Iridium Terminal
Iridium's low Earth orbit constellation gives pole-to-pole coverage that geostationary VSAT cannot reach, which is why an Iridium terminal stays fitted on vessels trading in high latitudes even where a broadband VSAT dome is also installed.
What to check on an Iridium Terminal.
25 models from SAILOR / Thrane & Thrane in Iridium Terminal. Below: the full model list.
What this type is
An Iridium terminal is a satellite communication unit that links to the Iridium constellation of low Earth orbit satellites rather than a single geostationary satellite. Because the satellites orbit close to the earth and cover the poles, an Iridium terminal keeps a signal in latitudes where GEO-based VSAT systems lose coverage entirely. The trade-off is bandwidth: classic Iridium voice and short-burst data is measured in kilobits, and even Iridium Certus broadband tops out well below a VSAT Ku- or Ka-band link. Vessels use Iridium as the resilient backup channel and for GMDSS, not as the primary internet pipe.
Main components
- Antenna/transceiver dome — a compact omnidirectional unit, far smaller than a VSAT dish, mounted with clear sky view fore and aft.
- Below-decks transceiver unit — handles call setup, data session management, and interfaces to the bridge network or SSAS/LRIT terminal.
- Subscriber Identity Module — an Iridium SIM tied to the airtime contract, similar in principle to a mobile SIM.
- Power supply and UPS backup — Iridium terminals used for GMDSS distress alerting must stay powered from the emergency source.
Selection and sizing
The deciding factor is not power but service class. A basic voice/SBD (Short Burst Data) unit suits SSAS reporting, crew calling and low-volume telemetry. Iridium Certus terminals step up to broadband speeds sufficient for email, weather routing files and some remote monitoring, at higher airtime cost. Fit is also driven by whether the terminal must serve a regulatory function.
| Service class | Typical use |
|---|---|
| Voice / SBD | Crew calls, SSAS, low-rate telemetry |
| Iridium Certus 100/200 | Email, weather files, light monitoring |
| Iridium Certus 700 | Broadband data, video, larger file transfer |
Regulations and class
Iridium is recognised under the GMDSS as an approved mobile satellite service alongside Inmarsat, so an Iridium terminal can fulfil the ship's GMDSS distress and safety communication requirement under SOLAS Chapter IV where fitted and type-approved for that purpose. Where used for the Ship Security Alert System, the terminal must meet the covert-alert requirements of SOLAS Chapter XI-2, including no on-board indication that an alert has been sent. Type approval and correct installation documentation are checked at survey.
Read the full guide
Typical faults
- Antenna cable or connector corrosion at the mast — intermittent loss of registration that is hard to diagnose from below decks.
- SIM or airtime contract lapse — unit reports no service despite hardware being fully functional.
- Firmware mismatch after a partial software update — data sessions drop while voice still works, or vice versa.
- UPS battery degraded — terminal loses power exactly when the main supply fails, defeating its purpose as a backup channel.
What to look for in a supplier
- Type approval certificate matching the specific GMDSS or SSAS role the terminal will perform.
- Confirmed compatibility with the airtime provider's activation process before installation, not after.
- Documented antenna cable run and connector spec for the actual mast height and exposure.
- Service support that covers both the hardware and the airtime account — the two are often sold by different parties.
Test the Iridium link on its own, with the VSAT dome powered down, at least once a voyage — a terminal that has silently been riding on the VSAT connection for months will fail exactly when the VSAT does.
Models in this type.
The best-documented model of each manufacturer first, then the next — 25 of 25 models in Iridium Terminal. Every row links to full specifications, documents and service notes.
Manufacturers.
All 5 manufacturers with models of Iridium Terminal. Names with a manufacturer page open it; the others open a search across the full library.
All manufacturersAlso in Navigation & Bridge Equipment.
The other equipment types in this category.
One request. A person reads it and replies by e-mail.
Tell us the manufacturer, the model and what you need — a part, a service call, a second opinion. A person reads every request and replies by e-mail.
No details at hand? A photo of the rating plate or the part is enough — simply attach it to the request.
Three things people ask first.
Is Iridium Terminal data free?
Yes. Every model page, every guide and every datasheet for this type is readable without an account. An account adds saved searches and requests, nothing is taken away.
My model is missing — what now?
Send us the nameplate. We identify it by hand, add it to the library, and if you need a part or a service, the request is already on our desk.
Can you source a Iridium Terminal part?
Yes. Tell us the manufacturer, the model and what you need — a person reads every request and replies by e-mail.