Beacon

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A beacon is an intentionally conspicuous device designed to attract attention to a specific location. A common example is the lighthouse, which provides a fixed location that can be used to navigate around obstacles or into port. More modern examples include a variety of radio beacons that can be read on radio direction finders in all weather, and radar transponders that appear on radar displays.

Contents

Beacons can also be combined with semaphoric or other indicators to provide important information, such as the status of an airport, by the colour and rotational pattern of its airport beacon, or of pending weather as indicated on a weather beacon mounted at the top of a tall building or similar site. When used in such fashion, beacons can be considered a form of optical telegraphy.

For navigation

A navigational beacon denoting the presence of Orontes Bank off Port Vincent, South Australia. Beacon at Orontes Bank.jpg
A navigational beacon denoting the presence of Orontes Bank off Port Vincent, South Australia.

Beacons help guide navigators to their destinations. Types of navigational beacons include radar reflectors, radio beacons, sonic and visual signals. Visual beacons range from small, single-pile structures to large lighthouses or light stations and can be located on land or on water. Lighted beacons are called lights; unlighted beacons are called daybeacons . Aerodrome beacons are used to indicate locations of airports and helipads.

Handheld beacons are also employed in aircraft marshalling, and are used by the marshal to deliver instructions to the crew of aircraft as they move around an active airport, heliport or aircraft carrier.

For defensive communications (historical)

16th-century beacon hut in Culmstock, Devon, England Culmstock, Culmstock Beacon - geograph.org.uk - 213525.jpg
16th-century beacon hut in Culmstock, Devon, England

Classically, beacons were fires lit at well-known locations on hills or high places, used either as lighthouses for navigation at sea, or for signalling over land that enemy troops were approaching, in order to alert defenses. As signals, beacons are an ancient form of optical telegraph and were part of a relay league.

Systems of this kind have existed for centuries over much of the world. The ancient Greeks called them phryctoriae , while beacons figure on several occasions on the column of Trajan.

In ancient China, sentinels on and near the Great Wall of China used a sophisticated system of daytime smoke and nighttime flame to send signals along long chains of beacon towers. [1]

Legend has it that Zhōu Yōu Wáng, king of the Western Zhou dynasty, played a trick multiple times in order to amuse his often melancholy concubine, ordering beacon towers lit to fool his Marquess and soldiers. At some point, friends became enemies and when enemies, led by Marquess of Shen really arrived at the wall. But this time, when the towers were lit, no defenders came, leading to Yōu's death and the colapse of the Western Zhou dynasty. [1] [2] [3]

In the 10th century, during the Arab–Byzantine wars, the Byzantine Empire used a beacon system to transmit messages from the border with the Abbasid Caliphate, across Anatolia to the imperial palace in the Byzantine capital, Constantinople. It was devised by Leo the Mathematician for Emperor Theophilos, but either abolished or radically curtailed by Theophilos' son and successor, Michael III. [4] Beacons were later used in Greece as well, while the surviving parts of the beacon system in Anatolia seem to have been reactivated in the 12th century by Emperor Manuel I Komnenos. [4]

In Scandinavia many hill forts were part of beacon networks to warn against invading pillagers. In Finland, these beacons were called vainovalkeat, "persecution fires", or vartiotulet, "guard fires", and were used to warn Finn settlements of imminent raids by the Vikings.

In Wales, the Brecon Beacons were named for beacons used to warn of approaching English raiders. In England, the most famous examples are the beacons used in Elizabethan England to warn of the approaching Spanish Armada. Many hills in England were named Beacon Hill after such beacons. In England the authority to erect beacons originally lay with the King and later was deligated to the Lord High Admiral. The money due for the maintenance of beacons was called Beaconagium and was levied by the sheriff of each county. [5] In the Scottish borders country, a system of beacon fires was at one time established to warn of incursions by the English. Hume and Eggerstone castles and Soltra Edge were part of this network. [6] The Great Wall of China is also a beacon network.

In Spain, the border of Granada in the territory of the Crown of Castile had a complex beacon network to warn against Moorish raiders and military campaigns. [7]

On vehicles

Beacon positions on police car Beacon positions.jpg
Beacon positions on police car

Vehicular beacons are rotating or flashing lights affixed to the top of a vehicle to attract the attention of surrounding vehicles and pedestrians. Emergency vehicles such as fire engines, ambulances, police cars, tow trucks, construction vehicles, and snow-removal vehicles carry beacon lights.

