Extended Operational and Trade Vocabulary

Maritime Satcom and Telecommunications glossary

The satellite-communications vocabulary: accounting authority identification codes, antenna acquisition and beam handover, active phased arrays and stabilized above-decks equipment, adjacent-satellite interference, and the VSAT, Inmarsat Fleet, Iridium, and Starlink LEO terms. Grounds each term in the satcom system, the airtime service, or the antenna technology it belongs to.

453 defined terms.

Showing 250 on this page (page 1 of 2).

A

AAIC: Accounting Authority Identification Code used by Inmarsat to route satellite call billing to a designated maritime accounting authority.
Acquisition (satellite): Initial process by which a stabilized maritime antenna locates and locks onto the assigned satellite after power-up or beam handover.
Active Phased Array: Antenna in which each radiating element has its own transmit and receive amplifier, enabling rapid electronic beam steering without moving parts.
ADE (Above Decks Equipment): Outdoor portion of a satellite terminal comprising the radome, antenna pedestal, and outdoor electronics.
Adjacent Satellite Interference: Unwanted signal energy received from a neighboring geostationary satellite operating on the same frequency.
AES (Aircraft Earth Station): Inmarsat terminal class historically used in aviation but referenced in shared maritime ground infrastructure.
AgilePlans: KVH subscription program bundling VSAT hardware, airtime, installation, and crew content for a single monthly fee.
AIS: Automatic Identification System, a VHF data broadcast system mandated by SOLAS V/19.2.4.
AIS Class A: Mandatory transponder for SOLAS vessels broadcasting MMSI, position, course, speed.
AIS Class B: Lower-power transponder used by smaller, non-SOLAS craft.
ALL.SPACE: British manufacturer, formerly Isotropic Systems, of multi-beam electronically steered antennas suitable for maritime use.
Alphasat: Inmarsat I-4A F4 satellite launched in 2013 to extend L-band capacity over Europe, the Middle East, Africa, and parts of Asia.
Always-On Connection: Maritime satellite service model where IP connectivity is maintained continuously rather than per-call.
Amplifier (BUC): Block Up Converter that translates the modem L-band output to the satellite uplink band and amplifies it for transmission.
Anik F2: Telesat Ka-band satellite, historically referenced as an early commercial Ka-band platform influencing maritime Ka adoption.
Antenna Gain: Measure of how strongly an antenna concentrates radio energy in a given direction, expressed in dBi.
Antenna Pointing: Process of orienting a maritime antenna toward the satellite and maintaining lock despite vessel motion.
Anuvu: Connectivity and content provider, formed from the maritime and aviation operations of Global Eagle Entertainment.
Apogee: Point in the Moon's orbit farthest from Earth.
Application Acceleration: Edge optimization that improves performance of HTTP, email, and file transfer protocols over high-latency satellite links.
ARPA: Automatic Radar Plotting Aid training course required for officers operating ARPA equipped radars under STCW Table A-II/1.
Atmospheric Attenuation: Reduction in satellite signal strength caused by absorption and scattering in the atmosphere, more severe at Ka-band.
Attitude Control: Spacecraft subsystem maintaining the satellite orientation relative to Earth and the Sun.
AURIS: Onboard Inmarsat support service for FleetBroadband legacy reporting platforms, historically used by some shipping lines.
Auto-Acquire: Antenna feature that automatically searches for and locks onto the correct satellite after vessel position change or signal loss.
Automatic Beam Switching: Capability of a VSAT terminal to migrate between satellite beams or satellites as the vessel transits coverage boundaries.
Automatic Gain Control: Receiver function that adjusts amplifier gain to compensate for varying signal strength.
Availability (link): Percentage of time a satellite link meets its committed performance, often expressed as 99.5 percent or higher.
Azimuth: Bearing of a celestial body measured from true north.

