Furuno FEA-2107-BB - Maximum Number and Range for Displaying AIS Targets on ECDIS; Source of AIS Target Related Alarms

21. AIS Target Functions
21-4
21.2.4 Maximum number and range for displaying AIS targets on
ECDIS
Filter
RANGE
You can choose the maximum number of AIS targets to display on the
ECDIS. Further, you can also define the range within which to show
AIS targets and how to sort them. These items are available on the
Targets page in the Chart Display dialog box.
In this example the max number of AIS targets to display is 200, the
targets must be within 48 nm of your ship, and those targets are sorted
by Range.
The Filter function sorts AIS targets according to its setting, Range,
CPA or TCPA. The targets are sorted according the settings for
maximum number of targets and maximum range, and those targets
are displayed with an AIS symbol.
21.2.5 Source of AIS target related alarms
The alarm "3500 AIS Target Overflow" warns that the maximum number of AIS targets set to display on the ECDIS
has exceeded the operator-specified maximum range. It is possible that some of the AIS targets are not displayed on
the ECDIS. To display all AIS targets, increase maximum number of AIS targets or decrease value of maximum
range. This can be done on the Targets page in the Chart Display dialog box.
The alarm "3501 AIS Target storage full" warns that the maximum number of AIS targets which can be stored for
displaying on ECDIS has been exceeded.
The alarm "4037 AIS receive error" warns that data from an AIS transponder is not correctly received.
AIS target overflow
A Hysteresis is forced on the threshold ship count value that will trigger the alarm, as shown below. An AIS target
count that is approximately the same as the set threshold does not consecutively trigger the alarm, even if it
frequently exceeds the entered ECDIS threshold.
No. of ships (set on menu) No. of ships at time of alarm No. of ships at time alarm is cleared
200 (Ｍaximum)
201 189
100 101 94
40 41 37
20 21 18
AIS target storage full
Like the AIS target overflow arrangement, the set threshold does not consecutively trigger the alarm.
AIS target capacity No. of ships at time of alarm No. of ships at time alarm is cleared
1500 (Ｍaximum)
1501 1424