|
Galaxy IV
Galaxy IV was a model HS-601 satellite built by Hughes Space and Communications Company (HSC). The satellite, which carried a payload of both C band and Ku band transponders, was launched on June 24, 1993 and operated by PanAmSat Corporation. It was in geostationary orbit at 99°W. Failure Control of Galaxy IV was lost on May 19, 1998 when the satellite's primary control processor failed. The backup control processor had suffered a previously undetected anomaly, and PanAmSat was not able to regain control of the spacecraft. Galaxy IV was declared a loss on May 20, 1998. Failure of the primary control processor was attributed to tin whisker growth, a phenomenon in which tendrils grow from solder, causing an electrical short circuit. Engineers believe that a hole developed in the conformal wax coating over the solder, allowing whiskers to develop. The satellite manufacturer, Hughes, has replaced pure tin plating with nickel to alleviate the problem in newer designs, adding per ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hughes Aircraft Company
The Hughes Aircraft Company was a major American aerospace and defense contractor founded on February 14, 1934 by Howard Hughes in Glendale, California, as a division of Hughes Tool Company. The company was known for producing, among other products, the Hughes H-4 Hercules ''Spruce Goose'' aircraft, the atmospheric entry probe carried by the ''Galileo'' spacecraft, and the AIM-4 Falcon guided missile. Hughes Aircraft was founded to construct Hughes' H-1 Racer world speed record aircraft, and it later modified aircraft for his transcontinental and global circumnavigation speed record flights. The company relocated to Culver City, California, in 1940 and began manufacturing aircraft parts as a subcontractor. Hughes attempted to mold it into a major military aircraft manufacturer during World War II; however, its initial military projects ended in failure, with millions of dollars in U.S. government funds expended but only three aircraft actually built, resulting in a high ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geostationary Orbit
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 s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Communications Satellites In Geostationary Orbit
Communication (from la, communicare, meaning "to share" or "to be in relation with") is usually defined as the transmission of information. The term may also refer to the message communicated through such transmissions or the field of inquiry studying them. There are many disagreements about its precise definition. John Peters argues that the difficulty of defining communication emerges from the fact that communication is both a universal phenomenon and a specific discipline of institutional academic study. One definitional strategy involves limiting what can be included in the category of communication (for example, requiring a "conscious intent" to persuade). By this logic, one possible definition of communication is the act of developing meaning among entities or groups through the use of sufficiently mutually understood signs, symbols, and semiotic conventions. An important distinction is between verbal communication, which happens through the use of a language, and n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Satellites Using The BSS-601 Bus
A satellite or artificial satellite is an object intentionally placed into orbit in outer space. Except for passive satellites, most satellites have an electricity generation system for equipment on board, such as solar panels or radioisotope thermoelectric generators (RTGs). Most satellites also have a method of communication to ground stations, called transponders. Many satellites use a standardized bus to save cost and work, the most popular of which is small CubeSats. Similar satellites can work together as a group, forming constellations. Because of the high launch cost to space, satellites are designed to be as lightweight and robust as possible. Most communication satellites are radio relay stations in orbit and carry dozens of transponders, each with a bandwidth of tens of megahertz. Satellites are placed from the surface to orbit by launch vehicles, high enough to avoid orbital decay by the atmosphere. Satellites can then change or maintain the orbit by propuls ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Galaxy 4R
Galaxy 4R was a communications satellite operated by PanAmSat from 2000 to 2006, and by Intelsat from 2006 to 2009. It spent most of its operational life at an orbital location of 99° W, a slot once occupied by the Galaxy IV, which suffered a failure in 1998. G4R was launched on April 18, 2000, with an Ariane launch vehicle, and covered North America with twenty-four transponders each on the C- and Ku bands. The satellite is currently at 76.8°W, inclined. Users included Warner Brothers, National Public Radio, Public Radio International, Buena Vista Television Distribution, FOX, and Televisa. The satellite was also utilized for satellite internet services through DirecPC. Much of the Ku side was occupied by the HITS service, which re-distributes programming found on other satellites to cable providers. Designed for an operational lifespan of 15 years, Galaxy 4R suffered a propulsion system failure in 2003 and was replaced by Galaxy 16 on August 14, 2006. It was moved t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
National Public Radio
National Public Radio (NPR, stylized in all lowercase) is an American privately and state funded nonprofit media organization headquartered in Washington, D.C., with its NPR West headquarters in Culver City, California. It differs from other non-profit membership media organizations such as the Associated Press, in that it was established by an act of Congress. Most of its member stations are owned by non-profit organizations, including public school districts, colleges, and universities. It serves as a national syndicator to a network of over 1,000 public radio stations in the United States. , NPR employed 840 people. NPR produces and distributes news and cultural programming. The organization's flagship shows are two drive-time news broadcasts: ''Morning Edition'' and the afternoon ''All Things Considered'', both carried by most NPR member stations, and among the most popular radio programs in the country. , the drive-time programs attract an audience of 14.9 million and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reuters
