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4. Tracked Target (TT) Operation
4-7
4.7 TT Symbols and TT Symbol Attributes
4.7.1 TT symbols
The symbols used in this equipment comply with IEC 62388.
Item Symbol Status Remarks
Initial stage
Broken circle around an echo to indicate the target
under acquisition and initial stage of tracking,
before steady-state tracking.
Within one minute after acquisition (vector still
unreliable).
Steady tracking
Solid circle with vector indicating steady state
tracking (within three minutes after acquisition).
(flashing)
CPA alarm Plotting symbol (red) flashes to indicate the target is
predicted to come into CPA or TCPA.
CPA alarm acknowledge Shown in red, and TT symbol disappears after
CPA/TCPA alarm is acknowledged.
Automatically
acquired targets
(flashing)
Lost target A red X is crossed through the TT symbol to
indicate that it is a lost target. Flashing stops after
lost target alarm is acknowledged.
Initial stage
Plotting symbol selected for a target acquired
manually is shown in broken lines.
Within one minute after acquisition.
Steady tracking Manual plotting symbol in a solid circle (within
three minutes after acquisition).
(flashing)
CPA alarm
(collision course)
Plotting symbol (red) flashes to indicate the target is
predicted to come into CPA or TCPA.
TT symbol disappears after CPA/TCPA alarm is
acknowledged.
Manually
acquired targets
(flashing)
Lost target A red X is superimposed on the TT symbol to
indicate a lost target. Flashing stops after lost target
alarm is acknowledged. See the next page for lost
target criteria.
Acquisition zone
(flashing)
On target passing
through operator-set
acquisition zone
Symbol is red and flashing.
Target selected
for data readout
On selected target Target data (range, bearing, course, speed, CPA and
TCPA).
Reference target
R
After
acquisition,
changes to
"O" R
On reference target Used to calculate own ship’s over-the-ground speed
(echo-referenced speed) for ground stabilization.
Trial maneuver T
(flashing)
Bottom center
Appears during execution of a trial maneuver.
TT performance test S
(flashing)
Bottom center Appears during the TT performance test.
Lost target criteria
Targets not detected in five consecutive scans become "lost targets." A lost target is shown in the display with a red
X superimposed on the TT symbol. The TT symbol disappears after lost target alarm is acknowledged.
If you are in an area where TTs are lost frequently you may want to disable the lost target alarm against TTs by
maximum range or minimum speed. See section 5.11.1 How to enable, disable audio alarm for lost target.