It is popular to blame new technology for killing things. The Internet killed newspapers. Video killed the radio star. Is FT8, a new digital technology, poised to kill off ham radio? The community seems evenly divided.
That really misses the point though anyway. Many antenna designs exhibit this property. The problem is, the antenna elements are typically about a half wavelength in size. On 2 metres the directional aerial is usually a small Yagi antenna which has a peak Prsion strip search one direction. For the military, RDF is a key tool of signals Amateur radio df. Yes I have. I call BS on that!
My neighbours hot mom. Latest RDF News Headlines
ARDF equipment is a specialty market, raido much of what is available for purchase comes from small commercial vendors or small-batch production by individuals. Email or Phone Password Forgot account? VE's conduct Amateur radio df license exams to others on a volunteer basis. See also: Radio direction finder. Each competitor receives a detailed topographic map of the competition area. Appleyard, S. Camel rxdio Greyhound racing Horse Amateur radio df Pigeon racing Sled dog racing. It has been suggested that Tracking transmitter be merged into this article. A small vertical antenna element can be combined with the Gay cockwear or ferrite rod antenna to change the receiving pattern to a cardioid shape, but the resulting null in the cardioid is not as sensitive as the nulls in the Nude ar receiving pattern. Alpine skiing Cross-country skiing Snowboarding Speed skating Sledding. September,pp. Competitors start at 2 min intervals and have to visit between 3 and 5 controls out of the first set according to their age class before visiting the compulsory spectator control.
Direction Finding DF is an international competative sport where a team or individual has to locate a number of hidden transmitters using basic equipment, namely: a receiver, directional antenna and usually a map.
- Great picnic at Saul Junction last night!
- Direction finding DF , or radio direction finding RDF , is the measurement of the direction from which a received signal was transmitted.
- Amateur radio direction finding ARDF , also known as radio orienteering , radio fox hunting and radiosport is an amateur racing sport that combines radio direction finding with the map and compass skills of orienteering.
Amateur radio direction finding ARDF , also known as radio orienteering , radio fox hunting and radiosport is an amateur racing sport that combines radio direction finding with the map and compass skills of orienteering.
It is a timed race in which individual competitors use a topographic map , a magnetic compass and radio direction finding apparatus to navigate through diverse wooded terrain while searching for radio transmitters. The rules of the sport and international competitions are organized by the International Amateur Radio Union. ARDF events use radio frequencies on either the two-meter or eighty-meter amateur radio bands. These two bands were chosen because of their universal availability to amateur radio licensees in all countries.
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 sport originated in Northern Europe and Eastern Europe in the late s.
Amateur radio was widely promoted in the schools of Northern and Eastern Europe as a modern scientific and technical activity. One of the activities that schools and radio clubs promoted was radio direction finding, an activity that had important civil defense applications during the Cold War.
Interest in this kind of on-foot radio direction finding activity using detailed topographic maps for navigation spread throughout Scandinavia, Eastern and Central Europe , the Soviet Union , and the People's Republic of China. Formal rules for the sport were first proposed in England and Denmark in the s. The first World Championship was held in in Cetniewo, Poland , where competitors from eleven European and Asian countries participated. World Championships have been generally held in even-numbered years since , although there was no World Championship in , and there was a World Championship in Asian nations began sending national teams to international events in , and teams from nations in Oceania and North America began competing in the s.
Athletes from twenty-six nations attended the World Championship in Nanjing , China, the first to be held outside of Europe. As the sport grew in the s and s, each nation devised its own set of rules and regulations. These rules have been revised and updated over the years, increasing the number of gender and age categories into which competitors are classified, as well as formalizing the start and finish line procedures. The IARU divides the world into three regions for administrative purposes.
These regions correspond with the three regions used by the International Telecommunications Union for its regulatory purposes, but the IARU has also used these regions for sports administration.
ARDF is a sport that spans much of the globe. Although they represent a broad range of amateur radio interests in their nations today, several member societies of the International Amateur Radio Union were originally formed for the promotion and organization of the sport and continue to use the term radiosport in their society name.
An ARDF competition normally takes place in diverse wooded terrain, such as in a public park or natural area but competitions have also been held in suitable suburban areas. Each competitor receives a detailed topographic map of the competition area. The map will indicate the location of the start with a triangle and the location of the finish with two concentric circles.
Somewhere within the competition area designated on the map, the meet organizer will have placed five low power radio transmitters. The locations of the transmitters are kept a secret from the competitors and are not marked on the map. Each transmitter emits a signal in Morse code by which it is easily identifiable to the competitors.
