HeterodyneA heterodyne is a signal frequency that is created by combining or mixing two other frequencies using a signal processing technique called heterodyning, which was invented by Canadian inventor-engineer Reginald Fessenden. Heterodyning is used to shift signals from one frequency range into another, and is also involved in the processes of modulation and demodulation. The two input frequencies are combined in a nonlinear signal-processing device such as a vacuum tube, transistor, or diode, usually called a mixer.
Geosynchronous orbitA geosynchronous orbit (sometimes abbreviated GSO) is an Earth-centered orbit with an orbital period that matches Earth's rotation on its axis, 23 hours, 56 minutes, and 4 seconds (one sidereal day). The synchronization of rotation and orbital period means that, for an observer on Earth's surface, an object in geosynchronous orbit returns to exactly the same position in the sky after a period of one sidereal day.
Bell MediaBell Media Inc. (French: Bell Média inc.) is a Canadian media conglomerate that is the mass media subsidiary of BCE Inc. (also known as Bell Canada Enterprises, the owner of telecommunications company Bell Canada). Its operations include national television broadcasting and production (including the CTV and CTV 2 television networks), radio broadcasting (through iHeartRadio Canada), digital media (including Crave) and Internet properties (including the now-defunct Sympatico portal).
DoordarshanDoordarshan (abbreviated as DD; distant vision, television) is an Indian public service broadcaster founded by the Government of India, owned by the Ministry of Information and Broadcasting and one of Prasar Bharati's two divisions. As one of India's largest broadcasting organisations in studio and transmitter infrastructure, it was established on 15 September 1959. Doordarshan, which also broadcasts on digital terrestrial transmitters, provides television, radio, online and mobile service throughout metropolitan and regional India and overseas.
SubcarrierA subcarrier is a sideband of a radio frequency carrier wave, which is modulated to send additional information. Examples include the provision of colour in a black and white television system or the provision of stereo in a monophonic radio broadcast. There is no physical difference between a carrier and a subcarrier; the "sub" implies that it has been derived from a carrier, which has been amplitude modulated by a steady signal and has a constant frequency relation to it.
S bandThe S band is a designation by the Institute of Electrical and Electronics Engineers (IEEE) for a part of the microwave band of the electromagnetic spectrum covering frequencies from 2 to 4 gigahertz (GHz). Thus it crosses the conventional boundary between the UHF and SHF bands at 3.0 GHz. The S band is used by airport surveillance radar for air traffic control, weather radar, surface ship radar, and some communications satellites, especially those satellites used by NASA to communicate with the Space Shuttle and the International Space Station.
Geosynchronous satelliteA geosynchronous satellite is a satellite in geosynchronous orbit, with an orbital period the same as the Earth's rotation period. Such a satellite returns to the same position in the sky after each sidereal day, and over the course of a day traces out a path in the sky that is typically some form of analemma. A special case of geosynchronous satellite is the geostationary satellite, which has a geostationary orbit – a circular geosynchronous orbit directly above the Earth's equator.
Public-access televisionPublic-access television (sometimes called community-access television) is traditionally a form of non-commercial mass media where the general public can create content television programming which is narrowcast through cable television specialty channels. Public-access television was created in the United States between 1969 and 1971 by the Federal Communications Commission (FCC), under Chairman Dean Burch, based on pioneering work and advocacy of George Stoney, Red Burns (Alternate Media Center), and Sidney Dean (City Club of NY).
Space industrySpace industry refers to economic activities related to manufacturing components that go into outer space (Earth's orbit or beyond), delivering them to those regions, and related services. Owing to the prominence of the satellite-related activities, some sources use the term satellite industry interchangeably with the term space industry. The term space business has also been used. A narrow definition encompasses only hardware providers (primarily related to launch vehicles and satellites).
TelstarTelstar is the name of various communications satellites. The first two Telstar satellites were experimental and nearly identical. Telstar 1 launched on top of a Thor-Delta rocket on July 10, 1962. It successfully relayed through space the first television pictures, telephone calls, and telegraph images, and provided the first live transatlantic television feed. Telstar 2 was launched May 7, 1963. Telstar 1 and 2—though no longer functional—still orbit the Earth.
