Leica Geosystems GPS Basics - Manual (Page 58)

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GPS Basics -1.0.0en Glossary
Transformation
The process of transforming coordinates
from one system to another.
Transit
The predecessor to GPS. A satellite
navigation system that was in service
from 1967 to 1996.
Transverse Mercator Projection
A conformal cylindrical map projection
which may be visualized as a cylinder
wrapped around the earth.
Translocation
The method of using simultaneous data
from separate stations to determine the
relative position of one station with
respect to another station. See differen-
tial positioning.
Universal time
Local solar mean time at Greenwich
Meridian
UT
Abbreviation for universal time
UT0 UT as deduced directly from
observation of stars
UT1 UT0 corrected for polar motion
UT2 UT1 corrected for seasonal
variations in the Earth’s rotation
rate
UTC Universal Time Coordinated;
uniform atomic time system kept
very close to UT2 by offsets.
User equivalent range error (UERE)
The contribution to the range measure-
ment error from an individual error
source, converted into range units,
assuming that error source is
uncorrelated with all other error sources.
User segment
The part of the GPS system that includes
the receivers of GPS signals.
UTM
Universal Transverse Mercator Projec-
tion. A form of Transverse Mercator
projection. The projection has different
zones, each 6° wide with a central scale
factor of 0.996. Which zone is used
depends upon your location on the earth.
Y-code
An encrypted version of the P-code that
is transmitted by a GPS satellite when in
the anti-spoofing mode.
WGS 84
World Geodetic System 1984. The
system on which all GPS measure-
ments and results are based.
Zenith angle
Vertical angle with 0° on the horizon and
90° directly overhead.