Communications satellite - Knowledge (XXG) (2024)

785:(COMSAT) private corporation, which was subject to instruction by the US Government on matters of national policy. Over the next two years, international negotiations led to the Intelsat Agreements, which in turn led to the launch of Intelsat 1, also known as Early Bird, on 6 April 1965, and which was the first commercial communications satellite to be placed in geosynchronous orbit. Subsequent Intelsat launches in the 1960s provided multi-destination service and video, audio, and data service to ships at sea (Intelsat 2 in 1966–67), and the completion of a fully global network with Intelsat 3 in 1969–70. By the 1980s, with significant expansions in commercial satellite capacity, Intelsat was on its way to become part of the competitive private telecommunications industry, and had started to get competition from the likes of817:

874:(GEO), which is 22,236 miles (35,785km) from Earth's surface. This orbit has the special characteristic that the apparent position of the satellite in the sky when viewed by a ground observer does not change, the satellite appears to "stand still" in the sky. This is because the satellite's orbital period is the same as the rotation rate of the Earth. The advantage of this orbit is that ground antennas do not have to track the satellite across the sky, they can be fixed to point at the location in the sky the satellite appears.4266:

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1039:, was launched. It was a medium Earth orbit satellite designed to help facilitate high-speed telephone signals. Although it was the first practical way to transmit signals over the horizon, its major drawback was soon realised. Because its orbital period of about 2.5 hours did not match the Earth's rotational period of 24 hours, continuous coverage was impossible. It was apparent that multiple MEOs needed to be used in order to provide continuous coverage.635:

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between 2 and 8 hours. MEO satellites have a larger coverage area than LEO satellites. A MEO satellite's longer duration of visibility and wider footprint means fewer satellites are needed in a MEO network than a LEO network. One disadvantage is that a MEO satellite's distance gives it a longer time delay and weaker signal than a LEO satellite, although these limitations are not as severe as those of a GEO satellite.

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continuous communications capability with these lower orbits requires a larger number of satellites, so that one of these satellites will always be visible in the sky for transmission of communication signals. However, due to their closer distance to the Earth, LEO or MEO satellites can communicate to ground with reduced latency and at lower power than would be required from a geosynchronous orbit.

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627:. Military planners had long shown considerable interest in secure and reliable communications lines as a tactical necessity, and the ultimate goal of this project was the creation of the longest communications circuit in human history, with the Moon, Earth's natural satellite, acting as a passive relay. After achieving the first transoceanic communication between5357:

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1589:, where no submarine cables are in service, need satellite telephones. There are also regions of some continents and countries where landline telecommunications are rare to non existent, for example large regions of South America, Africa, Canada, China, Russia, and Australia. Satellite communications also provide connection to the edges of731:. After an initial failure in 1961, a launch on 9 May 1963 dispersed 350 million copper needle dipoles to create a passive reflecting belt. Even though only about half of the dipoles properly separated from each other, the project was able to successfully experiment and communicate using frequencies in the1285:

The Molniya orbit is designed so that the satellite spends the great majority of its time over the far northern latitudes, during which its ground footprint moves only slightly. Its period is one half day, so that the satellite is available for operation over the targeted region for six to nine hours

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The definitions of FSS and DBS satellites outside of North America, especially in Europe, are a bit more ambiguous. Most satellites used for direct-to-home television in Europe have the same high power output as DBS-class satellites in North America, but use the same linear polarization as FSS-class

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Satellite phone systems can be accomplished by a number of means. On a large scale, often there will be a local telephone system in an isolated area with a link to the telephone system in a main land area. There are also services that will patch a radio signal to a telephone system. In this example,

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In the United States, the National Polar-orbiting Operational Environmental Satellite System (NPOESS) was established in 1994 to consolidate the polar satellite operations of NASA (National Aeronautics and Space Administration) NOAA (National Oceanic and Atmospheric Administration). NPOESS manages a

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Because of their low altitude, these satellites are only visible from within a radius of roughly 1,000 kilometres (620mi) from the sub-satellite point. In addition, satellites in low Earth orbit change their position relative to the ground position quickly. So even for local applications, many

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As satellites in MEO and LEO orbit the Earth faster, they do not remain visible in the sky to a fixed point on Earth continually like a geostationary satellite, but appear to a ground observer to cross the sky and "set" when they go behind the Earth beyond the visible horizon. Therefore, to provide

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Molniya orbits can be an appealing alternative in such cases. The Molniya orbit is highly inclined, guaranteeing good elevation over selected positions during the northern portion of the orbit. (Elevation is the extent of the satellite's position above the horizon. Thus, a satellite at the horizon

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was launched on 4 October 1960 to explore whether it would be possible to establish a global military communications network by using "delayed repeater" satellites, which receive and store information until commanded to rebroadcast them. After 17 days, a command system failure ended communications

