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.
of the decimator is 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.
You've reached the end of your free preview.
Want to read all 109 pages?
- Spring '17
- communications satellite, Geosynchronous orbit, Geostationary orbit