Inmarsat has become a limited company since 1999

INMARSAT has become a limited company since 1999. INMARSAT Ltd is a subsidiary of the INMARSAT
Ventures plc holding company, which operates a constellation of geosynchronous satellites for
worldwide mobile communications. The satellites are controlled from INMARSAT headquarters at
London, which is also home to INMARSAT ventures and a small Intergovernmental office created to
supervise the company’s public service duties for the maritime community i.e. Global Maritime Distress
and Safety System and Air traffic Control communications for the aviation industry.
Starting with a user base of about 900 ships in early 1980’s, the user base of INMARSAT grew to 210,000
ships, vehicles, aircrafts and portable terminals in 2001. INMARSAT Type A mobile terminals meant for
installation in large ships are quite expensive, whereas, portable INMARSAT mini-M terminals are small,
cost effective and easy to operate. The services provided by INMARSAT include telephone, fax and data
communications up to 64 kbps. Other services include videotext, navigation, weather information and
Search & Rescue. INMARSAT Satellites can also be used for emergency Land Mobile Communications
for relief work and to re-establish communications or to provide basic service where there is no
alternative. INMARSAT can also be used to alert people on shore for coordination of rescue activities.
Apart from maritime and Land Mobile Satellite Service, INMARSAT also provide aeronautical satellite
service for passenger communications.
INMARSAT system operates at C-band and L-band frequencies. The INMARSAT system uses allocations in
the 6 GHz band for the ground station to satellite link, 1.5 GHz for satellite terminal downlink, 1.6 GHz
for terminal to satellite uplink and 4 GHz for the satellite to ground station down link.

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COSPAS-SARSAT: COSPAS-SARSAT is a joint venture of Canada, France, Russia and US. It is a satellite
based international Search and Rescue, alert and location system using different low earth orbit
satellites operating in the frequency of 120 MHz and 406 MHz. Local Users Terminals operating in
different parts of the world pick-up the alert signals from Emergency Location Beacons carried by ships
and airplanes and pass on the information regarding the location of accident to the nearest rescue
centres for carrying out the rescue operations. Since the operationalisation of the satellite based Search
and Rescue System, hundreds of lives have been saved due to timely deployment of prompt rescue
operations.
Domestic Satellite Communications Systems
In the initial years of implementation of commercial Satellite Communications the emphasis was mainly
on the transoceanic and international communications. However use of satellite communications for
improvement of domestic communications also emerged as a distinct possibility. Countries like, USSR,
Canada, Indonesia took initiatives in implementing domestic satellite communications systems for the
respective countries. Satellite Communications System for domestic communications is cost effective
compared to the conventional terrestrial systems under the following conditions.