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GPS interference


Nonno's

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Would wooded area's hinder the correct co-ordinates being obtained? I hid cache twice in overcast forest area's, twice the gPS readings were wrong. If it dosnt affect the co-ords: i guess i bin my old GPS and get a new one. :mad: . i hate dissappointing fellow cachers

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It does weaken the satellite signals, which in turn can lessen accuracy. Older GPS receivers are affected by this more than newer ones. The new so-called "high sensitivity" receivers are quite resilient and are able to keep a GPS lock with at least decent accuracy when older receivers may even lose lock completely.

 

Question: What kind of GPS were you using? And how did you know that the coordinates were bad?

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There are two styles of antenna in common use in consumer GPRrs; Patch style and Quad Helix style. If you read the specs sheet for your GPSr or do an internet search you can find what style antenna your GPSr has. There is anecdotal evidence that the Quad Helix style antenna is more accurate under tree canopies.

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What do you mean by wrong? Most GPS readings are wrong. We played this sport for years with the older units and we found caches just fine, even under heavy tree cover. If you are talking coords 10-30 feet off then they aren't "wrong". They are well with the normal error of consumer grade GPS units. Besides, how much fun would this sport be if the coords put us dead on the cache every time?

Edited by briansnat
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Hi All,

 

Thanks for all the replies: I was using my dads Garmin etrex GPS a 1999 model. It isnt a high sensitivity model may hinder correct co-ords. 2 people had said the co-ords were wrong & pointing away from my hints and description of the hide area. I have temporaily disabled until i check them, thanks

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What do you mean by wrong? Most GPS readings are wrong. We played this sport for years with the older units and we found caches just fine, even under heavy tree cover. If you are talking coords 10-30 feet off then they aren't "wrong". They are well with the normal error of consumer grade GPS units. Besides, how much fun would this sport be if the coords put us dead on the cache every time?

 

Very true, if they were to precise it wouldnt make it as fun.

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What do you mean by wrong?

Looking at the OP's cache in question, the coordinates at publishing were ~300m off, which I would definitely classify as "wrong".

 

@Nonno's: That Etrex should easily be able to get accurate coordinates based on the reviews of other cachers here. I can't think of what might have happened for your coordinates to be that far off.

One thing I'll mention is that regardless of how old or new your GPS is, you should always take coordinates multiple times (preferably different days) and average them. The satellite constellation is constantly changing, and some configurations will give you more accuracy than others. Averaging coordinates will help reduce any errors that are introduced by a single set of "bad" coordinates. It's also a good idea to later navigate to your coordinates to make sure they bring you to the correct spot.

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1999? Does it support WAAS? (we do still have WAAS, don't we?)

 

Back at it... to increase accuracy, let the GPS sit for several minutes to stabalize. Don't stand over it watching the numbers, that compounds the issue.

 

That said, coordinates should be accurate. The hide should be at the coordiantes your GPS takes you to, not several feet away.

 

Save your pennies, you're gonna want a new GPS someday.

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Besides, how much fun would this sport be if the coords put us dead on the cache every time?

A good hide doesn't rely on the few meters of inaccuracy of GPS devices to make it challenging. A well thought out hide would still be enjoyable if the hider and seeker both hypothetically had completely accurate devices with no error at all.

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Hi All,

 

Thanks for all the replies: I was using my dads Garmin etrex GPS a 1999 model. It isnt a high sensitivity model may hinder correct co-ords. 2 people had said the co-ords were wrong & pointing away from my hints and description of the hide area. I have temporaily disabled until i check them, thanks

 

Looks like you're talking about GC39MGG Victoria Hill.

 

Did you try using the coords posted by Donnacha? Your corrected coordinates aren't close to what that cacher posted, so I'm wondering if you tested them to see if they were more accurate.

 

300 metres off is more than what one would expect from any gps.

 

Do you have your gps set to the correct format:

 

http://support.Groundspeak.com/index.php?pg=kb.page&id=208

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What do you mean by wrong?

Looking at the OP's cache in question, the coordinates at publishing were ~300m off, which I would definitely classify as "wrong".

 

@Nonno's: That Etrex should easily be able to get accurate coordinates based on the reviews of other cachers here. I can't think of what might have happened for your coordinates to be that far off.

One thing I'll mention is that regardless of how old or new your GPS is, you should always take coordinates multiple times (preferably different days) and average them. The satellite constellation is constantly changing, and some configurations will give you more accuracy than others. Averaging coordinates will help reduce any errors that are introduced by a single set of "bad" coordinates. It's also a good idea to later navigate to your coordinates to make sure they bring you to the correct spot.

 

Very useful,thanks!

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