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the signal coming from the source, toward the direction of the receiver. With passive satellites, the reflected signal is not amplified at the satellite, and only a small amount of the transmitted energy actually reaches the receiver. Since the satellite is so far above Earth, the radio signal is

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that worked on two frequencies of 20.005 and 40.002MHz, or 7 and 15 meters wavelength. The satellite was not placed in orbit to send data from one point on Earth to another, but the radio transmitter was meant to study the properties of radio wave distribution throughout the ionosphere. The

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A medium Earth orbit is a satellite in orbit somewhere between 2,000 and 35,786 kilometres (1,243 and 22,236mi) above the Earth's surface. MEO satellites are similar to LEO satellites in functionality. MEO satellites are visible for much longer periods of time than LEO satellites, usually

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It is also possible to offer discontinuous coverage using a low-Earth-orbit satellite capable of storing data received while passing over one part of Earth and transmitting it later while passing over another part. This will be the case with the CASCADE system of Canada's

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and so are obstructed by the curve of the Earth. The purpose of communications satellites is to relay the signal around the curve of the Earth allowing communication between widely separated geographical points. Communications satellites use a wide range of radio and

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or dish antennas. Due to launch costs, most current amateur satellites are launched into fairly low Earth orbits, and are designed to deal with only a limited number of brief contacts at any given time. Some satellites also provide data-forwarding services using the

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These orbits are Sun synchronous, meaning that they cross the equator at the same local time each day. For example, the satellites in the NPOESS (civilian) orbit will cross the equator, going from south to north, at times 1:30 P.M., 5:30 P.M., and 9:30 P.M.

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The bandwidth available from a satellite depends upon the number of transponders provided by the satellite. Each service (TV, Voice, Internet, radio) requires a different amount of bandwidth for transmission. This is typically known as link budgeting and a

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616:, so the signal received on Earth is very weak. Active satellites, on the other hand, amplify the received signal before retransmitting it to the receiver on the ground. Passive satellites were the first communications satellites, but are little used now.772:

active communications satellite was launched on 11 February 1965 to explore the feasibility of active solid-state X band long-range military communications. A total of nine satellites were launched between 1965 and 1976 as part of this series.

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used by DBS satellites), but this is a minor technical difference that users do not notice. FSS satellite technology was also originally used for DTH satellite TV from the late 1970s to the early 1990s in the United States in the form of

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Geostationary satellites must operate above the equator and therefore appear lower on the horizon as the receiver gets farther from the equator. This will cause problems for extreme northerly latitudes, affecting connectivity and causing

650:(ARPA) and launched on 18 December 1958, which used a tape recorder to carry a stored voice message, as well as to receive, store, and retransmit messages. It was used to send a Christmas greeting to the world from U.S. President511:. To avoid signal interference, international organizations have regulations for which frequency ranges or "bands" certain organizations are allowed to use. This allocation of bands minimizes the risk of signal interference.1066:

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operators have access to amateur satellites, which have been designed specifically to carry amateur radio traffic. Most such satellites operate as spaceborne repeaters, and are generally accessed by amateurs equipped with

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Within these regions, frequency bands are allocated to various satellite services, although a given service may be allocated different frequency bands in different regions. Some of the services provided by satellites are:

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is an equivalent ESA project that is stated to be compatible and providing navigational services for the lunar surface. Both programmes are satellite constellstions of several satellites in various orbits around the Moon.

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Command and Control subsystem, which maintains communications with ground control stations. The ground control Earth stations monitor the satellite performance and control its functionality during various phases of its

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signals. Communication signals were bounced off the satellite from one point on Earth to another. This experiment sought to establish the feasibility of worldwide broadcasts of telephone, radio, and television signals.

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technology as a reference, these antennas automatically re-aim to the satellite no matter where or how the vehicle (on which the antenna is mounted) is situated. These mobile satellite antennas are popular with some

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Thus, for areas close to the North (and South) Pole, a geostationary satellite may appear below the horizon. Therefore, Molniya orbit satellites have been launched, mainly in Russia, to alleviate this problem.

808:, with two high apogees daily over the northern hemisphere. This orbit provides a long dwell time over Russian territory as well as over Canada at higher latitudes than geostationary orbits over the equator.1025:

Typically the orbit of a medium Earth orbit satellite is about 16,000 kilometres (10,000mi) above Earth. In various patterns, these satellites make the trip around Earth in anywhere from 2 to 8 hours.

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Like LEOs, these satellites do not maintain a stationary distance from the Earth. This is in contrast to the geostationary orbit, where satellites are always 35,786 kilometres (22,236mi) from Earth.