B

Back-Off: Reduction in amplifier operating power below saturation to maintain linearity for multi-carrier transmission.
Backhaul: Return leg of a voyage, usually at lower freight rates than the headhaul.
Bandwidth Pool: Shared capacity model where multiple vessels draw from a common allocation of satellite throughput.
Baseband: Original frequency range of an information signal before modulation onto a carrier.
Beam (satellite): Defined coverage footprint produced by a satellite antenna, often classified as global, regional, or spot.
Beam Handover: Transfer of a terminal connection from one satellite beam to another as the vessel moves.
Beam Hopping: Technique allowing a satellite to allocate capacity dynamically by time-sharing across multiple spot beams.
BGAN: Broadband Global Area Network, Inmarsat L-band IP service delivered over the I-4 constellation.
BGAN M2M: Machine-to-machine variant of BGAN optimized for low data volumes and always-on telemetry.
Bird (slang): Informal industry term for an in-orbit communications satellite.
Bit Error Rate: Ratio of incorrectly received bits to total bits transmitted across a link.
Block Up Converter: See BUC.
Boeing 702HP: Satellite bus used for several maritime-relevant Ka-band and L-band platforms, including the Inmarsat I-5 Global Xpress series.
Bonded Connectivity: Combining multiple satellite or cellular links into a single logical pipe for higher throughput and resilience.
Bridge Integration: Connection of satellite communications equipment to ECDIS, radar, and VDR systems on the navigation bridge.
Broadband Global Area Network: Full name of Inmarsat BGAN.
BUC: Block Up Converter at the antenna that translates and amplifies the modem signal for satellite uplink.

C

C-band: Satellite frequency band roughly 4 to 6 GHz, valued for rain resilience and used by some maritime VSAT networks.
Captain's Phone: Dedicated voice line on a VSAT or FleetBroadband terminal reserved for command staff.
Carrier-to-Noise Ratio: Measure of received carrier power relative to noise power, governing achievable data rate and link availability.
Castor Marine: Maritime VSAT and IT services provider based in the Netherlands and the United States.
CCM (Constant Coding and Modulation): Satellite transmission mode using fixed modulation parameters regardless of link conditions.
Cellular at Sea: Onboard GSM base station service permitting crew and passengers to roam over a maritime cellular network.
Cellular Backup: Use of 3G, 4G, or 5G as a complementary or backup channel to VSAT when a vessel is near shore.
Certus: Iridium broadband service delivered over the Iridium NEXT constellation in L-band.
Certus 100: Iridium Certus service tier supporting lower-rate IP and voice channels for compact terminals.
Certus 200: Iridium Certus tier providing intermediate IP throughput for small vessel and IoT applications.
Certus 700: Iridium Certus tier delivering the highest published throughput of the Certus family for maritime use.
Channel Unit: Discrete modem channel within an Inmarsat C or Mini-C terminal handling a specific message stream.
Chinasat: Family of Chinese geostationary satellites carrying Ku and Ka capacity used by some maritime VSAT networks.
Class 2 Approval: Inmarsat terminal certification class historically used for FleetBroadband installations on certain vessel categories.
Closed User Group: Private dialing or addressing arrangement restricting communications to a defined set of terminals.
Co-channel Interference: Distortion from another carrier sharing the same frequency on an adjacent beam or satellite.
Cobham SATCOM: Maritime satellite terminal brand encompassing the SAILOR and Thrane and Thrane product lines.
Codec: Coder-decoder used for voice compression on Inmarsat, Iridium, and VSAT voice services.
Coherent Detection: Demodulation method using a locally generated reference carrier to recover the transmitted signal.
Coil-Cord Free Antenna: Maritime antenna design eliminating rotary joints that limit continuous azimuth rotation.
Comsat: Historical American satellite communications corporation that played a foundational role in Inmarsat services.
Comtech: American provider of satellite ground equipment including modems and amplifiers used in maritime networks.
Constellation: Group of satellites operated together to provide continuous or near-continuous coverage.
Contention Ratio: Ratio expressing how many users share a given amount of satellite bandwidth.
Continuity of Service: Inmarsat program structure ensuring legacy services such as Inmarsat C remain available alongside newer offerings.
Convolutional Coding: Forward error correction technique commonly used on satellite links.
Coverage Map: Diagram showing the geographic footprint of a satellite beam or constellation.
Crew Calling: Subscription voice service offering crew members discounted call rates from the vessel.
Crew Welfare: Category of maritime connectivity services covering email, voice, video, and social media access for seafarers.
Cross-Polarization: Use of orthogonal polarizations to reuse frequencies on the same satellite beam.
Cryosat: Earth observation reference platform sometimes used in maritime ice-routing data feeds delivered over satellite.

