I would echo Mike's comments here. You could try the google background imagery, in a few places in UK where I have checked their error is around 2m or better although in some places it can be a lot worse than this so it depends where you are as to how reliable this imagery is.
'Professional level' dgps can often give 1-2cm accuracy in real time using correction services such as Smartnet (in UK and parts of Europe) but the kit is expensive and you have to pay a license to use the correction service. Mike ________________________________________ From: Mike Shand [[email protected]] Sent: Wednesday, June 04, 2014 10:36 AM To: [email protected] Subject: Re: [Qgis-user] GPS issue on android tablet Zoltan, I suggest you create a Csv file and plot the points on a large scale map or hi-res satellite image. You say "varies very widely", a quick check indicated the max. variation between your points is approx 8m and the min. approx 1m. I would say if you are getting 3m GPS accuracy that is pretty good if you are outside the US or Europe. I assume you are using a dedicated GPS unit attached to your Tablet and not a built-in GPS on your Tablet. Bear in mind that the 3m accuracy deviation (imagine a 3m radius circle from where you mark the point) can be in any direction, so if you are 3m E out with first reading and 3m W with the second reading the error between the point could be 6m. Mike On 04/06/2014 10:14, Zoltan Szecsei wrote: > On 2014/06/04 11:07, Giuseppe De Marco wrote: >> hello, I've been using Qgis on android tablet (samsung galaxy tab 2) >> and I've been experimenting GPS connection. >> The issue is that even if Qgis finds and use several satellites (9 or more) >> precision never gets under 3.0 meters but what is strange is that >> coordinates value fro the same spot varies very widely: >> Time Coordinates Altitude >> 14:39:36 41.69528959 13.26464738 343.1 >> 14:39:54 41.69529880 13.26466761 341.8 >> 14:40:06 41.69528519 13.26470222 340.4 >> 14:41:18 41.69528944 13.26472418 341.1 >> 14:41:42 41.69529608 13.26471821 341.8 >> 14:41:54 41.69530621 13.26470892 342.5 >> >> I have colleagues who have experienced the same. >> Has anyone else experienced the same issue? >> Is that depending on GPS device or could it be a software related >> issue? >> > There are probably 10000 reasons for this. > I am surprised that you even think you are getting sub 5m accuracy. > Please plot the points on a cadastral map (or some basemap that is > "guaranteed" accurate) and see what you are really getting. > You also don't say whether you are in a tree'd or urban (or whatever) > area - but observing 9 satellites suggests somewhere in the open. > > For professional GPSes, to get sub 10cm accuracy, you need to observe > for 30-60 minutes, and do post processing. > > I am not a surveyor, so my info may be not 100% - Please can a surveyor > or someone well experienced in these issues chip in. > > Regards, > Zoltan > _______________________________________________ Qgis-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/qgis-user -- The Open University is incorporated by Royal Charter (RC 000391), an exempt charity in England & Wales and a charity registered in Scotland (SC 038302). The Open University is authorised and regulated by the Financial Conduct Authority. _______________________________________________ Qgis-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/qgis-user
