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GPS "off" ?


nikage2

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Commercial GPS receivers are only so accurate, which is why when hiding a cache, waypoint averaging is so important, to try to minimize positional error at the front end of the process.

 

Others have written much in these forums about GPS accuracy, "circular errors of probability" (sometimes referred to as "circular error of position") and "estimated position error." Rather than try to restate that information, I recommend you do a forum search.

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4 hours ago, geoawareUSA9 said:

Others have written much in these forums about GPS accuracy, "circular errors of probability

 

You or I did not understand the question of the TO.

I understood, that the coordinates ware correct for some time and now have "drivted" a considerable distance.  This could be an indication of wrong GPS settings.

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21 hours ago, nikage2 said:

Has anyone else noticed that cache coordinates are off?

My coordinates haven't changed on my hide (only 1) but the locator has drifted about 60 feet south.

I've noticed that the last three caches I've found were off as well.

Just curious

 

There have been logs about the coordinates being off, almost since your cache was published.  The other caches might be off as well.  Let the GPS settle for a while, and test the readings for consistency.  As mentioned, "averaging" can help (at least for placing a cache), but the main advantage of averaging is it requires you to let the GPS settle for a while. :)

 

 

Edited by kunarion
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If you don't trust your coordinates, then test them.

 

Enter your coordinates into your device, and then approach the cache location from at least 100ft/30m away. The arrow should point right at the cache location as you approach. Repeat the process, approaching the cache location from various directions, from at least 100ft/30m away each time. No matter which direction you approach from, the arrow should point right at the cache location.

 

If it doesn't, then adjust your coordinates until it does.

 

Bonus points for repeating the test on another day when the GPS satellites are in a different configuration.

 

Also, the Help Center article How to Get Accurate Coordinates should prove useful.

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Mousebiber is correct.

The coordinates have been fine for almost 2years(?) and just within the last few months, I'm hearing people are having a tough time finding the hide. When I checked it myself, the locator is now, indeed, about 60 feet south of original. It used to be spot on.

???

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I have located caches that other cachers logged as "coordinates were  right on', and my gadgets showed a different spot, some over 60 feet. Other caches were logged as "coordinates are way off" and they were right were my gadgets indicated  as GZ. 

 

And sometimes I am sure the cache was moved "to improve " it, and some new cachers think you are to re-hide a found cache in a new spot. 

 

Sorry I cannot help verify coordinates, it is a 20 hr 45 minute drive from my house one way -- not counting stops for other caches along the way.

Edited by Jayeffel
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1 hour ago, Jayeffel said:

I have located caches that other cachers logged as "coordinates were  right on', and my gadgets showed a different spot, some over 60 feet. Other caches were logged as "coordinates are way off" and they were right were my gadgets indicated  as GZ. 

 

And sometimes I am sure the cache was moved "to improve " it, and some new cachers think you are to re-hide a found cache in a new spot. 

 

+1.

 

If there are previous logs about "cache was 60 feet away", I might include the bearing if nobody mentioned that, assuming I can find it.  Occasionally I'll provide better coords although I don't know if any CO has ever used mine.  But if it's just my own reading, I might log that it wasn't where my iphone or Garmin said it is, or even that it's reading just fine if there's a log or 2 about it being "off".  Maybe it is in fact off, maybe I am.

 

But, yeah, I'm not there to check the coordinates, I'm simply getting as close as possible with the intent to find.  Even a cache 60 feet off may be findable in typical cache hides.  And if there are several logs about the cache "on the other side of the drive", I'll go look there for sure.

 

Edited by kunarion
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5 minutes ago, lee737 said:
On 12/26/2021 at 6:53 AM, niraD said:

Bonus points for repeating the test on another day when the GPS satellites are in a different configuration.

This is the answer to dead-on accurate coordinates IMO.....

 

I tried that on four separate days (7th, 8th, 20th and 22nd of November) on one of my hides and got four very different results over a range of some twenty metres:

 

CoordinateSpread.jpg.b2fee57e1cbec4e07f35ae0cdba5f61b.jpg

 

Some places just don't have very good GPS reception. The best I could do was pick an average somewhere in the middle and provide additional helper photos and hints on the cache page.

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2 hours ago, barefootjeff said:

Some places just don't have very good GPS reception. The best I could do was pick an average somewhere in the middle and provide additional helper photos and hints on the cache page.

I've found caches in places like that, where my device's Estimated Position Error was more than 100ft (30m). And the cache owners did indeed provide extra hints to help narrow down GZ, since they didn't have good GPS reception either.

 

I've also found a cache where past logs indicated that it was about 60ft (18m) north of GZ. Sure enough, we walked 60ft north of GZ and found the cache. But when I took new coordinates to include in my log, the coordinates I got were virtually identical to the published coordinates. And it wasn't like we were in a rocky canyon or under heavy tree cover. We were on a grassy hill with a clear view of the sky in all directions. Go figure...

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