A

AA (accounting authority): The organisation named on a commissioning application form to administer the billing and settlement of the communication charges incurred by an MES.

AAIC (accounting authority identification code): An unique code assigned by the ITU to identify an accounting authority.

Aero-HSD+: Thrane & Thrane’s aeronautical communication solution for services such as telephony, fax and data transmission. The Aero-HSD+ enables data speeds up to 128 kbps. Airtime: Use of Inmarsat’s services for e.g. telephony or data transmission.

AMVER (Automated Mutual-assistance Vessel Rescue system): A vessel position-reporting system operated by the United States Coast Guard for any merchant vessel of 1000grt or more on a voyage lasting longer than 24 hours, to and from anywhere on the world.

Analogue: Any signal which represents a changing value over time.

Answerback: An identifier given to an Inmarsat MES and used in message transmissions. The format must be four letters (A-Z; no numbers) finishing with an x.

AOR-E: Atlantic Ocean Region (East).

AOR-W: Atlantic Ocean Region (West).

Applicant: The person who completes and signs a maritime commissioning application form when applying to have an Inmarsat MES commissioned. The applicant must submit the form to the national routing organisation for the country where the vessel is registered.

ARQ (automatic request repeat): The error correction process used in store-and-forward messaging by which a receiver checks for errors in received data packets and requests the sending end to re-transmit any packets which were received containing an error.

ASCII (American Standard Code for Information Interchange): A standard alphanumeric character set based on 7-bit codes.

AUSREP: A vessel position-reporting system similar to AMVER, but operated by the Australian A­uthorities.

B

BBER: Bulletin Board Error Rate.

BGAN: Broadband Global Area Network, a new Inmarsat network launched in December 2005. The BGAN services enable e.g. data transmission speeds up to 492 kbps.

Bit: The basic unit of digital communications; may be either 1 or 0.

Bit Error Rate (BER): used as a measure of the quality of reception by the MES of the Bulletin Board of a TDM Channel.

BPS (bits per second): A unit of measurement for speed of data transfer or throughput.

Bulletin Board (in a TDM channel): A data packet transmitted in each frame of a TDM channel which contains information about the status of the Inmarsat B/M, mini-M and C network configurations and the current frame number, used by the MES as a timing reference.

Bulletin Board Service (BBS): A notice board on which information can be exchanged or posted for others to download.

Byte: One byte comprises eight bits and may represent either one alphanumeric character or numeric information.

C

CAG: Customer Activation Group.

Case-approval: The official approval given by Inmarsat to an MES model which is typically still undergoing development by a manufacturer so as to permit the model to access an Inmarsat communications system. See also type-approval.

CCITT (Comité Consultatif International Télé­graphique et Téléphonique): An advisory committee to the International Telecommunication Union (ITU). The CCITT publishes standards and recommendations to enable telecommunications systems and equipment world-wide to communicate with each other. Examples of CCITT standards are the X.25 and X.400 protocols used on PSDN land-lines.

Channel number: The number representing the frequency of an Inmarsat communications channel.

Character: One element of an alphanumeric character set. One character is equivalent to one byte or 8 bits.

Class 1 Inmarsat C MES: A Class 1 MES is capable of ship-to-shore and shore-to-ship message transfer and distress alerting, but is not capable of receiving EGC messages.

Class 2 Inmarsat C MES: A Class 2 MES is capable of two modes of operation (selected by the operator):

• As Class 1, and also capable of receiv­ing EGC messages when not engaged in Inmarsat C traffic.
• Ready for EGC message reception exclusively (and not available in that mode for Inmarsat C message transfer).

Class 3 Inmarsat C MES: A Class 3 MES has two independent receivers, one for receiving two-way Inmarsat C messages, the other for receiving EGC messages.

Closed network: A private network, with access limited to registered users. The Inmarsat C system allows two types of closed networks: data reporting networks, identified by a Data Rep­orting Network Identification (DNID) code, and EGC FleetNET networks, identified by an EGC Network Identification (ENID) code.

Commissioning: The process by which an MES is registered for use via the Inmarsat network.

