PSN-L Email List Message

Subject: Re: trouble shooting GPS antenna
From: Rob Vassar rvassar@.....................
Date: Thu, 10 Jan 2002 07:50:47 -0800


  I can't seem to find my coax loss table at the moment, but I suspect your problem lies
with the RG174.  You're probably loosing 5db of signal in the cable alone.  RG174 has
very poor characteristics even in the low VHF bands.  GPS is high UHF.  Add to this the
inevitable losses from the splices and various junctions between the antenna and the
first amplifier/mixer, and you end up with a receiver that can only hear satellites that
are directly overhead, where the signal is the strongest, or none at all.  UHF/Microwave
coax is hard to find, and expensive, but worth it.

Good Luck,


"angel@chiriqui" wrote:

> Hello,
> Yesterday I got and SDR system up with one of the GPS systems we
> bought as a group.  To lengthen the antenna I spliced in about 20 ft of RG174 into the
> little 5 foot cable of the antenna that came with the units.  Hooked
> it all up and It worked well.
> Last night and today all got was and SDR error message stating "not
> enough GPS stat's being tracked".
> I replaced the antenna with one that I got from Synergy and had
> reserved for another installation and the problem disappeared.
> Any idea on how to test or trouble shoot this antenna???
> Best regards,
> angel                          mailto:angel@............


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