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6:01 pm
March 20, 2010
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garcor wrote:
I get very frustrated when I am heading for a geocache and I get within 30' of GZ and my GPS gps arrow swings in a different direction sometimes right behind me. I am wondering if it is my GPSR or does this happen with all GPSR's or are some units better than others at maintaining signal.
This happens to me mostly in slight to heavy canopy but occasionally it happens in a wide open area on a clear day
Do you ever switch between profiles on your GPS? Switching between the "Auto Nav" and "Geocaching" profiles. Forgive me if I don't have the names correct. Or have you manually switched the routing options? When I ask this question, it doesn't have to have been recently, but at any time in the past. Also, do you have the newest firmware loaded on the unit?
I'm asking this question, because there were instances in the past when people were switching between Auto Nav routing and Geocache routing and the GPSr began to jump erratically when getting close to GZ. The first eX710 that I had did this and seem to absolutely lock up when getting within 70’ of a cache. However, what we found out was that the unit wasn’t switching out of the Auto Nav. Mode when switching from the Auto Routing profile back to the Geocaching profile and the timing intervals at which the unit reads the GPS if different for the two type of navigation, obviously reading less often at the higher speeds on for Auto Nav. There the results was a jumping/locking up when being used at hiking, walking or Geocaching speeds. One of the things that we found with this, is that if you’re having this problem – try switching between the Hiking profile and Geocaching profile a couple of times and see if the problem goes away. If it does, I need to know because this is something that most definitely needs to be passed on to Magellan.
However, if this isn’t the problem, you do need to know that “ALL” GPSrs will experience problems when in a canopy situation simply because of the design of the GPS system. Yes, higher end GPS antenna will perform better in these situations, but a GPS needs to be able to get a valid lock on at least 2 satellites for the 2D reading and at least 3 satellites for the standard 3D reading and even with the 3 sats it isn’t going to be as accurate as when the unit can pick up several sats and a WAAS sat as well…
David
5:12 pm
April 6, 2010
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It's maintaining a signal, but the problem is how fast the unit is updating it's position.
All GPSr units have this behavior to one degree or another.
Each of the manufacturers use a different formula for updating position & estimated accuracy.
At 30 feet you are close to the limit of accuracy for any & all GPS receivers, once I get to about 50 feet I slow down and see where the arrow is pointing.
Then I will slowly move toward the spot and give the unit a few seconds to update itself.
Plus if you are moving it updates position quicker than standing still, so I will just swing the unit six feet from side to side.
Remember that the absolute best accuracy, under perfect conditions, you can expect from any handheld GPSr is 15 - 16 feet.
That means that the target is somewhere in a 30 foot circle, no matter what the unit says about distance to target!
Sometimes the unit is right on the money, sometimes not.
I amuse myself by putting the GPSr down for 30 minutes and see where the track went, it will usually show that it wandered over 50 feet away.
I've done this with Magellan, Garmin and DeLorme GPSrs and they all do it.
So don't depend on the arrow to point right at the cache, use your eyes and experience to figure out exactly where the cache is hidden.
When in trouble or in doubt, run in circles, scream and shout
4:36 pm
June 9, 2011
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I get very frustrated when I am heading for a geocache and I get within 30' of GZ and my GPS gps arrow swings in a different direction sometimes right behind me. I am wondering if it is my GPSR or does this happen with all GPSR's or are some units better than others at maintaining signal.
This happens to me mostly in slight to heavy canopy but occasionally it happens in a wide open area on a clear day
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