Reuters ( ) is a news agency owned by Thomson Reuters Corporation. It employs around 2,500 journalists and 600 photojournalists in about 200 locations worldwide. Reuters is one of the largest news agencies in the world. The agency was established in London in 1851 by the German-born Paul Reuter. It was acquired by the Thomson Corporation of Canada in 2008 and now makes up the media division of Thomson Reuters. History 19th century Paul Reuter worked at a book-publishing firm in Berlin and was involved in distributing radical pamphlets at the beginning of the Revolutions in 1848. These publications brought much attention to Reuter, who in 1850 developed a prototype news service in Aachen using homing pigeons and electric telegraphy from 1851 on, in order to transmit messages between Brussels and Aachen, in what today is Aachen's Reuters House. Reuter moved to London in 1851 and established a news wire agency at the London Royal Exchange. Headquartered in London, R ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pager
A pager (also known as a beeper or bleeper) is a wireless telecommunications device that receives and displays alphanumeric or voice messages. One-way pagers can only receive messages, while response pagers and two-way pagers can also acknowledge, reply to and originate messages using an internal transmitter. Pagers operate as part of a paging system which includes one or more fixed transmitters (or in the case of response pagers and two-way pagers, one or more base stations), as well as a number of pagers carried by mobile users. These systems can range from a restaurant system with a single low power transmitter, to a nationwide system with thousands of high-power base stations. Pagers were developed in the 1950s and 1960s, and became widely used by the 1980s. In the 21st century, the widespread availability of cellphones and smartphones has greatly diminished the pager industry. Nevertheless, pagers continue to be used by some emergency services and public safety personne ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territories, nine Minor Outlying Islands, and 326 Indian reservations. The United States is also in free association with three Pacific Island sovereign states: the Federated States of Micronesia, the Marshall Islands, and the Republic of Palau. It is the world's third-largest country by both land and total area. It shares land borders with Canada to its north and with Mexico to its south and has maritime borders with the Bahamas, Cuba, Russia, and other nations. With a population of over 333 million, it is the most populous country in the Americas and the third most populous in the world. The national capital of the United States is Washington, D.C. and its most populous city and principal financial center is New York City. Paleo-Americ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telecommunications
Telecommunication is the transmission of information by various types of technologies over wire, radio, optical, or other electromagnetic systems. It has its origin in the desire of humans for communication over a distance greater than that feasible with the human voice, but with a similar scale of expediency; thus, slow systems (such as postal mail) are excluded from the field. The transmission media in telecommunication have evolved through numerous stages of technology, from beacons and other visual signals (such as smoke signals, semaphore telegraphs, signal flags, and optical heliographs), to electrical cable and electromagnetic radiation, including light. Such transmission paths are often divided into communication channels, which afford the advantages of multiplexing multiple concurrent communication sessions. ''Telecommunication'' is often used in its plural form. Other examples of pre-modern long-distance communication included audio messages, such as coded d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Whisker (metallurgy)
Metal whiskering is a phenomenon which occurs in electrical devices when metals form long whisker-like projections over time. Tin whiskers were noticed and documented in the vacuum tube era of electronics early in the 20th century in equipment that used pure, or almost pure, tin solder in their production. It was noticed that small metal hairs or tendrils grew between metal solder pads, causing short circuits. Metal whiskers form in the presence of compressive stress. Germanium, zinc, cadmium, and even lead whiskers have been documented. Many techniques are used to mitigate the problem, including changes to the annealing process (heating and cooling), the addition of elements like copper and nickel, and the inclusion of conformal coatings. Traditionally, lead has been added to slow down whisker growth in tin-based solders. Following the Restriction of Hazardous Substances Directive (RoHS), the European Union banned the use of lead in most consumer electronic products from 2006 du ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PanAmSat
The former PanAmSat Corporation founded in 1984 by Reynold (Rene) Anselmo, was a satellite service provider headquartered in Greenwich, Connecticut, United States. It operated a fleet of communications satellites used by the entertainment industry, news agencies, internet service providers, government agencies, and telecommunication companies. Anselmo got the idea for PanAmSat from Norm Leventhal, a communications lawyer in Washington, D.C., to whom he had turned to for advice regarding difficulties he was encountering in getting reasonably priced satellite transmission for his Spanish International Network (SIN), the current-day Univision. Anselmo financed the entire project himself and Leventhal's law firm, hiring Martin Rothblatt for special satellite technical advice, filed for approval from the Federal Communications Commission (FCC) and lining up an initial satellite from RCA Astro-Electronics and a heavily discounted launch from Arianespace. PanAmSat effectively broke ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
