7E Communications

Glossary Terms Beginning I

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International Air Transport Association: international civil aviation industry body.
Input back-off: see Back-off.
IDR framing
See Overhead framing.
Intermediate data rate: refers to INTELSAT's general data services.
Institute of Electrical and Electronics Engineers (US).
IEEE 1394
See Firewire.
Intermediate frequency signal, between stages in an uplink or downlink transmission chain - typically at frequencies of 70 or 140 MHz, or in the L-band (at around 1000 MHz or 1 GHz).
Interruptible foldback or interruptible feedback: allows a producer, director etc. to communicate with the reporter during a 'live' remote transmission.
Intergovernmental organization.
INMARSAT mobile number.
International Maritime Organisation: founder of INMARSAT.
International mobile telecommunications for the second millenium: ITU equivalent to European UMTS.
Angle between the orbital plane of a satellite and the equatorial plane of the Earth.
Inclined orbit
Satellite status near the end of its operational life, when North- South station-keeping manoeuvres are largely abandoned; this type of capacity is often used for SNG.
Information rate
Fundamental video data rate.
International Non-Ionizing Radiation Committee.
Injection orbit
See Transfer orbit.
In-line fed prime focus
Antenna where the feedhorn is directly in front of the vertex of the antenna.
International Maritime Satellite Organisation: operates a network of satellites for international transmissions for all types of international mobile services including maritime, aeronautical and land mobile.
Input back-off
IBO: where the input signal to the HPA is reduced so that the TWT is operating on the linear part of its power transfer curve; expressed in dB.
International Telecommunications Satellite Organisation.
Energy which interferes with the reception of desired signals.
Where consecutive bits are interleaved amongst other bits in the bit-stream over a certain period of time to improve ruggedness of data.
Intermodulation products
IP: spurious signals generated typically in the HPA which cause interference to other adjacent signals.
The ability of one manufacturer's equipment (e.g. an MPEG-2 encoder), compliant to an agreed standard, to operate in harmony with the same type of equipment from another manufacturer.
Interview mode
Low-latency mode (typically less than 250 ms) on an MPEG-2 encoder.
Intra-frame coding
Form of compression of looking for spectral and spatial redundancy inside each frame without reference to any other frame, and sending such frames in a continuous sequence.
DCT Reverse process to DCT coding.
Electrical powering device that produces 110/240 V from a 12/24 V source, e.g. a vehicle battery.
Ionizing radiation
Electromagnetic radiation of X-rays, gamma radiation, neutrons and alpha particles, that can have sufficient energy to permanently alter cell structures.
Indian Ocean Region: describes coverage area of a satellite.
Intermodulation product; Internet protocol.
Incidental power flux density: a measure of the illumination of the satellite by the uplink.
Integrated receiver decoder: an integrated MPEG-2 digital receiver which combines a downconverter, a demodulator and a compression decoder.
Integrated services digital network: ITU-T term for integrated transmission of voice, video and data on the digital public telecommunications network.
International Standards Organization.
Broadcasting industry lobby group of the WBU, which seeks to influence particularly in the areas of SNG and contribution circuits.
Isotropic antenna
A hypothetical omni-directional point-source antenna that radiates equal electromagnetic power in all directions - the gain of an isotropic antenna is 0 dBi - that serves as an engineering reference for the measurement of antenna gain.
International Telecommunications Union: undertakes global administration of spectrum. Founded in 1865 as the International Telegraph Union, it changed its name to the International Telecommunication Union in 1934.
ITU development sector: provides technical assistance to developing countries.
ITU telecommunication sector: establishes global agreements on standards for telecommunications.