Re: [Melb] POTS (Position of Trains System)

["Dave Proctor" <daproc@sd5.mailbank.com>]

Jackson Harding <jaxsonjo@camtech.net.au> wrote in message
38325B15.7099172E@camtech.net.au">news:38325B15.7099172E@camtech.net.au...

> GPS on the civilian band is meant to be accurate to within 100m 95% of
> the time.  This means that for 5% of the time (roughly one hour per day)
> it may be more than that.  Most current model receivers usually manage
> better than that (20m is about right).  For critical tracking
> applications one needs to use DGPS, which said by some to be as accurate
> or even more accurate than the military systems.  The idea is simple, a
> hyper accurate survey is made of a location and a GPS unit stationed
> there.  It then compares it's known location with the GPS signal and
> transmits a correction factor to any nearby DGPS unit.

Yep - know ALL of that - and your point is?

--
DaveProctor
thadocta AT dingoblue.net.au