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- Direction_finding abstract "Direction finding (DF), or radio direction finding (RDF), refers to the measurement of the direction from which a received signal was transmitted. This can refer to radio or other forms of wireless communication. By combining the direction information from two or more suitably spaced receivers (or a single mobile receiver), the source of a transmission may be located in space via triangulation. Radio direction finding is used in the navigation of ships and aircraft, to locate emergency transmitters for search and rescue, for tracking wildlife, and to locate illegal or interfering transmitters.RDF systems can be used with any radio source, although the size of the receiver antennas are a function of the wavelength of the signal - very long wavelengths (low frequencies) require very large antennas, and are generally used only on ground-based systems. These wavelengths are nevertheless very useful for marine radio navigation as they can travel very long distances "over the horizon", which is valuable for ships when the line-of-sight may be only a few tens of kilometres. For aerial use, where the horizon may extend to hundreds of kilometres, higher frequencies can be used, allowing the use of much smaller antennas. An automatic direction finder, which could be tuned to radio beacons called non-directional beacons or commercial AM radio broadcasters, was until recently, a feature of most aircraft, but is now being phased out For the military, RDF is a key component of signals intelligence systems and methodologies. The ability to locate the position of an enemy broadcaster has been invaluable since World War I, and played a key role in World War II's Battle of the Atlantic. It is estimated that the UK's advanced "huff-duff" systems were directly or indirectly responsible for 24% of all U-Boats sunk during the war. Modern systems often used phased array antennas to allow rapid beamforming for highly accurate results, and are part of a larger electronic warfare suite.Several distinct generations of RDF systems have been used over time, following the development of new electronics. Early systems used mechanically rotated antennas that compared signal strengths, and several electronic versions of the same concept followed. Modern systems use the comparison of phase or doppler techniques which are generally simpler to automate. Early British radar sets were referred to as RDF, which is often stated was a deception. In fact, the Chain Home systems used large RDF receivers to determine directions. Later radar systems generally used a single antenna for broadcast and reception, and determined direction from the direction the antenna was facing.".
- Direction_finding thumbnail Radiotriangulation.jpg?width=300.
- Direction_finding wikiPageExternalLink ap_index.htm.
- Direction_finding wikiPageExternalLink 0,8599,1735091,00.html?.
- Direction_finding wikiPageID "820724".
- Direction_finding wikiPageRevisionID "602636803".
- Direction_finding hasPhotoCollection Direction_finding.
- Direction_finding subject Category:Automatic_identification_and_data_capture.
- Direction_finding subject Category:Avionics.
- Direction_finding subject Category:Radio-frequency_identification.
- Direction_finding subject Category:Radio_navigation.
- Direction_finding comment "Direction finding (DF), or radio direction finding (RDF), refers to the measurement of the direction from which a received signal was transmitted. This can refer to radio or other forms of wireless communication. By combining the direction information from two or more suitably spaced receivers (or a single mobile receiver), the source of a transmission may be located in space via triangulation.".
- Direction_finding label "Direction finding".
- Direction_finding label "Funkpeilung".
- Direction_finding label "Radiogoniométrie".
- Direction_finding label "Radionamierzanie".
- Direction_finding label "Радиопеленгация".
- Direction_finding sameAs Funkpeilung.
- Direction_finding sameAs Radiogoniométrie.
- Direction_finding sameAs Radionamierzanie.
- Direction_finding sameAs m.03d__p.
- Direction_finding sameAs Q1367488.
- Direction_finding sameAs Q1367488.
- Direction_finding wasDerivedFrom Direction_finding?oldid=602636803.
- Direction_finding depiction Radiotriangulation.jpg.
- Direction_finding isPrimaryTopicOf Direction_finding.
