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Astra 1D
Astra 1D is a geostationary communications satellite launched in 1994 by the Société Européenne des Satellites ( SES). , the craft remains in service for occasional use. Astra 1D was the fourth, and under original plans, last Astra communications satellite from SES. It was launched to SES' original solitary operational position at 19.2° East, and was intended as an in-orbit spare for Astra's Astra 1A, 1B and 1C and to carry digital TV transmissions. However, development of digital reception equipment in Europe was not sufficiently advanced for Astra 1D to be SES' first digital satellite (the later Astra 1E fulfilled that role) and demand for additional capacity for both British and German television channels led to 12 of the satellite's transponders being leased to broadcast analogue TV channels before the satellite had been launched. History After launch to 19.2° East, Astra 1D served two periods as a spare at the Astra 28.2°E position colocated with Astra 2A, f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Communications Satellite
A communications satellite is an artificial satellite that relays and amplifies radio telecommunication signals via a Transponder (satellite communications), transponder; it creates a communication channel between a source transmitter and a Radio receiver, receiver at different locations on Earth. Communications satellites are used for television, telephone, radio, internet, and military applications. Many communications satellites are in geostationary orbit above the equator, so that the satellite appears stationary at the same point in the sky; therefore the satellite dish antennas of ground stations can be aimed permanently at that spot and do not have to move to track the satellite. Others form satellite constellations in low Earth orbit, where antennas on the ground have to follow the position of the satellites and switch between satellites frequently. The radio waves used for telecommunications links travel by Line-of-sight propagation, line of sight and so are obstructe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ku Band
The Ku band () is the portion of the electromagnetic spectrum in the microwave range of frequencies from 12 to 18 gigahertz (GHz). The symbol is short for "K-under" (originally ), because it is the lower part of the original NATO K band, which was split into three bands (Ku, K, and Ka) because of the presence of the atmospheric water vapor resonance peak at 22.24 GHz, (1.35 cm) which made the center unusable for long range transmission. In radar applications, it ranges from 12 to 18 GHz according to the formal definition of radar frequency band nomenclature in IEEE Standard 521–2002. Ku band is primarily used for satellite communications, most notably the downlink used by direct broadcast satellites to broadcast satellite television, and for specific applications such as NASA's Tracking Data Relay Satellite used for International Space Station (ISS) communications and SpaceX Starlink satellites. Ku band satellites are also used for backhauls and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astra 2B
Astra 2B is an Astra communications satellite, owned and operated by SES. Launched in September 2000 to join Astra 2A at the Astra 28.2°E orbital position providing digital television and radio broadcast services to the United Kingdom and Ireland, the satellite has also served at the Astra 19.2°E and the Astra 31.5°E positions. History The satellite provides two broadcast beams, each with horizontal and vertical polarisation, across two footprints - 2B North (covering Central Europe and Scandinavia) and 2B South (covering Central Europe and the Iberian Peninsula and Canary Islands). While at 28.2° East, television signals could be received with a 43 cm dish across the majority of the British Isles with a 60 cm dish required in the extreme north and west, although the official footprint maps now show a 60 cm dish as required across all of Western Europe. At 28.2° East, 17 transponders on Astra 2B were used by BSkyB to provide the Sky Digital televis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transponder (satellite Communications)
A communications satellite's transponder is the series of interconnected units that form a communications channel between the receiving and the transmitting antennas. It is mainly used in satellite communication to transfer the received signals. A transponder is typically composed of: * an input band-limiting device (an input band-pass filter), * an input low-noise amplifier (LNA), designed to amplify the signals received from the Earth station (normally very weak, because of the large distances involved), * a frequency translator (normally composed of an oscillator and a frequency mixer) used to convert the frequency of the received signal to the frequency required for the transmitted signal, * an output band-pass filter, * a power amplifier (this can be a traveling-wave tube or a solid-state amplifier). Most communication satellites are radio relay stations in orbit and carry dozens of transponders, each with a Bandwidth (signal processing), bandwidth of tens of megahertz. M ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astra 2A
Astra 2A is one of the Astra communications satellites owned by SES. Launched in 1998 into the 28.2° East orbital position, half its expected end-of-life capacity of 28 transponders were pre-booked by BSkyB, who utilised it to launch their new Sky Digital service. History The satellite suffered pre-launch technical issues with its apogee motors and was moved to a launch by the Proton-K / DM-03 rather than the Ariane 5, as the Proton can inject directly in geostationary orbit (GEO). When positioned at 28.2 East, it joined DFS Kopernikus-1, which served mainly Eastern Europe. The satellite was the first of Astra's craft to never carry analogue television services (with the exception of a solitary test card in 1999 ), and as of 2006, carried standard definition digital television, digital radio, and high-definition digital television, as well as Sky Interactive streams and the AVC Broadband and Silvermead satellite Internet services. Two beams "2A North" and "2A South" tra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Digital TV
