Glossary Terms Beginning I

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IATA: International Air Transport Association: international civil aviation industry body.
IBO: Input back-off: see Back-off.
IDR framing: See Overhead framing.
IDR: Intermediate data rate: refers to INTELSAT’s general data services.
IEEE: Institute of Electrical and Electronics Engineers (US).
IEEE 1394: See Firewire.
IF: 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).
IFB: Interruptible foldback or interruptible feedback: allows a producer, director etc. to communicate with the reporter during a ‘live’ remote transmission.
IGO: Intergovernmental organization.
IMN: INMARSAT mobile number.
IMO: International Maritime Organisation: founder of INMARSAT.
IMT-2000: International mobile telecommunications for the second millenium: ITU equivalent to European UMTS.
Inclination: 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.
INIRC: 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.
INMARSAT: 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.
INTELSAT: International Telecommunications Satellite Organisation.
Interference: Energy which interferes with the reception of desired signals.
Interleaving: 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.
Interoperability: 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.
Inverse: DCT Reverse process to DCT coding.
Inverter: 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.
IOR: Indian Ocean Region: describes coverage area of a satellite.
IP: Intermodulation product; Internet protocol.
IPFD: Incidental power flux density: a measure of the illumination of the satellite by the uplink.
IRD: Integrated receiver decoder: an integrated MPEG-2 digital receiver which combines a downconverter, a demodulator and a compression decoder.
ISDN: Integrated services digital network: ITU-T term for integrated transmission of voice, video and data on the digital public telecommunications network.
ISO: International Standards Organization.
ISOG: 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.
ITU: 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-D: ITU development sector: provides technical assistance to developing countries.
ITU-T: ITU telecommunication sector: establishes global agreements on standards for telecommunications.