[time-nuts] altitude difference between two gps

[Richard W. Solomon]

-800 meters ??
Live in a mine ??
How can that be ?

73, Dick, W1KSZ

-----Original Message-----
>From: "James R. Gorr" <n3toy at yahoo.com>
>Sent: Dec 27, 2008 9:26 PM
>To: time-nuts at febo.com
>Subject: [time-nuts] altitude difference between two gps
>
>Hello everyone!
>
>I have a tbolt that I am monitoring with tboltmon.exe and some off-brand 12 channel GPS (I bought from Sure Electronics on eBay) that I am monitoring with VisualGPS.  Both are fed from the same GPS antenna through a symmetricom splitter.  There is a 30 meter difference in the altitude readings between the two.  My tbolt says my altitude (after a self-survey) is ~761 meters and the 12 channel Sure Electronics GPS says my altitude is ~791 meters after 7,500+ readings.  I took my hand held Garmin 12XL outside and it says my altitude is ~790 meters at street level.
>
>Anyone have an idea why my tbolt might be reading different from the other two devices?  I am assuming the tbolt is reading low. 
>
>Jamie
>
>
>      
>
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