927:(LEO) typically is a circular orbit about 160 to 2,000 kilometres (99 to 1,243mi) above the Earth's surface and, correspondingly, a period (time to revolve around the Earth) of about 90 minutes.1884:

A satellite radio or subscription radio (SR) is a digital radio signal that is broadcast by a communications satellite, which covers a much wider geographical range than terrestrial radio signals.

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A geostationary orbit is useful for communications because ground antennas can be aimed at the satellite without their having to track the satellite's motion. This is relatively inexpensive.

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almost any type of satellite can be used. Satellite phones connect directly to a constellation of either geostationary or low-Earth-orbit satellites. Calls are then forwarded to a satellite

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number of satellites for various purposes; for example, METSAT for meteorological satellite, EUMETSAT for the European branch of the program, and METOP for meteorological operations.

938:(signal strength falls off as the square of the distance from the source, so the effect is considerable). Thus there is a trade off between the number of satellites and their cost.1207:, to distribute programming to their local affiliate stations. Satcom 1 was widely used because it had twice the communications capacity of the competing Westar 1 in America (245900:

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spacecraft in orbit over the European continent. Because of this, the terms FSS and DBS are more so used throughout the North American continent, and are uncommon in Europe.

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To an observer on Earth, a satellite in a gestationary orbit appears motionless, in a fixed position in the sky. This is because it revolves around the Earth at Earth's own

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Allocating frequencies to satellite services is a complicated process which requires international coordination and planning. This is carried out under the auspices of the

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Ward, William W.; Floyd, Franklin W. (1997). "Chapter 8: Thirty Years of Space Communications Research and Development at Lincoln Laboratory". In Butrica, Andrew J (ed.).

1669:. They are normally used for broadcast feeds to and from television networks and local affiliate stations (such as program feeds for network and syndicated programming,1597:. Other land use for satellite phones are rigs at sea, a backup for hospitals, military, and recreation. Ships at sea, as well as planes, often use satellite phones.753:. It revolved around the Earth once per day at constant speed, but because it still had north–south motion, special equipment was needed to track it. Its successor,654:. The satellite also executed several realtime transmissions before the non-rechargeable batteries failed on 30 December 1958 after eight hours of actual operation.2514:

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1122:, was launched on 6 April 1965 and placed in orbit at 28° west longitude. It was the first geostationary satellite for telecommunications over the Atlantic Ocean.2394:

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van Keuren, David K. (1997). "Chapter 2: Moon in Their Eyes: Moon Communication Relay at the Naval Research Laboratory, 1951-1962". In Butrica, Andrew J (ed.).

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Low-Earth-orbiting satellites are less expensive to launch into orbit than geostationary satellites and, due to proximity to the ground, do not require as high

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services in some countries, notably the United States. Mobile services allow listeners to roam a continent, listening to the same audio programming anywhere.

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was the first active, direct relay communications commercial satellite and marked the first transatlantic transmission of television signals. Belonging to

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Operating at lower frequency and lower power than DBS, FSS satellites require a much larger dish for reception (3 to 8 feet (1 to 2.5 m) in diameter for K

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as opposed to the 12 of Westar 1), resulting in lower transponder-usage costs. Satellites in later decades tended to have even higher transponder numbers.

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3343:"DIRECTV's Spaceway F1 Satellite Launches New Era in High-Definition Programming; Next Generation Satellite Will Initiate Historic Expansion of DIRECTV"2463:

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796:, who did not participate in the Intelsat agreements. The Soviet Union launched its first communications satellite on 23 April 1965 as part of the6239:

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Altshuler, José (1997). "Chapter 18: From Shortwave and Scatter to Satellite: Cuba's International Communications". In Butrica, Andrew J (ed.).

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1752:(usually 18 to 24 inches or 45 to 60cm in diameter). Direct broadcast satellites generally operate in the upper portion of the microwave1417:

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used to keep the satellite in the right orbit, with its antennas pointed in the right direction, and its power system pointed towards the Sun

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every second revolution. In this way a constellation of three Molniya satellites (plus in-orbit spares) can provide uninterrupted coverage.

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1219:) had built nearly 40 percent of the more than one hundred satellites in service worldwide. Other major satellite manufacturers include1216:

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Region A, Low Earth Orbit (or LEO) Region – spherical region that extends from the Earth's surface up to an altitude (Z) of 2,000 km

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using the satellite. Additionally, it was the first satellite used by broadcast television networks in the United States, like

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distribution, the savings in ground equipment can more than outweigh the cost and complexity of placing a satellite into orbit.

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In addition, there are important differences in the onboard and ground equipment needed to support the two types of missions.