Companded: A method of transmission, meaning 'compressed/expanded', which is used to improve signal-to-noise ratio. At the sending end, a 'compressor' electronic circuit amplifies low-level signals and reduces high levels to a mean level according to an algorithm. At the receiving end, an 'expander' circuit uses similar methods to return the signal levels to their original values before passing them on to other circuits. See also uncompanded.

COSPAS-SARSAT: A satellite-based distress beacon locating system.

Coverage area: See footprint.

CSS: Co-ordinator Surface Search.

D

Data report (programmed unreserved, P): A short collection of data (up to 32 bytes in three packets) which is transmitted by an MES at random times in unreserved time slots of a signalling channel after receipt of a polling command from an operational centre.

Data report (reserved, R): A small amount of data (up to 32 bytes in three packets) which is transmitted by an MES in reserved times slots in a signalling channel, in response to an earlier polling command from an operational centre.

Data report (unreserved, U): A small amount of data (up to 32 bytes in three packets) which is transmitted in unreserved time slots of a signalling channel by an MES to an operational centre.

Data services: This is how a terminal may send and receive electronic messages such as e-mail.

DCE: Data circuit terminating equipment: a component part of an Inmarsat C MES. An MES contains a DCE receiver and a DCE transmitter which are used for communication between the MES and an Inmarsat C LES.

DECCA Navigator: A position-fixing system, based on chains of shore-based radio transmissions.

DHSD: Duplex high-speed data (see HSD).

Differential GPS: A global positioning system used with Inmarsat terminals and based on GPS satellites, with accuracy enhanced by the use of transmission of differential corrections from suitably located shore-based radio beacons.

Digital: A signal which represents values in the form of binary numbers.

Distress alerting: A facility available on all maritime MESs, enabling the MES to send distress priority messages through the Inmarsat system to a rescue co-ordination centre (RCC). This is not available on the Inmarsat-mini-M network.

Distress priority message: This is a message prepared and sent with distress priority using the Inmarsat system to a rescue co-ordination centre (RCC).

DMG: Distress Message Generator.

DNIC: Data Network Identification Code.

DNID: Data reporting Network Identification code. See data report (unreserved), data report (reserved) and data report (pre-assigned).

Downloading: The process by which an Inmarsat C MES receives information from a service provider. For data reporting purposes, an operational centre downloads a DNID code and Member Number to the MES. In the EGC FleetNETTM service, an information provider downloads an EGC Network Identification (ENID) code to an MES.

DTE (data terminal equipment): a component part of an Inmarsat C MES, used primarily for storage and interfacing external devices (such as a keyboard or monitor). For other Inmarsat systems, this can be a computer connected to the MES for use for data communications.

Duplex: The ability of a communications channel to transmit data simultaneously in both directions. Also known as Full Duplex.

E

EGC: The EGC (Enhanced Group Call) services provided in the Inmarsat C system are EGC SafetyNET, EGC FleetNET and Inmarsat system messages.

EIRP: Effective Isotropically Radiated Power, a measure of transmitted power.

E-mail: Electronic mail: a global message-handling system whereby subscribers to commercial e-mail services can exchange electronic messages and data files between computers. E-mail services are provided by some service providers and private organisations. Access to e-mail services may be via PSTN, PSDN networks or the Internet.

ENID: EGC network identification (ENID) code.

EPIRB: Emergency position-indicating radio beacon.

ESAS: Electronic Service Activation System.

F

Fax: Abbreviation for 'facsimile', a device used to transmit a copy of an original document. The Inmarsat-A, B/M and mini-M systems support two-way fax transmissions. The Inmarsat C system is able to send only text messages (no graphics) to a fax terminal in the ship-to-shore direction. It is only possible to send text messages (no graphics) in the shore-to-ship direction by using a third party fax bureau.

Fax bureau service: A service offered by some private organisations and service providers to send and receive fax messages.

FleetNET: A service provided by FleetNET information providers to distribute commercial information to MESs belonging to a FleetNET group, identified by an unique ENID code.

