[Loadstone] better accuracy by position prediction

Rob Melchers rob at loadstone-gps.com
Tue Oct 23 08:32:03 BST 2007


Some sort of user definable track smoothing would be possible, we've seen 
that from the data gathered during the '3 receivers test'. In fact, looking 
at the RTB the jumping around of heading is not so bad at all in our test. 
Having said that, every receiver comes with its own set of DOP masks as set 
by the manufacturer and you never know what they are, since GPS receivers 
makers seem to be extremely careful supplying this kind of data. It means, 
that every receiver needs its own approach. Also I found that some 
receivers apply their own track smoothing algorithms, so go figure.

At 10/22/2007, you wrote:
>The position data from the receiver is usually only about a second behind,
>maybe less. The speed data is maybe 2 seconds behind. I don't think there's
>any way around this since you need some data to calculate speed. Since the
>speed and position are both being provided by the receiver I doubt you could
>use speed to correct position.
>At some point there will be software calculations for heading and speed but
>that'll be to correct for those receivers that have proven almost useless
>for pedestrian use. Those receivers seem to give accurate position data
>thoe. If we had another source of data then maybe correction factors could
>be applied.
>
>On Tue, 23 Oct 2007, Hasan Karahasan wrote:
>
> > Hi folks,
> > we all know that a gps based system takes some time to react on any 
> changes.
> > When you are standing, yourr speed will be zero at optimal gps conditions.
> > When you suddenly start to move, the system needs several seconds to notice
> > this and to offer the correct data. This happens to any change. The
> > receiver's data is always some seconds behind the real data. Can we improve
> > that indolent and sluggish behaviour by doing some prediction? I am sure
> > that commercial software does similar things. We could do this by
> > calculating an acceleration factor. While one thread measures the speed and
> > calculates the accelleration periodically, another thread uses the 
> result to
> > correct the receiver's position permanently. If speed is in an increasing
> > state, we know that the real position is more towards our current 
> direction.
> > We can add some meters to the receiver's position.
> > If speed is decreasing, we can subtract something from the receiver's data.
> > All loadstone functions would benefit from such a correction.
> > What do you think about this?
> >
> > Hasan
> >
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> > http://www.loadstone-gps.com/mailman/listinfo/loadstone
> >
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