|
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 obt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Satcom (satellite)
Satcom, a portmanteau of satellite communications, was a brand of artificial geo-stationary communications satellites originally developed and operated by RCA American Communications ( RCA Americom) that facilitated wide-area telecommunications by receiving radio signals from Earth, amplifying them, and relaying them back down to terrestrial receivers. Satcom was one of the early geostationary satellites; the first were the Syncom series, in 1964. The first Satcom satellite, Satcom 1, was launched on 13 December 1975. The last satellite, Satcom K2, was placed into orbit on 27 November 1985 and was de-orbited in February 2002. Satcom was first superseded and then replaced by the GE series of satellites. The Satcom system passed to General Electric with its purchase of RCA in 1986. RCA Americom became GE American Communications (GE Americom) and the satellite construction division became GE Astro Space. GE Astro Space was sold to Martin Marietta (now Lockheed Martin Spac ... [...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 S.A., 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. 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 2600 digital television channels (675 in high definition) via five main satellite orbital positions to households across Asia, Australia, Africa, Americas, Europe, New Zealand, M ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reaction Wheel
A reaction wheel (RW) is used primarily by spacecraft for three-axis attitude control, and does not require rockets or external applicators of torque. They provide a high pointing accuracy, and are particularly useful when the spacecraft must be rotated by very small amounts, such as keeping a telescope pointed at a star. A reaction wheel is sometimes operated as (and referred to as) a momentum wheel, by operating it at a constant (or near-constant) rotation speed, to provide a satellite with a large amount of stored angular momentum. Doing so alters the spacecraft's rotational dynamics so that disturbance torques perpendicular to one axis of the satellite (the axis parallel to the wheel's spin axis) do not result directly in spacecraft angular motion about the same axis as the disturbance torque; instead, they result in (generally smaller) angular motion (precession) of that spacecraft axis about a perpendicular axis. This has the effect of tending to stabilize that spacecraft ax ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solar Wind
The solar wind is a stream of charged particles released from the upper atmosphere of the Sun, called the corona. This plasma mostly consists of electrons, protons and alpha particles with kinetic energy between . The composition of the solar wind plasma also includes a mixture of materials found in the solar plasma: trace amounts of heavy ions and atomic nuclei such as C, N, O, Ne, Mg, Si, S, and Fe. There are also rarer traces of some other nuclei and isotopes such as P, Ti, Cr, 54Fe and 56Fe, and 58Ni, 60Ni, and 62Ni. Superposed with the solar-wind plasma is the interplanetary magnetic field. The solar wind varies in density, temperature and speed over time and over solar latitude and longitude. Its particles can escape the Sun's gravity because of their high energy resulting from the high temperature of the corona, which in turn is a result of the coronal magnetic field. The boundary separating the corona from the solar wind is called the Alfvén surface. At a distance of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sparklies
Sparklies is a form of interference on analogue satellite television transmissions. Sparklies are black or white 'hard' interference dots (as opposed to the 'soft' interference patterns of terrestrial television), caused either by too weak or too strong a signal. When within the satellite's rated reception footprint, sparklies are most likely to be caused by a misaligned dish, or LNBs which are too high- or too low-gain for the dish and receiver. The term "sparklies" is used by British Sky Broadcasting (BSkyB) and a number of hardware makers including Amstrad and Pace. Sparklies do not occur on digital satellite systems; similar problems with digital signals cause MPEG artifacts. See also * Salt and pepper noise Salt-and-pepper noise, also known as impulse noise, is a form of noise sometimes seen on digital images. This noise can be caused by sharp and sudden disturbances in the image signal. It presents itself as sparsely occurring white and black pixe ... References ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Analog Television
Analog television is the original television technology that uses analog signals to transmit video and audio. In an analog television broadcast, the brightness, colors and sound are represented by amplitude, instantaneous phase and frequency, phase and frequency of an analog signal. Analog signals vary over a continuous range of possible values which means that Noise (electronics), electronic noise and interference may be introduced. Thus with analog, a moderately weak signal becomes Noise (video), snowy and subject to interference. In contrast, picture quality from a digital television (DTV) signal remains good until the signal level drops below digital cliff, a threshold where reception is no longer possible or becomes intermittent. Analog television may be wireless (terrestrial television and satellite television) or can be distributed over a cable network as cable television. All broadcast television systems used analog signals before the arrival of DTV. Motivated by the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Attitude Control
