[time-nuts] GPS position averaging software?

[lists at lazygranch.com]

Google earth isn't very accurate, so I would chalk this up to coincidence. 
There is a USGS website with accurate waypoints, some of which are visible via satellite. (Literally X marks the spot. They can be seen on google earth.) I don't recall the URL at the moment, but I'm sure somebody on the list has it. I've used this to test GPSs in the past. I've found my Garmin gps60csx locks in to 4ft, pretty much the resolution. 

The vast majority of these reference marks are in the middle of the road. It takes a bit of work to find one that you can visit (public land) and linger on scene to do averaging.  

It is the USGS NAIS database IIRC. 

------Original Message------
From: David VanHorn
Sender: time-nuts-bounces at febo.com
To: Discussion of precise time and frequency measurement
ReplyTo: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] GPS position averaging software?
Sent: Apr 13, 2011 7:44 AM


I did this with our newly installed Thunderbolt.  When I plugged the coordinates into Google Earth, the center of the image was dead on with the skylight where the antenna is.
Not just pointing at the skylight, but the correct part of the skylight.   Could be coincidence, but I'd say the error was <1'.  I don't have any convenient surveyed points available to check with.

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