GMDSS - GLOSSARY OF TERMS


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A

AAIC

Accounting Authority Identification Code


ADRS

Admiralty Digital Radio Signals.

AIS

Automatic Identification System


AIS–SART

AIS Search and Rescue Transmitter.

ALRS

Admiralty List of Radio Signals.

AM

Amplitude Modulation. A form of modulation where the amplitude of a carrier wave is made to vary in sympathy with the amplitude of the input signal. It is also known as A3E, when used for analogue voice double

Amp

The short–form term for ampere. A measurement of electrical current in a circuit, commonly called an ‘amp’. One ampere is a certain number of electrons passing by the point of measurement in one second. Symbol for ampere(s) is A.

AMSA

Australian Maritime Safety Authority.

AMVER

Automated Mutual–Assistance Vessel Rescue System. AMVER is a computer–based voluntary global ship reporting system used worldwide by search and rescue authorities to arrange assistance to persons in distress at sea. It is sponsored by the United States Coast Guard.

ANSWERBACK

A string of telex characters which uniquely identify an individual telex machine or terminal. It can be sent from a telex terminal via the ‘HERE IS’ command, and requested from another telex machine via the ‘WRU?’ (Who are you?) command.

APR

Automated Position Reporting. Used in Ship Reporting Systems. Not used in MASTREP or REEFREP which rely on AIS.

ARPA

Automatic Radar Plotting Aid. An automatic radar plotting aid that complies with IMO regulations.

ARQ

Automatic Retransmission Request. A NBDP (telex) technique for detecting and correcting transmitted errors, requiring an automatic transmitted response from the receiving station. Communications are limited to a single transmitting and a single receiving station.

ASCII

American Standard Code for Information Interchange. A popular code for the exchange of information between computers, computer terminals and other data applications.

AtoN

Aid To Navigation.

B

BIIT

Built–in Integrity Test. Used in AIS equipment.

bit

Binary Digit. One of the digits 0 or 1 used in binary notation. It is the basic unit of information in computers, data processing or digital communications.

BITE

Built–in Test Equipment. Used in radio and other electronic equipment.

byte

A group of bits taken together and treated as a unit in computers, data processing or digital communications. Typically one byte consists of 8, 16, 32, 64 or 128 bits, depending on the technology.

C

CCIR

The Consultative Committee on International Radio (Replaced by the ITU–R). Formulated new technical standards for radio equipment and the recommendations on the use of radio spectrum.

CIRM

Centro Internazionale Radio Medico. International Radio Medical Centre based in Rome.

Coast Station

A land station in the maritime mobile service providing terrestrial communications to and from ships at sea.

COMSAR

Communications Search and Rescue. IMO Sub–committee on Radiocommunications and Search and Rescue. Replaced by the NCSR.

COSPAS–SARSAT

Cosmicheskaya Sistyema Poiska Avariynich Sudov–Search and Rescue Satellite Aided Tracking. A satellite–aided search and rescue system. Designed to locate emergency radio beacons transmitting on the frequencies of 406.025, 406.028 and 406.037 MHz, with 121.5 MHz for homing.

CQ

General call to all stations. Frequently used in Morse transmissions, and sometimes in voice communications.

CTR

Conformance Test Report. A report certifying LRIT conformance as per SOLAS regulations.

D

DE

‘from.’ Used to precede the name or identification of the calling station. Frequently used in Morse and telex transmissions.

Digital Selective Calling (DSC)

A system in the GMDSS for transmitting distress alerts from ships and for transmitting associated acknowledgements from shore stations. It is also used for relaying distress alerts and for alerts prior to the broadcast of urgency and safety messages.

Distress alert

The DSC transmission of a distress alert indicates that a mobile unit (ship, aircraft or other vehicle) or person is threatened by grave and imminent danger and requests immediate assistance. It is sent using a DSC format in the bands used for terrestrial radiocommunications or a distress message format, in which case it is relayed through space stations. It is normally followed by a distress call on the associated R/T channel. The distress alert shall provide the identification of the station in distress and its position.

DNID

Data Network Identifier. A digital ID downloaded to a ship’s Inmarsat–C terminal, to permit Automated Position Reporting (i.e. to allow polling of the ship’s position).

DRF

Disaster Recovery Facility. (ie. AMSA backup facility)

Duplex

Operating method in which transmission is possible simultaneously in both directions of a telecommunication channel.

E

ECDIS

Electronic Chart Display and Information System. A computer–based navigation information system that complies with IMO regulations.

EHF

Extra High Frequency. (30 to 300 GHz)

Enhanced Group Calling (EGC)

A system in the GMDSS to broadcast MSI (SafetyNET) and routine/ public correspondence (FleetNET) anywhere in the Inmarsat coverage area, via the Inmarsat satellite system.

