[juneau-lug] GPS mapping datum

Yes, there are many mapping datums world wide that exist to correct the 
curvature flaws for exactly the reason you identified.
My GPS is currently set to NAD83.  But I did cycle through the whole 
list of mapping datums that this GPS supports (about 50?) and none of 
them corrected the error I was seeing.  So I think it must be something 
additional.  The coordinates we get from the geocaching hunts work 
perfectly, so I don't suspect a GPS error.  It has to do with 
translating to the map coordinates.  And as I mentioned, the error is 
evident in programs besides GPSDrive.

Kevin Miller wrote:

>>In downloading the waypoints and tracks I found a bug in the perl
>>script that converts the data for GPSDrive.  If that's any use to you
>>- I'll dig it out and send it.  Also I'm perplexed as to a map
>>syncing error in GPSDrive that consistently throws off my position
>>(maybe 400 ft WNW).  I see the same error in MS Streets & Trips. 
>>Anyways lets compares notes sometime - at a JLUG meeting or otherwise.
>>    
>>
>
> What NAD ("reference datum") is your GPS set to?  I don't understand it
>exactly, but apparently there's a couple different NADs; NAD27 and NAD83.
>Mixing them throw off the reference by a few seconds (60' per second I
>believe).  I think it has something to do w/trying to map a curved surface
>(the earth) to a flat piece of paper.  Or it could be something else
>completely...
>
>
>...Kevin
>  
>

-- 
Browns Homepage  http://jdb.homelinux.net


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