Circular Letter
SN/Circ.227
As
amended by SN.1/Circ.227/Corr.1 (10 December 2008)
As amended by SN.1/Circ.227/Corr.2 (27 April 2017)
GUIDELINES FOR THE INSTALLATION OF A SHIPBORNE AUTOMATIC IDENTIFICATION SYSTEM
(AIS)
(adopted
on 6 December 2002)
1. The Sub-Committee on Safety of Navigation (NAV), at its
forty-eighth session (8 to 12 July 2002), agreed on Guidelines for the
Installation of a Shipborne Automatic Identification System (AIS), as given at
Annex, and also agreed that they should be issued for use on a voluntary basis.
The Guidelines describe the shipborne AIS installation matters and are meant to
be used by manufacturers, installers and surveyors to ensure good installation
practices.
2. The Maritime Safety Committee, at its seventy-sixth session (2
to 13 December 2002), concurred with the Sub-Committee's views, approved the
Guidelines as set out at Annex and encouraged their use for AIS installation
purposes on a voluntary basis.
3. Member Governments are invited to bring the annexed Guidelines
to the attention of all concerned.
ANNEX.
GUIDELINES FOR INSTALLATION OF SHIPBORNE AUTOMATIC IDENTIFICATION SYSTEM (AIS)
Contents
1. General
1.1 Survey
1.2 Documentation
2. AIS Installation
2.1 Interference to the
Ship's VHF Radiotelephone
2.2 VHF Antenna Installation
2.3 GNSS Antenna
installation
2.4 Power Source
2.5 Synchronization
3. Bridge Arrangement
3.1 Minimum Keyboard and
Display
3.2 Pilot plug
3.3 Display system
3.4 Installation of the BIT
(Built-in Integrity Test) function
4. Dynamic data input
4.1 External Sensors
4.2 Position, COG and SOG
4.3 Heading
4.4 Rate of Turn
4.5 Navigational Status
5. Static Information
5.1 Entered at initial
installation of AIS
5.2 Reference point of
position
5.3 Ship's dimensions
6. Long-Range function
Annex 1 — Rate of Turn
Annex 2 — Type of ship table
Annex 3 - Recommended IEC 61162 sentences
The Automatic Identification System (AIS) Class A is defined by
IMO and has been made a carriage requirement by the latest revision of SOLAS Chapter
V. AIS provides information that may be used for the navigation of the ship. It
is therefore essential that the information provided by AIS be reliable.
The AIS itself has been standardised by the International
Telecommunications Union (ITU) and the International Electrotechnical
Commission (IEC) and is subject to type approval. In order to fulfil the
reliability requirements of information exchange, care should be taken to
ensure the AIS is correctly installed.
This document contains guidelines for manufacturers, installers,
yards, suppliers and ship surveyors. It does not replace documentation supplied
by the manufacturer.
The guidelines take into account the following conventions,
regulations, instructions and guidelines:
- IMO Resolution MSC.99(73)
Annex 7, Adoption of amendments to the International Convention for the Safety
of Life at Sea, 1974, as amended;
— IMO Resolution MSC.74(69)
Annex 3, Recommendation on performance standards for AIS;
- ITU Radio Regulations
(RR);
— IEC 60092 (series),
Electrical Installations on Ships;
— IEC 60533 Electrical and
Electronic Installations in Ships — Electromagnetic Compatibility
The AIS is considered part of the ship's radio station and is
surveyed together with radio installation. Surveys on Convention ships should
be carried out in accordance with the rules laid down in IMO resolution
A.746(18) "Survey Guidelines under the harmonised system of survey and
certification" and "Protocol of 1988 relating to the International Convention
for the Safety of Life at Sea, 1974, as amended."
For the AIS installation the following drawings shall be
submitted:
- Antenna layout;
— AIS arrangement drawing;
- Block diagram
(interconnection diagram);
An
initial installation configuration report should be produced during
installation and kept on board.
2.1 Interference to the Ship's VHP
Radiotelephone
The AIS shipborne equipment, like any other shipborne transceiver
operating in the VHP maritime band, may cause interference to a ship's VHP
radiotelephone. Because AIS is a digital system, this interference may occur as
a periodic (e.g. every 20 s) soft clicking sound on a ship's radiotelephone.
This affect may become more noticeable when the VHP radiotelephone antenna is
located near the AIS VHP antenna and when the radiotelephone is operating on
channels near the AIS operating channels (e.g. channels 27, 28 and 86).
