Post Processing DGPS
Not all DGPS applications are created equal. Some don't need the radio link because
they don't need precise positioning immediately.
It's one thing if you're trying to position a drill bit over a particular spot on the
ocean floor from a pitching boat, but quite another if you just want to record the track
of a new road for inclusion on a map.
For applications like the later, the roving receiver just needs to record all of its
measured positions and the exact time it made each measurement.
Then later, this data can be merged with corrections recorded at a reference receiver
for a final clean-up of the data. So you don't need the radio link that you have to have
in real-time systems.
If you don't have a reference receiver there may be alternative source for corrections
in your area. Some academic institutions are experimenting with the Internet as a way of