Fleet77: Maritime communication solution provided by Thrane & Thrane, typically used on large merchant and fi shing
vessels as well as mega yachts. The Fleet77 offers e.g. telephony and data transmission speeds up to 128 kbps.

Fleet55: Maritime communication solution provided by Thrane & Thrane, typically used on small merchant and
fi shing vessels as well as yachts. The Fleet55 off ers e.g. telephony and data transmission speeds up to 64 kbps.

Fleet33: Maritime communication solution provided by Thrane & Thrane, typically used for telephony and data
transmission on small merchant vessels, large fishing vessels and yachts.

FleetBroadband: Inmarsat’s future broadband service enabling data transmission speeds up to 432 kbps.

Footprint (of a satellite): The area on the Earth's surface (sea or land) covered by the satellite and where an antenna can obtain line-of-sight communications. In the Inmarsat systems, this area is also known as the ocean region or coverage area.

G

Gateway: An interface between communications systems such as the Inmarsat C system and the national and international telecommunications networks.

Geostationary satellites: Satellites that orbit the earth at a height of approximately 36,000 km

Glonass: A global positioning system similar to GPS but using satellites of the former Soviet Union.

GMDSS: The Global Maritime Distress and Safety System: the Inmarsat-A/B and C systems are the only Inmarsat networks included in the GMDSS by the IMO International Maritime Organisation.

Gold Franc (GF): A nominal currency used by LESs and accounting authorities to calculate communication charges incurred by an MES. A fixed rate of exchange exists between the GF and the nominal currency the SDR: 1 SDR = 3.061 GF.

GPS (Global Positioning System): System which provides the geographic location of a vessel. This service uses American military satellites which have been made available for civilian use.

Ground segment: The network of LESs which provide a link between the space segment and the terrestrial telecommunication networks.

H

HSD: High-speed data. This service allows for data to be transferred at data rates of up to 64kbit/s.

HF: High Frequency, frequencies between 4.2 and 30.0 MHz. Used for maritime radio communication

I

IA5: International Alphabet 5 - a standard alpha- numeric character set, also known as ASCII, based on 7-bit codes. Supports both upper and lower case characters.

IHO: International Hydrographic Organisation.

IMN (Inmarsat Mobile Number): The number assigned by the national routing organisation to an Inmarsat MES as its identity number. An Inmarsat-A maritime IMN has the format 1xxxxxx; an Inmarsat-B maritime IMN has the format 3xxxxxxxxx; an Inmarsat C maritime IMN has the format 4xxxxxxxxx; an Inmarsat-M maritime IMN has the format 6xxxxxxxxx; and an Inmarsat-mini-M maritime IMN has the format 76xxxxxxxx.

IMO: International Maritime Organisation.

Information provider: An organisation which provides MSI messages for broadcasting to MESs via the EGC SafetyNETTM service, which can be received by vessels fitted with an EGC receiver.

Inmarsat: The operator of global mobile satellite communications, part of the Inmarsat Ventures Ltd group of companies.

Inmarsat A: The original Inmarsat system, which has been operating since 1982, based on analogue techniques and capable of global two-way telephony, facsimile, data and telex communications.

Inmarsat B: An Inmarsat system based on digital technology, and capable of high quality telephony, facsimile, data and telex services.

Inmarsat C: A digital system based on a low-cost MES with low power consumption. This system provides global two-way store-and-forward messaging, distress alerting, EGC SafetyNETTM and FleetNETTM, data reporting and polling.

Inmarsat E: A distress alerting system based on EPIRBs.

Inmarsat M: Introduced in 1993, based on digital technology and capable of two-way voice telephony, distress alerting, fax and data services at lower data rates.

Inmarsat mini M: Introduced in 1995, based on digital technology and capable of two-way voice telephony, alerting, fax and data services. Operates only in the reduced coverage offered by the spot beams

Inter-station Signalling Links (ISLs): These signalling channels are used between an NCS and the LESs in its ocean region to pass system information around the system.

Internet: An international network of computers linked to enable information to be exchanged.

IOR: Indian Ocean Region.

