Communications satellite

Communications satellite

Overview
A communications satellite (sometimes abbreviated to COMSAT) is an artificial satellite
Satellite
In the context of spaceflight, a satellite is an object which has been placed into orbit by human endeavour. Such objects are sometimes called artificial satellites to distinguish them from natural satellites such as the Moon....

 stationed in space for the purpose of telecommunications. Modern communications satellites use a variety of orbits including geostationary orbit
Geostationary orbit
A geostationary orbit is a geosynchronous orbit directly above the Earth's equator , with a period equal to the Earth's rotational period and an orbital eccentricity of approximately zero. An object in a geostationary orbit appears motionless, at a fixed position in the sky, to ground observers...

s, Molniya orbit
Molniya orbit
Molniya orbit is a type of highly elliptical orbit with an inclination of 63.4 degrees, an argument of perigee of -90 degree and an orbital period of one half of a sidereal day...

s, other elliptical orbits and low (polar
Polar orbit
A polar orbit is an orbit in which a satellite passes above or nearly above both poles of the body being orbited on each revolution. It therefore has an inclination of 90 degrees to the equator...

 and non-polar) Earth orbits.

For fixed (point-to-point) services, communications satellites provide a microwave radio relay technology complementary to that of communication cables.
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Encyclopedia
A communications satellite (sometimes abbreviated to COMSAT) is an artificial satellite
Satellite
In the context of spaceflight, a satellite is an object which has been placed into orbit by human endeavour. Such objects are sometimes called artificial satellites to distinguish them from natural satellites such as the Moon....

 stationed in space for the purpose of telecommunications. Modern communications satellites use a variety of orbits including geostationary orbit
Geostationary orbit
A geostationary orbit is a geosynchronous orbit directly above the Earth's equator , with a period equal to the Earth's rotational period and an orbital eccentricity of approximately zero. An object in a geostationary orbit appears motionless, at a fixed position in the sky, to ground observers...

s, Molniya orbit
Molniya orbit
Molniya orbit is a type of highly elliptical orbit with an inclination of 63.4 degrees, an argument of perigee of -90 degree and an orbital period of one half of a sidereal day...

s, other elliptical orbits and low (polar
Polar orbit
A polar orbit is an orbit in which a satellite passes above or nearly above both poles of the body being orbited on each revolution. It therefore has an inclination of 90 degrees to the equator...

 and non-polar) Earth orbits.

For fixed (point-to-point) services, communications satellites provide a microwave radio relay technology complementary to that of communication cables. They are also used for mobile applications such as communications to ships, vehicles, planes and hand-held terminals, and for TV and radio broadcasting
Broadcasting
Broadcasting is the distribution of audio and video content to a dispersed audience via any audio visual medium. Receiving parties may include the general public or a relatively large subset of thereof...

, for which application of other technologies, such as cable television
Cable television
Cable television is a system of providing television programs to consumers via radio frequency signals transmitted to televisions through coaxial cables or digital light pulses through fixed optical fibers located on the subscriber's property, much like the over-the-air method used in traditional...

, is impractical or impossible.

History


See: Geostationary Orbit
Geostationary orbit
A geostationary orbit is a geosynchronous orbit directly above the Earth's equator , with a period equal to the Earth's rotational period and an orbital eccentricity of approximately zero. An object in a geostationary orbit appears motionless, at a fixed position in the sky, to ground observers...

 and Geosynchronous orbit
Geosynchronous orbit
A geosynchronous orbit is an orbit around the Earth with an orbital period that matches the Earth's sidereal rotation period...

 Satellites.

The first artificial satellite was the Soviet Sputnik 1
Sputnik 1
Sputnik 1 ) was the first artificial satellite to be put into Earth's orbit. It was launched into an elliptical low Earth orbit by the Soviet Union on 4 October 1957. The unanticipated announcement of Sputnik 1s success precipitated the Sputnik crisis in the United States and ignited the Space...

, launched on October 4, 1957, and equipped with an on-board radio
Radio
Radio is the transmission of signals through free space by modulation of electromagnetic waves with frequencies below those of visible light. Electromagnetic radiation travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space...

-transmitter
Transmitter
In electronics and telecommunications a transmitter or radio transmitter is an electronic device which, with the aid of an antenna, produces radio waves. The transmitter itself generates a radio frequency alternating current, which is applied to the antenna. When excited by this alternating...

 that worked on two frequencies, 20.005 and 40.002 MHz. The first American satellite to relay communications was Project SCORE
Project SCORE
Project SCORE was the world’s first communications satellite. Launched aboard an Atlas rocket on December 18, 1958, SCORE provided a first test of a communications relay system in space, as well as the first successful use of the Atlas as a launch vehicle...

 in 1958, which used a tape recorder to store and forward
Store and forward
Store and forward is a telecommunications technique in which information is sent to an intermediate station where it is kept and sent at a later time to the final destination or to another intermediate station. The intermediate station, or node in a networking context, verifies the integrity of...

 voice messages. It was used to send a Christmas greeting to the world from U.S. President Dwight D. Eisenhower
Dwight D. Eisenhower
Dwight David "Ike" Eisenhower was the 34th President of the United States, from 1953 until 1961. He was a five-star general in the United States Army...

. NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...

 launched an Echo satellite
Echo satellite
Project Echo was the first passive communications satellite experiment. Each of the two American spacecraft was a metalized balloon satellite acting as a passive reflector of microwave signals. Communication signals were bounced off of them from one point on Earth to another.-Echo 1:NASA's Echo 1...

 in 1960; the 100 feet (30.5 m) aluminized PET film
PET film (biaxially oriented)
BoPET is a polyester film made from stretched polyethylene terephthalate and is used for its high tensile strength, chemical and dimensional stability, transparency, reflectivity, gas and aroma barrier properties and electrical insulation.A variety of companies manufacture boPET and other...

 balloon served as a passive reflector for radio communications. Courier 1B
Courier 1B
Courier 1B was the world's first active repeater satellite after launch on 4 October 1960. Courier was built by the Palo Alto, California–based Western Development Labs division of Philco, previously known as Army Fort Monmouth Laboratories and now the Space Systems/Loral division of Loral Space &...

