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EPE (Magellan) or Stated Accuracy (Garmin)?


4x4van

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Posted

I have a Magellan SporTrak Pro and love it. I just picked up a Garmin yellow E-Trex for my son, and have a quick question. The SporTrak Pro is WAAS enabled, and the yellow E-Trex is not, so in theory the SporTrak should be at least a bit more accurate. Yet, the E-Trex "tells" me that the accuracy is usually just as close, or even closer, than what my SporTrak "tells" me, even when I have good view of both WAAS satelites.

 

My conclusion is that the accuracy or EPE being reported by the units are only a "guestimate" by the units themselves anyway based on satelite strength, and perhaps the Garmin firmware is a bit more optimistic than the Magellan firmware? Any thoughts?

 

We don't stop playing because we grow old...we grow old because we stop playing!

Posted

"Estimate" as in "E"PE or "guestimate", yeah basically the same thing, doesn't really mean anything in absolute terms.

 

With both being "estimates", I wouldn't get to optimistic with either of them being better than the other.

 

Cheers, Kerry.

 

I never get lost icon_smile.gif everybody keeps telling me where to go icon_wink.gif

Posted

I am certainly not one to discuss the details that go into the algorithms used for location locks, etc., but the way I look at EPE is it is the unit's level of confidence on it's location based on averaging and the variance of successive readings. Just because it says EPE=10' doesn't mean the actual error couldn't be closer to 50' or more. Or Less. I have always left WAAS on on my SporTrak, but there are many threads on the subject that have differing opinions. My suggestion: Try it both ways in your typical environment and see which works better for you. I don't think there will be so much difference to dramatically effect the accuracy one way or the other. In either event, it will get you close enough for your instincts to "finish the hunt". Most important, have fun while your doing it.

 

If you don't know where you're going, any road will take you there.

Posted

WAAS is not meant to be turned off.

 

There are no logical arguments that suggest that turning off WAAS improves the operation of your GPSr. The arguments for saving battery life are weak at best.

 

If you still want to pursue this. There might be a secret button combination for turning WAAS off. For the Meridian you would hold down certain buttons while powering up. Then select it in the menu. Then reboot. There maybe a similar process for the Sport trac.

 

Someone in the Yahoo Meridain group may be able to direct you to some info.

Posted

ALL WAAS receivers regardless should have a clear and concise user friendly ON/OFF option instead of all this underhanded undocumented secret service stuff.

 

Really what's the big deal it should be a user option, pure and simple.

 

Magellan undocumented codes

 

Cheers, Kerry.

 

I never get lost icon_smile.gif everybody keeps telling me where to go icon_wink.gif

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