[MLB-WIRELESS] OT: increasing GPS accuracy

[Rowan 2006]

Just a quick OT question as I know many of you fiddle with GPS: if you had
a reference GPS in a fixed location with long-term averaged co-ordinates,
could you use the difference between the current and long-term reading
from that GPS, to correct another (portable) GPS unit nearby?

eg, say the long term position is x,y. At 09:01:30 the current reading is
x+3,y-2. Can this offset be retroactively applied to the reading saved at
the same time from a portable GPS?

TIA

Cheers