DF

apparatus for determining the source of a conveyed signal, radio signal receiver

DF or df may stand for:df (Unix), a Unix command to report disk space usage by filesystemDanish People's Party (Dansk Folkeparti)Dean FoodsDirection finding, a technique used to locate a radio transmitterDistrito Federal, e.g. the Mexican Federal District or Brazilian Federal DistrictDegrees of freedom, a measure of the number of independent pieces of information on which a parameter estimate is basedDespair Faction, a fan club for the band AFIMethylphosphonyl difluoride, a chemical weapons precursor listed in schedule 1 of the Chemical Weapons ConventionDensity function, a mathematical function which has a wide range of applications such as in the study of macromolecular structureDigital Fantasticness, a local band in Blythe, CADistrict Fellows, the 16-20 age group of the Woodcraft FolkDF is the chemical formula for deuterium fluoride: see for example deuterium fluoride laserDF, a Gangsta rapper from Winnende in GermanyDragonForce, a British power metal bandDungeon Family, an Atlanta hip hop music collectiveDark Future, a 1988 miniature wargame by Games WorkshopStar Wars: Dark Forces, a 1995 first-person shooter by LucasArtsSlaves to Armok II: Dwarf Fortress, a 2006 computer game by Bay 12 GamesDragonFable, a single-player RPG that runs on a browserDongfeng, see Dongfeng (disambiguation)DeFRaG, an unofficial Quake III Arena modification
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Mexico City, capital city of Mexico (country in southern North America)

Federal District

A radio receiver equipped with a directional sensing antenna used to take bearings on a radio transmitter. Specialized radio direction finders are used in aircraft as air navigation aids. Others are ground-based, primarily to obtain a "fix" on a pilot requesting orientation assistance or to locate downed aircraft. A location "fix" is established by the intersection of two or more bearing lines plotted on a navigational chart using either two separately located Direction Finders to obtain a fix on an aircraft or by a pilot plotting the bearing indications of his Direction Finder (DF) on two separately located ground-based transmitters both of which can be identified on his chart. (FAA4) (FAA8)