JRC JMA-5212-4/6 User Manual page 307

Lost Target Alarm
Attention
z If the gain, sea clutter suppression, rain/snow clutter
suppression are not adjusted adequately, the lost
target alarm may be easily generated. So such
adjustments should be mad carefully.
When it is impossible to continue tracking any acquired and tracked target, or the data of AIS target cannot
received for a specified time, the LOST alarm will be generated. The typical causes for alarm generation are
shown below, but not limited to the following:
x The target echo is very weak.
x The target is shadowed by a shore or a large ship and its echo is not received.
x The target echo is blurred by sea clutter returns.
If a target under tracking goes into a range of 32 nm and can no longer be tracked, it is canceled without a lost
target alarm being issued.
Status Symbol on display
12
Lost target
AIS12
Red Blinking
The AIS symbol blinks for x only.
Lost Target Alarm
Alarm characters Alarm sound
sound (pee)
Beep
Lost
Alarm
acknowledgeable
5 66
5.5 ALARM DISPLAY
Conditions
The alarm will sound once
when a lost target symbol is
displayed.
yy
yyy
5