A GPS "fix" can be inaccurate - no matter how "confident" the GPS device is :)
My experience here is from GPS units mounted on multiple trains travelling about the UK, recording their position every few seconds. A small percentage of the values we recieved from the GPS units were completly un-trustworthy (ie. the train would have had to do over 200mph to get between the last fix and the current positon). For a similar small percentage the train was NOT on a track! We realised we had to sanitise the data returned from the GPS units. We did this at 2 levels: 1) on the Train - no point processing (storing) a GPS position when the calcuated speed (NOT the speed from the GPS unit but calculated by us from the previous good fix) was totally unreasonable. 2) in the backend applcation - Trains travel on tracks (hopefully) so ignore all GPS positions that we cannot map on to a track. Conslusion - a single GPS position should NOT be used at the application level unless it makes sense - for a given value of sanity :) /Richard On Jul 9, 3:50 pm, "Maps.Huge.Info (Maps API Guru)" <cor...@gmail.com> wrote: > Question: How are you getting your location fix? Are you using > "ACCURACY_FINE" and assuming it will use the GPS? Unless you > specifically test for the provider being GPS, it might default to > network, which would give you a position with limited accuracy. I've > seen this bouncing around effect when the wireless location (network) > provider is trying to figure out where the device is, as it zeros in > on the location, it can hop all over the map. > > Bottom line: Don't assume that ACCURACY_FINE will be GPS, unless you > have GPS satellites in view and the user has enabled GPS, you'll be > using the network location service instead. > > -John Coryat -- You received this message because you are subscribed to the Google Groups "Android Developers" group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
