List of abbreviations: I

IAA International Academy of Astronautics
IAF International Astronautical Federation
IAG International Association of Geodesy
IAGA International Association of Geomagnetism and Aeronomy
IAGC International Association of Geochemistry and Cosmochemistry
IAMAP International Association of Meteorology and Atmospheric Physics
IARU International Amateur Radio Union
IATA International Air Transport Agency
IAU International Astronomical Union
IBCN Integrated Broadband Communication
IBS INTELSAT Business Service
IBW Instantaneous Bandwidth
ICAO International Civil Aviation Organization
ICAS International Council of the Aeronatical Sciences
ICO Intermediate Circular Orbit
ICSTI International Council for Scientific and Technical Information
ICSU International Council for Scientific Unions
IDR Intermediate Data Rate
IEC International Electrotechnical Commission
IEE Institution of Electrical Engineers
IEEE Institution of Electrical and Electronics Engineers
IF Intermediate Frequency
IFF Identification Friend or Foe
IFL International Frequency List
IFRB International Frequency Registration Board (ITU-R)
IFRC International Frequency Registration Circular (ITU-R)
IIASA International Institute of Applied Systems Analysis
IISL International Institute of Space Law
ILS Instrument Landing System
IMASS Intelligent Multiple Access Spectrum Sharing
IMO International Maritime Organization
IMT International Mobile Telecommunications
IMT-2000 International Mobile Telecommunication System
INAF National Institute for Astrophysics (I)
INMARSAT INternational MAritime SATellite organization
INPE Instituto Nacional de Psequisas Espaciais
INSU Institut National des Sciences de l’Univers (F)
INTA Instituto Nacional de Tècnica Aerospacial
INTELSAT International Telecommunications Satellite Organization
ION The Institute of Navigation (US)
IR Infrared
IRAM Institut de Radio Astronomie Millimétrique
IRG Independent Regulatory Group (EC)
IRT Institut für Rundfunktechnik (D)
ISAR Inverse Synthetic-Aperture Radar
ISAS Institute of Space and Astronautical Science
ISDN Integrated Services Digital Network
ISL Inter-Satellite Link
ISM Industrial, Scientific, Medical
ISO International Organization for Standardization
ISR Incoherent Scatter Radar
ISRO Indian Space Research Organization
ISS Inter-Satellite Service
IT Information Technology
ITA Industrial Telecommunication Association (USA)
ITFS Instructional Television Fixed Service
ITU International Telecommunication Union
ITU-D International Telecommunication Union – Telecommunication Development Sector
ITU-R International Telecommunication Union – Radiocommunication Sector
ITU-T International Telecommunication Union – Telecommunication Standardization Sector
ITWG International TOVS Working Group
IUCAF Scientific Committee on the Allocation of Frequencies for Radio Astronomy and Space Science (UNESCO)
IUGG International Union for Geodesy and Geophysics
IVS International VLBI Satellite
IWG Intersessional working group (of the SFCG)
IWP Interim Working Party (ITU-R)
IZMIRAN Institute of Terrestrial Magnetism, Radio Research and the Ionosphere (Russia)

Committee on Radio Astronomy Frequencies