The transmitters automatically transmit one after another in a repeating cycle. Depending on entry classification, a competitor will attempt to locate as many as three, four, or all five of the transmitters in the woods, and then travel to the finish line in the shortest possible time.
Standings are determined first by the number of transmitters found, then by shortest time on course. Competitors who take longer than the specified time limit to finish may be disqualified. ARDF events use radio frequencies on either the 2-meter or meter amateur radio bands. Each band requires different radio equipment for transmission and reception , and requires the use of different radio direction finding skills. Radio direction finding equipment for eighty meters, an HF band, is relatively easy to design and inexpensive to build.
Bearings taken on eighty meters can be very accurate. Competitors on an eighty-meter course must use bearings to determine the locations of the transmitters and choose the fastest route through the terrain to visit them. Competitors on a two-meter course must learn to differentiate between accurate, direct bearings to the source of the radio signal and false bearings resulting from reflections of the signal off hillsides, ravines, buildings, or fences. Large national or international events will have one day of competition using a 2-meter frequency and one day of competition using an meter frequency.
In addition to the rules of the sport, ARDF competitions must also comply with radio regulations. Because the transmitters operate on frequencies assigned to the Amateur Radio Service, a radio amateur with a license that is valid for the country in which the competition is taking place must be present and responsible for their operation.
Individual competitors, however, are generally not required to have amateur radio licences, as the use of simple handheld radio receivers does not typically require a license.
Regulatory prohibitions on the use of amateur radio frequencies for commercial use generally preclude the awarding of monetary prizes to competitors.
Typical awards for ARDF events are medals, trophies, plaques, or certificates. Current IARU rules divide entrants into different categories based on their age and gender. These competitions are restricted to competitors aged sixteen years or younger. The IARU rules go into great detail about certain procedures that are unique to international championships events.
Not every ARDF competition follows all of these rules. Common variations to the generally accepted rules exist at local events. Some events will use simpler start procedures, such as using only one starting corridor instead of two. ARDF events on the two meter band in North America sometimes use frequency modulation instead of amplitude modulation for the transmission of the Morse code identifications.
In fact, many ARDF competitions use existing orienteering maps , in collaboration with the orienteering clubs that created those maps. Course design is an important element of a successful competition. The international rules adopted by the IARU include both requirements and recommendations for basic course design.
The IARU rules for international competitions recommend that courses be designed for six to ten kilometers of total travel distance through the terrain. ARDF equipment is a specialty market, and much of what is available for purchase comes from small commercial vendors or small-batch production by individuals. Building equipment, such as handheld antennas , from published designs or kits is also a popular activity. ARDF transmitters have a low power output and operate in either the two meter or eighty meter amateur radio band.
The transmissions are in Morse code. Each transmitter sends a unique identification that can be easily interpreted even by those unfamiliar with the Morse code by counting the number of dits that follow a series of dashes.
The transmitters on course all transmit on the same frequency and each transmit in sequence for one minute at a time in a repeating cycle. Within a few meters of each transmitter, an orienteering control flag and punch device will be present. For many events and all major events, the punch device is an electronic system, such as SPORTident, used in orienteering competitions. This records the time competitors visit each control on a small device that they carry.
An alternative is to use pin punches which the competitor uses to make a distinct pattern on a control card they carry. Competitors need to locate the control flag at the transmitter site and use the punch device to record their visit. Good course design will attempt to preclude, as much as possible, runners interfering with the transmitter equipment as they approach the control.
At large international or national events, jurors might be present at transmitter controls to ensure fair play. The IARU rules include detailed technical specifications for transmitter equipment. The transmitter antennas used on two meters must be horizontally polarized and omnidirectional. Transmitters for eighty meters are typically one to five watts power output keyed CW modulation. The transmitter antennas used on eighty meters must be vertically polarized and omnidirectional.
It is common for the transmitter, a battery , and any controlling hardware to be placed inside a weatherproof container such as an old ammunition case or large plastic food storage container for protection from the elements and wildlife. 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.
This includes a radio receiver that can tune in the specific frequency of transmission being used for the event, an attenuator or variable gain control, and a directional antenna. Flexible steel tape enables the antenna elements to flex and not break when encountering vegetation in the forest. On the eighty meter band, two common receiver design approaches are to use either a small loop antenna or an even smaller loop antenna wound around a ferrite rod.
