[ntp:questions] Sure Electronics GPS board: Amazing performance. :-)

Chris Albertson albertson.chris at gmail.com
Thu Mar 31 18:02:32 UTC 2011

On Thu, Mar 31, 2011 at 9:44 AM, Uwe Klein
<uwe_klein_habertwedt at t-online.de> wrote:
> unruh wrote:

>> My only concern is that the unit places its location 12m away from its
>> actual location on Googleearth-- ie, either googleearth is 12 m out in
>> its alignment to lat/long grid at my house, or the unit is misreporting
>> its position.

Another possibility to check is that both are not using the same
system.  What spheroid dose Google use?  Is it WGS84?   The GPS would
need to be set to match whatever Google uses.  Errors on the order of
up to 100M are posable.  Not everyone uses the same system.

Better than Google are the USGS topographic maps.  These are now
available on-line for free.  These are surveyed maps verified by
surveyors on the ground.  If you are worried about errors on the order
of a few meters Google is likely not the best source (except to help
you find the USGS.)

I've got it easy because a while back we did some construction at the
house and the city made us hire a survey team to find the true
location of the lot lines.  So now I have a surveyed bronze marker
right on the driveway.
Chris Albertson
Redondo Beach, California

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