|
Les-3
Lincoln Experimental Satellite 3, also known as LES-3, was a communications satellite, the third of nine in the Lincoln Experimental Satellite. Launched by the United States Air Force (USAF) on 21 Dec 1965, it was stranded in a Geostationary Transfer Orbit rather than its planned circular high orbit. Despite this, LES-3 returned good data on communications propagation in the UHF band. Background After the successful development and deployment of Project West Ford, a passive communications system consisting of orbiting copper needles, MIT's Lincoln Laboratory turned to improving active-satellite space communications. In particular, Lincoln aimed to increase the transmission capability of communications satellites ("downlink"), which was necessarily constrained by their limited size. After receiving a charter in 1963 to build and demonstrate military space communications, Lincoln focused on a number of engineering solutions to the downlink problem including improved antennas, be ... [...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] |
Project West Ford
Project West Ford (also known as Westford Needles and Project Needles) was a test carried out by Massachusetts Institute of Technology's Lincoln Laboratory on behalf of the United States military in 1961 and 1963 to create an artificial ionosphere above the Earth. This was done to solve a major weakness that had been identified in military communications. History At the height of the Cold War, all international communications were either sent through submarine communications cables or bounced off the natural ionosphere. The United States military was concerned that the Soviets might cut those cables, forcing the unpredictable ionosphere to be the only means of communication with overseas forces. To mitigate the potential threat, Walter E. Morrow started Project Needles at the MIT Lincoln Laboratory in 1958. The goal of the project was to place a ring of 480,000,000 (Abstract) copper dipole antennas in orbit to facilitate global radio communication. The dipoles collectively prov ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spacecraft Launched In 1965
A spacecraft is a vehicle that is designed to fly and operate in outer space. Spacecraft are used for a variety of purposes, including communications, Earth observation, meteorology, navigation, space colonization, planetary exploration, and transportation of humans and cargo. All spacecraft except single-stage-to-orbit vehicles cannot get into space on their own, and require a launch vehicle (carrier rocket). On a sub-orbital spaceflight, a space vehicle enters space and then returns to the surface without having gained sufficient energy or velocity to make a full Earth orbit. For orbital spaceflights, spacecraft enter closed orbits around the Earth or around other celestial bodies. Spacecraft used for human spaceflight carry people on board as crew or passengers from start or on orbit (space stations) only, whereas those used for robotic space missions operate either autonomously or telerobotically. Robotic spacecraft used to support scientific research are space prob ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cape Canaveral Air Force Station Space Launch Complex 41
Space Launch Complex 41 (SLC-41), sometimes referred to as "Slick Forty-one," is one of two launch sites at the Integrate-Transfer-Launch Complex in Cape Canaveral Space Force Station, Florida. Originally built as Launch Complex 41 (LC-41), it and the neighboring Space Launch Complex 40 were designed for the United States Air Force's Titan III rocket program, where it launched the Titan IIIC in the 1960s and the Titan IIIE in the 1970s. In the 1990s, the Air Force and Martin Marietta upgraded the pad for use by the Titan III's successor, the Titan IV. During the early 2000s, SLC-41 underwent modifications by Lockheed Martin in order to support the launch operations of the Atlas V. It was later transferred to United Launch Alliance (ULA)—a joint venture between Lockheed Martin and Boeing—who continues to use the pad today for launches of the Atlas V and its successor, Vulcan Centaur. History Titan IIIC and IIIE (1965–1977) Launch Complex 41 was originally built as part of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
OSCAR 4
OSCAR IV ( OSCAR 4) was the fourth amateur radio satellite launched by Project OSCAR and the first targeted for Geostationary orbit on 12 December 1965. The satellite was launched piggyback with three United States Air Force satellites on a Titan IIIC launch vehicle. Due to a booster failure, OSCAR 4 was placed in an unplanned and largely unusable Geostationary transfer orbit. Project OSCAR Project OSCAR Inc. was started in 1960 by members of the TRW Radio Club of Redondo Beach, California as well as persons associated with Foothill College to investigate the possibility of putting an amateur satellite in orbit. Project OSCAR was responsible for the construction of the first Amateur Radio Satellites: OSCAR 1, launched from Vandenberg AFB in California on 12 December 1961, which transmitted a “HI” greeting in Morse Code for three weeks, OSCAR 2, and OSCAR 3. Spacecraft OSCAR 4 massed and was a regular tetrahedron with edges long. It had four independent monopole antennae ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
OV2-3