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antennas of ground stations can be aimed permanently at that spot and do not have to move to track the satellite. Others form

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launch of Sputnik 1 was a major step in the exploration of space and rocket development, and marks the beginning of the

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via broadband data connections. This can be very useful for users who are located in remote areas, and cannot access a

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There are plans and initiatives to bring dedicated communications satellite beyond geostationary orbits. NASA proposed

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of the concept of the communications satellite, and the term 'Clarke Belt' is employed as a description of the orbit.

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668:'s satellite applications program launched the first artificial satellite used for passive relay communications in327:

3096:. INTER-AGENCY SPACE DEBRIS COORDINATION COMMITTEE: Issued by Steering Group and Working Group 4. September 2007.6001:

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Pelton, Joseph N. (2015). "History of Satellite Communications". In Pelton J.; Madry S.; Camacho-Lara S. (eds.).

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in geostationary orbits to relay radio signals. Because of this, Arthur C. Clarke is often quoted as being the

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3199:"TYCHO: Supporting Permanently Crewed Lunar Exploration with High-Speed Optical Communication from Everywhere"1619:

As television became the main market, its demand for simultaneous delivery of relatively few signals of large

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The first and historically most important application for communication satellites was in intercontinental

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The Atlas-B with SCORE on the launch pad; the rocket (without booster engines) constituted the satellite.

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Some manufacturers have also introduced special antennas for mobile reception of DBS television. Using

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service has also recently used FSS technology as well for their programming packages requiring their

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become successful, because these channels distributed their programming to all of the local cable TV

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are also proposed for communication satellites covering the Moon alike communication satellites in

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of 86.4° and inter-satellite links provide service availability over the entire surface of Earth.

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2436:. Vol.51, no.10. Arthur C. Clarke Institute for Space Education. pp.305–308.1937:

After the 1990s, satellite communication technology has been used as a means to connect to the

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program. This program was also unique at the time for its use of what then became known as the

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3070:"SKYTRAC #SatcomSeries: The Differences, Strengths, and Weaknesses of LEO and GEO Satellites"864:

are used to further specify orbital details. MEO and LEO are non-geostationary orbit (NGSO).

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Another passive relay experiment primarily intended for military communications purposes was

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Satellite communications are still used in many applications today. Remote islands such as

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caused some decline in the use of satellites for fixed telephony in the late 20th century.

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Region 1: Europe, Africa, the Middle East, what was formerly the Soviet Union, and Mongolia

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supporting different missions on surface and other orbits are considered, such as the

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satellites over North America provide a quite large amount of FTA channels on their K

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has zero elevation and a satellite directly overhead has elevation of 90 degrees.)

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in the United States, which, ironically, was then bought by its archrival in 2005.

562:

265:

2628:"United States Aeronautics and Space Activities - first Annual Report to Congress"1469:(ITU). To facilitate frequency planning, the world is divided into three regions:1125:

On 9 November 1972, Canada's first geostationary satellite serving the continent,

1042:

In 2013, the first four of a constellation of 20 MEO satellites was launched. The

3481:

Beyond Sputnik and the Space Race: The Origins of Global Satellite Communications

2395:"Military Satellite Communications Fundamentals | The Aerospace Corporation"749:, launched on 26 July 1963. Syncom 2 was the first communications satellite in a5991:

5857:

5547:

5530:

5402:

5242:

4892:

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4566:

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1773:

1716:

1692:

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comsats. Two satellite types are used for North American television and radio:

1530:

1354:

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999:

communications satellite. Another system using this store and forward method is

712:(Post Office) to develop satellite communications, it was launched by NASA from709:

581:

508:

441:

190:

107:

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19:

2425:"Extra-terrestrial Relays: Can Rocket Stations Give World-wide Radio Coverage?"1479:

Region 3: Asia (excluding region 1 areas), Australia, and the southwest Pacific

6125:

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5730:

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895:(LEO), and is about 160 to 2,000 kilometres (99 to 1,243mi) above Earth.658:

528:

published an article titled "Extraterrestrial Relays" in the British magazine

496:

453:

277:

241:

167:

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2510:

1695:

satellite TV channels are also usually distributed on FSS satellites in the K

619:

Work that was begun in the field of electrical intelligence gathering at the

6135:

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5584:

5505:

5488:

5232:

4697:

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4059:

3771:

3044:

2077:

1982:

1942:

1878:

1813:

1730:

1640:

1594:

1555:

1412:

Communications Satellites are usually composed of the following subsystems:

886:

range from 2,000 to 36,000 kilometres (1,200 to 22,400mi) above Earth.

701:

681:

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558:

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539:

535:

505:

457:

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2568:

1437:

Power subsystem, used to power the Satellite systems, normally composed of

1396:

cover the Earth. Also, dedicated communication satellites in orbits around

1274:(caused by signals reflecting off the ground and into the ground antenna).760:

A direct extension of the passive experiments of Project West Ford was the

657:

The direct successor to SCORE was another ARPA-led project called Courier.