, built by Philco
Philco
Philco, the Philadelphia Storage Battery Company , was a pioneer in early battery, radio, and television production as well as former employer of Philo Farnsworth, inventor of cathode ray tube television...

, also launched in 1960, was the world’s first active repeater satellite. With the launch of Alouette 1 in 1962 Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

 became the third country to put a man-made satellite into space. Because Canada did not have any domestic launch capabilities of its own, (and still does not), Alouette 1, which was entirely built and funded by Canada, was launched by the American National Aeronautics and Space Administration (NASA) from Vandenberg AFB in California.

Telstar
Telstar
Telstar is the name of various communications satellites, including the first such satellite to relay television signals.The first two Telstar satellites were experimental and nearly identical. Telstar 1 was launched on top of a Thor-Delta rocket on July 10, 1962...

 was the first active, direct relay communications satellite. Belonging to AT&T as part of a multi-national agreement between AT&T, Bell Telephone Laboratories
Bell Labs
Bell Laboratories is the research and development subsidiary of the French-owned Alcatel-Lucent and previously of the American Telephone & Telegraph Company , half-owned through its Western Electric manufacturing subsidiary.Bell Laboratories operates its...

, NASA, the British General Post Office, and the French National PTT
France Télécom
France Telecom S.A. is the main telecommunications company in France, the third-largest in Europe and one of the largest in the world. It currently employs about 180,000 people and has 192.7 million customers worldwide . In 2010 the group had revenue of €45.5 billion...

 (Post Office) to develop satellite communications, it was launched by NASA from Cape Canaveral
Cape Canaveral
Cape Canaveral, from the Spanish Cabo Cañaveral, is a headland in Brevard County, Florida, United States, near the center of the state's Atlantic coast. Known as Cape Kennedy from 1963 to 1973, it lies east of Merritt Island, separated from it by the Banana River.It is part of a region known as the...

 on July 10, 1962, the first privately sponsored space launch. Telstar was placed in an elliptical orbit
Orbit
In physics, an orbit is the gravitationally curved path of an object around a point in space, for example the orbit of a planet around the center of a star system, such as the Solar System...

 (completed once every 2 hours and 37 minutes), rotating at a 45° angle above the equator
Equator
An equator is the intersection of a sphere's surface with the plane perpendicular to the sphere's axis of rotation and containing the sphere's center of mass....

.

An immediate antecedent of the geostationary satellites was Hughes
Hughes Aircraft
Hughes Aircraft Company was a major American aerospace and defense contractor founded in 1932 by Howard Hughes in Culver City, California as a division of Hughes Tool Company...

’ Syncom 2, launched on July 26, 1963. Syncom 2 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.

Geostationary orbits




A satellite in a geostationary orbit appears to be in a fixed position to an earth-based observer. A geostationary satellite revolves around the earth at the same angular velocity
Angular velocity
In physics, the angular velocity is a vector quantity which specifies the angular speed of an object and the axis about which the object is rotating. The SI unit of angular velocity is radians per second, although it may be measured in other units such as degrees per second, revolutions per...

 of the earth itself, 360 degrees every 24 hours in an equatorial orbit, and therfore it seems to be in a fixed position over the equator.The launch of Anik A-1 in 1972, made Canada the first country in the world to establish its own domestic geostationary communication satellite network.

The geostationary orbit is useful for communications applications because ground based antennas, which must be directed toward the satellite, can operate effectively without the need for expensive equipment to track the satellite’s motion. Especially for applications that require a large number of ground antennas (such as DirectTV distribution), the savings in ground equipment can more than justify the extra cost and onboard complexity of lifting a satellite into the relatively high geostationary orbit. The main drawback of a geostationary satellite , however, is that it cannot be "seen" from polar regions, so it cannot provide commumications to extreme northerly or southerly areas of the globe. Another drawback of GEO satellites is their distance from earth (~37,000 kilometers), which requires more powerful transmitters, larger (usually dish) antennas, and high sensitivity receivers to Satellite Earth Stations. This distance also introduces a large (~0.25 second) delay into satellite communications link which has to be taken into account.

The concept of the geostationary communications satellite was first proposed by Arthur C. Clarke
Arthur C. Clarke
Sir Arthur Charles Clarke, CBE, FRAS was a British science fiction author, inventor, and futurist, famous for his short stories and novels, among them 2001: A Space Odyssey, and as a host and commentator in the British television series Mysterious World. For many years, Robert A. Heinlein,...

, building on work by Konstantin Tsiolkovsky
Konstantin Tsiolkovsky
Konstantin Eduardovich Tsiolkovsky was an Imperial Russian and Soviet rocket scientist and pioneer of the astronautic theory. Along with his followers the German Hermann Oberth and the American Robert H. Goddard, he is considered to be one of the founding fathers of rocketry and astronautics...

 and on the 1929 work by Herman Potočnik
Herman Potocnik
Herman Potočnik was an Austro-Hungarian rocket engineer and pioneer of cosmonautics . He is chiefly remembered for his work addressing the long-term human habitation of space.- Early life :Potočnik was born in Pola, southern Istria, Austria-Hungary...

 (writing as Herman Noordung) Das Problem der Befahrung des Weltraums - der Raketen-motor. In October 1945 Clarke published an article titled “Extra-terrestrial Relays” in the British magazine Wireless World
Wireless World
Wireless World was the pre-eminent British magazine for radio and electronics enthusiasts. It was one of the very few "informal" journals which were tolerated as a professional expense.- History :...

. The article described the fundamentals behind the deployment of artificial satellites in geostationary orbits for the purpose of relaying radio signals. Thus, Arthur C. Clarke is often quoted as being the inventor of the communications satellite.

Syncom 3, launched on August 19, 1964. It was placed in orbit at 180° east longitude
Longitude
Longitude is a geographic coordinate that specifies the east-west position of a point on the Earth's surface. It is an angular measurement, usually expressed in degrees, minutes and seconds, and denoted by the Greek letter lambda ....

, over the International Date Line
International Date Line
The International Date Line is a generally north-south imaginary line on the surface of the Earth, passing through the middle of the Pacific Ocean, that designates the place where each calendar day begins...

