Furuno FAR-2107(-BB) - Manual (Page 62)

1. RADAR OPERATION
1-40
Note 1: If you wish to create a target alarm zone having a 360-degree coverage
around own ship, set point "B" in almost the same direction as point "A."
Note 2: Two target alarm zones may be set. Note however that the 2 nd target
alarm zone is available only when the 1 st target alarm zone is active.
Note 3: When the target alarm zone is not within the range in use the indication
UP RNG appears to the right of the ALARM box. In this case select a
range that will display the target alarm zone.
1.23.2 Acknowledging the target alarm
A target in the target alarm zone produces both visual (flashing) and audible
(beep) alarms. To silence the audio alarm, press the [ALARM ACK] key on the
full keyboard or select the appropriate ALARM box then push the left button. The
ALARM box shows "ALARMx ACK." This will deactivate the audio alarm but will
not stop the flashing of the offending target. To reactivate the audio alarm, press
the [ALARM ACK] key again or select the ALARM box then push the left button.
(When an external buzzer is connected, the audio alarm does not stop until the
alarm zone itself is deactivated.) The ALARM box shows "ALARMx WORK."
1.23.3 Deactivating a target alarm
Left-click ALARM1 or ALARM2 box, whichever alarm you wish to deactivate,
until the alarm status in the ALARM box disappears. In this radar deactivation of
the target alarm zone 1 deactivates target alarm zone 2
.