I have done quite a bit of testing of the software in land.
1) With 4.6.4.487, the logging of GPS locations proceeded without a
significant problem. The problems with the previous version of the
software were obviously related to that specific version on my machine.
I can stop and restart the GPS logging and it stops and resumes as expected.
2) Logging did not occur at 3 min intervals, but at about 5-min
intervals. The software behaves almost like the minimum allowed
between-record interval is 5 minutes and it substitutes my 3-min
interval with 5-min.
3) Walking at a speed of about 4.5 km/h and the between location
parameters set at 3 minutes and 100 m, the locations were at longer
intervals (around 5-11 minutes) compared to walking at a slower speed.
Walking at about 2 km/h, the records were mostly around 5 min apart.
Could it be that it captures a moving GPS with less accuracy at speed
and if one moves faster it takes longer to obtain a valid plot?
4) As far as accuracy is concerned, the error in GPS position was around
20m, with one record off by around 1.6 km at the fast walking speed. At
a slow walking speed the accuracy was within 7m.
I have the numeric data behind most of the above.
I think there is room for experimentation with the algorithm that does
the GPS recording. I suspect that a single plot is obtained from several
GPS data points and the criteria for determining an accurate plot are
set quite tight so that data points need to be very close together for
the software to record a single GPS position in the list of GPS
positions. If this is the case, then one should experiment with the
number of repeat points required for a single GPS position as well as
the degree to which these repeats need to be similar in order to be
accepted as a valid GPS record. This is the only way in which I can make
sense of this.
I scratched around in the mobile-widgets, core and Qt-models directories
to look for the code where the actual GPS recording takes place but I
have not yet found it. I am not sure at what low level the GPS chip is
accessible from our code.
Kind regards,
willem
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