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An AIS-equipped system on board a ship presents the bearing and distance of nearby vessels in a radar-like display format. A graphical display of AIS data on board a ship. The automatic identification system (AIS) is an automatic tracking system that uses transceivers on ships and is used by vessel traffic services (VTS).
The frequencies which would have been the second frequencies on half-duplex channels are not used for marine purposes and can be used for other purposes that vary by country. For example, 161.000 to 161.450 MHz are part of the allocation to the Association of American Railroads channels used by railways in the US and Canada.
2182 kHz is analogous to channel 16 on the marine VHF band, but unlike VHF which is limited to ranges of about 20 to 50 nautical miles (40 to 90 km) depending on antenna height, [3] communications on 2182 kHz and nearby frequencies have a reliable range of around 50 to 100 nautical miles (90 to 190 km) during the day and 150 to 300 nautical miles (280 to 560 km) or sometimes more at night.
Maritime identification digits are used by radio communication facilities to identify their home country or base area in digital selective calling (DSC), Automatic Transmitter Identification System (ATIS), and Automatic identification system (AIS) messages as part of their Maritime Mobile Service Identities.
AIS technology is used mainly for collision avoidance and maritime domain awareness, search and rescue, and environmental monitoring. ORBCOMM leased the capabilities of two additional satellites, VesselSat-1 and VesselSat-2 , launched in October 2011 and January 2012, respectively, for its AIS service from Luxspace .
Maritime mobile operation is defined as operating a transmitter that is located on any vessel at sea. This means any manned structure afloat outside the high-water mark. Operating on vessels on inland waterways is defined as mobile work, and so requires /M to be added to the callsign, not /MM as for maritime mobile operations. [1]
Digital selective calling (DSC) is a standard for transmitting predefined digital messages via the medium-frequency (MF), high-frequency (HF) and very-high-frequency (VHF) maritime radio systems. It is a core part of the Global Maritime Distress Safety System (GMDSS). [1] A DSC touch screen control panel showing a (simulated) distress message ...
An AIS-SART is a self-contained radio device used to locate a survival craft or distressed vessel by sending updated position reports using a standard Automatic Identification System (AIS) class-A position report. The position and time synchronization of the AIS-SART are derived from a built in GNSS receiver (e.g. GPS). [1]