Digital television (DTV) is the transmission of television signals using digital encoding, in contrast to the earlier analog television technology which used analog signals. At the time of its development it was considered an innovative advancement and represented the first significant evolution in television technology since color television in the 1950s. Modern digital television is transmitted in high-definition television (HDTV) with greater resolution than analog TV. It typically uses a widescreen aspect ratio (commonly 16:9) in contrast to the narrower format ( 4:3) of analog TV. It makes more economical use of scarce radio spectrum space; it can transmit up to seven channels in the same bandwidth as a single analog channel, and provides many new features that analog television cannot. A transition from analog to digital broadcasting began around 2000. Different digital television broadcasting standards have been adopted in different parts of the world; below are the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astra 1B
Astra 1B was the second of the Astra communications satellites launched and operated by SES (Société Européenne des Satellites) to add extra capacity to the satellite television (direct broadcasting) services from 19.2° East, serving Germany, the United Kingdom and Ireland. Satcom K3 SES bought the satellite in 1989 from failed direct broadcast satellite (DBS) company Crimson Satellite Associates while still under construction by GE Astro Space (as Satcom K3). Twelve years later, in 2001, SES acquired GE Americom, which originally was to operate the Satcom K3 satellite (and was itself the result of General Electric's purchase of RCA Corporation in 1986) and renamed it "SES Americom". It was merged with SES New Skies to form SES World Skies before the company was merged into its parent company, SES S.A. in 2011. Mission On 4 June 1991, Astra 1B suffered an attitude control failure, causing minor drift in north–south direction, meaning that it became difficult to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astra 1A
Astra 1A was the first satellite launched and operated by SES (Société Européenne des Satellites), launched in December 1988. During its early days, it was often referred to as the Astra Satellite, as SES only operated one satellite originally. The satellite provided 16 transponders(+6 as rescue) and television coverage to Western Europe from 1989 to 2004. Astra 1A was retired and became derelict in December 2004. Channels Among the channels carried in the early years after launch were the entire four channel Sky Television (later British Sky Broadcasting, after the merger with rival British Satellite Broadcasting on the Marcopolo satellite), the services consisted of Sky Channel, Sky News, Sky Movies and Eurosport, the Scandinavian TV3 and TV1000, the German Pro7, Sat.1, RTL plus, 3sat and Teleclub, the Dutch RTL 4 as well as FilmNet, Screensport, MTV Europe, The Children's Channel and Lifestyle. Astra 1A began television broadcasts on 5 February 1989. U ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astra (satellites)
Astra is the brand name for a number of geostationary communication satellites, both individually and as a group, which are owned and operated by SES, a global satellite operator based in Betzdorf, in eastern Luxembourg. The name is also used to describe the pan-European broadcasting system provided by these satellites, the channels carried on them, and even the reception equipment. At the time of the launch of the first Astra satellite, Astra 1A in 1988, the satellite's operator was known as Société Européenne des Satellites ("European Satellite Company"). In 2001 SES Astra, a newly formed subsidiary of SES, operated the Astra satellites and in September 2011, SES Astra was consolidated back into the parent company, which by this time also operated other satellite families such as AMC, and NSS. Astra satellites broadcast 2,600 digital television channels (675 in high definition) via five main satellite orbital positions to households across Asia, Australia, Africa, Am ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Communications Satellite
A communications satellite is an artificial satellite that relays and amplifies radio telecommunication signals via a Transponder (satellite communications), transponder; it creates a communication channel between a source transmitter and a Radio receiver, receiver at different locations on Earth. Communications satellites are used for television, telephone, radio, internet, and military applications. Many communications satellites are in geostationary orbit above the equator, so that the satellite appears stationary at the same point in the sky; therefore the satellite dish antennas of ground stations can be aimed permanently at that spot and do not have to move to track the satellite. Others form satellite constellations in low Earth orbit, where antennas on the ground have to follow the position of the satellites and switch between satellites frequently. The radio waves used for telecommunications links travel by Line-of-sight propagation, line of sight and so are obstructe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geostationary
A geostationary orbit, also referred to as a geosynchronous equatorial orbit''Geostationary orbit'' and ''Geosynchronous (equatorial) orbit'' are used somewhat interchangeably in sources. (GEO), is a circular geosynchronous orbit in altitude above Earth's equator, in radius from Earth's center, and following the direction of Earth's rotation. An object in such an orbit has an orbital period equal to Earth's rotational period, one sidereal day, and so to ground observers it appears motionless, in a fixed position in the sky. The concept of a geostationary orbit was popularised by the science fiction writer Arthur C. Clarke in the 1940s as a way to revolutionise telecommunications, and the first satellite to be placed in this kind of orbit was launched in 1963. Communications satellites are often placed in a geostationary orbit so that Earth-based satellite antennas do not have to rotate to track them but can be pointed permanently at the position in the sky where the sat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astra 1E
Astra 1E is one of the Astra communications satellites in geostationary orbit owned and operated by SES. It was launched in October 1995 to the Astra 19.2°E orbital slot initially to provide digital television and radio for direct-to-home (DTH) across Europe. Astra 1E was the first Astra satellite to be dedicated to digital television broadcasting and it carried many of the first digital television channels from networks broadcasting to France, Germany, and other European countries in the 1990s. The satellite originally provided two broadcast beams, of horizontal and vertical polarisation, for Fixed Service Satellite (FSS) (10.70-10.95 GHz) and for Broadcast Satellite Service (BSS) (11.70-12.10 GHz) frequency bands. The FSS beams provide footprints that cover essentially the same area of Europe – northern, central and eastern Europe, including Spain and northern Italy – while the BSS horizontal beam excludes Spain and extends further east, and the BSS vertical be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
