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.

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.

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

A phase

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

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.

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

Global Maritime Distress and Safety System.

Greenwich Mean Time (see also UTC).

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