navigation acronyms, abbreviations and definitions - International ...

US user segment
USB Universal Serial Bus (computer connection at 12 Mbps - intro Jun 98)
USC United States Code
USCA ATCOs’ union in Spain
USCAHC US/Canada Hydrographic Commission
USCG United States Coast Guard
USGIC US GPS Industry Council
USGS US Geological Survey
USL Uniform Shipping Laws
USNO US Naval Observatory
USPA user-specific performance analysis
USSPACECOM US Space Command
UT Universal Time
UT unscented transformation (using Kalman filter)
UT user terminal
UT0 Uncorrected Universal Time
UT1 UT0 corrected for polar variation
The mean solar time of the prime meridian obtained from direct
astronomical observation and corrected for the effects of small
movements of the earth relative to the axis of rotation (polar
variation).
UT2 UT0 corrected for polar & seasonal variations
UTC Co-ordinated Universal Time
Corresponds exactly with TAI but differs from it by an integral
number of seconds - positive or negative leap seconds - to ensure that
the departure of UTC from UT1 never exceeds ±0.9 secs. GPS time
differed by 13 leap seconds in Oct 2000, otherwise always within
100ns.
UTC Universal Time Control (Galileo)
UTC urban traffic control
UTD user terminal demonstator (eg Galileo)
UTM Universal Transverse Mercator (using a meridian as line of contact)
UTM Unusable Time (see also EUTM and AUTM)
When a NELS Loran-C transmitter does not transmit signals or when
signal is out of tolerance.
UTMC Urban Traffic Management and Control (DTLR 5-year R&D prog)
UTP unshielded twisted pair (of wires carrying data)
UTP user terminal prototype (eg STENAV)
UUV unmanned underwater vehicle
UWB ultra-wide band (transmission - typically of GHz over short range )
V&V verification and validation
V2I (also V2X) vehicle-to-infrastructure (part of CVIS)
V2V vehicle-to-vehicle comms (part of CVIS)
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