direction finder


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direction finder,

electronic device used to determine the position of a ship or aircraft. In a simple direction finder a radio receiver is equipped with a revolving directional antenna. The antenna receives the strongest radio signal when it is pointing directly at a transmitter. By determining the direction of two land-based transmitters, a navigator may plot his position by triangulation. Direction finders have been replaced in many applications with more accurate systems, such as radarradar,
system or technique for detecting the position, movement, and nature of a remote object by means of radio waves reflected from its surface. Although most radar units use microwave frequencies, the principle of radar is not confined to any particular frequency range.
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 and satellite navigation systems (see satellite, artificialsatellite, artificial,
object constructed by humans and placed in orbit around the earth or other celestial body (see also space probe). The satellite is lifted from the earth's surface by a rocket and, once placed in orbit, maintains its motion without further rocket propulsion.
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).

Direction Finder

 

an instrument used in marine and air navigation to determine the direction in degrees to external reference points such as coastal or floating objects, heavenly bodies, and so on.

direction finder

[də′rek·shən ‚fīnd·ər]
(navigation)

direction finder (DF)

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. UDFs (ultrahigh frequency direction finders) receive signals in the ultrahigh frequency radio broadcast band; VDFs in the very high frequency band; and UVDFs (UHD/VHD direction finder) in both bands. See automatic direction finder.
References in periodicals archive ?
Included in this class of direction finders are the Watson-Watt and Wullenweber systems.
A wide range of systems was accepted for this sampling, from traditional radio direction finders to personal navigational aids.
The Vizir-80 automatic direction finder will locate the source of A1, A2, A3, A3A, A3J, F1 and F3 signals via a loop antenna.
The light-cone direction finder improves the localisation of multiple radio signals and the rejection of spurious signals in a complex electromagnetic environment and is significantly superior to current systems.
The software consolidates data gathered from sensors like radars, Automatic Identification System (AIS), Radio Direction Finders (RDF), cameras, weather stations and sonars.
For radar applications, CPI's antenna products include direction finders, air traffic control antennas and weather radar antennas up to 14 meters in size.
The modular Xpeller product family includes various sensors such as radar systems, cameras and radio frequency detectors as well as direction finders and jammers, it added.
VHF Direction Finders awarded the tender to the British Borneo Defence - Australia through Messrs.
Final approval by the Korea Communications Commission came earlier this month with the granting of a license to Apple to offer so-called location-based services, which include functions such as maps and direction finders that are available on the iPhone.
* Direction finders while driving, hiking or boating
Voice-Enabled Mobile Devices Two forces are driving speech technology in the car: Automobile manufacturers are embedding speech in the dashboard, and independent vendors provide car add-ons such as cell-phone holders and interactive direction finders. Voice-controlled cameras, MP3 players, video players, and phones are or will soon be available.
The system consists of three primary components: transmitters, receivers and direction finders. An individual transmitter, small enough to fit in a specially designed pocket on the float coat, is water-activated within three to five seconds after full submersion.

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