True Heading AIS-CTRX CARBON, Operation & Installation Manual

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AIS-CTRX CARBON Class B AIS Transponder Manual
1.1E 15 CTRX CARBON Manual
are collected from the same sensor systems that provides the same information used in the navigation
e.g. in radars or ECDIS and this is normally based on GPS or DGPS. All ships within VHF coverage
will be able to receive AIS data and competent authorities that have installed networks with coastal
AIS coverage can receive the information. The capacity for the ships to report is defined by the IMO
performance standard to a minimum of 2000 data packages or slots per minute (see picture 2). ITU
(Technical Standard for the Universal AIS ) has been kind to double this and has provided AIS with
4500 data packages or slots per minute. The transmission is based on the (SO)TDMA ( Self-organized
Time Division Multiple Access) technique, that allows the system to overload with 400 till 500 % and
still give almost a 100 % message throughput between ships that are closer to each other than 8 to 20
nautical miles. In such case the system overloads targets far away will be discriminated in favor of
targets close to your own ship. In reality, the system capacity is unlimited and allows for a large
number of ships to communicate simultaneously.
Picture 2 The principle of AIS technology on the two radio channels.
Limitations with AIS
You should always be aware that all ship others ships and in particular pleasurecrafts, fishing boats,
warships and some coastal stations and VTS centers not will be equipped with AIS. Ships that have
been mandated to carry AIS can also under certain conditions turn of there AIS equipment at the
master’s disgrace. Therefore it is important to be aware that the information that AIS provides might
not be the full and complete picture of the situation around your ship.
Users of AIS must also be aware that transmission of false data can occur and that this will be
hazardous not only to your own ship but to other as well. The user is responsible for all data that is
entered into the system and for information provided by external sensors. The accuracy of received
AIS data is only as good as the information transmitted from the source of information.
You should always be aware that wrong configured or calibrated ship sensors (positions-, speed- or
heading sensors) could lead to that wrong information will be transmitted. Dangerous situations can
occur if faulty information is shown on another ship.