Re: Differential GPS

> One of the uses of DGPS is in container terminals at harbours. The
> carrier vehicles that move the containers about are tracked with the
> help of their DGPS systems. This allows to keep track of the positions
> of all the containers on the terminal. To do this, the accuracy must
be
> less than the width of a container (8 feet).
>

I use a non-dgps unit to mark positions of Flathead schools on the
bottom
during drift fishing - accuracy needs to be about 3-6 feet which is
perfectly achievable with a good civilian model now that the dither
factor
is gone - previously I would have needed to invest in an AUD $600
decoder to
attach to my hand held gps to get that level of accuracy. Customs in
Melbourne use the system you described as well as several taxi and
armoured
car companies in Sydney - the potential usage base is enourmous - most
of
which could not occur were the US govt to re-establish the limiters that
were originally installed (Yay ex-pres. Clinton! ).

Brendan