Direct broadcasting satellite

Delivery of continuing adult education via direct-broadcast satellite to rural India. 

In order to adequately address this problem, the analyst does not need to know much at all about how direct-broadcast satellites work. So long as he or she knows what the technology costs, who they need to run it, and similar details, a non-technical policy analyst can address this problem very well. Indeed, getting too bogged down in the technical details could easily distract the analyst from the most important issues. 

High-power direct broadcast satellites (DBS) or direct-to-home (DTH) satellites operate atKu-band. In the U.S., satellites operating in the broadcast sateUite service (BSS) with downlink frequencies of 12.2-12.7 GHz, deliver TV directly to home receivers having parabolic dish antennas as small as 46 cm (18 in) in diameter. DBS with digital modulation and compressed video is providing more than 150 National Television Systems Committee (NTSC) TV channels from a single orbital location having an allocation of 32 transponder channels, each with 24-MHz bandwidth. 

The first applications of HEMTs were in radio astronomy where they improved the performance of the existing radio telescopes. Later they became widely used in the receivers for the direct broadcast satellites and in cell phones. Recently ITEMT technology has been extended to GaN and InP to make high power, high frequency transmitters. 

Topic narrowed The Involvement of the United Nations in the Regulation of Direct Broadcasting from Satellites... 

Finally, I hope that we will shortly be able to rid ourselves of the burden of onboard recording with magnetic tapes. Taperecorders have all proved disappointing. They introduce new spurious noise, which increases as they deteriorate, and cuts down the useful life of the satellites. A broad international agreement could lead to direct broadcasting of all information gathered by onboard instruments to stations... 

Due to their main characteristics (fixed position over one point on the Earth), these satellites are mainly used for telecommunications hy operators that have assembled fleets covering the Earth (direct home TV broadcasting, voice and internet Intelsat, Eutelsat, Astra satellites, etc.). It is also important to remember that GEO satellites are used for Earth observation purposes (remote sensing) in addition to communication applications meteorological satellites are also positioned in geostationary orbits (Meteosat and National Oceanic and Atmospheric Administration satellites). 

Many military strategists believe that the greatest prospects for advancing a country s ability to fight more effectively lie in the development of more sophisticated tools for information warfare. Devices already available, such as GPS, surveillance satellites, and radar have proven effective in combat however, refinements to improve their accuracy and reliability, especially in the face of electronic countermeasures, will continue to be required. Electronic command and control tools—instruments such as the Internet and handheld devices that rely on satellites for broadcast capability—will also require constant updating or replacement with yet-undiscovered technologies that can give commanders improved ability to communicate with subordinates or superiors to direct activities and provide necessary support on the battlefield. 

The impact of satellites on world communications since commercial operations began in the mid-1960s is such that we now take for granted many services that were not available a few decades ago worldwide TV, reliable communications with ships and aircraft, wide-area data networks, communications to remote areas, direct TV broadcast to homes, position determination, and Earth observation (weather and mapping). New and proposed satellite services include global personal communications to hand-held portable telephones and broadband voice, video, and data to and from small user terminals at customer premises around the world. 

This table was prepared from the viewpoint of direct image production. In practice, radiation detected by the instruments, i.e., on a satellite or aircraft, is recorded on magnetic tape which is played back on command and recorded at the receiving station (some spectral bands are broadcast live from the carrying platform (satellite)). These ground recordings are used for production of pictures and numerical data. 

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