Garmin eTrex Legend CX Accuracy

[ROENIGK]

I have a eTrex Legend CX it is about 3 years old. I have used the average function when trying to pinpoint my cache. I is always 15-20 feet off, even on a clear day. Is this normal? Is my device just getting old or am I doing something wrong?

[+phlatlander]

This post is not meant in the least to be flippant, but what how do your know your Legend CX is "...always 15-20 feet off, even on a clear day." ?

Most commerically available handheld gps are "off" but that doesn't mean they are inaccurate. To establish the accuracy of your device you have to locate a nearby geodetic benchmark location. The position of these benchmarks is considered to be exact inasmuch as this is possible. I have taken both my (long gone) Etrex Legend and my newer Oregon550 to such a location (West of Winnipeg MB CA) and left it sitting on the benchmark for 20 minutes. I don't recall the reading for the Etrex but it wasn't more than .001 from my Oregon.

49 51.255 // Oregon550 = .256

97 28.695 // Oregon550 = .694

As I understand it my Oregon550 is "off" by 8-12 feet to the North and 7-10 feet to East. When I set a geocache I average three, 5 minute readings and each reading is on a different day or separated by several hours. Check out the archived geocache GC2FNTX to see real-life gps results.

 

** UPDATE **

Hmm, I think I misread your post. I have never (yet) used the built-in waypoint averaging so perhaps my response is off target - excuse the pun. I'll give it a try and also use my old method and compare results.

Edited April 30, 2013 by phlatlander