idea for Neo 2nd generation: Accelerometer

Jeff Andros jeff at
Fri Jan 26 07:41:11 CET 2007

as I understand it, you can get more value out of the accellerometer than

in the simplest case, we know a gps can be off by a certain percent.  say
you leave the phone still for a long time, you could average the error and
get more precise over time (yeah, there'll be some skew... but we can trust
the law of averages to help us out some)

now, say you were aware of the motion of the device, you could still account
for that motion in the averaging process (A-meter says I've gone 2 feet, gps
says I've gone 3... pretty safe to say I'm between those)

one of the real weaknesses of the accellerometer(INS) are long-term
integration errors, and the biggest weakness of gps is short term
precision... put the two together and they complement each other REALLY
well.  our (US) military has been using this combination for years with
really great(horrible?) results... it'd be great to put this to a peaceful
use as well

On 1/25/07, Marcus Bauer <marcus.bauer at> wrote:
> On Thu, 2007-01-25 at 20:00 +0100, Ortwin Regel wrote:
> > The only situation where I can see the
> > accelerometer being really useful is where Apple is using it: For
> > changing the screen orientation of things according to how you hold
> > the phone.
> An accelerometer is a nice to have for navigation too. When losing the
> GPS signal, i.e. in a tunnel, you can go on doing dead reckoning.
> And it helps to get the vector map data coordinated with the GPS
> position.
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