A small vertical antenna element can be combined with the loop or ferrite rod antenna to change the receiving pattern to a cardioid shape, but the resulting null in the cardioid is not as sensitive as the nulls in the bidirectional receiving pattern. A switch is often used to allow the competitor to select the bidirectional or cardioid patterns at any moment. ARDF receiver equipment is designed to be lightweight and easy to operate while the competitor is in motion as well as rugged enough to withstand use in areas of thick vegetation.
The IARU rules specify that the choice of clothing is an individual decision of the competitor, unless the meet director specifies otherwise.
Nylon pants, shirts, or suits, gaiters or padded socks for lower leg protection, and specialty shoes for cross-country running through wooded terrain are popular choices. Some competitors may choose to carry food or water on course, and wear a small waist pack or hydration pack for this purpose.
At large international or national events, competitors may be required by the meet director to wear identifying numbers pinned to their clothing, and many wear team uniforms in their national colors. In addition to the radio equipment and topographic map, an ARDF competitor uses a magnetic compass for navigation. Some events may require or suggest that competitors carry a whistle for emergency use.
In at least one World Championship event, competitors were provided with cards written in the native language of the host country, intended to aid in communications with local citizens in the event that a competitor needed emergency aid or directions. In general, the use of cellular phone , or two-way radio equipment on course is prohibited. Sprint events have shorter courses with an expected winning time of 15 minutes and use either a or map.
There is also a "spectator" control and a "beacon" control which both operate on different frequencies to the other ten, so four frequencies are used in total.
It is possible to combine the spectator control with the beacon control. Competitors start at 2 min intervals and have to visit between 3 and 5 controls out of the first set according to their age class before visiting the compulsory spectator control.
They then visit the requisite controls from the second set before punching the compulsory beacon control, prior to finishing. The location of each transmitter will be indicated on the map with a circle. The transmitter does not need to be exactly at the circle's center or even located inside the circle, but one should be able to receive its transmissions everywhere within the area indicated by the circle.
A competitor must use orienteering skills to navigate to the area of the circle on the map and only then use radio direction finding skills to locate the very low power transmitter. The transmitters are physically small, and marked with a control card that is no larger than a typical postcard with a unique number identification.
From Wikipedia, the free encyclopedia. This article relies too much on references to primary sources. Please improve this by adding secondary or tertiary sources.
Because the transmitters operate on frequencies assigned to the Amateur Radio Service, a radio amateur with a license that is valid for the country in which the competition is taking place must be present and responsible for their operation. Bearings taken on eighty meters can be very accurate. Map orienteering map Navigation cardinal direction resection route choice wayfinding waypoint Racing hiking running walking skiing mountain biking. Shortwave radio Amateur radio operator. ARDF events on the two meter band in North America sometimes use frequency modulation instead of amplitude modulation for the transmission of the Morse code identifications. Competitors need to locate the control flag at the transmitter site and use the punch device to record their visit. Open water swimming Marathon swimming Paralympic swimming.
Amateur radio df. The Art and Science of Radio Direction Finding (RDF)
Also includes collecting old wireless and telegraph keys. DX Clusters tell others when unusual stations are on the air. Boy Scout Radio merit badge. An "Elmer" is an amateur radio mentor. This is the only way to get a license today. Who was the first "amateur" radio operator? Einar Dessau of Denmark is regarded as the first ham radio operator with his transmission using a shortwave radio set to communicate with a government radio post six miles away on 18 March Please e-mail your suggestions!
Special Equipment or Requirements. Operating amateur radio stations on non-commercial alternative and emergency power sources. ATV can transmit full-motion video over the air compatible with standard television. NJ Antique Radio Boatanchors. Collecting, repairing, and maybe selling old broadcast receivers and other radios. APRS , findU. Use of the Global Positioning System GPS to provide one's location over the air, which can then be plotted on a map on a computer screen.
ARRL qsl. Assisting the United States Coast Guard in various functions, including communications. Use of amateur radio in support of community activities, such as charity events, civil celebrations, etc. Log book or computer, Contest Calendar , rules of contest. Locating a transmitter using direction-finding techniques. Trying to work as many stations in distant and remote locations as possible. An on-air packet network called DXCluster provides "spots" of rare stations.
An expedition to a remote location where few or no amateurs already live in order to permit other hams to "work" a new country. Using amateur radio to provide backup communications during emergencies and disasters, such as floods, storms, etc.
