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Satellite Communication
A communications satellite is an artificial satellite that relays and amplifies radio telecommunication signals via a transponder; it creates a communication channel between a source transmitter and a 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 high frequency radio waves used for telecommunications links travel by line of sight and so are obstructed by the curve of the Earth. The purpose of communications satell ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
AEHF 1
Advanced Extremely High Frequency (AEHF) is a constellation of communications satellites operated by the United States Space Force. They are used to relay secure communications for the United States Armed Forces, the British Armed Forces, the Canadian Armed Forces, the Netherlands Armed Forces and the Australian Defence Force. The system consists of six satellites in geostationary orbits. The final satellite was launched on 26 March 2020. AEHF is backward compatible with, and replaces, the older Milstar system and will operate at 44 Hertz, GHz uplink (extremely high frequency (EHF) band) and 20 GHz downlink (super high frequency (SHF) band). The AEHF system is a joint service communications system that provides survivable, global, secure, protected, and jam-resistant communications for high-priority military ground, sea and air assets. Overview AEHF satellites use many narrow spot beams directed towards the Earth to relay communications to and from users. Crosslinks between th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radio Wave
Radio waves are a type of electromagnetic radiation with the longest wavelengths in the electromagnetic spectrum, typically with frequencies of 300 gigahertz ( GHz) and below. At 300 GHz, the corresponding wavelength is 1 mm (shorter than a grain of rice); at 30 Hz the corresponding wavelength is (longer than the radius of the Earth). Like all electromagnetic waves, radio waves in a vacuum travel at the speed of light, and in the Earth's atmosphere at a close, but slightly lower speed. Radio waves are generated by charged particles undergoing acceleration, such as time-varying electric currents. Naturally occurring radio waves are emitted by lightning and astronomical objects, and are part of the blackbody radiation emitted by all warm objects. Radio waves are generated artificially by an electronic device called a transmitter, which is connected to an antenna which radiates the waves. They are received by another antenna connected to a radio receiver, w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sergey Korolev
Sergei Pavlovich Korolev (russian: Сергей Павлович Королёв, Sergey Pavlovich Korolyov, sʲɪrˈɡʲej ˈpavləvʲɪtɕ kərɐˈlʲɵf, Ru-Sergei Pavlovich Korolev.ogg; ukr, Сергій Павлович Корольов, Serhiy Pavlovych Korol'ov, sɛrˈɦij ˈpavlovɪtʃ koroˈlʲou̯) 14 January 1966) was a lead Soviet rocket engineer and spacecraft designer during the Space Race between the United States and the Soviet Union in the 1950s and 1960s. He is regarded by many as the father of practical astronautics. He was involved in the development of the R-7 Rocket, Sputnik 1, launching Laika, Sputnik 3, the first human-made object to make contact with another celestial body, Belka and Strelka, the first human being, Yuri Gagarin, into space, Voskhod 1, and the first person, Alexei Leonov, to conduct a spacewalk. Although Korolev trained as an aircraft designer, his greatest strengths proved to be in design integration, organization and strategic plann ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mikhail Tikhonravov
Mikhail Klavdievich Tikhonravov (July 29, 1900 – March 3, 1974) was a Soviet engineer who was a pioneer of spacecraft design and rocketry. Mikhail Tikhonravov was born in Vladimir, Russia. He attended the Zhukovsky Air Force Academy from 1922 to 1925, where he was exposed to Konstantin Tsiolkovsky's ideas of spaceflight. After graduation and until 1931 worked in several aircraft industries and was engaged in developing gliders. From 1931 and on, devoted himself to the development of the field of rocketry. In 1932, he joined Group for the Study of Reactive Motion (GIRD), as one of the four brigade leaders. His brigade built the GIRD-09 rocket, fueled by liquid oxygen and jellied gasoline, and launched on August 17, 1933. Tikhonravov became part of the Reactive Scientific Research Institute (RNII) when GIRD and the Gas Dynamics Laboratory (GDL) merged in 1933. From 1938 Tikhonravov researched rocket engines with liquid fuel and developed rockets for the purpose of upper atm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Soviet Union
The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a Federation, federal union of Republics of the Soviet Union, fifteen national republics; in practice, both Government of the Soviet Union, its government and Economy of the Soviet Union, its economy were highly Soviet-type economic planning, centralized until its final years. It was a one-party state governed by the Communist Party of the Soviet Union, with the city of Moscow serving as its capital as well as that of its largest and most populous republic: the Russian Soviet Federative Socialist Republic, Russian SFSR. Other major cities included Saint Petersburg, Leningrad (Russian SFSR), Kyiv, Kiev (Ukrainian Soviet Socialist Republic, Ukrainian SSR), Minsk (Byelorussian Soviet Socialist Republic, Byelorussian SSR), Tas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sputnik 1 Sputnik 1 (; see § Etymology) was the first artificial Earth satellite. It was launched into an elliptical low Earth orbit by the Soviet Union on 4 Oc |
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