SHORAN is an acronym for SHO rt RA nge N avigation, a type of electronic navigation and bombing system using a precision radar beacon. It was developed during World War II and the first stations were set up in Europe as the war was ending, and was operational with Martin B-26 Marauders based in Corsica, and later based in Dijon and in B2-6's given to the South African Airforce in Italy. The first 10/10 zero visibility bombing was over Germany in March 1945. It saw its first combat use in the B-25, B-26 and B-29 bomber aircraft during the Korean War .
34-412: SHORAN used ground-based transponders to respond to interrogation signals sent from the bomber aircraft. By measuring the round-trip time to and from one of the transponders, the distance to that ground station could be accurately determined. The aircraft flew an arcing path that kept it at a set distance from one of the stations. The distance to a second station was also being measured, and when it reached
68-455: A flight transponder is an automated transceiver in an aircraft that emits a coded identifying signal in response to an interrogating received signal. In a communications satellite , a satellite transponder receives signals over a range of uplink frequencies, usually from a satellite ground station ; the transponder amplifies them, and re-transmits them on a different set of downlink frequencies to receivers on Earth, often without changing
102-760: A trilateration network, and permitting the positioning of European triangulation stations relative to the North American Datum . From July to September 1953, the US Air Force used HIRAN to survey a link between three geodetic stations in Norway and three on the Scottish mainland and Shetland islands . This marked the initial phase of a larger project which connected surveys of Norway, Iceland, and Greenland to Canada . The network linking Scotland to Norway comprised fifteen measured lines: three among
136-414: A lap they swipe or touch the receiver which is connected to a computer and log their lap time. NASCAR uses transponders and cable loops placed at numerous points around the track to determine the lineup during a caution period. This system replaced a dangerous race back to the start-finish line . Many modern automobiles have keys with transponders hidden inside the plastic head of the key. The user of
170-460: A new offensive opened. B-29's began the campaign, but only a dozen aircraft were available, so they were soon supplanted by B-26s to maintain constant bombing of the airfields. The possible offensive never occurred; the armistice was signed in July. It was not used after that point, due to Strategic Air Command 's increasing focus on long-range bombing with nuclear weapons . Although SHORAN was used by
204-556: A project known as the North Atlantic Tie. Shortly after World War II, the US Air Force had carried out a readjustment of all the triangulations of continental Europe to produce a geodetic datum known as ED50 , a single system on the Universal Transverse Mercator coordinate system . The North Atlantic Tie initiative aimed to create a geodetic link between North America and Europe, by measuring
238-540: A resident's car with simple transponder is parked in the vicinity, any vehicle can come up to the automated gate, triggering the gate interrogation signal , which may get an acceptable response from the resident's car. Such units properly installed might involve beamforming , unique transponders for each vehicle, or simply obliging vehicles to be stored away from the gate. Retriangulation of Great Britain Too Many Requests If you report this error to
272-520: A result, differences in transponder functionality also might influence the functional description of related optical modules like transceivers and muxponders . Another type of transponder occurs in identification friend or foe (IFF) systems in military aviation and in air traffic control secondary surveillance radar (beacon radar) systems for general aviation and commercial aviation . Primary radar works best with large all-metal aircraft, but not so well on small, composite aircraft. Its range
306-578: A set distance from that station as well, the bombs were dropped. The basic idea was similar to the Oboe system developed by the Royal Air Force , but in Oboe the transponder was on the aircraft. This limited Oboe to guiding a single aircraft per ground station, while SHORAN could guide dozens, limited only by how rapidly the ground station's transponders could respond. SHORAN was sent into combat due to
340-418: A ship's radar screen. Sonar transponders operate under water and are used to measure distance and form the basis of underwater location marking, position tracking and navigation . Electronic toll collection systems such as E-ZPass in the eastern United States use RFID transponders to identify vehicles. Transponders are used in races for lap timing. A cable loop is dug into the race circuit near to
374-405: A single aircraft, unlike Shoran which could guide multiple. On the return flight, nearly all information on Shoran was lost in a plane crash, and Seeley was forced to recreate the records from his own memory. He received a Magellanic award for his work in 1960. SHORAN, which operates at 300 MHz, requires an airborne AN/APN-3 set and two AN/CPN-2 or 2A ground stations. The equipment on board