Attitude control is the process of controlling the orientation of an aerospace vehicle with respect to an inertial frame of reference or another entity such as the celestial sphere, certain fields, and nearby objects, etc. Controlling vehicle attitude requires sensors to measure vehicle orientation, actuators to apply the torques needed to orient the vehicle to a desired attitude, and algorithms to command the actuators based on (1) sensor measurements of the current attitude and (2) specification of a desired attitude. The integrated field that studies the combination of sensors, actuators and algorithms is called guidance, navigation and control (GNC). Aircraft attitude control An aircraft's attitude is stabilized in three directions: ''Yaw (rotation), yaw'', nose left or right about an axis running up and down; ''pitch'', nose up or down about an axis running from wing to wing; and ''roll'', rotation about an axis running from nose to tail. Elevator (aeronautics), Elevat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SES World Skies
SES World Skies was a short lived company formed as a result of the merger between the two SES subsidiaries, ''SES Americom'' and ''SES New Skies''. The company was merged into its parent company, SES S.A. in 2011. History SES Americom SES Americom traces its roots back to RCA Americom, formed in 1975. RCA Americom was notable for launching the Satcom series of satellites which were instrumental in helping early American cable TV channels gain traction. In 1986, General Electric acquired RCA and renamed the Americom unit to GE Americom. Fifteen years later, in 2001, GE sold its GE Americom unit to SES (Société Européenne des Satellites) for US$5 billion in cash and stock. SES New Skies In 1998, Intelsat transferred 5 of its 24 satellites to New Skies Satellites N.V., a Dutch start up company formed by Intelsat to help move Intelsat towards privatisation. In June 2004, New Skies Satellites was sold to The Blackstone Group for US$956 million. Eighteen months later, S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RCA Corporation
The RCA Corporation was a major American electronics company, which was founded as the Radio Corporation of America in 1919. It was initially a patent trust owned by General Electric (GE), Westinghouse, AT&T Corporation and United Fruit Company. In 1932, RCA became an independent company after the partners were required to divest their ownership as part of the settlement of a government antitrust suit. An innovative and progressive company, RCA was the dominant electronics and communications firm in the United States for over five decades. RCA was at the forefront of the mushrooming radio industry in the early 1920s, as a major manufacturer of radio receivers, and the exclusive manufacturer of the first superheterodyne sets. RCA also created the first nationwide American radio network, the National Broadcasting Company (NBC). The company was also a pioneer in the introduction and development of television, both black and white and especially color television. During this peri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
General Electric
General Electric Company (GE) is an American multinational conglomerate founded in 1892, and incorporated in New York state and headquartered in Boston. The company operated in sectors including healthcare, aviation, power, renewable energy, digital industry, additive manufacturing and venture capital and finance, but has since divested from several areas, now primarily consisting of the first four segments. In 2020, GE ranked among the Fortune 500 as the 33rd largest firm in the United States by gross revenue. In 2011, GE ranked among the Fortune 20 as the 14th most profitable company, but later very severely underperformed the market (by about 75%) as its profitability collapsed. Two employees of GE – Irving Langmuir (1932) and Ivar Giaever (1973) – have been awarded the Nobel Prize. On November 9, 2021, the company announced it would divide itself into three investment-grade public companies. On July 18, 2022, GE unveiled the brand names of the companies it will ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SES Americom
SES Americom was a major commercial satellite operator of North American geosynchronous satellites based in the United States. The company started as RCA Americom in 1975 before being bought by General Electric in 1986 and then later acquired by SES S.A. in 2001. In September 2009, SES Americom and SES New Skies merged into SES World Skies. History RCA American Communications (RCA Americom) was founded in 1975 as an operator of RCA Astro Electronics-built satellites. The company's first satellite; Satcom 1, was launched on 12 December 1975. Satcom 1 was one of the earliest geostationary satellites. Satcom 1 was instrumental in helping early cable TV channels (such as Superstation TBS and CBN) to become initially successful, because these channels distributed their programming to all of the local cable TV headends using the satellite. Additionally, it was the first satellite used by broadcast TV networks in the United States, like American Broadcasting Company (ABC), NBC, an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Satellite Television
Satellite television is a service that delivers television programming to viewers by relaying it from a communications satellite orbiting the Earth directly to the viewer's location. The signals are received via an outdoor parabolic antenna commonly referred to as a satellite dish and a low-noise block downconverter. A satellite receiver then decodes the desired television program for viewing on a television set. Receivers can be external set-top boxes, or a built-in television tuner. Satellite television provides a wide range of channels and services. It is usually the only television available in many remote geographic areas without terrestrial television or cable television service. Modern systems signals are relayed from a communications satellite on the X band (8–12 GHz) or Ku band (12–18 GHz) frequencies requiring only a small dish less than a meter in diameter. The first satellite TV systems were an obsolete type now known as television receive-only. Thes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
_logo.jpg "Click for more on -> RCA Corporation"){kind=logo}