Attention should be paid to the location and installation of
different antennas in order to obtain the best possible efficiency. Special
attention should be paid to the installation of mandatory antennas like the AIS
antennas.
Location of the mandatory AIS VHP antenna should be carefully
considered. Digital communication is more sensitive than analogue/voice
communication to interference created by reflections in obstructions like masts
and booms. It may be necessary to relocate the VHP radiotelephone antenna to
minimize interference effects.
To minimise interference effects, the following guidelines apply:
- the AIS VHP
antenna should have omnidirectional vertical polarisation;
- the AIS VHP antenna should
be placed in an elevated position that is as free as possible with a minimum of
2. m in horizontal direction from constructions made of conductive materials.
The antenna should not be installed close to any large vertical obstruction.
The objective for the AIS VHP antenna is to see the horizon freely through
360°;
— the AIS VHP antenna should
be installed safely away from interfering high-power energy sources like radar
and other transmitting radio antennas, preferably at least 3. m away from and out of the transmitting beam;
- ideally there
should not be more than one antenna on the same level. The AIS VHP antenna
should be mounted directly above or below the ship's primary VHP radiotelephone
antenna, with no horizontal separation and with a minimum of 2 m vertical
separation. If it is located on the same level as other antennas, the distance
apart should be at least 10 m.
The cable should be kept as short as possible to minimise
attenuation of the signal. Double screened coaxial cables equal or better than
RG214 are recommended.
All outdoor installed connectors on the coaxial cables should be
waterproof by design to protect against water penetration into the antenna
cable.
Coaxial cables should be installed in separate signal cable
channels/tubes and at least 10 cm away from power supply cables. Crossing of
cables should be done at right angles (90°). Coaxial cables should not be
exposed to sharp bends, which may lead to change the characteristic impedance
of the cable. The minimum bend radius should be 5 times the cable's outside
diameter.
Coaxial down-leads should be used for all antennas, and the
coaxial screen should be connected to ground at one end.
Class A AIS should be connected to a GNSS antenna.
The GNSS antenna should be installed where it has a clear view of
the sky. The objective is to see the horizon freely through 360° with a
vertical observation of 5 to 90° above the horizon. Small diameter
obstructions, such as masts and booms, do not seriously degrade signal
reception, but such objects must should not eclipse more than a few degrees of
any given bearing.
Locate the antenna at least three meters away from and out of the
transmitting beam of high-power transmitters (S-Band Radar and/or Inmarsat
systems). This includes the ship's own AIS VHP antenna if it is designed and
installed separately.
If a DGNSS system is included or connected to the AIS system, the
installation of the antenna should be in accordance with IEC 61108-4, Ed 1,
annex D.
To achieve optimum performance, the gain of the antenna
pre-amplifier should match the cable attenuation. The resulting installation
gain (pre-amplifier gain — cable attenuation) should be within O to 10 dB.
The coaxial cable between the antenna and the AIS shipborne
station connector should be routed directly in order to reduce electromagnetic
interference effects. The cable should not be installed close to high-power
lines, such as radar or radio-transmitter lines or the AIS VHP antenna cable. A
separation of one meter or more is recommended to avoid degradation due to
RF-coupling. Crossing of antenna cables should be done at 90° to minimise
magnetic field coupling.
All outdoor installed connectors on the coaxial cables should be
waterproof by design to protect against water penetration into the antenna cable.
The AIS should be connected to an emergency power source.
After installation, the AIS should be synchronised properly on UTC
and that position information, if provided, should be correct and valid.
3.1 Minimum Keyboard and Display
The functionality of the Minimum Keyboard and Display (MKD) should
be available to the mariner at the position from which the ship is normally
operated. This can be by means of the AIS' internal MKD (integrated or remote)
or through the equivalent functionality on a separate display system.
A pilot input/output port is part of an AIS Class A station. A
plug connected to this port should be installed on the bridge near the pilot's
operating position so that a pilot can connect a Personal Pilot Unit (PPU).
