Re: FreightCorp Radios

["David Proctor" <daproc@bigfoot.com>]

David Johnson <trainman@ozemail.com.au> wrote in article
<34B44CCE.F3670ED0@ozemail.com.au>...
> tezza wrote:
> 
> > Supposed to be accurate to within 100 metres
> > (the system to be used, not GPS in general)
> 
> Civilian GPS is accurate to within 100 metres.  Military GPS is accurate
to
> within 10 metres.

There is a system currenlt in use in civil aviation called DGPS -
Differential GPS - this could easily be utilised by the railways if
accuracy was required, and provides an accurate position to within a few
metres.

The system utilises a ground station that knows its exact position - it
then gets the GPS signal, and compares the position given by the GPS with
the position that it is actually located at. It then works out the current
error in the GPS system, and braodcasts it to all aircraft in the area. The
GPS equipment on the aircraft then factor in this known arror to come up
with an accurate position.

Because of this, the US Defence Department is reportedly softening its
stance on the application of the more accurate military band GPS in the
civilian sector.

> 
> --
> David Johnson
> CityRail Guard
> trainman@ozemail.com.au
> http://www.ozemail.com.au/~trainman/
> 
> 
> 

-- 
Regards

David Proctor
daproc@bigfoot.com