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dynamic ship data is transmitted quite frequently compared to the
static and journey-related data, which is only sent at minute intervals.
The transmission of data telegrams happens automatically, in short
time intervals, depending on the situation, i.e. speed and current
maneuver situation. For example, if a commercial ship lies at anchor it
only sends a message every three minutes, if it is moving and putting
about at the same time it sends at two second intervals.
1.1
What AIS standards do exist and are valid?
The “Class A” AIS service is described in the document ITU-R M.1371-1
where R stands for „Recommendation“.
This „standard document“ is valid for AIS data transfer with
specifications for the so-called „Class A“ and „Class B“ Service.
As mentioned previously, “Class A“ Transceivers operate with the so-
called SOTDMA method.
The use of „Class A“ Transceivers is mandatory in the professional
shipping as they are obliged to report.
Operation of „Class B“ Transceivers is described in document EN62287.
The observation of the properties specified in the standards is
obligatory for „Class B“ Transceivers.
„Class B“ Transceivers are not mandatory and are commonly used in
the leisure boat area.
The devices of the product line easyTRX2S are „Class B“ Transceivers.
1.2
Summarized (abridged) content of the
“Class A” standard: EN61993-2-2002
The telegram of a „Class A“ transmission consists of three different
types of messages:
Dynamic information:
•
MMSI number
•
Position of the ship (derived from GPS)
