSIDE my house and while the signal levels all
> dropped to between 5.0 to 8.0, indicated performance as reported
> by T-bolt Mon is still solid.
> 
> Mike Baker
> ------------------------
> 
> 
> 
> 
> 
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