Planning for and assisting in emergency preparedness for state, county and local governments. Searching for signs of intelligent extraterrestrial life through detection of radio signals. Flea markets where you can buy or sell used or new equipment, supplies, books, etc. Building one's own amateur radio equipment from scratch or from kits. Good Interference handbook , direction finding equipment, test equipment. Use of the Internet to relay amateur radio calls around the world, creating networks linked by VoIP.
As usual, with Monday 27th May being a Bank Holiday, there is no meeting at the club. See our website for details about operating from Crickley Hill. Good explanation of the Koch method. New radio amateurs interested in learning morse should read this before starting any tuition. Monday 15th April - no meeting, school closed.
Very clear and essentially so simple! Not yet made it across the pond to the USA, but stations are present. If you have hesitated to give this mode a go, I can recommend it - I can see how it could become addictive! Jump to. Sections of this page. Accessibility Help. Email or Phone Password Forgot account?
Log In. Forgot account? Not Now. Visitor Posts. Brian Woodcock. Information about Page Insights Data.
2M DF Antenna | Ham Radio | Ham radio antenna, Ham radio, Ham
Direction finding DF , or radio direction finding RDF , is the measurement of the direction from which a received signal was transmitted. 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.
In the former, the Air Ministry also used RDF to locate its own fighter groups and vector them to detected German raids. RDF systems can be used with any radio source, although very long wavelengths low frequencies require very large antennas, and are generally used only on ground-based systems. These wavelengths are nevertheless used 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. For the military, RDF is a key tool of signals intelligence. Early radio direction finders 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. Later radar systems generally used a single antenna for broadcast and reception, and determined direction from the direction the antenna was facing.
Many antenna designs exhibit this property. For example, a Yagi antenna has quite pronounced directionality, so the source of a transmission can be determined simply by pointing it in the direction where the maximum signal level is obtained. A simple form of directional antenna is the loop aerial. This consists of an open loop of wire on an insulating former, or a metal ring that forms the antenna elements itself, where the diameter of the loop is a tenth of a wavelength or smaller at the target frequency.
This is caused by the phase output of the transmitting beacon. Turning the loop face on will not induce any current flow. Simply turning the antenna to obtain minimum signal will establish two possible directions from which the signal could be emanating.
The NULL is used, as small angular deflections of the loop aerial near its null positions produce larger changes in current than similar angular changes near the loops max positions. For this reason, a null position of the loop aerial is used. To resolve the two direction possibilities, a sense antenna is used, the sense aerial has no directional properties but has the same sensitivity as the loop aerial. A dipole antenna exhibits similar properties, and is the basis for the Yagi antenna, which is familiar as the common VHF or UHF television aerial.
For much higher frequencies still, parabolic antennas can be used, which are highly directional, focusing received signals from a very narrow angle to a receiving element at the centre. Government as early as Single-channel DF uses a multi-antenna array with a single channel radio receiver. Since it only uses one receiver, mobility and lower power consumption are benefits. The two main categories that a single channel DF algorithm falls into are amplitude comparison and phase comparison.
Some algorithms can be hybrids of the two. The pseudo-doppler technique is a phase based DF method that produces a bearing estimate on the received signal by measuring the doppler shift induced on the signal by sampling around the elements of a circular array. The original method used a single antenna that physically moved in a circle but the modern approach uses a multi-antenna circular array with each antenna sampled in succession.
The Watson-Watt technique uses two Adcock antenna pairs to perform an amplitude comparison on the incoming signal. An Adcock antenna pair is a pair of monopole or dipole antennas that takes the vector difference of the received signal at each antenna so that there is only one output from the pair of antennas. Two of these pairs are co-located but perpendicularly oriented to produce what can be referred to as the N-S North-South and E-W East-West signals that will then be passed to the receiver.
In the receiver, the bearing angle can then be computed by taking the arctangent of the ratio of the N-S to E-W signal. The basic principle of the correlative interferometer consists in comparing the measured phase differences with the phase differences obtained for a DF antenna system of known configuration at a known wave angle reference data set.
The comparison is made for different azimuth values of the reference data set, the bearing is obtained from the data for which the correlation coefficient is at a maximum. If the direction finding antenna elements have a directional antenna pattern, then the amplitude may be included in the comparison.
Radio direction finding , radio direction finder , or RDF , was once the primary aviation navigational aid. Range and Direction Finding was the abbreviation used to describe the predecessor to radar. Since the signal transmitted contains no information about bearing or distance, these beacons are referred to as non-directional beacons , or NDB in the aviation world.
