Radio direction finding

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Topic: Radio direction finding

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	Radio direction finding - Wikipedia, the free encyclopedia
		Radio direction finder, or RDF, is a term used to describe a navigational device for finding the direction to a radio transmitter source.
		There are two common technical approaches to radio direction finding; one approach involves the use of directional antennas, and the other exploits the effects of Doppler shift.
		Directional antennas are designed to be more sensitive to received signals in some directions than in others.
	en.wikipedia.org /wiki/Radio_direction_finding (925 words)

	Amateur Radio Direction Finding - Wikipedia, the free encyclopedia
		The radio equipment carried by competitors on a course must be capable of receiving the signal being transmitted by the five transmitters and useful for radio direction finding, including a radio receiver, attenuator, and directional antenna.
		The radio equipment carried on course must be capable of receiving the signal being transmitted by the five transmitters and useful for radio direction finding.
		Radio direction finding equipment for eighty meters, an HF band, is relatively easy to design and inexpensive to build.
	en.wikipedia.org /wiki/Amateur_Radio_Direction_Finding (3400 words)

	Radio direction finding systems - Patent 4328499
		A radio direction finding system in accordance with claim 2 wherein said remaining antenna elements are connected in turn to said other receiving arrangement to provide a succession of phase difference signals from which a value for the angle of arrival of said radio signals may be derived.
		A radio direction finding system in which the angle of arrival of radio signals incident on a group of antenna elements is determined from the relative phase or phases of the radio signals incident upon two or more of said antenna elements.
		In particular the invention is concerned with direction finding systems in which a value for the direction of arrival of radio signals incident upon two or more spaced antenna elements is derived from the relative phases of said radio signals at the two or more antenna elements.
	www.freepatentsonline.com /4328499.html (1448 words)

	Radio Direction-finding for Wildlife Research
		In 1960 very small radio transmitters were attached to a cottontail rabbit and a mallard duck, which were then tracked by direction-finding in Allerton Park, Piatt County, and about the prairie of Champaign County, Illinois [1].
		The design of this system will be described, with emphasis on the direction finding array and on the antenna arrangement on the target animal, typically a small bird.
		Unlike peak-null switching, which provides no directional cue, the beam that produces the strongest signal indicates the direction in which the antennas must be rotated in order to bring the transmitter in line with the boresight, a key feature for automatic operation.
	userweb.piasanet.com /sparrow/Direction-finding.html (3494 words)

	Definition: radio direction-finding
		radio direction-finding [RDF]: Radiodetermination using the reception of radio waves for the purpose of determining the direction of a station or object.
	www.its.bldrdoc.gov /fs-1037/dir-030/_4368.htm (37 words)

	rdf.htm
		Hidden Transmitter Hunting has been one of the aspects of amateur radio which always interested me. I have built many projects over the years and have placed construction details for a few of them here.
		If you find anything which is either incorrect or misrepresented, send me a note and I'll make the corrections as appropriate.
		I will add to this collection as I find the time to build the web pages (and the projects).
	home.att.net /~jleggio/projects/rdf/rdf.htm (254 words)

	Doppler-Shift Radio Direction Finding - March 11th Fact-of-the-Day
		Doppler-shift is an alternative radio direction finding technology that doesn't require a directional antenna.
		Radio amateurs most often use the directional characteristics of antennas to find bearings to unknown signals.
		To understand the principle underlying Doppler direction finding, visualize a vertical dipole mounted on the end of an arm that rotates rapidly around its opposite end.
	www.smeter.net /daily-facts/3/fact11.php (143 words)

	Amateur Radio Direction Finding Home
		It consists of a gathering of the local radio amateurs, mostly living on the island of Penang, who finds that this form of radio orienteering enhances their skills to seek out spurious transmissions caused by jammed transmitters and encouraging the participants to homebrew their own gadgets, like portable directional antennas, etc.
		The Penang Group of Radio Amateurs are promoting this form of Radio Sport, to foster closer ties with fellow amateurs.
		Normally, a time period of 1 to 2 hours is allocated for the hunters to find the beacons in the field, however, more time may be given if the beacons are made less accessible.
	www.myardfsport.com (226 words)

	Direction Finding
		The purpose of Direction Finding is to locate a radio transmitting device through signal measurement and triangulation.
		Fox hunters often use directional antennas, known as yagis or beams to determine the direction of the transmitter.
		The principle behind simple direction finding is to travel in a straight direction while noticing the signal strength.
	www.ranv.org /df.html (927 words)

	Annex C - World War II Ground Radar
		On 21 June 1943 the allied "Committee on RDF" was renamed the "Committee on Radar" and on 23 August 1943 the American term "RADAR" (RAdio Direction And Ranging) was officially adopted in place of "Radio Direction Finding".
		Early RCAF radio direction finding, later radar, stations often included the type of radar used within the unit title.
		In April 1941 recruiting of RCAF "radio technicians" for "Overseas Duty" began and in June 1941 preparatory radio training for candidates was begun in Canada.
	www.img.forces.gc.ca /commelec/Brhistory/anxc_e.htm (1695 words)