D

D+ Antenna: KVH classification used historically for certain TracPhone models supporting integrated mini-VSAT broadband.
Dashboard (NOC): Operator-facing console displaying vessel terminal status, throughput, and alerts across a fleet.
Data Allowance: Monthly or per-cycle data volume included in a maritime broadband subscription before throttling or charges apply.
Data Compression: Reduction of payload size to improve effective throughput across satellite links.
De-emphasis: Receive-side filtering used in some legacy satellite voice systems.
Deep Packet Inspection: Network analysis technique that examines protocol payloads, used selectively in shipboard monitoring.
Demodulator: Equipment that extracts the original information signal from a modulated satellite carrier.
DESS (Distress Safety Service): Inmarsat C category for SOLAS-compliant distress messaging to maritime rescue coordination centers.
Diagnostics Port: Service interface on a satellite terminal used for installation, monitoring, and firmware updates.
Dialog (Newtec): Multiservice VSAT platform from ST Engineering iDirect, formerly Newtec, used in maritime networks.
Digital Selective Calling: VHF and MF/HF technique used in GMDSS for alerting, sometimes integrated with satellite distress paths.
Direct-to-Cell (Starlink): SpaceX initiative to provide cellular service from low Earth orbit satellites, of emerging interest to maritime users.
Distress alert: GMDSS message indicating grave and imminent danger.
DLR (Downlink): Direction of transmission from satellite to ship terminal.
DNS Filtering: Network policy used onboard to restrict access to specific categories of internet content over satellite.
DNVL: Distinct fleet network reference identifier used in some maritime SD-WAN deployments.
Doppler shift: Frequency change of sound due to relative motion; used by ADCPs to measure current speed.
Downlink: Radio path from satellite to terminal.
DSL Backup: Use of port-side wired broadband to complement or fall back from a vessel satellite link while alongside.
Dual Antenna Configuration: Installation of two satellite antennas to mitigate mast blockage on the opposite side.
DVB-RCS: Return channel via satellite standard historically used in some maritime VSAT systems.
DVB-S: Digital Video Broadcasting Satellite standard, the first generation modulation used on many VSAT carriers.
DVB-S2: Second-generation DVB satellite standard widely used on maritime VSAT networks.
DVB-S2X: Extension of DVB-S2 adding more modulation and coding options for improved efficiency.
Dynamic Bandwidth Allocation: Mechanism that assigns capacity to terminals on demand based on traffic and contention rules.

E

Earth Station: Ground-based facility providing satellite uplink and downlink between space and terrestrial networks.
ECDIS: Electronic Chart Display and Information System per IMO MSC.232(82).
Edge Router: Onboard device sitting between the satellite modem and the vessel local area network.
Effective Isotropic Radiated Power: See EIRP.
EIRP: Effective Isotropic Radiated Power, the transmit power referenced to an isotropic antenna.
ELERA: Inmarsat L-band global network brand encompassing FleetBroadband, IsatPhone, BGAN, and related services.
Elevation Angle: Vertical angle from the local horizon to the satellite, important for line-of-sight planning at high latitudes.
Email Compression: Software at the vessel and shore that reduces email size for transit over satellite links.
EPIRB: Emergency Position-Indicating Radio Beacon required under SOLAS IV/7.
Equatorial Orbit: Orbit lying in the equatorial plane, used by geostationary maritime satellites.
ESA (Electronically Steered Antenna): Flat panel antenna that points electronically rather than mechanically, used in some Starlink maritime and aviation terminals.
ESS (Earth Station on Vessel): ITU regulatory category for VSAT terminals operated on moving maritime platforms.
Ethernet Handoff: Customer-side interface presenting the satellite link as a standard Ethernet connection to vessel networks.
Eutelsat: European satellite operator providing Ku and Ka capacity used by several maritime VSAT integrators.
Exede Maritime: Historical Viasat maritime brand using Ka-band capacity, now part of Viasat Maritime.

