Module4.pptx
- 2. Communication-related Applications of Satellites • Telecommunication satellites provide a varied range of services mainly including television broadcasting, international telephony and data communication services, most of these services being multipurpose in nature. • GEO satellites in point-to-multipoint configuration are employed for satellite TV applications. There are primarily two types of satellite television distribution systems, namely the television receive-only (TVRO) and the direct broadcasting satellite (DBS) systems. • Satellites also provide data communication services including data, broadcast and multimedia services such as data collection and broadcasting, image and video transfer, voice, internet, two-way computer interactions and database inquiries.
- 3. Geostationary Satellite Communication Systems • These satellites were used for international, regional and domestic telephone and video distribution services. Some of the important geostationary satellite missions include Intelsat, Inmarsat, Telstar • The most important applications of geostationary communication satellites in the current scenario include DTH satellite television broadcasting services and VSAT services.
- 4. Non-geostationary Satellite Communication Systems • Non-geostationary satellite communication systems are emerging to provide mobile communication services as well as other services like messaging, video, fax and data communication. • Constellations of satellites orbiting in LEO or MEO orbits can provide global mobile communication services
- 11. Payloads
- 12. Transponder • The device on board the satellite that performs the amplification and frequency conversion is referred to as a transponder and is the main payload of any communication satellite. • Transponders may be broadly classified into two types depending upon the manner in which they process the signal: 1. Transparent or bent pipe transponders 2. Regenerative transponders
- 13. Transparent or Bent Pipe Transponders
- 14. Regenerative Transponders • Regenerative transponders are those in which some onboard processing is done and the received signal is altered before retransmission • These repeaters are also called digital processing repeaters as they use various digital techniques like narrowband channel selection and routing, demodulation, error correction, reformatting of data, etc., for processing the received signal.
- 15. Satellite versus Terrestrial Networks • Broadcast property – wide coverage area • Wide bandwidth – high transmission speeds and large transmission capacity • Geographical flexibility – independence of location • Easy installation of ground stations. • Uniform service characteristics. • Immunity to natural disaster • Independence from terrestrial infrastructure. • Cost aspects – low cost per added site and distance insensitive costs
- 16. Disadvantages of Satellites with Respect to Terrestrial Networks • Transmission delay • Echo effects • Launch cost of a satellite.
- 18. A Typical Satellite TV Network
- 19. Direct Broadcasting Satellite (DBS) Services
- 20. Satellite Radio • A satellite providing high fidelity audio broadcast services to the broadcast radio stations is referred to as a satellite radio and is a major revolution in the field of radio systems. • Sound quality is excellent in this case due to a wide audio bandwidth of 5– 15 kHz and low noise provided over the satellite link. Satellite radio like the satellite TV employ GEO satellites and the network arrangement for the satellite radio is more or less identical to that used for TV broadcasting. • Usingpoint-to-multipoint connectivity, the audio signals from various music channels, news and sports centres are transmitted by the satellite to a conventional AM or FM radio station.
- 21. Regional Satellite Systems • Regional satellite missions were established with the aim of strengthening the communication resources of the countries belonging to the same geographical area. • Some of the regional satellite systems include Eutelsat, Arabsat, AsiaSat, Measat, ACeS (Asia cellular satellite), Thuraya, etc. • EUTELSAT operates a fleet of satellites that provide communication services to Europe, theMiddle East, Africa and large parts of the Asian and American continents.
- 22. • Arabsat satellites provide satellite communication services to the Middle East, Africa and large parts of Europe. • The AsiaSatellite Telecommunications Company Limited (AsiaSat) and Measat systems are Asia’s regional satellite operators, providing satellite services to the Asia Pacific region. • ACeS is another satellite-based regional communication system providing services to Asia. It provides fully digital video, voice and data services throughout Asia. • The Thuraya system provides mobile communication services to the Middle East, North and Central Africa, Europe, Central Asia and the Indian subcontinent
- 23. EUTELSAT (European Telecommunication Satellite Organization) • The EUTELSAT organization was formed in the year 1977 to commission the design and construction of satellites and to manage the operation of regional satellite communication services in Europe. • The first communication satellite to be launched by EUTELSAT was the orbital test satellite (OTS) in the year 1978, which carried out link tests with small Earth stations with the help of a powerful antenna on board the satellite. • The ECS satellite programme was renamed the Eutelsat satellite programme. • Eutelsat satellites provide television, telephony and data transmission services on a regional basis. • The more advanced satellites in this series also provided specific services like business communication services and mobile communication services. • In addition to the Eutelsat satellites, other series of satellites, namely the Hot Bird, Eurobird and Atlantic Bird series, were launched to expand the horizon of the services offered and the coverage area of the satellites of the EUTELSAT organization.
- 24. National Satellite SystemS • National satellite systems, also referred to as domestic satellite systems, provide services to a particular country. • National satellite systems were originally established by developed countries like the USA, USSR and Canada to serve their country’s population according to their specific needs. • Today, in addition to these developed countries, some developing nations like India, China, Japan, etc., also have their own national satellite systems. • Some of the domestic satellite systems include Galaxy, Satcom, EchoStar and Telestar of the USA, Brasilsat of Brazil, INSAT of India, Optus of Australia and Sinosat of China
- 25. INSAT (Indian National Satellite) • Owned by the Indian Department of Space, named the Indian Space Research Organization (ISRO),INSAT is one of the largest domestic communication satellite networks in the world, providing services in the areas of telecommunications, television broadcasting, mobile satellite services and meteorology including disaster warning. • INSAT is a joint venture of the Department of Space (DOS), Department of Telecommunications (DOT), Indian Meteorological Department (IMD), All India Radio (AIR) and Doordarshan. • Making a modest beginning with the launch of INSAT-1A in 1982, the INSAT satellite programme has come a long way today.
- 26. • INSAT-1A belonged to the INSAT-1 series, further comprising INSAT- 1B, 1C and 1D satellites. The INSAT-1 series was followed by INSAT-2 and INSAT-3 series of satellites. • They were super ceded by the INSAT-4 series of satellites.