[OSM-talk] Strange GPS trace - drifting?

[Andy Robinson]

Barry Crabtree wrote:
>Sent: 31 October 2006 8:21 AM
>To: talk at openstreetmap.org
>Subject: [OSM-talk] Strange GPS trace - drifting?
>
>Hi
>
>I've been out mapping round a local residential area. Everything seemed ok
>plenty of satellites in view, but when I look at the trace it seems that
>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 but
>haven't uploaded the gpx file because it doesn't look right!
>
>Any thoughts on what might have happened. I've been collecting traces for a
>month & this is the first time I've seen anything like this. Have I done
>something stupid?
>

No I don't think it's likely that you were doing anything stupid. I've had
this problem now and again and I'm sure it's normally to do with either a
new satellite emerging over the horizon reducing the accuracy or the
satellites that were already there or the sats are in poor configuration.
There are occasions when I just give up because the satellites that are
present are in poor alignment for good triangulation. This happened when Ben
and I were cycling around Oakham on the Friday night of the Rutland weekend.
I threw my log away. Ben's is there to see but it's not particularly good.

So your trace wasn't all bad. You should still upload and use. Just consider
rolling down those streets with a problem again when you get a chance.

>Cheers. Baz.
>