[time-nuts] Health of GPS constellation questioned

Neon John jgd at johngsbbq.com
Thu Sep 7 07:33:14 EDT 2006


On Thu, 7 Sep 2006 13:12:07 +0200 (CEST), "Bart Smit" <bit at pipe.nl>
wrote:

>
>On Wed, September 6, 2006 5:22, Christopher Hoover said:
>
>> [ the story seems overblown to me, but still worth sharing.  follow
>> the last link for some real data. - ch ]
>
>The last link is interesting indeed. Seems that the problems are more
>perceived than real, with the GPS constellation operating well within
>spec, but users wanting more.

A more basic question.  Do these degradations affect ordinary users?
The reason I ask is that I have a GPS navigation system on in my truck
24/7 and use it every waking hour (I'm a retired engineer who's living
a childhood fantasy - driving a long-haul 18-wheeler :-)  Fairly
frequently I experience fairly long intervals where the system goes
completely dead.  The satellite screen is all red - the system knows
where the satellites are but no signal is received.  This can last for
miles.  I've relocated the receiver, even stopping and removing the
receiver from the truck just in case EMI was the culprit.  Then just
as quickly, the receiver gets lock and everything is fine.

The distance traveled - sometimes 10 miles or more - during an outage
is such that ground interference can fairly confidently be eliminated.
Almost all my running is on open interstates so ground factors can be
eliminated.

I've gotten curious enough about this to bring along another receiver
but so far nothing has happened to give me an opportunity to check
with the second receiver.

The system is Street Atlas with the Delorme Earthmate hockey-puck
receiver.  I've had this system about 4 years and it is only in the
last few months that this has started happening.  I'd attribute this
to something in my receiver except that I recall also having
occasional loss of signal on my other receiver, a Magellan Meridian
Platinum, which I just attributed to "stuff happens".

John
---
John De Armond
See my website for my current email address
http://www.neon-john.com
Cleveland, Occupied TN
Don't let your schooling interfere with your education-Mark Twain



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