. It was used that same year to relay experimental television coverage of the 1964 Summer Olympics
1964 Summer Olympics
The 1964 Summer Olympics, officially known as the Games of the XVIII Olympiad, was an international multi-sport event held in Tokyo, Japan in 1964. Tokyo had been awarded with the organization of the 1940 Summer Olympics, but this honor was subsequently passed to Helsinki because of Japan's...

 in Tokyo, Japan to the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

, making these Olympic games the first to be broadcast internationally. Although Syncom 3 is sometimes credited with the first television transmission to cross the Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

, the Relay 1 satellite first broadcast from the United States to Japan on November 22, 1963.

Shortly after Syncom 3, Intelsat I
Intelsat I
Intelsat I was the first communications satellite to be placed in geosynchronous orbit, on April 6, 1965...

, aka Early Bird, was launched on April 6, 1965 and placed in orbit at 28° west longitude. It was the first geostationary satellite for telecommunications over the Atlantic Ocean
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...

.

On November 9, 1972, Canada's first geostationary satellite serving the continent, Anik A1, was launched by Telesat Canada
Telesat Canada
Telesat Canada is a Canadian satellite communications company founded on May 2, 1969. The company is headquartered in Ottawa, Ontario as well as having offices in the United States and Brazil.On October 5, 2007 Loral Space & Communications Inc...

, with the United States following suit with the launch of Westar 1
Westar 1
Westar 1 was America's first domestic and commercially launched geostationary communications satellite, launched by Western Union and NASA on April 13, 1974. It was built by Hughes for Western Union, using the HS-333 platform of spin-stabilized satellites. Westar 1 was the first of five Westar...

 by Western Union
Western Union
The Western Union Company is a financial services and communications company based in the United States. Its North American headquarters is in Englewood, Colorado. Up until 2006, Western Union was the best-known U.S...

 on April 13, 1974.

On May 30, 1974, the first geostationary communications satellite in the world to be three-axis stabilized was launched: the experimental satellite ATS-6
ATS-6
ATS-6 was a NASA experimental satellite, built by Fairchild Space and Electronics Division It has been called the world's first educational satellite as well as world's first experimental Direct Broadcast Satellite as part of the Satellite Instructional Television Experiment between NASA and ISRO...

 built for NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...



After the launches of Telstar, Syncom 3, Early Bird, Anik A1, and Westar 1, RCA Americom (later GE Americom, now SES Americom
SES Americom
SES Americom was a major commercial satellite operator based in the United States. Formerly RCA Americom and GE Americom, the company became one of the principal parts of SES S.A.....

) launched Satcom 1 in 1975. It was Satcom 1 that was instrumental in helping early cable TV channels such as WTBS (now TBS Superstation), HBO, CBN
Christian Broadcasting Network
The Christian Broadcasting Network, or CBN, is a fundamentalist Christian television broadcasting network in the United States. Its headquarters and main studios are in Virginia Beach, Virginia.-Background:...

 (now ABC Family
ABC Family
ABC Family, stylized as abc family, is an American television network, owned by ABC Family Worldwide Inc., a subsidiary of the Disney-ABC Television Group division of The Walt Disney Company...

), and The Weather Channel become successful, because these channels distributed their programming to all of the local cable TV headends
Cable television headend
A cable television headend is a master facility for receiving television signals for processing and distribution over a cable television system. The headend facility is normally unstaffed and surrounded by some type of security fencing and is typically a building or large shed housing electronic...

 using the satellite. Additionally, it was the first satellite used by broadcast television networks in the United States, like ABC
American Broadcasting Company
The American Broadcasting Company is an American commercial broadcasting television network. Created in 1943 from the former NBC Blue radio network, ABC is owned by The Walt Disney Company and is part of Disney-ABC Television Group. Its first broadcast on television was in 1948...

, NBC
NBC
The National Broadcasting Company is an American commercial broadcasting television network and former radio network headquartered in the GE Building in New York City's Rockefeller Center with additional major offices near Los Angeles and in Chicago...

, and CBS
CBS
CBS Broadcasting Inc. is a major US commercial broadcasting television network, which started as a radio network. The name is derived from the initials of the network's former name, Columbia Broadcasting System. The network is sometimes referred to as the "Eye Network" in reference to the shape of...

, 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 (24 transponders
Transponder (Satellite communications)
A communications satellite’s transponder, is the series of interconnected units which form a communications channel between the receiving and the transmitting antennas .A transponder is typically composed of:...

 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.

By 2000, Hughes Space and Communications (now Boeing Satellite Development Center
Boeing Satellite Development Center
The Boeing Satellite Development Center is a major business unit of Boeing Defense, Space & Security. It brought together Boeing satellite operations with that of GM Hughes Electronics' Space and Communications division.-History:...

) had built nearly 40 percent of the more than one hundred satellites in service worldwide. Other major satellite manufacturers include Space Systems/Loral
Space Systems/Loral
Space Systems/Loral , of Palo Alto, California, is the wholly owned manufacturing subsidiary of Loral Space & Communications. It was acquired in 1990 for $715 million by Loral Corp. from Ford Motor Company as the Space Systems Division of Ford Aerospace...

, Orbital Sciences Corporation
Orbital Sciences Corporation
Orbital Sciences Corporation is an American company which specializes in the manufacturing and launch of satellites. Its Launch Systems Group is heavily involved with missile defense launch systems...

 with the STAR Bus
STAR Bus
STAR Bus is a satellite platform manufactured by Orbital Sciences Corporation with an apogee kick motor to place a communications satellite into geostationary orbit, a thruster to provide the satellite with orbital station-keeping for a 15 year mission, and solar arrays to provide the satellite...

 series, Indian Space Research Organization, Lockheed Martin
Lockheed Martin Space Systems
Lockheed Martin Space Systems Company is one of the four major business divisions of Lockheed Martin. It is headquartered in Denver, Colorado with additional sites in Sunnyvale, California; Newtown, Pennsylvania; Huntsville, Alabama; and elsewhere in the US and UK...