F

Fade Margin: Extra link budget allocated to absorb atmospheric and pointing losses.
Fair Access Policy: Service provider rules limiting peak data use to protect shared satellite resources.
FEC: Forward Error Correction added to digital satellite transmissions to recover from channel errors.
Fleet Care: Inmarsat managed service offering proactive monitoring, remote support, and field maintenance.
Fleet Data: Inmarsat platform that collects and forwards onboard sensor data to a secure cloud environment.
Fleet Edge: Inmarsat IoT and edge computing offering delivered alongside Fleet Xpress.
Fleet Hotspot: Inmarsat crew Wi-Fi service overlay providing prepaid internet access on vessels.
Fleet Mail: Inmarsat secure shipboard email service tuned for satellite delivery.
Fleet One: Inmarsat L-band entry service for small vessels.
Fleet Secure: Inmarsat maritime cybersecurity service comprising unified threat management and endpoint protection.
Fleet Xpress: Inmarsat Ka-band/L-band hybrid service.
FleetBroadband: Inmarsat L-band IP service in 150, 250 and 500 kbps classes (e.g., FB150, FB250, FB500).
FleetBroadband FB150: Smaller-aperture FleetBroadband terminal for vessels with limited size and weight budgets.
FleetBroadband FB250: Mid-tier FleetBroadband terminal balancing antenna size and IP throughput.
FleetBroadband FB500: Top-tier FleetBroadband terminal providing the highest committed information rate of the family.
Fluid Connectivity Manager: General term for software that orchestrates multiple links such as VSAT, L-band, and cellular on a vessel.
Footprint: Geographic area covered by a satellite beam.
Forward Channel: Direction of transmission from the network hub through the satellite to the vessel.
Frequency Reuse: Use of the same frequency band across multiple beams or polarizations to multiply capacity.
FX (Fleet Xpress): Common abbreviation for the Inmarsat Fleet Xpress service.

G

G/T: Antenna gain divided by system noise temperature, a figure of merit for receive performance.
Gateway: Device that bridges different protocols or zones, often the interface between OT and IT on board.
GEO: Common abbreviation for geostationary orbit.
Geostationary Orbit: Circular orbit at approximately 35,786 km altitude where a satellite remains fixed relative to the Earth.
Gilat: Israeli ground equipment vendor supplying VSAT platforms and electronically steered antennas used in maritime networks.
Global Beam: Wide footprint from a satellite covering an entire visible hemisphere.
Global Eagle: Former connectivity provider whose maritime business became part of Anuvu.
Global Maritime Distress and Safety System: The radiocommunications regime examined under VIQ Chapter 4 (Navigation).
Global Xpress: Inmarsat Ka-band global network comprising the I-5 satellites and the backbone of Fleet Xpress.
GMDSS: Global Maritime Distress and Safety System under SOLAS Chapter IV.
GMDSS Sea Area A1: Coastal area within VHF range of a shore station fitted with continuous DSC alerting.
GMDSS Sea Area A2: Area within MF range of a shore station with continuous DSC, beyond A1.
GMDSS Sea Area A3: Area within coverage of an approved GMDSS satellite service, between roughly 76 degrees north and south.
GMDSS Sea Area A4: Polar regions outside satellite coverage where HF radio is the primary GMDSS bearer.
GMR: GEO-Mobile Radio interface used in some satellite handheld services.
GPS Augmentation: Use of satellite communications to deliver differential corrections to onboard GNSS receivers.
Ground Segment: Network of teleports, hubs, and operations centers supporting a satellite system.
GX Terminal: Inmarsat-approved Ka-band terminal certified for use on the Global Xpress network.
Gyro Stabilization: Use of mechanical or fiber-optic gyros to keep a maritime antenna pointed at the satellite despite vessel motion.