The color of the lamps varies by jurisdiction; typical colors are blue and/or red for police, fire, and medical-emergency vehicles; amber for hazards (slow-moving vehicles, wide loads, tow trucks, security personnel, construction vehicles, etc.); green for volunteer firefighters or for medical personnel, and violet for funerary vehicles. Beacons may be constructed with halogen bulbs similar to those used in vehicle headlamps, xenon flashtubes, or LEDs. [8] Incandescent and xenon light sources require the vehicle's engine to continue running to ensure that the battery is not depleted when the lights are used for a prolonged period. The low power consumption of LEDs allows the vehicle's engine to remain turned off while the lights operate nodes.

Other uses

Beacons and bonfires are also used to mark occasions and celebrate events.

The Mishna describes a system of fire beacons used by the high court in Jerusalem to communicate the declaration of a new month to Jews in Israel and Babylon. [9]

Beacons have also allegedly been abused by shipwreckers. An illicit fire at a wrong position would be used to direct a ship against shoals or beaches, so that its cargo could be looted after the ship sank or ran aground. There are, however, no historically substantiated occurrences of such intentional shipwrecking.

In wireless networks, a beacon is a type of frame which is sent by the access point (or WiFi router) to indicate that it is on.

Bluetooth based beacons periodically send out a data packet and this could be used by software to identify the beacon location. This is typically used by indoor navigation and positioning applications. [10]

Beaconing is the process that allows a network to self-repair network problems. The stations on the network notify the other stations on the ring when they are not receiving the transmissions. Beaconing is used in Token ring and FDDI networks.

In fiction

In Aeschylus' tragedy Agamemnon , [11] a chain of eight beacons manned by so-called lampadóphoroi inform Clytemnestra in Argos, within a single night's time, that Troy has just fallen under her husband king Agamemnon's control, after a famous ten years siege.

In J. R. R. Tolkien's high fantasy novel, The Lord of the Rings , a series of beacons alerts the entire realm of Gondor when the kingdom is under attack. These beacon posts were manned by messengers who would carry word of their lighting to either Rohan or Belfalas. [12] In Peter Jackson's film adaptation of the novel, the beacons serve as a connection between the two realms of Rohan and Gondor, alerting one another directly when they require military aid, as opposed to relying on messengers as in the novel.

In retail

Beacons are sometimes used in retail to send digital coupons or invites to customers passing by. [13] [14]

Types

Infrared beacon

An infrared beacon (IR beacon) transmits a modulated light beam in the infrared spectrum, which can be identified easily and positively. A line of sight clear of obstacles between the transmitter and the receiver is essential. IR beacons have a number of applications in robotics and in Combat Identification (CID).

Infrared beacons are the key infrastructure for the Universal Traffic Management System (UTMS) in Japan. They perform two-way communication with travelling vehicles based on highly directional infrared communication technology and have a vehicle detecting capability to provide more accurate traffic information. [15]

A contemporary military use of an Infrared beacon is reported in Operation Acid Gambit.

Sonar beacon

A sonar beacon is an underwater device which transmits sonic or ultrasonic signals for the purpose of providing bearing information. The most common type is that of a rugged watertight sonar transmitter attached to a submarine and capable of operating independently of the electrical system of the boat. It can be used in cases of emergencies to guide salvage vessels to the location of a disabled submarine. [16]

See also

Related Research Articles

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Optical communication communication at a distance using light to carry information

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Level crossing Place where a road crosses a railway at the same level

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Weather satellite type of satellite

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A distress signal, also known as a distress call, is an internationally recognized means for obtaining help. Distress signals are communicated by transmitting radio signals, displaying a visually observable item or illumination, or making a sound audible from a distance.

Automotive lighting lighting system of a motor vehicle

The lighting system of a motor vehicle consists of lighting and signalling devices mounted or integrated to the front, rear, sides, and in some cases the top of a motor vehicle. This lights the roadway for the driver and increases the visibility of the vehicle, allowing other drivers and pedestrians to see a vehicle's presence, position, size, direction of travel, and the driver's intentions regarding direction and speed of travel. Emergency vehicles usually carry distinctive lighting equipment to warn drivers and indicate priority of movement in traffic.

