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S A TE L L I TE S I G N AL
Transmitted electromagnetic
measured by the navigator t o calculate the position of the navigator antenna.
is
SE LE C
I V
E
AVA I LAB
T
A system whereby the accuracy of
U.S. Department o f Defense.
S/N (SIGNAL-TO-NOISE RATIO)
Quantitative relationship between the useful and non-useful part of the received
satellite signal. A high S/N indicates a good signal strength.
SOFTWARE
Values programmed and loaded into memory. The values represent a permanent
set of instructions for running the automatic functions (computations) of the
navigator.
SOG - SPEED OVER GROUND
Speed in relation t o the sea bed.
COMPASS
STEERING
The compass used for navigation.
TIME OFFSET
The number of hours by which the time zone differs from Universal Time
Coordinated (UTC).
of
24
the
longitudinal segments around the world, each generally
degrees and 1 hour wide. In some regions there are half-hour time zones.
TRUE HEADING
Direction in relation to true north. True heading is compass heading corrected
for MAGNETIC VARIATION and deviation.
TRUE NORTH
Direction along the meridian of the observer to the north
U N I VERSA L TI M E
sonal variation in the earth's rotation.
UPDATE
See POSITION UPDATE.
point,
nates n a y be stored in the navigator. The? point position is the basis of the
range, heading-to-steer, estimated time of arrival and steering display
WORLD GEODETIC SYSTEM (WGS)
Worldwide datums (WGS 72 and WGS 84) used for satellite navigation sys-
all
tems. For
practical purposes the t w o datums may be considered identical
may
thus use the WGS72 offset figures from the chart in the navigators
us Offset datum (00). All charts will e v e n t u ~ l ~ ~
energy
from
I L I
TY
S /A
G P S
D I N ATE D
planned track of the vessel whose position coordi-
R.
a
is reduced. S/A is controlled b y the
pole.
be converted to
37
15
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