Christian.Beier at STUD.TU-Ilmenau.de
Tue Apr 1 16:09:21 CEST 2008
Am Fri, 28 Mar 2008 19:09:14 +0100
schrieb Peter Kraker <peter.kraker at volja.net>:
> Unfortunately you need accurate speed to be able to get usable data
> from accelerometers for that. That's why some GPS modules have an
> interface for tachometer.
May be the history of GPS could be used to approximate the speed. Of
course, it's not accurate but when you assume facts like:
* you have already slow down your vehicle before entering the tunnel
* you will never accelerate in the tunnel
* max tunnel length of 3km
the variance should not be so huge. At least it's easier than connect
the tachometer. The other question is: do you really need the correct
position in the tunnel? If you know the position when the signal get
lost and know that you are in that special tunnel it should be enough.
Of course, it makes more sens in urban "tunnels" between huge buildings.
Correct me if I'm wrong, don't know tunnels outside Europe.
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