Sensor Notes - ACR Electronics Nauticast Y1-03-0204 Installation Manual

3.6 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 conform data to IEC 61162 – sensor data. For Example ACR Converter
type P/N 2641.
*1)
The fact that AIS is fitted on board a vessel does NOT entail the need to install additional sensors
other than 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.
• AIS is able to process two reference points for its antenna position, one for external, and
one for an internal sensor. If more than one external reference point is used, the appropriate
information needs to be input to the AIS, so that the reference point information is suitably
adjusted.
External Heading
A gyrocompass providing heading information is a mandatory sensor input to the AIS. A
converter unit (synchro or step-signal converter to NMEA 0183 v.3.0 for example ACR
Converter type P/N 2641 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).
Installation Manual 13 Y1-03-0204 Rev.K