Koden MDC-7010, Operation Manual

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Chapter 4 Target (AIS, TT and Trial manoeuvre) MDC-7000/7900 Series
0093169010-10 4-20
Reference target acquisition
If SDME or EPFS is not usable due to malfunction or other reason, then COG/SOG can be obtained by
setting Reference target.
By tracking 1 or 2 stationary targets, the true speed course can be used.
This stationary tracked target is called [Reference target].
A letter “R” denoting reference and number are attached to the lower left of Reference target symbol.
Note:
• Reference target can be used only when COG/SOG is not available.
• HDG input is necessary to use a reference target.
• Reference target has considerable error factor caused by target size, backlash and distance.
Accordingly, if COG/SOG is obtained from the reference target, then its accuracy is generally not
good. It is probable to mistake a moving target for a reference target. Therefore, if a reference target
is used, then CPA/TCPA of TT (ARPA), relative vector and relative speed are prohibited by IEC
62388. For this reason, if a reference target is used, its speed and vector should be only informative.
• Pay attention to that, if a reference target is lost, then accuracy of the true speed/the true course is
significantly reduced.
• Select a stationary target as a reference target to calculate own ship speed as ground tracking speed.
Do not choose a moving target as a reference target. A moving produces target error in the vector for
TT and AIS, which results in wrong collision avoidance information. Further, an unstable stationary
target produces inaccurate speed data and the target itself may become lost.
• The combined use with AIS function cannot be performed.
• When a reference target is lost, that reference target mark blinks and the indication “Ref tracked target
is lost
” appears in the alarm display area.
• If the target is lost for 20 seconds, then reference target function is considered a lost target. If a lost
target happens, then the numerical indication of COG/SOG becomes XXX.X in orange color.
Then stabilization mode automatically changes from ground stabilization to water stabilization.
• Loss of reference target will affect the calculation of true speed and true course of targets. Further,
own ship speed will be inaccurate.
By using menu
1
Move cursor using Trackball to the stationary target to be acquired.
2
Press MENU
key to display “Menu”.
Select [TARGET] => [TT] => [REF ACQ], and press ENT key.
3
When reference target is tracked, [GYRO] characters in the own ship information area at right side
of the display change to yellow. Move cursor using Trackball to the [GYRO] characters, then press
ENT key. [GYRO] characters change to [REF] characters.
COG/SOG computed by the reference target can be used.