4-1
4. AIS OPERATION
An AIS transponder can be connected to this radar to overlay AIS targets on the radar
display. The radar can store up to 1,000 AIS targets in its storage buffer. When this
buffer becomes full of AIS targets, the Alert 190 "TARGET CAPACITY (AIS CAPACI-
TY FULL)" is generated to inform you that the storage buffer is full. The storage buffer
contains automatic dead reckoning for all AIS targets, which is based on reported
Speed Over the Ground (SOG), Course Over the Ground (COG), Rate Of Turn (ROT)
and heading. The storage buffer also contains calculation of range, bearing, CPA, TC-
PA, etc. The CPA and TCPA limits set for dangerous targets are common for TT and
AIS targets.
This radar can activate 40 AIS targets. The Alert 190 "TARGET CAPACITY (ACTIVE
AIS FULL)" is generated when 40 AIS targets are activated.
This radar can display a maximum of 300 AIS targets. The Alert 190 "TARGET CA-
PACITY (AIS DISPLAY FULL)" is generated when 300 AIS targets, which includes
both activated and sleeping targets, are displayed.
The frequency for update of AIS transponder-sent data depends on speed and course
of tracked AIS target. The table below shows the IMO standardized reporting rates for
the AIS transponder. Based on the table below, the radar defines which AIS targets
are in tracking or lost. When you acknowledge a lost target alert, the corresponding
AIS symbol will be removed from the display.
An AIS transponder “sees” all ships fitted with an AIS transponder belonging to either
a Class A or Class B AIS. Additionally, the AIS transponder receives messages from
ships and non-ships (AIS SAR aircraft, AIS aid to navigation, AIS base station, and
AIS search and rescue transmitter).
Type of Ship
IMO nominal
reporting interval
Lost target
indication
(reporting
interval >)
Class A: Navigation status is “anchor” or “not under
command” or “moored” or “aground”, and SOG d
3kn
3 min 10 min
Class A: Navigation status is “anchor” or “not under
command” or “moored” or “aground”, and SOG > 3kn
10 s 50 s
Class A: 0kn d
SOG < 14kn 10 s 50 s
Class A: 14kn d
SOG d 23kn 6 s 30 s
Class A: SOG > 23kn 2 s 10 s
Class B: “CS” SOG < 2kn 3 min 10 min
Class B: “CS” SOG t
2kn 30 s 150 s
Class B: “SO” 0 kn d SOG < 2kn 3 min 10 min
Class B: “SO” 2 kn d SOG < 14kn 30 s 150 s
Class B: “SO” 14 kn d SOG d
23kn 15 s 75 s
Class B: “SO” SOG > 23kn 5 s 25 s
Class A and Class B: no SOG available N/A 10 min
AIS SAR aircraft 10 s 50 s
AIS aid to navigation 3 min 10 min
AIS base station 10 s 50 s
AIS search and rescue transponder N/A 10 min
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