[SailfishDevel] GPS initially shows old location

Marcel marcel at aliquis.de
Fri Jan 17 18:12:08 UTC 2014


Hi,

I can see the same behaviour, too. The timestamp is not really helpfull, as 
this is the timestamp when you get the position, not when this position was 
seen. And while waiting for a fix you get an updated position every 30 seconds 
with a new, current timestamp. Another observation I made is that the 
horizontal accuracy is always set to 15m and the vertical accuracy is not 
valid while waiting for a fix.

If the fix is found you can get an accurate position like every second. I 
would expect that while waiting for a fix the Valid-Properties (like 
langitudeValid) of the Position should be false, and switch to true if they 
are really valid after the GPS fix.

Greets,
Marcel

Am Freitag, 17. Januar 2014 schrieb Juha Siltanen <jsiltane at gmail.com>:
> Chris,
> 
> I see the same behaviour. But won't the timestamp method in
> QGeoPositionInfo help you? If the stamp differs a lot from current time,
> then it is likely to be invalid in your case. At least that is what I see
> in my application, the first update has the timestamp set to the time when
> GPS was last used.
> 
> /jsl
> 
> 
> 
> 2014/1/17 <christopher.lamb at thurweb.ch>
> 
> > Hi all
> >
> > 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.
> >
> > Chris
> >
> > _______________________________________________
> > SailfishOS.org Devel mailing list
> >


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