"Paul Saccani" wrote in message
...
On Wed, 10 Sep 2008 16:01:32 +1000, "RT"
wrote:
That really is a fascinating idea - sort of poor man's differential
GPS.....

Yes, that order of precision and accuracy for navigation.

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 :-)

That's about it. I thought it was used from scratch for aircraft
systems with combined INS and GPS - the cost of the filter is a
fraction of the cost of the system, particularly if their is already
room available on the computing side of things to do it. Its
certainly done with the PPS and SPS on military systems.

However, on reflection, there are probably many aircraft where GPS has
been added to an existing inertial based system and the integration
only goes so far as to allow a position update to correct drift.

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

Me two...

Heh. Mentioned this to Her Indoors. She was mightily unimpressed. "Of
course we were updating inertial nav - using radar - now do you want a cup
of tea?"

Friggin hell! :-)

Mind you, her field was ICBMs, not IC domestic transport :-)

(For those that tuned in late, my Missus was a fairly senior control systems
engineer in the old USSR)