3456:

Manual on sea level measurement and interpretation, volume V: Radar gauges

931:

satellites are needed if the mission requires uninterrupted connectivity.

5227:

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4959:

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4073:

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1973:. Examples of military systems that use communication satellites are the1938:

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The first satellite purpose-built to actively relay communications was

477:

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1860:

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to many receivers being a more precise match for the capabilities of

1330:

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Communications satellites usually have one of three primary types of

782:

754:

746:

735:

669:

3397:. Berlin, Heidelberg: Springer Berlin Heidelberg. pp.311–328.2635:

Published as House Document Number 71, 86th Congress, first Session

1293:

series was launched on 23 April 1965 and was used for experimental

1065:

764:

program, also conducted by the Lincoln Laboratory on behalf of the

5237:

5174:

4482:

3918:

3715:

3393:

Kramer, Herbert J. (2002). "Data Collection (Messaging) Systems".

3369:"India's first 'military' satellite GSAT-7 put into earth's orbit"2728:

Martin, Donald; Anderson, Paul; Bartamian, Lucy (March 16, 2007).

2600:

Martin, Donald; Anderson, Paul; Bartamian, Lucy (March 16, 2007).

1708:

1529:

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769:

633:

578:

544:

534:. The article described the fundamentals behind the deployment of461:

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18:

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Some satellites have been launched that have transponders in the

1799:

for each of the transponders' RF input and output (as opposed to

1239:(owns the former RCA Astro Electronics/GE Astro Space business),1167:

in 1975. It was Satcom 1 that was instrumental in helping early

5179:

3735:

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2218:

Orbital periods and speeds are calculated using the relations 4π

2089:

1997:. India has launched its first Military Communication satellite1986:

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1920:

1836:

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1785:

1738:

1397:

1153:

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and low-speed data services, primarily to remote areas, are the

741:

An immediate antecedent of the geostationary satellites was the

716:

on 10 July 1962, in the first privately sponsored space launch.

665:

5375:

4283:

4032:

3526:

5830:

5371:

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4222:

3218:"TYCHO mission to Earth-Moon libration point EML-4 @ IAC 2013"2002:

1907:

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1200:

1176:

1043:

3516:

Beyond The Ionosphere: Fifty Years of Satellite Communication

3046:

Beyond The Ionosphere: Fifty Years of Satellite Communication

2786:

Beyond The Ionosphere: Fifty Years of Satellite Communication

2570:

Beyond The Ionosphere: Fifty Years of Satellite Communication

1737:'s "must-carry" regulations, and for more bandwidth to carry4028:

1795:

band, and 12 feet (3.6 m) or larger for C band). They use

1388:

Other orbits are also planned to be used. Positions in the

1133:, with the United States following suit with the launch of1093:

In applications that require many ground antennas, such as

1748:

is a communications satellite that transmits to small DBS

1376:

as a data network aiming to provide a „Lunar Internet for

597:

There are two major classes of communications satellites,

2021:

bands. Typically military satellites operate in the UHF,

1427:

Engines used to bring the satellite to its desired orbit

700:

as part of a multi-national agreement between AT&T,

2538:"Design of the first artificial satellite of the Earth"955:

A group of satellites working in concert is known as a

2997:"NASA Compendium Of Satellite Communications Programs"2922:"NASA Compendium Of Satellite Communications Programs"2831:"NASA Compendium Of Satellite Communications Programs"2687:. The White House. 18 January 1961. pp.12–13, 261945:

connection, or require high availability of services.

2756:"United States Aeronautics and Space Activities 1962"2682:"United States Aeronautics and Space Activities 1960"1839:

have also launched experimental satellites carrying K

1605:

connected to the Public Switched Telephone Network .

1329:. In November 1967 Soviet engineers created a unique971:

systems. The Iridium system has 66 satellites, which

472:

applications. Many communications satellites are in

1989:

satellites, United Kingdom satellites (for instance

1432:

station keeping tracking and stabilization subsystem

6144:

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5696:

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2761:. The White House. 28 January 1963. pp.20, 961855:owners. Such mobile DBS antennas are also used by781:In the United States, 1962 saw the creation of the3317:"Indian GSLV successfully lofts GSAT-14 satellite"2637:. The White House. 2 February 1959. pp.13–142285:Approximately 8.6 times when the Moon is nearest2104:). The data rate is typically much lower than in1768:, DISH Network and Orby TV in the United States,889:The region below medium orbits is referred to as6235:Telecommunications-related introductions in 19622389:

2387:

1476:Region 2: North and South America and Greenland959:. Two such constellations, intended to provide2084:. It may be based on a secondary payload of a1215:By 2000, Hughes Space and Communications (now593:Early active and passive satellite experiments16:Artificial satellite that relays radio signals5387:

4295:

4044:

3960:Consultative Committee for Space Data Systems3538:

3002:. NASA. December 1975. pp.10-1 to 10-642256:is the gravitational constant, approximately401:

8:

3453:. "Equipment needed for Telemetry of Data".3395:Observation of the Earth and Its Environment1416:Communication Payload, normally composed of672:on 12 August 1960. Echo 1 was an aluminized499:used for telecommunications links travel by5310:Global telecommunications regulation bodies3427:"Satellite Data Telecommunication Handbook"2927:. NASA. December 1975. pp.9-1 to 9-562836:. NASA. December 1975. pp.5-1 to 5-161760:. DBS technology is used for DTH-oriented (1441:, and batteries that maintain power during777:International commercial satellite projects5693:

5394:

5380:

5372:

5346:

4302:

4288:

4280:

4051:

4037:

4029:

3545:

3531:

3523:

3451:Intergovernmental Oceanographic Commission1461:Frequency allocation for satellite systems1457:can be used to arrive at the exact value.577:. Sputnik 1 was equipped with an on-board408:

394:

206:

172:

29:

3986:List of communication satellite companies3091:"IADC Space Debris Mitigation Guidelines"2676:

2674:

2305:, to 9.6 times when the Moon is farthest2139:List of communication satellite companies1148:was launched: the experimental satellite452:. Communications satellites are used for3483:(Johns Hopkins University Press, 2022);2946:

2944:

2942:

2778:

2776:

2603:Communications Satellites: Project SCORE2268:is the mass of Earth, approximately 5.982134:Inter-satellite communications satellite1784:in the UK, Ireland, and New Zealand and1345:, that was based on Molniya satellites.815:

476:22,236 miles (35,785km) above the5879:Effect of spaceflight on the human body3981:List of communications satellite firsts3502:Communications satellites short history2371:"Satellites - Communication Satellites"2337:

2211:

2144:List of communications satellite firsts1965:Communications satellites are used for1910:radio equipment and highly directional1035:In 1962, the communications satellite,621:United States Naval Research Laboratory565:on 4 October 1957. It was developed by41:

5901:Psychological and sociological effects3863:Shanghai Spacecom Satellite Technology3113:The Basics of Satellite Communications2548:from the original on 26 September 20232100:) or in dedicated satellites (such as1639:satellites. Examples of these are the1106:The first geostationary satellite was882:(MEO) satellites are closer to Earth.3349:from the original on 20 December 20232589:from the original on 29 October 2023.2517:from the original on 24 November 20232443:from the original on 19 November 20231467:International Telecommunication Union725:Massachusetts Institute of Technology7:

5356:

4011:

1494:Broadcasting satellite service (BSS)783:Communications Satellite Corporation1217:Boeing Satellite Development Center822:medium altitude orbits around Earth766:United States Department of Defense689:More firsts and further experiments5610:Weather and environment monitoring2953:Handbook of Satellite Applications2731:Communications Satellites: Telstar2476:from the original on 13 April 20232423:Clarke, Arthur C. (October 1945).2248:is the orbital period in seconds;2244:is the radius of orbit in metres;2072:), may use satellites for one-way1971:Global Command and Control Systems1424:, amplifiers and switching systems1380:spacecraft and Installations. The1233:Indian Space Research Organisation561:, which was put into orbit by the14:

3644:Automatic Tracking Satellite Dish1955:Military communications satellite1764:) satellite TV services, such as1548:Public Switched Telephone Network1504:Radionavigation-satellite service648:Advanced Research Projects Agency6193:

6183:

6182:

5355:

5345:

5336:

5335:

5324:

4945:Free-space optical communication4264:

4254:

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1993:), and satellites of the former1661:, and the lower portions of the1509:Meteorological-satellite service981:satellite internet constellation868:Geostationary satellites have a432:telecommunication signals via a377:

5654:Space launch market competition3116:. Intl. Engineering Consortiu.3068:Mann, Reuben (April 26, 2022).2495:Siddiqi, Asif (November 2007).2345:Labrador, Virgil (2015-02-19).1848:Global Positioning System (GPS)1564:submarine communications cables1402:Mars Telecommunications Orbiter623:in 1951 led to a project named6240:Wireless communication systems5891:Health threat from cosmic rays3497:Satellite Industry Association3216:Hornig, Andreas (2013-10-06).3197:Hornig, Andreas (2022-05-01).3138:"Soyuz Flight VS05 Launch Kit"2124:High-altitude platform station2001:, its transponders operate in1961:X Band Satellite Communication1812:band form for the now-defunct820:Clickable image, highlighting762:Lincoln Experimental Satellite1:

2462:Mills, Mike (3 August 1997).2252:is the orbital speed in m/s;1877:Satellite radio offers audio1681:by schools and universities,1677:), as well as being used for1489:Fixed satellite service (FSS)1313:and the Russian Far East, in5331:Telecommunication portal5112:Telecommunications equipment4346:

4261:Telecommunication portal3965:ETSI Satellite Digital Radio3689:Very-small-aperture terminal2497:"The Man Behind the Curtain"2401:. 2010-04-01. Archived from2129:History of telecommunication1225:Orbital Sciences Corporation6007:Self-replicating spacecraft5843:International Space Station4848:Alexander Stepanovich Popov3741:Digital audio radio service3649:Motor-driven Satellite dish3403:10.1007/978-3-642-56294-5_43345:. SpaceRef. 26 April 2005.2502:Air & Space/Smithsonian1390:Earth-Moon-Libration points1289:The first satellite of the1171:channels such as WTBS (now1048:broadband internet services702:Bell Telephone Laboratories350:List of space organizations6258:

5521:Space Liability Convention4552:Telecommunications history3110:Pelton, Joseph N. (2006).2119:Commercialization of space1958:

1952:

1930:

1891:

1870:

1746:direct broadcast satellite1629:Direct broadcast satellite1612:

1523:

1368:Beyond geostationary orbit1352:

1262:

1114:. Shortly after Syncom 3,1058:

1010:

948:

907:

607:. Passive satellites only555:artificial Earth satellite448:at different locations on428:that relays and amplifies6220:Communications satellites6177:

5884:Space adaptation syndrome5319:

5160:Public Switched Telephone4972:telecommunication circuit4933:Fiber-optic communication4678:Francis Blake (telephone)4473:Optical telecommunication4251:

4136:Communications satellites3994:

3796:Relay satellite companies3593:High-throughput satellite3578:Satellite Internet access3265:"Orby TV (United States)"2373:. Satellites.spacesim.org2347:"satellite communication"1933:Satellite Internet access1859:for DirecTV (supplied by1055:Geostationary orbit (GEO)989:satellite Internet access846:Van Allen radiation belts5617:Communications satellite5071:Orbital angular-momentum4508:Satellite communications4347:Communications satellite3554:Satellite communications2154:Reconnaissance satellite2054:environmental monitoring1655:Fixed Service Satellites1499:Mobile-satellite service1007:Medium Earth orbit (MEO)625:Communication Moon Relay486:satellite constellations422:communications satellite6121:reusable launch systems5738:Extravehicular activity5649:Commercial use of space5553:Militarisation of space5526:Registration Convention5442:Accidents and incidents4950:Molecular communication4773:Gardiner Greene Hubbard4602:Undersea telegraph line4337:Cable protection system4131:Cable protection system3902:Satellite manufacturers3049:. NASA History Office.2789:. NASA History Office.2184:Satellite space segment1967:military communications1894:Amateur radio satellite1843:band beacons recently.1633:Fixed Service Satellite1544:long distance telephony987:, that aims for global957:satellite constellation951:Satellite constellation945:Satellite constellation862:orbital classifications842:Moon's orbital distance806:highly elliptical orbit743:Hughes Aircraft Company80:Timeline of spaceflight6225:Satellite broadcasting6169:Mission control center6131:Non-rocket spacelaunch5565:Billionaire space race5092:Communication protocol4878:Charles Sumner Tainter4693:Walter Houser Brattain4638:Edwin Howard Armstrong4446:Information revolution3293:. ISRO. Archived from2955:. New York: Springer.2734:(5thed.). AIAA.2606:(5thed.). AIAA.2159:Relay (disambiguation)1985:of the United States,1969:applications, such as1923:or similar protocols.1816:satellite TV service.1539:

1272:multipath interference1072:

853:

840:, at one ninth of the639:

575:Konstantin Tsiolkovsky573:, building on work by550:

384:Spaceflight portal300:Non-rocket spacelaunch70:History of spaceflight54:

27:

6019:Spacecraft propulsion5469:European Space Agency5066:Polarization-division4798:Narinder Singh Kapany4763:Erna Schneider Hoover4683:Jagadish Chandra Bose4663:Alexander Graham Bell4394:online video platform4271:Telephones portal2536:Zak, Anatoly (2017).1959:Further information:1801:circular polarization1533:

1243:, Alcatel Space, now1146:three-axis stabilized1068:

904:Low Earth orbit (LEO)819:

637:

548:

536:artificial satellites438:communication channel53:

22:

5644:Satellite navigation4908:Vladimir K. Zworykin4868:Almon Brown Strowger4838:Charles Grafton Page4493:Prepaid mobile phone4421:Electrical telegraph4233:Telephone newspapers3568:Satellite television3518:(NASA SP-4217, 1997)3236:"Connected:Maritime"1853:recreational vehicle1827:, such as DirecTV's1615:Satellite television1394:geosynchronous orbit1382:Moonlight Initiative1339:satellite television1309:stations located in1112:1964 Summer Olympics1079:(one revolution per804:, which describes a751:geosynchronous orbit704:, NASA, the British676:acting as a passive662:from the satellite.652:Dwight D. Eisenhower614:free-space path loss549:Replica of Sputnik 1426:artificial satellite6029:Electric propulsion5716:Life-support system5600:Imagery and mapping5560:Private spaceflight4858:Johann Philipp Reis4617:Wireless revolution4579:The Telephone Cases4436:Hydraulic telegraph4156:Mobile phone signal3953:Trade organizations3944:Thales Alenia Space3757:Astra Digital Radio3750:Broadcast companies3679:Satellite data unit3181:"Moonlight Webinar"3167:"Project Moonlight"3055:1997bify.book.....B2961:2017hsa..book.....P2809:"Project West Ford"2795:1997bify.book.....B2583:1997bify.book.....B2542:RussianSpaceWeb.com2469:The Washington Post2194:Traveling-wave tube2169:Satellite data unit2088:(as in the case of2056:equipment (such as2041:) frequency bands.1797:linear polarization1701:Intelsat Americas 51683:business television1566:through the use of1245:Thales Alenia Space1221:Space Systems/Loral1189:The Weather Channel1070:Geostationary orbit1061:Geostationary orbit1046:satellites provide973:orbital inclination871:geostationary orbit834:geostationary orbit723:, which was led by710:French National PTT706:General Post Office567:Mikhail Tikhonravov474:geostationary orbit222:Apollo Lunar Module6230:Satellites by type5982:Robotic spacecraft5908:Space and survival5763:Space colonization5659:Space architecture5511:Outer Space Treaty5056:Frequency-division5033:Telephone exchange4903:Charles Wheatstone4833:Jun-ichi Nishizawa4808:Innocenzo Manzetti4743:Reginald Fessenden4478:Optical telegraphy4311:Telecommunications4146:Free-space optical3772:Sirius XM Holdings3663:Parabolic antennas3511:by David J. Whalen3507:2015-05-12 at the2164:Satcom On The Move2106:satellite Internet2096:and others in the1867:Radio broadcasting1540:

1129:, was launched by1073:

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5930:

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5368:

5107:Store and forward5102:Data transmission5016:Network switching4967:Transmission line4813:Guglielmo Marconi4778:Internet pioneers4643:Mohamed M. Atalla4612:Whistled language4277:

4276:

4110:Answering machine4026:

4025:

3583:Amateur satellite3479:Slotten, Hugh R.3412:978-3-642-62688-33321:NASA Space Flight3297:on 8 January 20143123:978-1-931695-48-02272:10kg (1.3182086:weather satellite2074:data transmission1788:in South Africa.1770:Bell Satellite TV1687:Videoconferencing1679:distance learning1558:telephones to an1455:network simulator1141:on 13 April 1974.884:Orbital altitudes721:Project West Ford674:balloon satellite524:In October 1945,440:between a source418:

417:

312:Spaceflight types256:

255:

213:Crewed spacecraft205:

204:

120:Earth observation25:Iridium satellite6247:

6197:

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5674:Space technology5516:Rescue Agreement5396:

5389:

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4297:

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3323:. 4 January 20143313:

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3267:. Archived from3261:

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2062:weather stations1750:satellite dishes1575:Ascension Island1241:Northrop Grumman1085:equatorial orbit1077:angular velocity916:

830:High Earth orbit812:Satellite orbits629:Washington, D.C.526:Arthur C. Clarke410:

403:

396:

382:

381:

380:

207:

196:Cargo spacecraft173:

30:

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6210:

6209:

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6112:Escape velocity6093:

6045:

6012:Space telescope5965:Reentry capsule5927:

5867:

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5743:Overview effect5726:Bioastronautics5683:

5571:

5405:

5400:

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5325:

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5315:

5257:

5194:

5116:

5080:

5037:

4986:

4978:

4919:

4912:

4818:Robert Metcalfe4673:Tim Berners-Lee4621:

4441:Information Age4313:

4308:

4278:

4273:

4265:

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4253:

4247:

4228:Telephone calls4211:

4180:

4119:

4098:

4089:Satellite phone4079:Cable telephony4062:

4057:

4027:

4022:

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3924:Lockheed Martin3897:

3803:AST SpaceMobile3791:

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3598:Relay satellite3573:Satellite radio3556:

3551:

3509:Wayback Machine3493:

3476:

3474:Further reading3471:

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