Instruction manual

Glossary Page Gloss-3
Glossary
SA
Selective Availability. Intentional degrading of
GPS signal by US Department of Defense to
hamper use by enemy. Can be mostly nullified
by differential operation.
SV
space vehicle (satellite)
UBN
Output message containing CPD position,
velocity, and statistical information. Binary
only.
UDRE
User differential range error
Week number
Sequential GPS week number measured from 1/
5/80.
Z mode, Z-tracking™
Ashtech proprietary method for achieving
precise position when Anti-Spoofing (AS) is
on.