 (owns the former RCA Astro Electronics/GE Astro Space business), Northrop Grumman
Northrop Grumman
Northrop Grumman Corporation is an American global aerospace and defense technology company formed by the 1994 purchase of Grumman by Northrop. The company was the fourth-largest defense contractor in the world as of 2010, and the largest builder of naval vessels. Northrop Grumman employs over...

, Alcatel Space, now Thales Alenia Space
Thales Alenia Space
Thales Alenia Space is an aerospace company born after the Thales Group bought the participation of Alcatel in the two joint-ventures between Alcatel and Finmeccanica, Alcatel Alenia Space and Telespazio.-History:...

, with the Spacebus
Spacebus
Spacebus is a satellite bus produced at the Cannes Mandelieu Space Center in France by Thales Alenia Space. Spacebuses are typically used for geostationary communications satellites, and fifty-two have been launched since development started in the 1980s. Spacebus was originally produced by...

 series, and Astrium.

Low-Earth-orbiting satellites




A Low Earth Orbit
Low Earth orbit
A low Earth orbit is generally defined as an orbit within the locus extending from the Earth’s surface up to an altitude of 2,000 km...

 (LEO) typically is a circular orbit about 400 kilometres above the earth’s surface and, correspondingly, a period (time to revolve around the earth) of about 90 minutes. Because of their low altitude, these satellites are only visible from within a radius of roughly 1000 kilometres 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, a large number of satellites are needed if the mission requires uninterrupted connectivity.

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 signal strength
Signal strength
In telecommunications, particularly in radio, signal strength refers to the magnitude of the electric field at a reference point that is a significant distance from the transmitting antenna. It may also be referred to as received signal level or field strength. Typically, it is expressed in...

 (Recall that signal strength falls off as the square of the distance from the source, so the effect is dramatic). Thus there is a trade off between the number of satellites and their cost. In addition, there are important differences in the onboard and ground equipment needed to support the two types of missions.

A group of satellites working in concert is known as a satellite constellation
Satellite constellation
A group of artificial satellites working in concert is known as a satellite constellation. Such a constellation can be considered to be a number of satellites with coordinated ground coverage, operating together under shared control, synchronised so that they overlap well in coverage and...

. Two such constellations, intended to provide satellite phone
Satellite phone
A satellite telephone, satellite phone, or satphone is a type of mobile phone that connects to orbiting satellites instead of terrestrial cell sites...

 services, primarily to remote areas, are the Iridium
Iridium (satellite)
Iridium Communications Inc. is a company, based in McLean, VA, United States which operates the Iridium satellite constellation, a system of 66 active satellites used for worldwide voice and data communication from hand-held satellite phones and other transceiver units...

 and Globalstar
Globalstar
Globalstar is a low Earth orbit satellite constellation for satellite phone and low-speed data communications, somewhat similar to the Iridium satellite constellation and Orbcomm satellite systems.-History:...

 systems. The Iridium system has 66 satellites. Another LEO satellite constellation known as Teledesic
Teledesic
Teledesic was a company founded in the 1990s to build a commercial broadband satellite constellation for Internet services. Using low-earth orbiting satellites small antennas could be used to provide uplinks of as much as 100 Mbit/second and downlinks of up to 720 Mbit/second...

, with backing from Microsoft
Microsoft
Microsoft Corporation is an American public multinational corporation headquartered in Redmond, Washington, USA that develops, manufactures, licenses, and supports a wide range of products and services predominantly related to computing through its various product divisions...

 entrepreneur Paul Allen
Paul Allen
Paul Gardner Allen is an American business magnate, investor, and philanthropist. Allen co-founded Microsoft with Bill Gates...

, was to have over 840 satellites. This was later scaled back to 288 and ultimately ended up only launching one test satellite.

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
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

’s CASSIOPE
CASSIOPE
CASSIOPE is a hybrid satellite project of the Canadian Space Agency. Planned for launch in an elliptical polar orbit in 2011, it will carry a commercial communications system called Cascade and a scientific experiment package called ePOP...

 communications satellite. Another system using this store and forward method is Orbcomm
Orbcomm
ORBCOMM is a company that offers M2M global asset monitoring and messaging services from its constellation of 29 LEO communications satellites orbiting at 775 km. Like its voice-centric competitors Iridium and Globalstar, it filed for Chapter 11 protection, in September, 2000. ORBCOMM issued...

.

Molniya satellites


Geostationary satellites must operate above the equator and will therefore appear lower on the horizon as the receiver gets the farther from the equator. This will cause problems for extreme northerly latitudes, affecting connectivity and causing multipath
Multipath interference
Multipath interference is a phenomenon in the physics of waves whereby a wave from a source travels to a detector via two or more paths and, under the right condition, the two components of the wave interfere...

 (interference caused by signals reflecting off the ground and into the ground antenna). For areas close to the North (and South) Pole, a geostationary satellite may appear below the horizon. Therefore Molniya orbit satellite have been launched, mainly in Russia, to alleviate this problem. The first satellite of the Molniya
Molniya (satellite)
Molniya was a military communications satellite system used by the Soviet Union. The satellites were placed into highly eccentric elliptical orbits known as Molniya orbits, characterised by an inclination of +63.4 degrees and a period of around 12 hours...

 series was launched on April 23, 1965 and was used for experimental transmission
Transmission (telecommunications)
Transmission, in telecommunications, is the process of sending, propagating and receiving an analogue or digital information signal over a physical point-to-point or point-to-multipoint transmission medium, either wired, optical fiber or wireless...

 of TV signal from a Moscow uplink
Uplink
A telecommunications link is generally one of several types of information transmission paths such as those provided by communication satellites to connect two points on earth.-Uplink:...

 station to downlink stations located in Siberia
Siberia
Siberia is an extensive region constituting almost all of Northern Asia. Comprising the central and eastern portion of the Russian Federation, it was part of the Soviet Union from its beginning, as its predecessor states, the Tsardom of Russia and the Russian Empire, conquered it during the 16th...

 and the Russian Far East, in Norilsk
Norilsk
Norilsk is an industrial city in Krasnoyarsk Krai, Russia, located between the Yenisei River and the Taymyr Peninsula. Population: It was granted city status in 1953. It is the northernmost city in Siberia and the world's second largest city north of the Arctic Circle...

