[OSM-talk] Strange GPS trace - drifting?

[lars]

Barry Crabtree wrote:

> over the space of a few minutes it has shifted what looks like 
> about 50/100 metres. I've put a screenshot of the trace at 
> http://wiki.openstreetmap.org/index.php/Image:Grangefarm-wierd.jpg

Judging by the 196 meter scale in the picture (is that correct?), 
the shift (inaccuracy) is 10-20 meters, not 50-100 meters.  That 
would be pretty normal if you are moving while only seeing 4--5 
satellites.

Or are the 2nd and 3rd lines from the bottom also supposed to be 
one road?

At the far left in the picture, it looks as if the curve suddenly 
readjusts (at B-C) when you come out of a forrest and suddenly see 
more satellites.

             B------------A
            /
    D------C
    E---------------------F

You could try again while paying more attention to how you hold 
your receiver and its antenna.  Find some road in a forrest where 
satellites are hard to see, and experiment with different ways to 
hold your reciever.


-- 
  Lars Aronsson (lars at aronsson.se)
  Aronsson Datateknik - http://aronsson.se