EPIRB

Emergency Position Indicating Radio Beacon.

F

F1B

A frequency–modulated mode of emission using digital information for automatic reception, without the use of a modulating sub–carrier.

F3E

A frequency–modulated mode of emission using analogue telephony (i.e. voice).

FEC

Forward Error Correction. An error–tolerant broadcast mode for NBDP, where the sending station transmits to an unlimited number of receiving stations.

Fleet77

Provides global voice, fax and high–speed data communications at speeds up to 128 kb/s via Inmarsat. It is suitable for a wide range of vessels, from deep–sea ships to offshore support craft. Provides full support for GMDSS, including features such as emergency call prioritization, as stipulated by IMO Resolution A.888 (21).

FleetBroadband

Inmarsat broadband service simultaneously providing broadband data and voice (using internet protocol (IP)), whilst still supporting existing voice and ISDN data capability for legacy applications.

FleetNET

The international commercial service offered under Inmarsat–C’s EGC capability, which allows authorised information providers, such as commercial subscription services, shipping companies or governments to broadcast messages to selected groups of vessels, each of which has registered with the information provider, and been added to a FleetNET closed group / network.

FM

Frequency Modulation. The frequency of a carrier wave is made to vary in sympathy with the frequency of the input signal. Used for VHF marine band transmissions

G

G3E

A phase

GEOLUT

A Local User Terminal in the Cospas– Sarsat system for receiving signals from geostationary satellites fitted with Cospas–Sarsat packages. See also LUT.

Geostationary satellite

A satellite whose period of revolution is equal to the period of rotation of the earth and whose circular and direct orbit lies in the plane of the Earth’s equator; that is, a satellite which remains in the same relative position to any point on Earth. Approximate altitude of satellite is 36 000 km above earth’s surface.

GHz

Gigahertz (1 000 000 000 hertz). A measurement unit of radio frequency, oscillation and vibration equaling 1 000 000 000 cycles per second.

GMDSS

Global Maritime Distress and Safety System.

GMT

Greenwich Mean Time (see also UTC).

GNSS

Global Navigation Satellite System (eg. GPS,Glonass, Galileo).

GOC

General Operator’s Certificate of Proficiency

GPS

Global Positioning System. A satellite

GT

Gross Tonnage (replaces Gross Registered Tonnage (GRT))

H

H3E

Radiotelephony using amplitude modulation, single sideband, full carrier

HF

High Frequency (3 to 30 MHz)

Homing signals

Locating signals transmitted by a ship in distress or survival craft to provide a bearing for searching vessels and aircraft.

Hz

hertz

I

IAMSAR

International Aeronautical and Maritime Search and Rescue. The IAMSAR Manual is a joint publication of the IMO and ICAO.

ICAO

International Civil Aviation Organisation.

IMDG

International Maritime Dangerous Goods Code.

IMN

Inmarsat Mobile Number. The Inmarsat terminal identification number (ie: telephone number).

IMO

International Maritime Organisation.

IMSO

International Mobile Satellite Organisation.

Inmarsat

Inmarsat Ltd (formerly International Maritime Satellite Organisation)

INTERCO

International Code of Signals

IRCS

Integrated Radiocommunication System when used in the GMDSS (see IMO Res. A.811 (19)).

ISDN

Integrated Services Digital Network. A digital access network for data and voice, which provides an alternative to the public switched telephone network.

ISM

International Safety Management. Refers to the IMO’s International Safety Management (ISM) Code 2002, which provides an international standard for the safe management and operation of ships, and for pollution prevention.

ISN

Inmarsat Serial Number. A unique number for every Inmarsat terminal’s hardware.

ITU

International Telecommunication Union. The lead United Nations agency for information and communication technologies.

ITU—R

The ITU Radiocommunication Sector (ITU—R) is that part of the ITU which performs a major role in the global management of the radio—frequency spectrum and satellite orbits, for services such as fixed, mobile, broadcasting, amateur, space research, emergency telecommunications, meteorology, global positioning systems, environmental monitoring and communication services, that ensure safety of life on land, at sea and in the air. Formerly known as the CCIR.


ITU—T

The ITU Telecommunication Standardization Sector is that part of the ITU which defines elements in information and communication technology (ICT) infrastructure. Formerly known as the CCITT.


J

J2B

A single

J3E

Radiotelephony using amplitude modulation, single sideband, suppressed carrier. Often referred to as ‘SSB’.

JASREP

Japanese Ship Reporting System

JRCC

Australian Joint Rescue Coordination Centre, located in Canberra.