, Khabarovsk
Khabarovsk
Khabarovsk is the largest city and the administrative center of Khabarovsk Krai, Russia. It is located some from the Chinese border. It is the second largest city in the Russian Far East, after Vladivostok. The city became the administrative center of the Far Eastern Federal District of Russia...

, Magadan
Magadan
Magadan is a port town on the Sea of Okhotsk and gateway to the Kolyma region. It is the administrative center of Magadan Oblast , in the Russian Far East. Founded in 1929 on the site of an earlier settlement from the 1920s, it was granted the status of town in 1939...

 and Vladivostok
Vladivostok
The city is located in the southern extremity of Muravyov-Amursky Peninsula, which is about 30 km long and approximately 12 km wide.The highest point is Mount Kholodilnik, the height of which is 257 m...

. In November 1967 Soviet engineers created a unique system
System
System is a set of interacting or interdependent components forming an integrated whole....

 of national TV network
Television network
A television network is a telecommunications network for distribution of television program content, whereby a central operation provides programming to many television stations or pay TV providers. Until the mid-1980s, television programming in most countries of the world was dominated by a small...

 of satellite television
Satellite television
Satellite television is television programming delivered by the means of communications satellite and received by an outdoor antenna, usually a parabolic mirror generally referred to as a satellite dish, and as far as household usage is concerned, a satellite receiver either in the form of an...

, called Orbita
Orbita
Orbita is a Soviet-Russian system of broadcasting and delivering TV signals via satellites. It is considered to be the first national network of satellite television....

, that was based on Molniya satellites.

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

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

Structure of a Communications Satellite


Communications Satellites are usually composed of the following subsystems:
  • Communication Payload, normally composed of transponders
    Transponder (Satellite communications)
    A communications satellite’s transponder, is the series of interconnected units which form a communications channel between the receiving and the transmitting antennas .A transponder is typically composed of:...

    , antenna, and switching systems
  • Engines used to bring the satellite to its desired orbit
  • Station Keeping Tracking and stabilization subsystem 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
  • Power subsystem, used to power the Satellite systems, normally composed of solar cell
    Solar cell
    A solar cell is a solid state electrical device that converts the energy of light directly into electricity by the photovoltaic effect....

    s, and batteries that maintain power during solar eclipse
    Solar eclipse
    As seen from the Earth, a solar eclipse occurs when the Moon passes between the Sun and the Earth, and the Moon fully or partially blocks the Sun as viewed from a location on Earth. This can happen only during a new moon, when the Sun and the Moon are in conjunction as seen from Earth. At least...

  • 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 life-cycle.

Bandwidth of a satellite


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. The bandwidth of transponder is used to carry these services

Telephone



The first and historically most important application for communication satellites was in intercontinental long distance telephony. The fixed Public Switched Telephone Network
Public switched telephone network
The public switched telephone network is the network of the world's public circuit-switched telephone networks. It consists of telephone lines, fiber optic cables, microwave transmission links, cellular networks, communications satellites, and undersea telephone cables, all inter-connected by...

 relays telephone call
Telephone call
A telephone call is a connection over a telephone network between the calling party and the called party.-Information transmission:A telephone call may carry ordinary voice transmission using a telephone, data transmission when the calling party and called party are using modems, or facsimile...

s from land line telephones to an earth station
Earth station
A ground station, earth station, or earth terminal is a terrestrial terminal station designed for extraplanetary telecommunication with spacecraft, and/or reception of radio waves from an astronomical radio source. Ground stations are located either on the surface of the Earth, or within Earth's...

, where they are then transmitted to a geostationary satellite. The downlink follows an analogous path. Improvements in submarine communications cable
Submarine communications cable
A submarine communications cable is a cable laid on the sea bed between land-based stations to carry telecommunication signals across stretches of ocean....

s, through the use of fiber-optics, caused some decline in the use of satellites for fixed telephony in the late 20th century, but they still serve remote islands such as Ascension Island
Ascension Island
Ascension Island is an isolated volcanic island in the equatorial waters of the South Atlantic Ocean, around from the coast of Africa and from the coast of South America, which is roughly midway between the horn of South America and Africa...

, Saint Helena
Saint Helena
Saint Helena , named after St Helena of Constantinople, is an island of volcanic origin in the South Atlantic Ocean. It is part of the British overseas territory of Saint Helena, Ascension and Tristan da Cunha which also includes Ascension Island and the islands of Tristan da Cunha...

, Diego Garcia
Diego Garcia
Diego Garcia is a tropical, footprint-shaped coral atoll located south of the equator in the central Indian Ocean at 7 degrees, 26 minutes south latitude. It is part of the British Indian Ocean Territory [BIOT] and is positioned at 72°23' east longitude....

, and Easter Island
Easter Island
Easter Island is a Polynesian island in the southeastern Pacific Ocean, at the southeasternmost point of the Polynesian triangle. A special territory of Chile that was annexed in 1888, Easter Island is famous for its 887 extant monumental statues, called moai, created by the early Rapanui people...

, where no submarine cables are in service. There are also regions of some continents and countries where landline telecommunications are rare to nonexistent, for example large regions of South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...

, Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...

, Canada, China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...

, Russia, and Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

. Satellite communications also provide connection to the edges of Antarctica and Greenland
Greenland
Greenland is an autonomous country within the Kingdom of Denmark, located between the Arctic and Atlantic Oceans, east of the Canadian Arctic Archipelago. Though physiographically a part of the continent of North America, Greenland has been politically and culturally associated with Europe for...

.

Satellite phone
Satellite phone
A satellite telephone, satellite phone, or satphone is a type of mobile phone that connects to orbiting satellites instead of terrestrial cell sites...

s connect directly to a constellation of either geostationary or low-earth-orbit satellites. Calls are then forwarded to a satellite teleport connected to the Public Switched Telephone Network
Public switched telephone network
The public switched telephone network is the network of the world's public circuit-switched telephone networks. It consists of telephone lines, fiber optic cables, microwave transmission links, cellular networks, communications satellites, and undersea telephone cables, all inter-connected by...


