On the thunderbolt, what datum do you have selected in Setup > Packet Masks and Options? If it is 0 (WGS-84), try 2 (NAD-27). -30m is about right for the geoid height around Las Vegas. Ed, k1ggi
-----Original Message----- From: James R. Gorr [mailto:[email protected]] Sent: Saturday, December 27, 2008 9:26 PM To: [email protected] 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 _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
