| Target:
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Any object fixed or moving whose position and motion
is determined by measurements of range and bearing on radar.
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| Relative Course:
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The direction of motion of a target relative
to own ship's position expressed as an angular displacement from north.
It is deduced from a number of measurements of target range and bearing
on own ship's radar.
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| Relative Speed:
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The speed of a target relative to own
ship's position. It is deduced from a number of measurements of target
range and bearing on own ship's radar.
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| Relative Motion:
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The combination of relative course and
relative speed
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| True Course:
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The true direction of motion of a target
expressed as an angular displacement from north. It is obtained by
a vector combination of target relative motion and own ship's true
motion.footnote
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| True Speed:
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The speed of a target obtained by a vector combination
of target relative motion and own ship's true motion.footnote
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| True Motion:
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The combination of true course and true
speed.
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| True Bearing:
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The direction of a target from own ship
or from another target expressed as an angular displacement from north.
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| Relative Bearing:
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The direction of a target from own ship
expressed as an angular displacement from own ship's heading.
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| True Motion Display:
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A display across which own ship and each
target moves with its own true motion.
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| Relative Motion Display:
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A display on which the position of own
ship remains fixed and all targets move relative to own ship.
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| Azimuth Stabilised Display:
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A display on which the azimuth orientation
relative to a nominated true bearing is fixed.
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| North-up Display:
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An azimuth stabilised display in which
a line connecting the centre with the top of the display is north
true bearing.
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| Course-up Display:
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An azimuth stabilised display in which
a line connecting the centre with the top or the display is own ship's
intended course
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| Heading:
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The direction in which the bows of a ship are pointing
expressed as an angular displacement from north.
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| Target's Predicted Motion:
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A prediction of future target motion
based on linear extrapolation from its present motion as determined
by past measurements of its range and bearing on the radar.
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| Relative Vector:
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The predicted movement of a target relative
to own ship.
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| True Vector:
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The predicted True Motion of a target
as a result of own ship's direction and speed input. The True Vector
may be either displayed with reference to the sea or to the ground.
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| Acquisition:
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The process of selecting a target or
targets in order to initiate their tracking.
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| Tracking:
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The computer process of observing the sequential
changes in the position of a target in order to establish its motion.
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| Target Swop:
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A situation in which the incoming radar
data for a tracked target becomes incorrectly associated with another
tracked target or a radar echo.
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| Echo Reference:
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A facility for indicating that a particular
fixed Navigational Mark which is being tracked is to be used as a
Ground Stabilised reference.
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| CPA/TCPA:
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Closest Point of Approach and Time to Closest Point
of Approach limit as defined by the observer to give warning when
tracked or targets will close to within these limits from own ship.
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| Bad Echo:
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The name associated with a tracked target which
appears to have been temporarily lost or which has a poorly defined
radar aspect, in so much that, the target does not have tracking ability.
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| Lost Target
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The name associated with a target that is no longer
being tracked having become lost or obscured.
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| Sea Stabilization:
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A mode of display whereby own ship and
all targets are referenced to the sea, using gyro heading and single
axis Log Water speed inputs. This display is ideal for both Collision
Avoidance and Navigational purposes.
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| Ground Stabilization:
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A mode of display whereby own ship and
all targets are referenced to the Ground using Ground Track or Set
and Drift inputs. This display is ideal for Navigational purposes.
However it should be used with extreme caution when assessing close
quarter situations with other targets.
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