Satellite television


As television became the main market, its demand for simultaneous delivery of relatively few signals of large bandwidth to many receivers being a more precise match for the capabilities of geosynchronous comsats. Two satellite types are used for North American television and radio: Direct broadcast satellite
Direct broadcast satellite
Direct broadcast satellite is a term used to refer to satellite television broadcasts intended for home reception.A designation broader than DBS would be direct-to-home signals, or DTH. This has initially distinguished the transmissions directly intended for home viewers from cable television...

 (DBS), and Fixed Service Satellite (FSS)

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 satellites. Examples of these are the Astra
SES Astra
Astra is the name for the 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 sometimes also used to describe the channels broadcasting from these...

, Eutelsat
Eutelsat
Eutelsat S.A. is a French-based satellite provider. Providing coverage over the entire European continent, as well as the Middle East, Africa, India and significant parts of Asia and the Americas, it is one of the world's three leading satellite operators in terms of revenues.Eutelsat’s satellites...

, and Hotbird 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.

Fixed Service Satellite


Fixed Service Satellites use the C band
C band
The C band is a name given to certain portions of the electromagnetic spectrum, including wavelengths of microwaves that are used for long-distance radio telecommunications. The IEEE C-band - and its slight variations - contains frequency ranges that are used for many satellite communications...

, and the lower portions of the Ku bands. 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, live shot
Remote broadcast
In broadcast engineering, a remote broadcast is broadcasting done from a location away from a formal television studio and is considered an electronic field production . A remote pickup unit is usually used to transmit the audio and/or video back to the television station, where it joins the...

s, and backhauls), as well as being used for distance learning by schools and universities, business television (BTV), Videoconferencing
Videoconferencing
Videoconferencing is the conduct of a videoconference by a set of telecommunication technologies which allow two or more locations to interact via two-way video and audio transmissions simultaneously...

, and general commercial telecommunications. FSS satellites are also used to distribute national cable channels to cable television headends.

Free-to-air
Free-to-air
Free-to-air describes television and radio services broadcast in clear form, allowing any person with the appropriate receiving equipment to receive the signal and view or listen to the content without requiring a subscription or one-off fee...

 satellite TV channels are also usually distributed on FSS satellites in the Ku band. The Intelsat Americas 5, Galaxy 10R
Galaxy 10R
Galaxy 10R was an American communications satellite which was operated by PanAmSat, and later Intelsat. It was constructed by Hughes and is based on the HS-601HP satellite bus. Launch occurred on 25 January 2000, at 01:04...

 and AMC 3
AMC 3
AMC-3 is a commercial broadcast communications satellite owned by SES World Skies, formerly SES Americom and before that GE Americom. Launched on September 4, 1997, from Cape Canaveral, Florida, AMC-3 is a hybrid C band/Ku band satellite. It provides coverage to the continental United States,...

 satellites over North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

 provide a quite large amount of FTA channels on their Ku band transponder
Transponder
In telecommunication, the term transponder has the following meanings:...

s.

The American Dish Network
Dish Network
Dish Network Corporation is the second largest pay TV provider in the United States, providing direct broadcast satellite service—including satellite television, audio programming, and interactive television services—to 14.337 million commercial and residential customers in the United States. Dish...

 DBS
DBS
-Automobiles:*Aston Martin DBS, 1967–72 automobile model*Aston Martin DBS V12, 2008- automobile model, officially also called the Aston Martin DBS-Technology:*Database system*Discbox Slider, a carton board disc case...

 service has also recently utilized FSS technology as well for their programming packages requiring their SuperDish
SuperDish
The SuperDish is a satellite dish that was deployed by Dish Network in November 2003 as a means to provide more channels for subscribing customers. Its elliptical reflector is 36" x 20" - more than 50% larger than the round 20" Dish 500. The SuperDish receives signals from three orbiting...

 antenna, due to Dish Network needing more capacity to carry local television stations per the FCC
Federal Communications Commission
The Federal Communications Commission is an independent agency of the United States government, created, Congressional statute , and with the majority of its commissioners appointed by the current President. The FCC works towards six goals in the areas of broadband, competition, the spectrum, the...

's "must-carry" regulations, and for more bandwidth to carry HDTV channels.

Direct broadcast satellite



A direct broadcast satellite is a communications satellite that transmits to small DBS satellite dishes (usually 18 to 24 inches or 45 to 60 cm in diameter). Direct broadcast satellites generally operate in the upper portion of the microwave Ku band
Ku band
The Kμ band is a portion of the electromagnetic spectrum in the microwave range of frequencies. This symbol refers to —in other words, the band directly below the K-band...

. DBS technology is used for DTH-oriented (Direct-To-Home) satellite TV services, such as DirecTV
DirecTV
DirecTV is an American direct broadcast satellite service provider and broadcaster based in El Segundo, California. Its satellite service, launched on June 17, 1994, transmits digital satellite television and audio to households in the United States, Latin America, and the Anglophone Caribbean. ...

 and DISH Network in the United States, Bell TV and Shaw Direct in Canada, Freesat
Freesat
Freesat is a free-to-air digital satellite television joint venture between the BBC and ITV plc, serving the United Kingdom. The service was formed as a memorandum in 2007 and has been marketed since 6 May 2008...

 and Sky Digital
Sky Digital (UK & Ireland)
Sky is the brand name for British Sky Broadcasting's digital satellite television and radio service, transmitted from SES Astra satellites located at 28.2° east and Eutelsat's Eurobird 1 satellite at 28.5°E. The service was originally launched as Sky Digital, distinguishing it from the original...

 in the UK, the Republic of Ireland
Republic of Ireland
Ireland , described as the Republic of Ireland , is a sovereign state in Europe occupying approximately five-sixths of the island of the same name. Its capital is Dublin. Ireland, which had a population of 4.58 million in 2011, is a constitutional republic governed as a parliamentary democracy,...

, and New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

 and DSTV
DStv
DStv is MultiChoice's multi-channel digital satellite TV service in Africa, launched in 1995. It operates from two satellites over Africa, broadcasting on Ku band via Eutelsat W7 and Intelsat 7 , which only requires a small satellite dish...

 in South Africa .

