From: thompson@cactus.org (Charles Thompson)
Subject: How does "Differential Mode" GPS work???
Organization: Capital Area Central Texas UNIX Society, Austin, Tx
Lines: 15



I understand that the new GPS boxes now have an option
known as "differential ready".  Apparently land-based
beacons tranmit GPS correction information to your GPS 
receiver (with differential option installed).

How does this system work?  What frequency is used for
the land-based beacons?

Thanks in advance,

Charlie Thompson
.