Starting in the s, these beacons were generally replaced by the VOR system, in which the bearing to the navigational aid is measured from the signal itself; therefore no specialized antenna with moving parts is required. Due to relatively low purchase, maintenance and calibration cost, NDB's are still used to mark locations of smaller aerodromes and important helicopter landing sites.
Very few maritime radio navigation beacons remain active today as ships have abandoned navigation via RDF in favor of GPS navigation. In the United Kingdom a radio direction finding service is available on The service is based on a number of radio DF units located at civil and military airports and certain HM Coastguard stations. One of the problems with providing coverage of an area the size of the UK was installing sufficient DF stations to cover the entire area to receive skywave signals reflected back from the ionised layers in the upper atmosphere.
Even with the expanded network, some areas were not adequately covered and for this reason up to voluntary interceptors radio amateurs were recruited to detect illicit transmissions by ground wave. If a transmitter was identified by the fixed DF stations or voluntary interceptors, the mobile units were sent to the area to home in on the source.
The mobile units were HF Adcock systems. By only a couple of illicit transmitters had been identified in the UK; these were German agents that had been "turned" and were transmitting under MI5 control. Many illicit transmissions had been logged emanating from German agents in occupied and neutral countries in Europe.
The traffic became a valuable source of intelligence, so the control of RSS was subsequently passed to MI6 who were responsible for secret intelligence originating from outside the UK.
The direction finding and interception operation increased in volume and importance until The bearing obtained was considerably sharper than that obtained with the U Adcock system, but there were ambiguities which prevented the installation of 7 proposed S. L DF systems. The operator of an SL system was in a metal underground tank below the antennas. Seven underground tanks were installed, but only two SL systems were installed at Wymondham, Norfolk and Weaverthorp in Yorkshire.
Problems were encountered resulting in the remaining five underground tanks being fitted with Adcock systems. The rotating SL antenna was turned by hand which meant successive measurements were a lot slower than turning the dial of a goniometer. Another experimental spaced loop station was built near Aberdeen in for the Air Ministry with a semi-underground concrete bunker. This, too, was abandoned because of operating difficulties. By , a mobile version of the spaced loop had been developed and was used by RSS in France following the D-Day invasion of Normandy.
The loops were placed at the ends of a beam, all of which was located inside a wooden hut with the electronics in a large cabinet with cathode ray tube display at the centre of the beam and everything being supported on a central axis. The beam was rotated manually by the operator. They built groups of five DF stations, so that bearings from individual stations in the group could be combined and a mean taken. Groups were also built in Iceland, Nova Scotia and Jamaica. The anticipated improvements were not realised but later statistical work improved the system and the Goonhavern and Ford End groups continued to be used during the Cold War.
The Royal Navy also deployed direction finding equipment on ships tasked to anti-submarine warfare in order to try to locate German submarines, e. A network of remotely operated VHF direction finders are used mainly located around the major cities.
The transmissions from mobile telephone handsets are also located by a form of direction finding using the comparative signal strength at the surrounding local "cell" receivers. There are many forms of radio transmitters designed to transmit as a beacon in the event of an emergency, which are widely deployed on civil aircraft. Modern emergency beacons transmit a unique identification signal that can aid in finding the exact location of the transmitter.
Since the power of the beacon is so low the directionality of the radio signal is dominated by small scale field effects  and can be quite complicated to locate. The technique was first used in the early s, when the technology used in radio transmitters and batteries made them small enough to attach to wild animals , and is now widely deployed for a variety of wildlife studies.
When the researcher wants to locate a particular animal, the location of the animal can be triangulated by determining the direction to the transmitter from several locations.
Phased arrays and other advanced antenna techniques are utilized to track launches of rocket systems and their resulting trajectories. These systems can be used for defensive purposes and also to gain intelligence on operation of missiles belonging to other nations. These same techniques are used for detection and tracking of conventional aircraft. Events hosted by groups and organizations that involve the use of radio direction finding skills to locate transmitters at unknown locations have been popular since the end of World War II.
From Wikipedia, the free encyclopedia. For the navigation device used in aircraft, see Radio direction finder. It has been suggested that Tracking transmitter be merged into this article.
Discuss Proposed since April See also: Radio direction finder. Main article: Adcock antenna. Further information: Non-directional beacon. Main article: Radio direction finder. Main article: Amateur Radio Direction Finding. Archived from the original PDF on Air Band Radio Handbook 8th Edition. Sutton Publishing. Wireless Direction Finding 4th ed. London, UK: Iliffe.
Biyd; D. Harris; D. King; H. Welch, Jr. Electronic Countermeasures. Edgerly