Leica apMK12, Operation & Installation Manual

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190 Version 1.5
Operation & Installation Manual Glossary
GREAT CIRCLE NAVIGATION
Navigation based on a Great Circle calculation. The advantage of
Great Circle navigation is that it brings you the shortest way through
the active route. The disadvantage is that a Great Circle track may
differ from the straight rhumb line that is easily drawn on a Mercator
projected chart. Great Circle navigation is recommended for ocean
voyages only. The advantage increases by higher latitude (north or
south).
H DOP (Horizontal Dillution of Precision)
An indicator of the two dimensional accuracy in position (latitude
and longitude). See DILUTION OF PRECISION.
HEADING
The direction in which the vessel is pointed, expressed as angular
distance from north clockwise through 360 degrees. HEADING
should not be confused with COURSE. The HEADING is con-
stantly changing as the vessel yaws back and forth across the course
due to the effects of sea, wind, and steering error.
HEADING-TO-STEER
The angle of track required to steer the vessel or vehicle from its
present position to its planned destination point. This angle differs
from heading, which is its present angle of track with respect to
true north.
HEALTH
See SATELLITE HEALTH.
I NCLINED PLANE
A geometric surface that is tilted with respect to another arbitrary
reference plane (for example, the Earth’s equatorial plane).
INITIALIZE
To enter constants into the navigator to enable it to start position-
ing and/or navigating accurately.
INTERFACE
Electronic circuits that permit the passage of data between differ-
ent types of devices; For example, the speed and heading interface
circuit permits data from a speed log and compass to pass to the
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