Hella (company) German automotive part supplier

Hella KGaA Hueck & Co. is an internationally operating German automotive part supplier with headquarters in Lippstadt, North Rhine-Westphalia. The company develops and manufactures lighting and electronic components and systems for the automotive industry, and also has one of the largest trade organizations for automotive parts, accessories, diagnosis and services within Europe.

Emergency vehicle lighting Device used on a vehicle to signal emergencies

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Baily Lighthouse Lighthouse on the Howth peninsula, County Dublin, Ireland

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Emergency vehicle equipment Audio and visual warning signs on emergency vehicles

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New Presque Isle Light lighthouse in Michigan, United States

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Traffic signal preemption is a type of system that allows the normal operation of traffic lights to be preempted. The most common use of these systems is to manipulate traffic signals in the path of an emergency vehicle, halting conflicting traffic and allowing the emergency vehicle right-of-way, to help reduce response times and enhance traffic safety. Signal preemption can also be used by light-rail and bus rapid transit systems to allow public transportation priority access through intersections, or by railroad systems at crossings to prevent collisions.

Navigational aid Marker to assist in safe passage making

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Radio beacon

In navigation, a radio beacon is a kind of beacon, a device that marks a fixed location and allows direction-finding equipment to find relative bearing. Radio beacons transmit a radio signal that is picked up by radio direction-finding systems on ships, aircraft and vehicles to determine the direction to the beacon.

Radio Technology of using radio waves to carry information

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Belgian railway signalling is the signalling in effect on the Belgian rail network currently operated by Infrabel.

Byzantine beacon system

In the 9th century, during the Arab–Byzantine wars, the Byzantine Empire used a system of beacons to transmit messages from the border with the Abbasid Caliphate across Asia Minor to the Byzantine capital, Constantinople.

Pundit Beacon

A Pundit Beacon or Landmark Beacon was an airfield navigational and identification beacon, used by the British Royal Air Force (RAF) in the period around World War II.

References

  1. 1 2 https://www.travelchinaguide.com/china_great_wall/construction/tower/
  2. Cambridge History of Ancient China, 1999, pages 546 and 551
  3. Giles, Herbert A. (1912). The Civilization of China. Tutis Digital Publishing. ISBN   81-320-0448-5. Chapter 1
  4. 1 2 Foss, Clive (1991). "Beacon". In Kazhdan, Alexander (ed.). The Oxford Dictionary of Byzantium . Oxford University Press. pp. 273–274. ISBN   978-0-19-504652-6.
  5. The National Cyclopaedia of Useful Knowledge, Vol III, (1847) Charles Knight, London, p.25.
  6. Ritchie, Leitch (1835). Scott and Scotland. London: Longman, Rees, Orme, Brown, Green, and Longman, p. 53
  7. Els almogávers a la frontera amb el sarrains en el segle XIV. Maria Teresa Ferrer
  8. Bullough, John; Nicholas P Skinner (December 2009). "Evaluation of Light-Emitting Diode Beacon Light Fixtures" (PDF). Lighting Research Center – Rensselaer Polytechnic Institute. Archived from the original (PDF) on 2013-07-29. Retrieved 2010-06-05.
  9. Mishna Rosh Hashana 2:1-3
  10. "What is a Beacon? - Beacon Basics". Kontakt.io. 2016-09-20. Retrieved 2017-04-05.
  11. v. 281 et sqq.
  12. Tolkien, J. R. R. (2004). The Lord of the Rings (50th Anniversary Edition). The Return of the King . Houghton Mifflin Company. pp. 747–748.
  13. Peter Lewis (2016-08-19). "How Beacons Can Reshape Retail Marketing – Think with Google". Thinkwithgoogle.com. Retrieved 2017-04-05.
  14. ELON JOURNAL OF UNDERGRADUATE RESEARCH IN COMMUNICATIONS 2015, VOL. 6 NO. 1
  15. "Infrared Beacon Overview". Universal Traffic Management Society of Japan. 2007. Retrieved 2008-04-27.
  16. The ELAC SBE distress sonar beacon