Operating at lower frequency and lower power than DBS, FSS satellites require a much larger dish for reception (3 to 8 feet (1 to 2.5m) in diameter for Ku band, and 12 feet (3.6m) or larger for C band). They use linear polarization
Linear polarization
In electrodynamics, linear polarization or plane polarization of electromagnetic radiation is a confinement of the electric field vector or magnetic field vector to a given plane along the direction of propagation...

 for each of the transponders' RF input and output (as opposed to circular polarization
Circular polarization
In electrodynamics, circular polarization of an electromagnetic wave is a polarization in which the electric field of the passing wave does not change strength but only changes direction in a rotary type manner....

 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 TVRO (TeleVision Receive Only) receivers and dishes. It was also used in its Ku band form for the now-defunct Primestar
PrimeStar
PrimeStar was a U.S. direct broadcast satellite broadcasting company formed in 1991 by a consortium of cable television system operators. PrimeStar was the first medium-powered DBS system in the United States but slowly declined in popularity with the arrival of DirecTV in 1994 and Dish Network in...

 satellite TV service.

Satellites for communication have now been launched that have transponders in the Ka band
Ka band
The Ka band covers the frequencies of 26.5–40 GHz. The Ka band is part of the K band of the microwave band of the electromagnetic spectrum. This symbol refers to "K-above" — in other words, the band directly above the K-band...

, such as DirecTV's SPACEWAY-1
SPACEWAY-1
Spaceway F1 is part of DirecTV’s constellation of direct broadcast satellites. The satellite was launched via a Zenit 3SL rocket from Sea Launch’s Odyssey equatorial platform on April 26, 2005. Its operational position is in geosynchronous orbit above the equator at 102.8 degrees west longitude....

 satellite, and Anik F2
Anik (satellite)
The Anik satellites are geostationary communications satellites launched by Telesat Canada for television in Canada. In Inuktitut, Anik means "little brother".-The Satellites:-Anik A:...

. NASA as well has launched experimental satellites using the Ka band recently.

Mobile satellite technologies


Initially available for broadcast to stationary TV receivers, by 2004 popular mobile direct broadcast applications made their appearance with the arrival of two satellite radio systems in the United States: Sirius and XM Satellite Radio Holdings. Some manufacturers have also introduced special antennas for mobile reception of DBS television. Using Global Positioning System (GPS)
Global Positioning System
The Global Positioning System is a space-based global navigation satellite system that provides location and time information in all weather, anywhere on or near the Earth, where there is an unobstructed line of sight to four or more GPS satellites...

 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 recreational vehicle
Recreational vehicle
Recreational vehicle or RV is, in North America, the usual term for a Motor vehicle or trailer equipped with living space and amenities found in a home.-Features:...

 owners. Such mobile DBS antennas are also used by JetBlue Airways
JetBlue Airways
JetBlue Airways Corporation is an American low-cost airline. The company is headquartered in the Forest Hills neighborhood of the New York City borough of Queens. Its main base is John F. Kennedy International Airport, also in Queens....

 for DirecTV (supplied by LiveTV
LiveTV
LiveTV is a major provider of airline in-flight entertainment systems. Originally a joint venture of Harris Corporation and BE Aerospace , it is now a wholly owned subsidiary of JetBlue Airways Corporation...

, a subsidiary of JetBlue), which passengers can view on-board on LCD screens mounted in the seats.

Satellite radio



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

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.

Satellite radio offers a meaningful alternative to ground-based radio services in some countries, notably the United States. Mobile services, such as Sirius, XM, and Worldspace, allow listeners to roam across an entire continent, listening to the same audio programming anywhere they go. Other services, such as Music Choice or Muzak's satellite-delivered content, require a fixed-location receiver and a dish antenna. In all cases, the antenna must have a clear view to the satellites. In areas where tall buildings, bridges, or even parking garages obscure the signal, repeaters can be placed to make the signal available to listeners.

Radio services are usually provided by commercial ventures and are subscription-based. The various services are proprietary signals, requiring specialized hardware for decoding and playback. Providers usually carry a variety of news, weather, sports, and music channels, with the music channels generally being commercial-free.

In areas with a relatively high population density, it is easier and less expensive to reach the bulk of the population with terrestrial broadcasts. Thus in the UK and some other countries, the contemporary evolution of radio services is focused on Digital Audio Broadcasting (DAB) services or HD Radio, rather than satellite radio.

Amateur radio


Amateur radio
Amateur radio
Amateur radio is the use of designated radio frequency spectrum for purposes of private recreation, non-commercial exchange of messages, wireless experimentation, self-training, and emergency communication...

 operators have access to the OSCAR
OSCAR
OSCAR is an acronym for Orbiting Satellite Carrying Amateur Radio. OSCAR series satellites use amateur radio frequencies to facilitate communication between amateur radio stations. These satellites can be used for free by licensed amateur radio operators for voice and data communications...

 satellites that have been designed specifically to carry amateur radio traffic. Most such satellites operate as spaceborne repeaters, and are generally accessed by amateurs equipped with UHF
Ultra high frequency
Ultra-High Frequency designates the ITU Radio frequency range of electromagnetic waves between 300 MHz and 3 GHz , also known as the decimetre band or decimetre wave as the wavelengths range from one to ten decimetres...

 or VHF radio equipment and highly directional antennas such as Yagi
Yagi antenna
A Yagi-Uda array, commonly known simply as a Yagi antenna, is a directional antenna consisting of a driven element and additional parasitic elements...

s 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 AX.25
AX.25
AX.25 is a data link layer protocol derived from the X.25 protocol suite and designed for use by amateur radio operators. It is used extensively on amateur packet radio networks....

 or similar protocols.

Satellite Internet



After the 1990s, satellite communication technology has been used as a means to connect to the Internet
Internet
The Internet is a global system of interconnected computer networks that use the standard Internet protocol suite to serve billions of users worldwide...

 via broadband data connections. This can be very useful for users who are located in remote areas, and cannot access a broadband
Broadband
The term broadband refers to a telecommunications signal or device of greater bandwidth, in some sense, than another standard or usual signal or device . Different criteria for "broad" have been applied in different contexts and at different times...

 connection, or require high availability of services.

