"Paul Saccani" wrote in message
...
On Tue, 9 Sep 2008 22:14:49 +1000, "RT"
wrote:


"Paul Saccani" wrote in message
. ..
Aren't both sources integrated via a fast Kalman filter? GPS errors
are rapid and errors tend to clump around an accurate position, whilst
INS errors are slow and tend to drift away from an accurate position.
Integrating the systems via a Kalman filter results in a far more
accurate and precise position.

That really is a fascinating idea - sort of poor man's differential GPS.....
If you kept track of the average position by the GPS and the difference from
there to the inertial position, you'd be able calculate the inertial drift
and thence correct the GPS to inertial accuracy :-)

Be interested in the technicalities, having been obliged to use a 4th
order
Chebishev (sp?) filter for some DA years ago - got a URL ? (Too lazy to
look atm :-)


Chebyshev/Chebychev - ask the missus.

She wasn't available at the time or I woulda :-) Doubt if she ever used
'em herself though, as she was more into control theory (...yuk!).

These books are worthwhile :-

Global Positioning Systems, Inertial Navigation, and Integration, 2nd
Edition

http://www.wiley.com/WileyCDA/WileyT...470041900.html

Kalman Filtering: Theory and Practice Using MATLAB, 2nd Edition

http://www.wiley.com/WileyCDA/WileyT...471392545.html

The wiki write up on Fast Kalman seems reasonable too.

Many thanks - I'll have a prowl...tho me and Matlab never really got on....