Leica apMK12, Operation & Installation Manual

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Version 1.5 199
Glossary Operation & Installation Manual
Greenwich mean time corrected for polar motion of theEarth and
seasonal variation in the Earth’s rotation.
UPDATE
See POSITION UPDATE.
UTC
See UNIVERSAL TIME COORDINATED.
UTM
See UNIVERSAL TRANSVERSE MERCATOR.
UNIVERSAL TRANSVERSE MERCATOR
Alternative grid system used in harbor areas and for land applica-
tions instead of latitude and longitude.
V DOP (Vertical Dillusion of Precision)
An indicator of the accuracy in altitude. See DILUTION OF PO-
SITION.
VELOCITY MADE GOOD (VMG)
The speed by which the vessel is moving in the upwind direction.
When tacking, the optimization should be based on VMG (assum-
ing that TWD is expected to be fairly constant). See also
WAYPOINT CLOSURE VELOCITY.
VISIBLE SATELLITE
A satellite whose orbit has placed it above the earth’s horizon (el-
evation angle >0°) from the location of the navigator and is, there-
fore, available for acquisition. The navigator will not use satellites
with an elevation angle < 5°.
VMG
See VELOCITY MADE GOOD.
W AYPOINT
A point, usually along the track of the vessel or vehicle, whose
position coordinates may be stored in the navigator. The point
position is the basis for the heading, range, heading-to-steer, esti-
mated time of arrival, and steering display calculations.
WAYPOINT CLOSURE VELOCITY (WCV)
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