[SailfishDevel] GPS initially shows old location

Aaron McCarthy aaron.mccarthy at jolla.com
Mon Jan 20 06:56:26 UTC 2014


On Fri, 17 Jan 2014 17:09:37 christopher.lamb at thurweb.ch wrote:
> Is it possible that the Jolla GPS / GPS Software stack initially shows
> the last location acquired?
> This is the behaviour I am observing.
> At the moment I am sitting in an office building, which has poor GPS
> reception, yet my app immediately shows GPS Coordinates. By peaking I
> can see that the GPS icon is flashing, and thus no fix has been
> acquired.
> Having checked the GPS coordinates with Google Earth, the coords are
> actually for a location several kilometers away - in the middle of a
> set of railway tracks that I travel along to and from work. As I do
> lots of mobile development on the train, this is a plausible location
> for where the Jolla last got a fix.
> By comparison the same app running on my old Nokia N9 gets NaN from
> the GPS for longitude and lattitude until it gets a fix. I can then
> translate this into a user friendly text on the GUI "No valid position
> yet", and stop the user from proceeding further into the app until a
> true fix is acquired.
> If my understanding of the behaviour of the Jolla GPS is correct, is
> there anyway I can stop it giving me the old fix? It is important to
> my app that the coords shown are as accurate as possible, otherwise a
> recovery party / rescue helicopter may be mis-directed.

This is a feature in Qt Positioning. Only the coordinates and timestamp are 
saved. Use the timestamp to check if the location data is old. The accuracy 
values of the position will be NaN.


Aaron McCarthy

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