K

kb/s

Kilobits per second. One kilobit equals 1 000 bits.

kHz

Kilohertz (1 000 hertz). A measurement unit of radio frequency, oscillations and vibrations equaling 1 000 cycles per second

km

Kilometre. (1 000 metres)

kn

Knot. One nautical mile per hour.

knots

nautical miles per hour (1 nautical mile = 1 852 metres)

kW

Kilowatt (1 000 watts). A measurement unit of radio and electrical power (see watt).

L

L–band EPIRB

An EPIRB operating in the 1.6 GHz frequency band through the Inmarsat satellite system (also known as an Inmarsat EPIRB)

Land Earth Station (LES)

An earth station in the maritime mobile

LEOLUT

Low Earth Orbit Local User Terminal. As used in the Cospas–Sarsat system. See also LUT.

LES

see Land Earth Station

LF

Low Frequency (3 to 30 kHz)

Local (SSM)

Local Sea Safety Messages. Contain warnings which refer to hazards which are considered to be of a temporary nature, eg. floating logs, temporary buoys, etc, broadcast for a defined period.

Local User Terminal (LUT)

A ground receiving station which receives data from COSPAS and SARSAT satellites, calculates the position of the beacon and forwards the resultant information to rescue authorities.

Locating signals

Transmissions intended to facilitate the location of ship in distress or survival craft.

LRIT

Long Range Identification and Tracking. A ship reporting system requiring ships to automatically transmit their identity, position and date/time at 6–hour intervals, as part of Maritime Domain Awareness, by contracting Governments under SOLAS.

LSB

Lower Sideband mode of emission. A form of single sideband emission, where only the lower sideband is transmitted.

M

m

Metre. Unit of length.

Maritime Safety Information (MSI)

Distress Alerts, navigational warnings, meteorological warnings and forecasts and other important safety information for ships.

MASTREP

Modernised Australian Ship Tracking and Reporting System (replaces AUSREP).

MCS

Maritime Communications Station. Another term for a coast station.

MES

A Mobile Earth Station in the Inmarsat system, which includes mobile, land, ship and airborne Inmarsat terminals. On a ship it is more commonly referred to as a Ship Earth Station (SES).

METAREA

Meteorological Area: A meteorological service area with area limits similar to NAVAREA’s in the WWNWS.

MF

Medium Frequency (300 to 3 000 kHz).

MFAG

Medical and First Aid Guide. Part of the International Maritime Dangerous Goods Code.

MHz

Megahertz (1 000 000 hertz). A measurement unit of radio frequency, oscillation and vibration, equaling 1 000 000 cycles per second.

MID

Maritime Identification Digit. A 3 digit decimal number used as the first part of ship station identity (MMSI) to indicate nationality.

MKD

Minimum Keyboard and Display. A minimal text only display provided for AIS Class–A transceivers.

MMSI

Maritime Mobile Service Identity. The number used to identify coast stations’ and ships’ DSC, NBDP and AIS systems.

MPDS

Mobile Packet Data Service. An Inmarsat service allowing continuous connection of ships to terrestrial networks with payment for volume of data exchanged, rather than the duration of ‘airtime’ used.

MRCC

Maritime Rescue Coordination Centre. The Australian MRCC is located in Canberra and operated by AMSA (see also RCC and JRCC).

MROCP

Marine Radio Operator’s Certificate of Proficiency. Replaced by Long Range Operator Certificate of proficiency.

MROVCP

Marine Radio Operator’s VHF Certificate of Proficiency. Replaced by Short Range Operator Certificate of Proficiency.

MSC

Maritime Safety Committee of the IMO.

MSI

Maritime Safety Information. Navigational and meteorological warnings, meteorological forecasts and other urgent safety related messages.

MUF

Maximum Usable Frequency. The highest frequency which is reflected by the ionosphere over any particular path.

N

n mile

nautical mile (1 nautical mile = 1 852 m)

NAVAREA

A Navigation Area in the world

NAVAREA warning

Navigational warning broadcast issued by an area coordinator of the world

NAVTEX

Short range system for transmission of navigational and meteorological warnings to ships by NBDP. The International NAVTEX service is the system for broadcast and automatic reception of MSI by means of narrow

NBDP

Narrow Band Direct Printing. Formerly known as ‘telex over radio’.

NCS

Network Coordination Station in the Inmarsat system.

NCSR

Navigation, Communication and Search and Rescue. An IMO sub-committee.

O

On—scene communications

Communications between the distressed ship or survival craft and assisting units.

OTF

Optimum Traffic Frequency. The optimal frequency for sustained radio reliability, approximately 85% MUF.

P

PM

Phase Modulation. A form of amplitude modulation, very similar to FM, used in the VHF maritime mobile service.

PSTN

Public Switched Telephone Network.

PTT

Press to Talk. A switch used on microphones and control lines, to activate the voice path and activate transmitter circuitry.