H

Handheld Satellite Phone: Portable voice terminal such as the Iridium 9555 used for shipboard or lifeboat communications.
Handover: Transfer of an active connection from one satellite or beam to another.
HCM (High Performance Coding and Modulation): VSAT enhancement enabling higher spectral efficiency under favorable conditions.
HEMP Hardening: Protective design against high-altitude electromagnetic pulse, sometimes required for naval terminals.
High Throughput Satellite: Geostationary platform using narrow spot beams and frequency reuse to multiply capacity.
HNS (Hughes Network Systems): VSAT ground equipment manufacturer whose Jupiter platform is used in some maritime networks.
Horizon Mask: Visual or digital map of obstructions that limit antenna look angles on a particular vessel.
Hotspot Controller: Onboard device managing crew Wi-Fi authentication, vouchers, and accounting.
HSD (High Speed Data): Legacy Inmarsat Fleet streaming IP service rated at fixed data rates such as 64 or 128 kbps.
HTS: Common abbreviation for High Throughput Satellite.
Hub (VSAT): Central station that manages satellite carriers and provides backhaul for many remote terminals.
Hybrid Network: Maritime connectivity design combining VSAT, L-band, and cellular bearers under unified management.

I

I-3: Third-generation Inmarsat satellite series that supported services such as Inmarsat B, M, and Mini-M, now retired.
I-4: Fourth-generation Inmarsat satellite series supporting BGAN and FleetBroadband at L-band.
I-4 F1: First Inmarsat-4 satellite, providing L-band coverage over the Asia-Pacific region.
I-4 F2: Second Inmarsat-4 satellite, providing L-band coverage over the Atlantic and Americas.
I-4 F3: Third Inmarsat-4 satellite, providing L-band coverage over the Americas and Pacific.
I-5: Fifth-generation Inmarsat satellite series carrying the Global Xpress Ka-band payload.
I-5 F1: First Inmarsat-5 satellite, launched in 2013 to begin Global Xpress regional service.
I-5 F2: Second Inmarsat-5 satellite covering the Americas region.
I-5 F3: Third Inmarsat-5 satellite covering the Pacific region and completing global Ka-band coverage.
I-5 F4: Fourth Inmarsat-5 satellite providing additional Global Xpress capacity.
I-6 F1: Inmarsat-6 hybrid L-band and Ka-band satellite launched in December 2021.
I-6 F2: Inmarsat-6 hybrid satellite launched in February 2023.
iDirect: VSAT ground equipment vendor whose platforms underpin many maritime networks.
iDirect Velocity: iDirect platform designed for high-throughput satellite networks including maritime mobility.
IEC Telecom: Maritime satellite service provider and integrator with a focus on managed solutions.
IF Cable: Intermediate frequency coaxial cable connecting the modem indoors to the antenna outdoors.
Image Library Update: Distribution of ECDIS or weather imagery datasets over satellite to vessels.
IMO Number: Unique seven-digit ship identifier from IHS Markit on behalf of IMO.
IMSO: International Mobile Satellite Organization, oversees GMDSS satellite service providers.
In-Motion Antenna: Antenna designed to maintain a satellite link while the vessel is underway.
Inmarsat: Satellite communications provider for GMDSS and commercial services.
Inmarsat A: First-generation analog satellite voice and telex service for ships, now retired.
Inmarsat B: Digital successor to Inmarsat A providing voice, telex, fax, and data, now retired.
Inmarsat C: Polling/EGC/SafetyNET service in GMDSS.
Inmarsat D+: Two-way short message and tracking service used in some legacy maritime asset applications.
Inmarsat Fleet 33: Retired L-band Fleet service designed for small vessels.
Inmarsat Fleet 55: Retired mid-tier L-band Fleet service for medium vessels.
Inmarsat Fleet 77: Retired high-tier L-band Fleet service providing ISDN and voice for large vessels.
Inmarsat M: Retired digital voice and low-rate data service.
Inmarsat Mini-C: Smaller-antenna variant of Inmarsat C used widely for distress, safety, and tracking.
Inmarsat Mini-M: Retired compact digital voice and data service that succeeded Inmarsat M.
Inmarsat ORCHESTRA: Inmarsat roadmap for an integrated GEO, LEO, and terrestrial 5G network announced for the latter half of the 2020s.
Integrated Bridge System: Networked navigation and communications suite that incorporates satellite terminals.
Intellian: Korean maritime VSAT antenna manufacturer producing the v-series and t-series product lines.
Intellian t110W: Ku-band television receive-only maritime antenna.
Intellian v100NX: Mid-aperture maritime VSAT antenna with switchable feeds.
Intellian v240MT GX: Multi-orbit, multi-band maritime VSAT antenna certified for Inmarsat Global Xpress.
Intellian v60NX: Small-aperture maritime VSAT antenna with switchable feeds.
Interleaver: Forward error correction component that spreads burst errors across coded blocks.
International Maritime Organization: IMO, UN specialized agency for shipping, based in London.
Internet Cafe (vessel): Designated onboard space offering crew internet access over satellite.
IoT Edge Gateway: Onboard device that aggregates sensor data and forwards selected payloads over satellite.
IP at Sea: Generic term for native internet protocol connectivity provided over maritime satellite links.
IPv6 Support: Capability of a maritime satellite network to transport native IPv6 traffic.
Iridium: American satellite operator running a 66-satellite low Earth orbit constellation providing global coverage including the poles.
Iridium 9555: Iridium handheld satellite phone used widely in maritime applications.
Iridium 9575 Extreme: Ruggedized Iridium handheld with integrated GPS and emergency button.
Iridium 9770: Iridium Certus broadband transceiver module used by terminal manufacturers.
Iridium 9810: Iridium Certus transceiver module supporting higher Certus service classes.
Iridium 9830: Iridium Certus transceiver module integrated into many compact maritime terminals.
Iridium Certus: L-band satellite broadband service (GMDSS-recognized 2020).
Iridium Edge: Iridium satellite IoT device used for asset and small vessel tracking.
Iridium GMDSS: GMDSS satellite service approved by IMO Resolution MSC.451(99), operational from 13 December 2020.
Iridium NEXT: Second-generation Iridium constellation of 66 LEO satellites whose deployment was completed in January 2019.
Iridium OpenPort: Earlier Iridium maritime broadband service, withdrawn in 2018.
Iridium Pilot: Maritime terminal based on OpenPort, also withdrawn in 2018.
Iridium SBD: Short Burst Data telemetry widely used to relay oceanographic data.
IsatHub: Inmarsat L-band Wi-Fi terminal product line targeting small business and small vessel use.
IsatM2M: Inmarsat L-band machine-to-machine service for tracking and telemetry.
IsatPhone 2: Current Inmarsat L-band handheld satellite phone with extended battery life and rugged design.
IsatPhone Pro: Earlier Inmarsat L-band handheld satellite phone.
ISDN: Integrated Services Digital Network protocol used by retired Fleet 77 and similar legacy satellite services.
ITC Global: Panasonic-owned VSAT service provider with a maritime, energy, and mining customer base.
ITU Region 1: ITU radio region covering Europe, Africa, the Middle East, and parts of Asia, relevant to satellite frequency coordination.
ITU Region 2: ITU radio region covering the Americas.
ITU Region 3: ITU radio region covering most of Asia and Oceania.

