Users Manual Part 6

4. AIS OPERATION
4-18
4.11 Lost Target
A target is declared a lost target when it fails to produce data for six minutes or five
reporting intervals, whichever is the shorter. When this occurs, the target is marked
with the (flashing) lost target symbol and the message "AIS TARGET LOST" appears
in the Alert Box. To acknowledge a lost target, press the ALARM ACK key, or use the
trackball to select the [ALERT] box then press the left button.
4.11.1 How to set the lost target filter
If there are a lot of AIS targets in your area, the lost target alert can sound frequently.
In this case you may wish to have the alert ignore lost targets whose range, speed,
class or length are below the threshold value you specify.
1. Open the menu.
2. Select [5 TT•AIS].
3. For IMO-types, select [5 AIS].
For C-types, select [4 AIS].
4. Select [0 NEXT].
5. Select [3 AIS LOST TGT FILTER].
6. Select [MAX RANGE].
7. Referring to the following table, select the appropriate filter, then press the ENTER
MARK key.
8. Select [ON], then press the ENTER MARK key. The settings can now be adjust-
ed.
9. Spin the scrollwheel to adjust the setting as required, then left-click to apply the
setting.
10. Close the menu.
Filter type Definition
[MAX RANGE] Any AIS targets beyond the range set here will not trigger the
lost target alert.
[MIN SHIP SPEED] Any AIS targets slower than this setting will not trigger the lost
target alert.
[EXCEPT CLASS B] Select ON to prevent AIS targets class B triggering the lost tar-
get alert.