	Three Radio Direction-Finding Methods - March 10th Fact-of-the-Day
		A wide variety of radio direction-finding systems have been developed employing a similar variety of antennas.
		Radio direction-finders in the last category work the other way around in that they find bearings to receiving locations from one or more transmitting stations.
		Radio direction-finders in first two categories can be used to find azimuth bearings from receiving locations to transmitting stations.
	www.smeter.net /daily-facts/3/fact10.php (123 words)

	RTFTechnologies Radio Direction Finding System
		A time difference of arrival RDF unit utilizes the perceived frequency modulation of an incoming rf signal by switching between two antennas and comparing the timing of the antenna switching to the polarity of the tone generated in the receiver audio.
		If the antennas are equidistant from the transmitter there is no perceived frequency modulation, however if one antenna is closer to the transmitter then the other there will be a perceived frequency modulation at the point when the antennas are switched due to the phase difference of the RF signal at the antennas.
		The RF output from the antenna unit passes through a high pass filter to remove the 500Hz square wave and the signal is feed to the RF input connector on the radio.
	www.rtftechnologies.org /electronics/tdoardf.htm (343 words)

	Definition: radio direction-finding station
		radio direction-finding station: A radiodetermination station using radio direction-finding.
		This HTML version of Telecom Glossary 2K was last generated on Wed May 8 15:36:48 MDT 2002.
	www.its.bldrdoc.gov /projects/devglossary/_radio_direction-finding_station.html (26 words)

	Amateur Radio Direction Finding Web Ring
		Radio Direction Finding Projects which are simple and inexpensive to build.
		Transmitter hunting, radio direction finding in the San Francisco Bay Area.
		Images and descriptions of Foxhunting, ARDF and Radio Direction Finding equipment
	m.webring.com /hub?ring=foxhunt (711 words)

	RF Products Radio Direction Finder Applications Literature Index and Downloads
		RDF Products publishes a variety of applications literature both to aid users in their selection of new radio direction finding products as well as to help users more effectively deploy and operate their existing radio direction finding equipment:
		Discusses the relative merits of Adcock and loop DF Antennas for fixed-site radio direction finding applications using a 30 MHz installation as an example.
		RDF Products also publishes Application Notes to help illuminate various aspects of radio direction finding technology.
	www.rdfproducts.com /ap_index.htm (681 words)

	What is T-Hunting and ARDF? - Albuquerque Transmitter Hunting Homepage
		Transmitter Hunting (also known as T-Hunting, fox hunting, radio direction finding) is a popular activity among Amateur Radio operators where a transmitter - usually on the 2-meter band - is actually hidden somewhere and is "hunted" (found) using radio direction finding techniques.
		When the transmitter is on the air, the hunters "take bearings" using directional antennas by determining the direction where the signal is the strongest.
		The Georgia Radio Orienteering Club hosted the second 2002 USA ARDF Championships near Atlanta in April of 2002, five Members of team Albuquerque competed in the championships.
	home.att.net /~wb8wfk/whatis.html (1115 words)

	HOMING IN -- Radio Direction Finding
		Radio direction finding is used to find sources of interference to any form of wireless electronic communications, including broadcast and two-way radio, television, and telephones.
		He has designed new devices for radio direction finding and has written about RDF and other topics for almost every ham radio publication in the USA.
		TRANSMITTER HUNTING---Radio Direction Finding Simplified (THRDFS) by Moell and Curlee, a comprehensive illustrated text on all aspects of RDF including theory, techniques, and projects for the HF, VHF, and UHF bands.
	members.aol.com /homingin (3341 words)

	rf
		The owner and chief design engineer of the company has a diverse background in electronics and has specialized in the design of high performance, low cost radio direction finding products.
		We have been involved in Radio Direction Finding activities for several years.
		CSE is the worldwide distributor of low cost, excellent performing Radio Direction Finding Systems.
	www.cse-assoc.com /rf.html (224 words)

	Best Ham Radio Links - NØHR.com
		Someone hides a small, low-power transmitter in a town and the rest of the ham radio operators use direction finding equipment to locate the transmitter.
		Arrow antennas produces VHF and UHF beams, JPoles and handheld antennas for direction finding.
		Skills obtained in this "radio sport" are useful in real-world applications - such as finding a lost hiker or tracking down nuisance transmitters (interferenece).
	www.n0hr.com /total/display.php?catnum=135 (169 words)

	Radio Direction Finding, Bunny hunting, T-hunting, Amateur Radio Direction Finding is all the same known by different names, has been a very popularly growing Radio Sport
		Radio Direction Finding, Bunny hunting, T-hunting, Amateur Radio Direction Finding is all the same known by different names, has been a very popularly growing Radio Sport
		Japanese fear of DF caused strict radio silence to be observed.
		During World War I there were many RDF antennas and equipments developed and
	www.cqindia.com /ham_radio_india_f/fox_hunting_evolution.htm (1565 words)