R

R/T

Radiotelephony (i.e. voice).

RCC

Rescue Coordination Centre.

REEFREP

A mandatory Ship Reporting System for the Great Barrier Reef and Torres Strait. Otherwise known as the Great Barrier Reef and Torres Strait Ship Reporting System.

ReefVTS

a coastal Vessel Traffic Service declared by the IMO via Resolution MSC.161 (78) as a measure to further enhance navigational safety in Torres Strait and the Great Barrier Reef.

Rescue Coordination Centre (RCC)

A unit responsible for the efficient organisation of search and rescue services and the operation of these resources within a nominated area.

RTE

Radar Target Enhancer. A short range device used on small craft which receives, amplifies and stretches an incoming radar pulse, then re

Rx

Receiver or receive frequency

S

SafetyNET

Inmarsat satellite system for transmission of navigational and meteorological warnings to ships, complementary to the International NAVTEX service on 518 kHz. The ability to receive SafetyNET service information will generally be necessary for all ships which sail beyond the coverage of NAVTEX.

SAR

Search and Rescue.

SAR coordinating communications

Communications necessary for the coordination of ships and aircraft participating in a search and rescue operation.

SART

Search and Rescue Radar Transponder. Also known as a survival craft radar transponder or radar transponder.

Selcall

An identification number, 5 digits for ship stations and 4 digits for coast stations, programmed into NBDP (telex) equipment. In the ALRS Volume 1, the coast station Selcall is shown in square brackets, Guam [1096]. It is only required generally for ARQ mode of operation.

SHF

Super High Frequency (3 to 30 GHz).

Ship Earth Station (SES)

An earth station in the maritime mobile

Ship station

A station in the terrestrial radio

Simplex

Operating method in which transmission is made possible alternatively in each direction of a telecommunication channel, for example, by means of manual control (see single

Single frequency

The same frequency used for transmission and reception (simplex).

SMCP

Standard Marine Communication Phrases.

SOLAS

Safety of Life at Sea. International Convention for the Safety of Life at Sea.

SOLAS Convention

Safety of Life at Sea Convention as adopted by the IMO, and accepted by contracting governments.

SSAS

Ship Security Alert System. A system fitted under Regulation 6 of SOLAS chapter XI

SSB

Single Side Band mode of emission using amplitude modulation, where one sideband is reduced, suppressed or fully removed.

SSM

Sea Safety Message. A type of coastal warning referring to hazards which are considered to be of a temporary nature, eg. floating logs, temporary buoys, etc, usually broadcast for a defined period.

SSRM

Short Safety Related Messaging. A text

STCW

Seafarers’ Training, Certification and Watchkeeping (Code and International Convention on).

T

TMAS

Telemedical Maritime Advice Services.

Tx

Transmitter or transmit frequency

U

UHF

Ultra High Frequency. (300 to 3 000 MHz)

UPS

Uninterruptible Power Supply.

USB

Upper Sideband mode of emission. A form of single sideband emission where only the upper sideband is transmitted.

UTC

Temps Universel Coordonné (French). Coordinated Universal time (replaces Greenwich Mean Time (GMT) for practical purposes).

V

VDL

VHF Data Link. The AIS channels of AIS 1 and AIS 2.

VDU

Visual Display Unit.

VHF

Very High Frequency. (30 to 300 MHz)

VLF

Very Low Frequency. (30 to 300 kHz)

volt

A unit of electric potential and electromotive force. Equal to the difference of electric potential between two points on a conducting wire, carrying a constant current of one ampere when the power dissipated between the points is one watt. The symbol for the volt(s) is V.

VTS

Vessel Traffic Service. IMO Resolution A.857 (20), defines a Vessel Traffic Service (VTS) as ‘a service implemented by a Competent Authority that is designed to improve safety and efficiency of vessel traffic, and to protect the environment. The service shall have the capability to interact with traffic and respond to traffic situations developing situations in the VTS area’. It is referenced in SOLAS Chapter V, Regulation 12.

W

W/T

Wireless telegraphy (i.e. Morse code).

watt

the power required to do work at the rate of 1 joule per second, which is equal to the power dissipated in an electric circuit in which a potential difference of 1 volt causes a current of 1 ampere to flow. The symbol for watt(s) is W.

WRU?

Who Are You? A telex command used to request the Answerback from another telex machine.

WWMIWS

World–wide Met–Ocean Information and Warning Service. A service established by the World Meteorological Organisation for the purpose of coordinating the transmissions of meteorological warnings in defined geographical areas.

WWNWS

World–wide Navigational Warning Service. A service established by the International Hydrographic Organisation for the purpose of coordinating the transmissions of navigational warnings in defined geographical areas.


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