ISDN, Integrated Service Digital Network: A high capacity digital line which lets users send voice and data at 64kbit/s over one telephone line from a common network interface.

ISP (Inmarsat Service provider): An entity which establishes a contract with one or more of the SPs to bill, promote and retail the services of the contracted SPs to end users. It can be an alternative to an AA.

ITA2 (International Telegraph Alphabet 2): A standard alphanumeric character set, generally used for sending messages on the international telex networks. The character set is based on 5-bit codes, also known as telex format, or 5-bit packed.

ITU: The International Telecommunication Union, which publishes a list of approved accounting authorities. See also CCITT.

J

JASREP: A vessel position-reporting system similar to AMVER, but operated by the Japanese authorities.

K

Kbytes: 1024 bits or 128 characters.

Kbps: Kilobits per second.

Ku-band: Frequencies between 12 and 18GHz. The Ku-band is used e.g. for TV transmissions and enables high data
transmission speeds (2 Mbps or more).

L

LAN (Local Area Network): A network which allows computers and printers to communicate with each other, have access to and share expensive peripherals such as fax servers, modem servers and centralised databases.

Land earth station (LES): The name used in the Inmarsat network for a shore-based receiving and transmitting station which acts as an interface between MESs and the terrestrial comm­unications networks. LESs are owned and operated by service providers.

LES TDM channel: A TDM channel used by an LES to transmit system information and data addressed to an MES.

Log in: The action performed on an Inmarsat C MES to inform the NCS in an ocean region that the MES is available for communications.

Log out: The action performed on an Inmarsat C MES to inform the NCS in an ocean region that the MES is not available for communication.

LORAN-C: A position-fixing system, based on chains of shore-based, low-frequency radio transmissions.

M

MEM: Macro-encoded message.

Member number: The number downloaded with a DNID to an MES, when the MES is registered to a data-reporting network.

MES (mobile earth station): The generic name used to describe an Inmarsat-approved terminal which is allowed to access the network, and applicable to both maritime and land mobile communications.

Message channel: A channel assigned by the NCS for an MES to send a message through an LES to its required destination.

METAREA: Meteorological area corresponding to the NAVAREAs defined by the IMO.

MMSI (Maritime Mobile System Identity): A nine-digit format assigned by the maritime authority to identify a vessel. The first three digits are the code of the country where the vessel is registered as defined by the ITU.

Modem: MODulator/DEModulator, a device used to transmit digital data, by converting (modulating) a digital signal into an analogue form and re-converting (demodulating) the analogue signal into digital form at the receiving end.

MSI (Maritime Safety Information): Information supplied by shore-based information providers and forwarded to an Inmarsat C LES for broadcasting over the Inmarsat C system to MESs fitted with an EGC receive capability.

Multi-channel MES: An MES which is capable of making more than one call at a time. Most MESs are only single channel.

MF: Medium Frequency, frequencies between 1.6 and 4.2MHz. Used for maritime radio communication.

Mini-C: A new generation of the Inmarsat-C service. Thrane & Thrane’s mini-C terminal integrates antenna and terminal
in a single unit and targets the land mobile tracking market.

P

Protocol: A defi ned set of rules describing how terminals, satellites and land earth stations exchange data.

POR: Pacific Ocean Region.

R

RAN: Radio Access Network, a network station (land earth station) developed by Thrane & Thrane for Inmarsat’s BGAN
system.

S

SSAS: Ship Security & Alert Systems, an alarm system mandatory for all vessels of more than 500 GRT. Thrane & Thrane’s SSAS solution is based on the Inmarsat-C service.

SwiftBroadband: Inmarsat’s future aeronautical service for aircraft. SwiftBroadband will e.g. enable data transmission speeds up to 432 kbps.

T

Tracking: Monitoring or transmitting a position.

V

VHF: Very High Frequency, frequencies between 150.8 and 163.6 MHz. Used for maritime radio communication.

VSAT: Very Small Aperture Terminal. VSAT solutions are bigger and more expensive than Inmarsat-based communication solutions. VSAT uses e.g. Ku-band, enabling high data transmission speeds (2 Mbps or more).