The pilot plug should be configured as follows:
- AMP/Receptacle ((Square
Flanged (-1) or Free-Hanging (-2)), Shell size 11, 9-pin, Std. Sex 206486-1/2
or equivalent with the following terminations:
— TX A is connected to Pin 1
— TX B is connected to Pin 4
— RX A is connected to Pin 5
— RX B is connected to Pin 6
— Shield is connected to Pin
9
If there is navigational equipment capable of processing and
displaying AIS information such as ECDIS, radar or an integrated system
available onboard the ship, the AIS Class A mobile system may be connected to
that system via the AIS Presentation Interface (PI). The PI (input/output)
should meet the requirements of IEC 61162-2.
The display system can also include the functionality of an MKD,
see 3.1.
3.4 Installation of the BUT (Built-in
Integrity Test) function
The AIS requires that an alarm output (relay) be connected to an
audible alarm device or the ships alarm system, if available.
Alternatively, the BUT alarm system may use the alarm messages
output on the PI, provided its alarm system is AIS compatible.
The AIS has interfaces (configurable as IEC 61162-1 or 61162-2)
for position, 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*. The sensor information transmitted by AIS
should be the same information being used for navigation of the ship. The
interfaces should be configured as given in Annex 3. Interfacing problems might
occur if the existing sensors found on board do not have serial (IEC 61162)
outputs.
_______________
* Installation of the AIS does NOT establish a
need to install additional sensors above carriage requirements.
GNSS sensors normally have IEC 61162 outputs for position, COG and
SOG suitable for directly interfacing the AIS. However, it is important to note
that:
- The Geodetic
Datum of the position data transmitted by the sensor is WGS 84 and 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 to adjust reference point
information.
A compass providing heading information is a mandatory sensor
input to the AIS. A converter unit (e.g. stepper to NMEA) will be needed to
connect AIS if the ship's compass does not provide an IEC 61162 output. Some
ships of less than 500 gross tonnage may not carry a compass providing heading
information.
All ships may not carry a Rate-Of-Turn (ROT) Indicator according
to resolution A.526(13). 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, the
direction of turn may (optionally) be derived from heading information through:
— the compass itself;
- an external
converter unit (see paragraph 4.3);
- the AIS itself
(see Annex 1).
A simple means should be provided for the operator to input the
ship's navigational status (e.g. underway using engine, at anchor, not under
command, restricted in ability to maneuver, etc) information into the AIS. The AIS may be connected to
the ship's navigational status lights.
The AIS standards require that certain static, voyage- related,
and dynamic information be entered manually, normally by means of the MKD, or
by means of IEC 61162 sentences "SSD" and "VSD" via the
presentation interface if such provisions exist.
5.1 Entered at initial installation of AIS
Information that should be entered at the initial installation of
the AIS includes:
— Maritime Mobile Service
Identity (MMSI) number;
— IMO vessel number;
— radio call sign;
— name of ship; - type of
ship;
- dimension/reference
for position of the electronic position fixing device (EPFD) antenna (see
paragraph 5.2).
Access to MMSI, IMO number and other AIS controls (like power and
channel settings) will be controlled, e.g. by password.
The Call Sign, Name of Ship and Type of Ship should be input to
the AIS, either manually using the MKD or by means of IEC 61162 sentences
"SSD" and "VSD" via the PI. Type of Ship information should
be in accordance with the table given in Annex 2 (Table 18 from Rec. ITU-R
M.I371-1).
For example, a cargo ship not carrying dangerous goods, harmful
substances, or marine pollutants; would use identifier "70". Pleasure
craft would use identifier "37". Note that those ships whose type
identifier begins with a "3" should use the fourth column of the
table.
Depending on the vessel, cargo and/or the navigational conditions,
this information may be voyage related and would therefore need to be changed
before beginning or at some time during the voyage. This is defined by the
"second digit" in the fourth column of the table.
5.2 Reference point of position
The AIS stores one "external reference point" for the
external GNSS antenna position and one "internal reference point" if
an internal GNSS is to be used as fallback for position reporting. The locations
of these reference points have to be set during installation using values A, B,
C, D; as described in paragraph 5.3.
The external reference point may also be a calculated common
reference position.
Additionally, the content of the Ship Static Data
("SSD") sentence on the PI, including the "reference point for
position" is being processed by the AIS, and the AIS' memory for the
"external reference point" is set in accordance with the content of
this "SSD" (e.g. used by an INS).
Ship's dimensions should be entered using the overall length and
width of the ship indicated by the values A, B, C, and D in the following
figure.
Ship's dimensions (A + B and C + D) should be identical when
entering internal and external reference points.
|
|
Distance (m) |
|
A |
0-511; 511 = 511 m or greater |