Sperry Marine Visionmaster FT ECDIS, User Manual

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ECDIS User Guide Targets
65900012 10-53
Closest Point of Approach & Bow Crossing Limits
The system default values and the minimum/maximum infringement limits
for CPA/TCPA and BCR/BCT are shown in the table below.
Parameter CPA/BCR TCPA/BCT
System default value 2 NM 12 minutes
Range of values 0.1 to 20.0 NM 1 to 99 minutes
Target Association
Target association (correlation) enables the system to decide if two targets
displayed on one node are the same target or not. Most commonly this will
occur for a radar tracked target which is also an AIS target. Tracked
targets visible on a node can also be associated with each other, and if
targets are received from an external source these will also be associated
with other targets if appropriate. AIS targets are not associated with other
AIS targets.
The difference in the target's range, bearing and velocity values must be
less than the association limits for a target to be considered the same. If
targets do associate then they will be shown with the same ID on all nodes.
If targets change course, such that any of the values becomes greater than
the limits, the target association will split and each target will then have a
unique ID.
There are two defined settings for target association: Standard and Loose .
The default values for Standard and Loose settings and the
minimum/maximum limits for Target Association are shown in the table
below.
Target Association
Parameter Distance Angle Speed
Standard Setting 0.06 NM 1.0° 5.0 kn
Loose Setting 0.18 NM 2.0° 5.0 kn
Range of values 0.01 NM to 0.18 NM 0.1° to 3.6° 1.5 kn to 10 kn
If target association settings are changed the settings defined in the table
above may be re-applied by ticking the
Standard Setting or Loose
Setting check boxes.