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#1732783242904408-405: Is also limited by terrain and rain or snow and also detects unwanted objects such as automobiles, hills and trees. Furthermore, it cannot always estimate the altitude of an aircraft. Secondary radar overcomes these limitations but it depends on a transponder in the aircraft to respond to interrogations from the ground station to make the plane more visible. Depending on the type of interrogation,
442-412: Is mandatory in controlled airspace in many countries. Some countries have also required, or are moving toward requiring, that all aircraft be equipped with Mode S, even in uncontrolled airspace . However, in the field of general aviation there have been objections to these moves, because of the cost, size, limited benefit to the users in uncontrolled airspace, and, in the case of balloons and gliders ,
476-705: The Retriangulation of Great Britain between 1935 and 1962, the Ordnance Survey primary triangulation of the British Isles was connected to both Norway and Iceland using HIRAN, an enhanced version of SHORAN. Survey connections extending from primary triangulation points in Scotland to triangulation points in Norway and Iceland were facilitated by the US Air Force under the implementation of
510-544: The Army Air Force. Contract was awarded 9 months later, and SHORAN given its first military flight tests in August 1942. First procurement was spring 1944, with initial combat operations in northern Italy on December 11, 1944. During the system's development, Seeley and an RCA manager flew to England to describe the system to American and British air force personnel. There they observed the Oboe , which could guide only
544-454: The K-1A bombing computer combined with the navigation system was the first SHORAN. The SHORAN system is designed so that as the aircraft faces the target, the low-frequency station should be on the left, and the high-frequency station is on the right. This allows the computer to triangulate the two stations and the target. The limitations of SHORAN included: Little new top-of-the-line technology
578-586: The Norwegian stations, three among the Scottish and Shetlandic stations, and nine lines across the North Sea . The SHORAN geodetic stations did not precisely match the geodetic triangulation stations, but the proximity was considered such that no significant error was ascribed to the transfer from one to the other. The Norwegian stations were: And the British stations were: Each of the fifteen survey lines
612-739: The Ordnance Survey considered that the results were not of a geodetic standard necessary for primary triangulation, and a 12 metres (39 ft) discrepancy existed in the measurements between Norwegian stations. Beginning in the late 1940s and continuing into the 1980s surplus SHORAN systems had become widely used to provide precision navigation in oil and gas exploration industry. Companies like pioneer Offshore Navigation, Inc., Navigation Management, Coastal Surveys (based in Singapore) and Western Geophysical deployed SHORAN receivers to navigate seismic survey vessels and position drilling rigs around
646-471: The aircraft includes a transmitter, a receiver, an operator's console and a K-1A model bombing computer. The transmitter sends pulses to one of the ground stations and the system calculates the range in statute miles by clocking the elapsed time between transmitter pulse and the returned signal. The system was intended for use in navigation, but it became obvious that it would work well for blind targeting during bombing runs in poor visibility. The setup made up of
680-546: The car may not even be aware that the transponder is there, because there are no buttons to press. When a key is inserted into the ignition lock cylinder and turned, the car's computer sends a signal to the transponder. Unless the transponder replies with a valid code, the computer will not allow the engine to be started. Transponder keys have no battery; they are energized by the signal itself. Transponders may also be used by residents to enter their gated communities . However, having more than one transponder causes problems. If
714-695: The content of the received signal or signals. A communications satellite ’s channels are called transponders because each is a separate transceiver or repeater . With digital video data compression and multiplexing , several video and audio channels may travel through a single transponder on a single wideband carrier . Original analog video only has one channel per transponder, with subcarriers for audio and automatic transmission identification service ( ATIS ). Non-multiplexed radio stations can also travel in single channel per carrier (SCPC) mode, with multiple carriers (analog or digital) per transponder. This allows each station to transmit directly to
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#1732783242904748-432: The massive vacuum tube transmitters were fitted with solid-state control boxes for more reliable operation and to improve reception of weaker signals over the horizon. Transponder In telecommunications , a transponder is a device that, upon receiving a signal, emits a different signal in response. The term is a blend of transmitter and responder . In air navigation or radio frequency identification ,
782-443: The military only briefly, surplus equipment soon found a new use in the oil and gas industry, where it was used to position ships with high accuracy for seismic measurements. In 1938 RCA engineer Stuart William Seeley , while attempting to remove "ghost" signals from an experimental television system, realized that he could measure distances by time differences in radio reception. In summer 1940, Seeley proposed building SHORAN for
