[OSM-talk] Defective GPS trace

[Dave F.]

Steve Bennett wrote:
> I've got a trace from today which is significantly out of sync with a 
> path I traced from Nearmap:
>
> http://www.openstreetmap.org/edit?lat=-37.880138&lon=145.193417&zoom=19&gpx=594988 
> <http://www.openstreetmap.org/edit?lat=-37.880138&lon=145.193417&zoom=19&gpx=594988>
>
> The trace looks like I was wandering through the grassy paddock, but I 
> was actually following exactly that northern most "highway=path" in 
> the bush. So it looks like the trace is incorrectly recorded something 
> like 50m north of where I actually was. Now, since the discrepancy 
> seems to go away on that track a bit further east (later 
> chronologically), presumably the explanation is the GPS data is 
> faulty. Is this common? I'm new to GPSing, so I'm just surprised. It's 
> a Garmin Oregon 550. Is there anything I can do to reduce, or at least 
> detect, such errors?
>
> Steve
There are some good points in the previous messages, but I think there's 
an overall strategy & that's:

Don't be a slave to your GPS.

Be aware of your surroundings - Are you in thick undergrowth? Are you 
traveling at the bottom of a steep cliff?

As has been said, keep an eye on the accuracy reading (except if you're 
driving of course!)
If you are in an area where reception is poor make a note of it, either 
with a waypoint or, as I do, with old fashion paper & pencil.

I take photographs to help me remember what my route looked like. I find 
it extremely useful for recalling road signs & street names.

If your trace goes straight across a field, but you know you walked 
around the edge of it, mark it as you walked it, taking a best guess as 
to where you went. Then tag it with a note or Fixme explaining that it 
needs updating.

Cheers
Dave F.