J

Jamming: Radio frequency interference denying use of a service such as GNSS or VSAT.
Jitter: Variation in packet arrival times across a satellite link that affects voice and video quality.
Journaled Logging: Modem and router logging mode used to support post-incident link analysis.
Jupiter (Hughes): Hughes Network Systems VSAT platform used in some maritime broadband services.

K

Ka-band: 26.5 to 40 GHz satellite band used by Inmarsat Global Xpress.
Ka-Sat: Eutelsat Ka-band satellite referenced in some early commercial Ka HTS deployments.
Ku-band: 12 to 18 GHz satellite band used by many VSAT services.
KVH: Maritime satellite communications provider whose Ku and Ka band services are used by merchant and fishing fleets.
KVH AgilePlans: Subscription bundle from KVH integrating hardware, airtime, and content for vessel operators.
KVH OneCare: KVH support and warranty service for TracPhone terminals.
KVH TracNet: KVH hybrid maritime connectivity product that combines satellite and cellular bearers.
KVH TracPhone V11-IP: Large Ku and C-band capable maritime VSAT antenna.
KVH TracPhone V3-IP: Compact Ku-band maritime VSAT antenna for smaller vessels.
KVH TracPhone V30: Compact Ku-band antenna in KVH's HTS-capable mini-VSAT family.
KVH TracPhone V60: Mid-size Ku-band antenna in KVH's HTS-capable mini-VSAT family.
KVH TracPhone V7-IP: Mid-range Ku-band maritime VSAT antenna in the mini-VSAT Broadband family.