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 2,000 AIS targets in its storage buffer. When this
buffer becomes full of AIS targets, the Alert 533 (ALF format: 190,2) "AIS Target Ca-
pacity 100%" is generated to alert you to full storage buffer. The storage buffer con-
tains 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, TCPA,
etc. The CPA and TCPA limits set for dangerous targets are common for TT and AIS
targets.
This radar can activate 500 AIS targets. The Alert 535 (ALF format: 190,1) "AIS Target
Activate 100%" is generated when 500 AIS targets are activated.
This radar can display a maximum of 1,000 AIS targets. The Alert 531 (ALF format:
190,3) "AIS Target Display 100%" is generated when 1,000 AIS targets, which in-
cludes 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
Class A: Navigation status is “anchor” or “not under command” or “moored”
or “aground”, and SOG < 3 kn
3 min
Class A: Navigation status is “anchor” or “not under command” or “moored”
or “aground”, and SOG t
3kn
10 s
Class A: 0kn d
SOG < 14kn 10 s
Class A: 14kn d
SOG d 23kn 6 s
Class A: SOG > 23kn 2 s
Class B: “CS” SOG < 2kn 3 min
Class B: “CS” SOG t
2kn 30 s
Class B: “SO” 0 kn d SOG < 2kn 3 min
Class B: “SO” 2 kn d SOG < 14kn 30 s
Class B: “SO” 14 kn d SOG d
23kn 15 s
Class B: “SO” SOG > 23kn 5 s
Class A and Class B: no SOG available N/A
AIS SAR aircraft 10 s
AIS aid to navigation 3 min
AIS base station 10 s
AIS search and rescue transponder N/A
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