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Averaging?


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Hey all,

 

My first GPS was the Magellan GPS315. When getting close to a waypoint, you'd have to stop a minute or so to let it "average". (Catching up is more like it...) This process was somewhat tedious and took some time (few minutes +) to get a good set of cooridinates. It also resulted in the "boomerang" on most occasions. I just accepted that as "normal".

 

My new GPSMAP76c doesn't do that, but I do see the accuracy range fluctuating. Suffice to say, the cooridinates don't bounce around like the 315 did. It also isn't as

prone to "boomerang" me when coming up to a waypoint. It seems to keep me inside the accuracy circle. Quite different than the Maggie, which would let me move 50 foot or more before telling me I was off again.

 

I'm assuming this has something to do with how the units calculate the satellites. Can anyone enlighten me and other readers as to what the difference is?

 

Thanks,

Thad

AKA Old Bill

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IIRC the 315 started averaging when you dropped below a certain speed creating the need for the Maggie Dance (wild swinging of the 315 at arm's length) to break the unit out of averaging and update your position. Your Map76C will only average when you ask it to so continually updates your position.

 

It's normal for to see the accuracy range fluctuating as the satellite move across the sky or you move in and out from under obstructions.

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Magellans tend to use some sort of moving average of what your location is. The result was the boomerange effect, but it also resulted in more stable readings when in the woods. Garmin seems to just tell you where you are. You don't boomerating the caches but you will find you bounce around more in the woods.

 

That's been my experience.

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