[OSM-talk] Motion sensors for navigation

[Erik Lundin]

That's correct, but the earth's magnetic field is often the dominating. 
If a classical compass can point out the earth's magnetic field, why 
shouldn't it be possible with an electronic sensor? Quick fluctuations 
could be filtered out.

/Erik

John Smith skrev:
> On 25 March 2010 10:20, Erik Lundin <erik at lists.lun.nu> wrote:
>> I have thought of a solution were you have a GPS device together with an
>> electronic compass sensor. In the tunnel, the position is calculated by
>> knowing the last position, the speed (either from the speedometer in a
>> car or keeping the same speed as before the tunnel) and the compass
>> direction. Since the error in this case increases exponentially with
>> time (right?), it would help to drive through the tunnel in both directions.
> 
> Magnetometer sensors are sensitive to all sorts of magnetic fields,
> not just the magnet field of the earth and so aren't very accurate, to
> prove this point someone made a metal detector for android phones a
> while back and it really does detect metal, or at least the magnetic
> field around metal.