GPS accuracy
 

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Thurston Benchmark
Frary Benchmark
Willard Benchmark
Stationary Tracklogs
Split Tracks
Angels Landing
Sliding into a fix
Cache coordinates

E-Mail Jeff

Determining the absolute accuracy of various receivers is something I don't have the time, patience, expertise, or equipment to do. There are however already several good websites where they have done a great job of quantifying accuracy. I highly recommend reading through some of them.

While I can't necessarily give good statistical data on accuracy, I have provided a few pictures of my receivers by USGS waypoints. It shows what sort of accuracy I was getting at that spot on that day. I've also included a couple of tracks, and a scatter plot of waypoints I save when hiding a geocache on a mountainside. The data is primarily of use only in getting an idea of what to expect from your receiver behavior wise, not absolute accuracy wise.

The Thurston Benchmark page shows a picture of my legend positioned by the USGS marker on top of the peak. Excerpts from the USGS data sheet are enclosed for you to compare with.

The Frary Benchmark pages shows a snapshot of the GPSR screen with the receiver beside the USGS marker on the peak. I've included excerpts from the USGS data page for you to compare with.

The Willard Benchmark shows my Legend and Sportrak at a mountain top USGS benchmark. I saved three waypoints with each unit over the course of 10 minutes.

The Stationary Tracklog page shows the results of a tracks recorded at 5 second intervals while my GIII+ and Legend were stationary. Not only does it show the amount of position drift encountered, it shows some interesting differences in the way the receivers record tracks.

The Split tracks page shows Sportrak up and back tracks that don't line up, and aren't positionally correct. The terrain offered fair to good reception conditions.

The Angels Landing track is an out and back trail example of how the Sportrak can wander when it has reception problems, and shows what you can expect from the sportrak in tough reception conditions.

The Sliding into a fix page shows tracks that illustrate why I recommend waiting a few minutes after initial lock to save a waypoint.

The Cache Coordinates page shows the scatter plot of the waypoints I recorded when hiding a geocache.