how to check gps accuracy

[thedixon4]

How can you check to see if your gps is off, or can they be?I have a Mag. Explorist 500.

It seems that the last couple of finds it was at least 30-40 feet off.Before that it was

pretty close.Magellan says its accurate to about "10" ft. my old 2000 got me closer

than this.

[mcdhuibh]

That distance is to be expected.

[+Gitchee-Gummee]

You are probably not taking into account that a cache may not have been "accurately" placed.

Too, it's very common that the cache may well have been "hidden better" (moved) by another cacher.

 

THOSE things, in conjunction with the acceptable variations in your GPSr can make for some pretty fair distances.

[+mpilchfamily]

If the cache is found inside of 30 feet then your inside the margin of error. Give or take 15 feet for your GPSr and 15 feet for the CO's GPSr. Not to mention any environmental factors that may be in play at the time of placement and when you found it.

[+NicknPapa]

If you really want to check the accuracy find a benchmark and check against it. Ideally, one that is in the middle of a huge clear field and on a clear day.

You have to remember though, the accuracy can and does change from day to day, usually even faster. My GPS is almost always within about 3 feet of the benchmark I usually check it against but I never know which way it will be off

[+mpilchfamily]

More to the point of accuracy there should be a screen on the unit that shows what satellites your receiving from and your average accuracy at that time. As mentioned above the accuracy changes constantly based on a number of conditions.

[+ngrrfan]

How can you check to see if your gps is off, or can they be?I have a Mag. Explorist 500.

It seems that the last couple of finds it was at least 30-40 feet off.Before that it was

pretty close.Magellan says its accurate to about "10" ft. my old 2000 got me closer

than this.

Find a professional surveyor that uses GPS for their work and have them set a point for you. Then compare your reading to theirs.

 

In the Denver area there is a cache set using a surveyors GPS system, once you find GZ you can check your GPSr against the coords and see how far off you are.

[+StarBrand]

The general accuracy of most handheld GPS devices is around 15 to 25 feet. Remember though you have might have to add your potential error to any error the cache owner had when placing the cache. That means you could easily find yourself looking for a cache up to 50 feet from where your unit says ground zero is. Most of the time you will find them within 20 feet or less but do be prepared to widen your search. Put the GPS away when you are within 20 feet or so and start looking for likely hiding spots.

 

Back off and re-approach the area if necessary to verify you are looking in the right spot.

 

Also keep in mind that the signal strength, number and geometry of the sats overhead is constantly changing and so does the accuracy of the readings. Receiving or not receiving a WAAS signal plays an important role as well. You can carry 3 identical units held together and get readings as much as 20 feet apart among them under a clear view of the sky. The 10 foot figure you quoted is only under the most ideal of conditions.

 

I think you are fine.

Edited January 18, 2011 by StarBrand

[thedixon4]

Thanks folks for all the answers and comments. My family loves

this sport and we look forward for more to come!