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WGS84 vs. UTM


SixDogTeam

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My Magellan 310 displays minutes to two decimal places not three as listed on cache pages, so I have been using the UTM coordinates to find caches. If I mark a location using UTM, how do I translate that into Degrees and decimal minutes to three decimal places? which I will need to do to hide a cache...

 

woo-woo-wuf!!

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Not a good idea. Although you can translate the UTM to Minutes decimal places, since the Magellan is only giving the location to 2 decimal places in Minutes, your coordinates could be off an additional 60 feet in adition to the circle of inaccuracy inherent in all consumer grade GPR's. My guess is that even though you are taking a reading in UTM, you'll still begin with the same lack of precision.

 

You ought to be using a unit that gives the coordinates to 3 decimal places to begin with.

 

On the other hand I could be wrong about this since I don't own a Magellan 310/

 

Alan

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By the way, UTM has nothing to do with WGS84. WGS84 is the Datum while UTM is the position. Degrees and Minutes are also another type of position like UTM, but neither of them have anything to do with WGS84 or any other Datum.

 

MAybe someone else can explain this better thqan I can.

 

Alan

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quote:
Originally posted by Alan2:

Not a good idea. Although you can translate the UTM to Minutes decimal places, since the Magellan is only giving the location to 2 decimal places in Minutes, your coordinates could be off an additional 60 feet in adition to the circle of inaccuracy inherent in all consumer grade GPR's. My guess is that even though you are taking a reading in UTM, you'll still begin with the same lack of precision.


 

This is incorrect. The Magellan 310 limitation is only of the display; it measures the position to the same precision as newer models. You can get the additional precision by looking at the NMEA output.

 

The UTM precision is 1 meter, or about 3 feet. Plug the UTM coordinates into the coordinate translator at Jeeep.com and you'll get DD MM.MMM coordinates with sufficient precision.

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UTM might display to whole metres but doesn't necessarily mean that precision is 1 metre.

 

Some might have noticed that trying to enter some specific last digit UTM coords that what one tries to put in is actually changed by the receiver. Basically the receiver is conforming the display compatible with the underlying coordinate system the receiver is actually storing the information in.

 

Cheers, Kerry.

 

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

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