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Do any of you have problems with elevation reading ???


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Magellan says theirs can be off by 10 meters or so (33 feet) and from what I've seen that is fairly close to the truth.


If you are in deep woods or valleys and have trouble keeping a lock on the 4th satellite, then your elevation reading would suffer.



Not all those that wander are lost. But in my case... icon_biggrin.gif

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Most of the time, my accuaracy and view of satellites is good. I have taken the time to atop at differnt points on a big hill, and still sometimes is it off by hundreds of feet,,,.


A second Question......

My Vista has a barimetric pressure elevation, AND a satellite elevation,,, which would be better to use?

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I have never found any of the electronic altimeters that could touch my Thommen for accuracy, and no batteries to affect cold weather performance. Of course you do have to calibrate it, and recalibrate it periodically. The GPS altitude accuracy is hopeless, it sounds to me like that is what you were using. If you are using a pressure altimeter, you should be getting accuracy within 50 feet. The fact that you were registering no change when you changed 500 feet makes me certain you were not using the pressure altimeter.

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Wow! I'm surprised at some of the comments in this thread. I use a Magellan Meridian, and although I mostly don't pay much attention to the elevation... the few times I've been at a known elevation, the GPS was almost right on.


It just occurred to me. Are you asking about the barometric altimeter or the GPS derived elevation?


In any case, I've visited a handful of places (geographic markers and such) where the known elevation was posted. My GPS has been within 10 or so feet every time. On a number of trips to the coast, my GPS almost always reads single digit elevation when I'm near the water.



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The Vista, like many altimiters has to be recalibrated frequently. Changes in barometric pressure effects the accuracy.


I find mine to be incredibly accurate when properly calibrated.


"You can only protect your liberties in this world, by protecting the other man's freedom. "You can only be free if I am" -Clarence Darrow

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the GPS altimeter will be more accurate the more satellites you have.. i have seen it vary as much as 30 feet at my house... there are alot of factors.. even one that reads atmospheric pressure will vary due to the weather.. use it as a general guide, not a rule.....

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I use a Magellan SporTrak Pro and have found it to be fairly accurate. Yesterday I was prowling around at a little place we have on Iron Mountain ... my topo map showed me at an elevation of 4200' and my GPSr was reading 4208'. I dropped off the ridge I was on, to a lower one with a benchmark known to me. The elevation marked on the benchmark stated "3460'" and my GPSr was reading 3466'.


I think those are both pretty close for a little handheld unit. On a side note: My GPSr was maxing out 6 satellites plus WAAS. So that may have helped.



Changing some folks mind, is like trying to herd cats.



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You have to remember that the Vista (and this is the unit that this thread is about) uses a barometric altimiter. It is considerably more accurate than the sat based altimiters, as long as it is properly (and frequently) calibrated.


So where do you find a known location with a known elavation to calibrate the altimeter?


The easiest way is if you have the Mapsource Topo software. Walk to a specific countour line and calibrate from ther. This is how I do it. If you don't have the Mapsource Topo software, then use a topo map to calibrate your Vista. Simply find a spot on the map, go there and calibrate at the spot. Lakes, ponds and mountain peaks are great for this.


Or you can to to a website like topozone.com or lostoutdoors.com and find the elevaton of your home and cailbrate it before you leave.


"You can only protect your liberties in this world, by protecting the other man's freedom. "You can only be free if I am" -Clarence Darrow

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The elevation is baramotric not satellite reading. The vista and etrex summits (my unit) have very accurate barometric altimeters. However, they don'thave the adjustability of a standalone altimeter device such as the Suunto altimeter watch. It's important to keep checking the altimeter with the map and correct it at known elevations...e.g. a lake. If you do that, it will work just fine to within a few feet.

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Use the rule of thumb of vertical error is three times horizontal error. So if your unit says EPE is 5 meters, assume the elevation error is +/- 15 meters.


Some factory tech reps and nerdy types will dispute this. This rule was given to me at a users conference by a sales rep of a major [nameless] GPS manufacturer and mentioned again by a rep from an engineering firm. Both said this rule applies regardless of make/model.



Friends don't let Friends geocache drunk.

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