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MX535 UAIS Transponder Unit
Technical & Installation Manual
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12
3.4.1 Sensor Notes
External Sensor
The AIS has interfaces (configurable as IEC 61162-1 or 61162-2) for position, bottom track (BT) speed,
heading and rate of turn (ROT) sensors. In general, sensors installed in compliance with other carriage
requirements of SOLAS Chapter V should be connected to the AIS System.*1. The sensor information
transmitted by AIS should be the same information being used for navigation of the ship. Interfacing problems
might occur if the existing on board sensors do not have serial (IEC 61162) outputs. A converter is needed to
translate the non-conforming data to IEC 61162 – sensor data. For Example, Nauticast Converter type NAU-
Z002 or Raytheon Nav Data Repeater 133-812.
The fact that AIS is fitted on board a vessel does NOT entail the need to install additional sensors other that
those stated in the carriage requirements.
External GPS
GNSS position sensors normally have IEC 61162 outputs suitable for direct AIS interfacing. However, it is
important to note that:
• The Geodetic Datum of the position data is transmitted by the sensor in WGS84 so that an IEC 61162
DTM sentence is configured.
• The MX420/AIS or MKD is able to handle three reference points -- two external GPS antennas, and one
internal GPS antenna.
• External GPS antennas SHOULD NOT be connected directly to the MX535.
External Heading
A gyrocompass providing heading information (HDT) is a mandatory sensor input to the AIS. A converter unit
(synchro or step-signal converter to NMEA 0183 v.3.0) for example Nauticast Converter type NAU-Z002 or
Raytheon Nav Data Repeater 133-812 will be needed for AIS connection in the case that the ship’s
gyrocompass does not provide IEC 61162 output.
External Speed and Course
If a bottom track (BT)log for speed over ground (SOG) is available, it may be connected. A converter (for
example Raytheon converter type: 133-812) is needed if the BT-log does not provide IEC 61162 outputs
External Rate of Turn
Not all ships will carry a Rate-Of-Turn (ROT) indicator according to IMO A.526. However, if a rate-of-turn
indicator is available and it includes an IEC 61162 interface, it should be connected to the AIS.
If ROT information is not available from a ROT indicator, it may (optionally) be derived from heading
information through:
• The gyrocompass itself,
• An external converter unit (see Heading),
• The AIS itself (calculated ROT).