	Radio Foxhunting
		Radio Direction finding is a hobby shared by CB Radio operators and Amateur Radio operators alike.
		A completely external system would be good, but a hand operated directional antenna will do the job.
		The signal monitor would be yelling directions, the navigator trying to direct the driver and the driver trying to keep his cool.
	www.roity.com /rc/foxhunt.html (410 words)

	Fox, Bunny or T Hunting
		In Europe and Asia, radio direction finding evolved into a physical sport called (Amateur Radio Direction Finding ARDF), involving aspects of orienteering, a foot race over a large area through rugged terrain carrying a portable RDF unit, in search of several transmitters that are not necessarily concealed.
		Whatever you call it in your area, you are referring to a sport within the amateur radio hobby which is based on radio direction finding.
		One of the reasons why ARDF is gaining in popularity in North America and Britain is that it is an excellent public service for radio amateurs to help non-amateur youth participants in the hunt, and to introduce them to the fun of amateur radio.
	www.rac.ca /opsinfo/foxhunting.htm (232 words)

	Superresolution Direction Finding
		Superresolution Direction Finding systems based on our technology are operated at the UK Baldock Radio Station, in North America, Australia and a number of other countries around the world.
		Conventional direction finding techniques are capable of working successfully only when there is a single signal.
		The demonstration uses typical HF radio data where two signals are present on the same frequency channel.
	www.roke.co.uk /defence/srdf.asp (349 words)

	Safety@Sea (Aust) Radio Direction Finding
		Turning continuously around with the receiver in hand about 45 degrees, it is noticed that the signal is strongest in one direction.
		Since obstacles of terrain may change the direction and strenght of the signal.
		No matter which application you use, you can track the transmitter from your vehicle, boat or light plane by adding the mounting bracket, external antenna and car battery adapter.
	www.safetyatsea.com /aust/radiots.asp (640 words)

	UARC - Radio Direction Finding page
		Amateur ("Ham") Radio has had a long history of RDF as well: It is not surprising that radio enthusiasts would make a sport out of their hobby as well.
		Sometimes higher-powered radios start producing spurious signals when their output is "turned down" to a fraction of their designed power level.
		We spoke with the bench technician (who just happened to be a ham) and he'd gone through the radio (a 35 watt radio that was turned down to just 3 watts) and found it to be clean.
	www.ussc.com /~uarc/rptr/UARC_RDF1.html (2686 words)

	Direction Finding : Operating Modes: Radio Direction Finding
		Radiopejlorientering - Radio Direction Finding - The Swedish ARDF page is mainly presented in the Swedish language, but some articles are in English.
		Transmitter hunting - Locating or finding radio transmission sources or hidden radio transmitters is known as transmitter hunting.
		Triangulating a radio signal direction and plotting its bearing on a map.
	www.dxzone.com /catalog/Operating_Modes/Radio_Direction_Finding (1160 words)

	Radio Direction Finding Recreation, Directory
		Transmitter Hunting Amateur radio direction finding, transmitter hunting, by triangulating a radio signals direction and plotting its bearing on a map.
		N6QAB's Radio Direction Finding Web Page Pictures and descriptions of Radio Direction Finding and Transmitter Hunting equipment.
		RDF Fox Hunting Home Brew Projects Download free project plans for radio direction finders and locators.
	www.wtcpa.org /d3RfNDM5MzQ=.aspx (255 words)

	Amateur Radio Direction Finding
		ARDF (Amateur Radio Direction Finding) is like a cross between hidden transmitter hunting (or "foxhunting" as it's commonly known) and orienteering.
		Instead, competitors are equipped with a receiver with a directional antenna to locate the transmitters, and a compass for navigational assistance.
		In fact, ARDF is sometimes called "Radio Orienteering", which is a very accurate description of the sport.
	vkradio.com /ardf.html (482 words)

	Radio direction finding vehicle tracking systems
		An ACTIVE station is one who obtains an RDF (Radio Direction Finding) bearing to the target, displays the bearing on his own mapped screen, and telemeters his bearings via the packet data link to other stations on the net.
		Frequently, handheld radios can be used in applications where space and power is at a premium, such as a manportable RDF node.
		The range of the data link is not limited to the simplex (direct, radio to radio) range of the data transceivers.
	www.swssec.com /tracknet.html (1584 words)

	KI6KY Radio Direction Finding Page
		High Frequency radio direction finding is quite a challenge.
		Weak signals, rapid QSB, brevity of ssb transmissions, varing angles of arrival, all combine to exasperate the would be HF radio direction finding enthusiast!
		He could be a little further to the East but the equipment's lack of angular resolution, at this Northern distance, does not help.
	www.ky-filters.com /df.htm (250 words)

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In the News (Mon 16 Nov 09)