Etrex compass pointing wrong direction

[Core Eyes]

I have the yellow Etrex, which sometimes says north is south, thus pointing in the wrong "go to" direction. The "feet to go" goes down, while walking in the opposite direction of the pointer. Is this normal for this unit? My Magellan 315 never does this. Will downloading the latest software fix this? Thanks!

[Hinge Thunder]

quote:

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Originally posted by Core Eyes:

I have the yellow Etrex, which sometimes says north is south, thus pointing in the wrong "go to" direction. The "feet to go" goes down, while walking in the opposite direction of the pointer. Is this normal for this unit? My Magellan 315 never does this. Will downloading the latest software fix this? Thanks!

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I have also had this happen. It seems to mostly happen when the batteries are getting low.

 

In the GPS model of the universe, the shortest distance between two points is a straight line...through creeks, thorn bushes, horse piles, whatever....

[+LarsThorwald]

Never happened with my Vista...

 

Charlie

 

"One should never begin a journey by heading in the wrong direction."

[+Dekaner]

I have had this problem on my Garmin III+. It works fine when you're at a distance but gets confused when you get close. Follow the numbers as they go down, that's what I do.

 

- Dekaner of Team KKF2A

[jfitzpat]

If you don't have an eTrex Vista, or Meridian Platinum, your probably don't have a real compass.

 

The 'compass' (bearing needle) in most GPS receivers is inferred. The unit knows where you seem to be now and where it thought you were a second or so ago. So, it assumes that you are moving in a face line and looking where you are going.

 

But, if you are moving slowly and/or the reception is marginal, there is a very good chance that the unit has guessed wrong and is pointing off in la la land.

 

Here are a couple of ways this can happen - you turn slowly around, looking for the cache, then you look at the GPS display - you haven't shifted appreciably in location, so the GPS can't infer a new bearing. Similarly, positional accuracy drops (sat geometry, reception, etc.), you walk ten steps forward, but the unit thinks you have shifted 15 feet back and left of where you actually are. The measured 'vector' and your actual movement do not match, so, again, the arrow is wrong.

 

Even if you have a compass built in, remember that it needs to be calibrated (like the compass in most cars). Many cachers use a plain old compass when they get close, or just look at the coordinate readout and ignore the bearings when they are zoning in.

 

Good Luck,

-jjf

[twistedheart]

The yellow eTrex does NOT have a compass. (See page 12, left margin of the owners manual) The screen that looks like a compass is just the “Pointer” screen. And you must be moving for it to work.

 

I have the same eTrex. The only time it has done anything like you described is when I used the “TracBack” feature when I was not at the beginning of the track.

 

Also I see some complaining about getting a signal in trees and what not. I guess I have been lucky, my eTrex even works in my living room and will place me on the laptop screen in the same spot every time I turn it on. It takes longer to get to the “Ready to Navigate” but it always does.

[+Harrald]

I carry a real compass also. If I have problems with my yellow Etrex getting a proper signal I wait till I get a clean signal and take a bearing.

 

It's worth the few bucks. Also the batteries never go dead on magnetic north

 

 

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As always, the above statements are just MHO.

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[+Harrald]

I carry a real compass also. If I have problems with my yellow Etrex getting a proper signal I wait till I get a clean signal and take a bearing.

 

It's worth the few bucks. Also the batteries never go dead on magnetic north

 

 

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As always, the above statements are just MHO.

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[Hinge Thunder]

quote:

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Originally posted by Eric Egan:

The yellow eTrex does NOT have a compass. (See page 12, left margin of the owners manual) The screen that looks like a compass is just the “Pointer” screen. And you must be moving for it to work.

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NO DUH!! When he said compass, he was talking about the pointer (which is laid out like a compass). I personally have experienced what he was talking about. As you are walking toward the cache, and the distance is dropping, yet the pointer is pointing back the direction you are coming from, not toward the destination as usual. As I said previously, this usually happens when the batteries are getting low. I have replaced the batteries, and the problem goes away. It didn't happen often, but it did happen.

 

In the GPS model of the universe, the shortest distance between two points is a straight line...through creeks, thorn bushes, horse piles, whatever....

[davis513]

I have an Etrex Legend and have experienced this problem when I get close to the cache. What I have found works best is to switch from the navigation page (the one with the compass pointer) to the satellite page. I then watch the Lat/Long numbers at the bottom of the page and move around the area until I reach the exact Lat/long of the cache. It's then just a matter of looking around where I'm standing to find the cache.

[+Geo Leo]

The same thing happened to me once. I have a legend, and it started pointing in the opposite direction when I got close to a cache. As I continued toward the cache, the distance decreased, even though it continued to point in the opposite direction. I tried changing directions as well as walking in a straight line, but it did not correct itself. I don't know if my batteries were low or not as was previously suggested as the possible cause, but the problem has not recurred during the past 6 months since it happened. One possible solution is to download the most recent firmware upgrade from Garmin. I have downloaded the updates which may have corrected the problem.

 

Geo Leo

[LazyLeopard]

Does the yellow eTrex have a course pointer as well as a bearing pointer? Inadvertently switching to the course pointer and trying to follow it as if it were a bearing pointer can get mightily confusing...

 

Purrs... LazyLeopard http://www.lazyleopard.org.uk

[jfitzpat]

quote:

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Originally posted by Hinge Thunder:

 

NO DUH!! When he said compass, he was talking about the pointer (which is laid out like a compass). I personally have experienced what he was talking about. As you are walking toward the cache, and the distance is dropping, yet the pointer is pointing back the direction you are coming from, not toward the destination as usual. As I said previously, this usually happens when the batteries are getting low. I have replaced the batteries, and the problem goes away.

 

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What I tried to make clear in my post above is that actual vs. implied attitude AND actual vs. measured location can effect readout.

 

Positional error is not centered on the actual location. As you get close (60-100 feet), it is not unheard of for positional error to fool the unit into believing that movement is reversed. I've seen these with different makes and brands, particularly when there are hard vertical surfaces nearby.

 

The only reason that I can think of that batteries might be involved is that, when battery voltage drops, the noise floor in the receiver comes up, potentially causing a larger positional error. Switching batteries might then rectify the problem in a border line reception situation.

 

-jjf

[+sbell111]

I use a GPS3+. This has happened to me also. I haven't looked into whether there is a correlation between battery condition.

 

The bearing remains correct, the percieved direction of travel changes so it appears that I am walking away from the cache.

 

As others have said, this only happens as I near the cache location. I've always assumed that this is because I've slowed and the GPSr is having trouble figuring out what the heck I'm doing.

 

Just shoot a bearing with your normal compass and find the cache. No sweat.

[+Prime Suspect]

quote:

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Originally posted by sbell111:

 

As others have said, this only happens as I near the cache location. I've always assumed that this is because I've slowed and the GPSr is having trouble figuring out what the heck I'm doing.

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Yup, that's half the problem. For the pointer to act like a compass, it needs three pieces of information.

Where you are now

Where you were a second or two ago

Where you're trying to get to

The further apart these three locations are from each other, the more accurate the pointer appears to be. When you approach a cache location, you tend to slow down. This causes the first two locations to be closer together, which means the unit cannot determine your direction of travel as accurately as before. And since your closer to your destination, it's less accurate in pointing to the direction you need to go.