816-466: The power requirements during long flights. Transponders are used on some military aircraft to ensure ground personnel can verify the functionality of a missile’s flight termination system prior to launch. Such radar-enhancing transponders are needed as the enclosed weapon bays on modern aircraft interfere with prelaunch, flight termination system verification performed by range safety personnel during training test launches. The transponders re-radiate
850-741: The presence of the MiG-15 over Korea, which drove the B-29's from daylight combat in June 1951. Night operations were not very productive and the US Air Force became interested in any way to improve their results. The system was in place and the crews trained by November 1952, and SHORAN remained in use from then until the end of the war. It was particularly effective during early 1953 when the North Korean Air Force began to re-equip in case
884-467: The rejected survey missions deviated from the accepted measure by 0.0055 miles (29 feet), and the average disparity between a rejected measure and the mean of the accepted measures was 0.0013 miles (6 feet). The final results and assessment were computed from observation of ground survey positions, including stations in both Iceland and the Faroe Islands . The operation was largely successful, but
918-530: The satellite, rather than paying for a whole transponder, or using landlines to send it to an earth station for multiplexing with other stations. In fiber-optic communications , a transponder is the element that sends and receives the optical signal from a fiber . A transponder is typically characterized by its data rate and the maximum distance the signal can travel. The term "transponder" can apply to different items with important functional differences, mentioned across academic and commercial literature: As
952-850: The signals allowing for much longer communication distances. The International Maritime Organization 's International Convention for the Safety of Life at Sea (SOLAS) requires the Automatic Identification System (AIS) to be fitted aboard international voyaging ships with 300 or more gross tonnage (GT), and all passenger ships regardless of size. AIS transmitters/receivers are generally called transponders , but they generally transmit autonomously, although coast stations can interrogate class B transponders on smaller vessels for additional information. In addition, navigational aids often have transponders called RACON (radar beacons) designed to make them stand out on
986-436: The start/finish line. Each individual runner or car has an active transponder with a unique ID code. When the individual passes the start/finish line, the lap time and the racing position is shown on the score board. Passive and active RFID systems are used in motor sports , and off-road events such as Enduro and Hare and Hounds racing, the riders have a transponder on their person, normally on their arm. When they complete
1020-410: The system to the fullest extent. Changes were made and by June 1951 ground stations were located in more useful areas, such as islands and mountaintops, and training of operators and technicians familiarized them with the system. By November 1952 these changes had developed SHORAN into a reliable accurate blind-bombing system which was used by B-29 and B-26 aircraft for the remainder of the war. During
1054-467: The transponder sends back a transponder code (or "squawk code", Mode A) or altitude information (Mode C) to help air traffic controllers to identify the aircraft and to maintain separation between planes. Another mode called Mode S (Mode Select) is designed to help avoiding over-interrogation of the transponder (having many radars in busy areas) and to allow automatic collision avoidance. Mode S transponders are backward compatible with Modes A and C. Mode S
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1088-473: The world. The technology was key to the successful development of the offshore oil & gas industry in the postwar era. Truck-portable SHORAN transponders and up to 90-foot-tall (27 m) antennas were set up within a few feet of geodesic survey markers near the coast. SHORAN chains consisting of three or four shore stations were used to provide highly accurate navigation across large exploration tracts and as much as 200 miles (320 km) offshore. Frequently,
1122-432: Was gauged by six line crossings at each of two altitude levels, totalling twelve crossings, all forming part of a survey mission. The distance between two survey stations was derived from the minimum sum of the signal transit times from a transmitter, carried in an aircraft flying across the line to be measured, to a pair of terminals at each end of the line and back. A mission was approved provided: The most inaccurate of
1156-552: Was used in Korea, but SHORAN was an exception. B-26 planes were first equipped with the system in January, 1951, and first carried it into battle the following month. Some problems immediately recognized were that ground stations tended to be too far from the targets, the ground and aircraft equipment was not maintained properly, few technicians knew how to work the equipment, and operators were too unfamiliar with Korean geography to use
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