Orbiting Vehicle 2-3 (COSPAR ID: 1965-108A, also known as OV2-3), the second satellite of the second series of the United States Air Force's Orbiting Vehicle program, was an American solar astronomy, geomagnetic and particle science research satellite. Launched 22 December 1965 along with three other satellites, the mission resulted in failure when the spacecraft failed to separate from the upper stage of its Titan IIIC. Background The Orbiting Vehicle satellite program arose from a US Air Force initiative, begun in the early 1960s, to reduce the expense of space research. Through this initiative, satellites would be standardized to improve reliability and cost-efficiency, and where possible, they would fly on test vehicles or be piggybacked with other satellites. In 1961, the Air Force Office of Aerospace Research (OAR) created the Aerospace Research Support Program (ARSP) to request satellite research proposals and choose mission experiments. The USAF Space and Missiles Organi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hertz
The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), often described as being equivalent to one event (or Cycle per second, cycle) per second. The hertz is an SI derived unit whose formal expression in terms of SI base units is 1/s or s−1, meaning that one hertz is one per second or the Inverse second, reciprocal of one second. It is used only in the case of periodic events. It is named after Heinrich Hertz, Heinrich Rudolf Hertz (1857–1894), the first person to provide conclusive proof of the existence of electromagnetic waves. For high frequencies, the unit is commonly expressed in metric prefix, multiples: kilohertz (kHz), megahertz (MHz), gigahertz (GHz), terahertz (THz). Some of the unit's most common uses are in the description of periodic waveforms and musical tones, particularly those used in radio- and audio-related applications. It is also used to describe the clock speeds at which computers and other electronics are driven. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Super High Frequency
Super high frequency (SHF) is the ITU designation for radio frequencies (RF) in the range between 3 and 30 gigahertz (GHz). This band of frequencies is also known as the centimetre band or centimetre wave as the wavelengths range from one to ten centimetres. These frequencies fall within the microwave band, so radio waves with these frequencies are called microwaves. The small wavelength of microwaves allows them to be directed in narrow beams by aperture antennas such as parabolic dishes and horn antennas, so they are used for point-to-point communication and data links This article from the beginning of the microwave era predicted the future value of microwaves for point-to-point communication. and for radar. This frequency range is used for most radar transmitters, wireless LANs, satellite communication, microwave radio relay links, satellite phones (S band), and numerous short range terrestrial data links. They are also used for heating in industrial microwave h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
LES-1
Lincoln Experimental Satellite 1, also known as LES-1, is a communications satellite, the first of nine in the Lincoln Experimental Satellite program. Launched by the United States Air Force (USAF) on February 11, 1965, it pioneered many then-advanced technologies including active use of the military's SHF (super high frequency) band (7 to 8 GHz) to service hundreds of users. LES-1 did not have a successful operational life due to being placed in a suboptimal orbit, and it ceased transmissions in 1967. After 45 years of inactivity, LES-1 spontaneously resumed transmissions in 2012 making it one of the oldest zombie satellites. Background The Lincoln Experimental Satellite (LES) series was MIT's Lincoln Laboratory's first active communications satellite project. Lincoln had previously successfully developed and deployed Project West Ford, a passive communications system consisting of orbiting copper needles. The goal of LES was to increase the transmission capability of comm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Error Detection And Correction
In information theory and coding theory with applications in computer science and telecommunications, error detection and correction (EDAC) or error control are techniques that enable reliable delivery of digital data over unreliable communication channels. Many communication channels are subject to channel noise, and thus errors may be introduced during transmission from the source to a receiver. Error detection techniques allow detecting such errors, while error correction enables reconstruction of the original data in many cases. Definitions ''Error detection'' is the detection of errors caused by noise or other impairments during transmission from the transmitter to the receiver. ''Error correction'' is the detection of errors and reconstruction of the original, error-free data. History In classical antiquity, copyists of the Hebrew Bible were paid for their work according to the number of stichs (lines of verse). As the prose books of the Bible were hardly ever w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Downlink
In a telecommunications network, a link is a communication channel that connects two or more devices for the purpose of data transmission. The link may be a dedicated physical link or a virtual circuit that uses one or more physical links or shares a physical link with other telecommunications links. A telecommunications link is generally based on one of several types of information transmission paths such as those provided by communication satellites, terrestrial radio communications infrastructure and computer networks to connect two or more points. The term ''link'' is widely used in computer networking to refer to the communications facilities that connect nodes of a network. Sometimes the communications facilities that provide the communication channel that constitutes a link are also included in the definition of ''link''. Types Point-to-point A point-to-point link is a dedicated link that connects exactly two communication facilities (e.g., two nodes of a network, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