Military uses


Communications satellites are used for military communications
Military communications
Historically, the first military communications had the form of sending/receiving simple signals . Respectively, the first distinctive tactics of military communications were called Signals, while units specializing in those tactics received the Signal Corps name...

 applications, such as Global Command and Control System
Global Command and Control System
Global Command and Control System is a collection of SOA systems and applications which was developed to replace the Worldwide Military Command and Control System...

s. Examples of military systems that use communication satellites are the MILSTAR, the DSCS, and the FLTSATCOM of the United States, NATO satellites, United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

 satellites (eg. Skynet), and satellites of the former Soviet Union
Soviet Union
The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....

. Many military satellites operate in the X-band, and some also use UHF radio links, while MILSTAR also utilizes Ka band
Ka band
The Ka band covers the frequencies of 26.5–40 GHz. The Ka band is part of the K band of the microwave band of the electromagnetic spectrum. This symbol refers to "K-above" — in other words, the band directly above the K-band...

.

See also



  • Broadcasting Satellite (Japanese)
  • Commercialization of space
    Commercialization of space
    Commercialization of space is the use of equipment sent into or through outer space to provide goods or services of commercial value, either by a corporation or state. Examples of the commercial use of space include satellite navigation systems, satellite television and satellite radio...

  • COMSAT
    COMSAT
    The Communications Satellite Corporation is a global telecommunications company, based in the USA, and with branches in Brazil, Argentina, Colombia, Mexico, Peru, Venezuela and several other countries in the Americas. It is present also in Turkey...

     Corporation
  • Data Transmission Network
    Data Transmission Network
    DTN, formerly known as Data Transmission Network, is a subscription-based service for the delivery of real-time weather, agricultural and commodity market information. Telvent DTN is the name of the service that is owned by its parent company Telvent...

  • DBS
    Direct broadcast satellite
    Direct broadcast satellite is a term used to refer to satellite television broadcasts intended for home reception.A designation broader than DBS would be direct-to-home signals, or DTH. This has initially distinguished the transmissions directly intended for home viewers from cable television...

     satellite
  • DVB
  • DigiCipher 2
    DigiCipher 2
    DigiCipher 2, or simply DCII, is a proprietary standard format of digital signal transmission and encryption with MPEG-2 signal video compression used on many communications satellite television and audio signals...

  • DSCS satellite
  • free-space optical communication
    Free-space optical communication
    Free-space optical communication is an optical communication technology that uses light propagating in free space to transmit data for telecommunications or computer networking."Free space" means air, outer space, vacuum, or something similar...

    s
  • FLTSATCOM satellite
  • Intelsat
    Intelsat
    Intelsat, Ltd. is a communications satellite services provider.Originally formed as International Telecommunications Satellite Organization , it was—from 1964 to 2001—an intergovernmental consortium owning and managing a constellation of communications satellites providing international broadcast...

     organization

  • Integral Satcom Initiative
    Integral Satcom Initiative
    The Integral Satcom Initiative is the European Technology Platform on Satellite Communications, whose membership embraces major part of relevant private and public stakeholders from Satellite Communications and Space sector in Europe...

     European Technology Platform
  • Intersputnik
    Intersputnik
    The Intersputnik International Organization of Space Communications commonly known as Intersputnik is an international satellite communications services organization founded on November 15, 1971, in Moscow by the Soviet Union along with a group of eight formerly socialist states...

     organization
  • List of communications satellite firsts
  • List of communication satellite companies
  • List of orbits
  • MILSTAR - the Military Strategic and Tactical Relay satellite
    Military Strategic and Tactical Relay satellite
    Milstar, originally meaning Military Strategic and Tactical Relay, is a constellation of communications satellites in geostationary orbit, which are operated by the United States Air Force, and provide secure and jam resistant worldwide communications to meet the requirements of the Armed Forces of...

     system
  • Moonbounce
    EME (communications)
    Earth-Moon-Earth, also known as moon bounce, is a radio communications technique which relies on the propagation of radio waves from an Earth-based transmitter directed via reflection from the surface of the Moon back to an Earth-based receiver....

  • Reconnaissance satellite
  • PanAmSat
    PanAmSat
    The former PanAmSat Corporation founded in 1984 by Reynold Anselmo, was a satellite service provider headquartered in Greenwich, Connecticut. It operated a fleet of communications satellites used by the entertainment industry, news agencies, internet service providers, government agencies, and...

     Corp.
  • Project West Ford
    Project West Ford
    Project West Ford 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...


  • Satellite dish
    Satellite dish
    A satellite dish is a dish-shaped type of parabolic antenna designed to receive microwaves from communications satellites, which transmit data transmissions or broadcasts, such as satellite television.-Principle of operation:...

  • Satmodem
  • Satellite radio
    Satellite radio
    Satellite radio is an analogue or digital radio signal that is relayed through one or more satellites and thus can be received in a much wider geographical area than terrestrial FM radio stations...

  • Satellite space segment
    Satellite space segment
    thumb|300px|right|A telecommunications satellite. The space segment is comprised by the uplink, the satellite itself, and the downlinkthumb|right|200px|A large parabolic antenna in a satellite Earth station...

  • Spacebus
    Spacebus
    Spacebus is a satellite bus produced at the Cannes Mandelieu Space Center in France by Thales Alenia Space. Spacebuses are typically used for geostationary communications satellites, and fifty-two have been launched since development started in the 1980s. Spacebus was originally produced by...

  • Symphonie
    Symphonie
    The Symphonie satellites were the first communications satellites built by France and Germany to provide geostationary orbit injection and station-keeping during their operational lifetime...

  • Submarine communications cable
    Submarine communications cable
    A submarine communications cable is a cable laid on the sea bed between land-based stations to carry telecommunication signals across stretches of ocean....

  • Telesat
  • Telstar
    Telstar
    Telstar is the name of various communications satellites, including the first such satellite to relay television signals.The first two Telstar satellites were experimental and nearly identical. Telstar 1 was launched on top of a Thor-Delta rocket on July 10, 1962...

     satellite
  • VSAT satellite terminal


External links