[SailfishDevel] GPS initially shows old location

christopher.lamb at thurweb.ch christopher.lamb at thurweb.ch
Mon Jan 20 18:40:03 UTC 2014

Hi Aaron

Thanks, I will give that a whorl and report back.

I guess something like if the timestamp is older than say 10 minutes  
they should not be trusted (either not shown, or marked in some way).


Zitat von "Aaron McCarthy" <aaron.mccarthy at jolla.com>:

> Hi,
> 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.
> Cheers,
> --
> Aaron McCarthy
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