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.
A geodetic datum or geodetic system is a coordinate system, and a set of reference points, used to locate places on the Earth. An approximate definition of sea level is the datum WGS 84, an ellipsoid, whereas a more accurate definition is Earth Gravitational Model 2008 (EGM2008), using at least 2,159 spherical harmonics. Other datums are defined for other areas or at other times; ED50 was defined in 1950 over Europe and differs from WGS 84 by a few hundred meters depending on where in Europe you look. Mars has no oceans and so no sea level, but at least two martian datums have been used to locate places there.
A lighthouse is a tower, building, or other type of structure designed to emit light from a system of lamps and lenses and to serve as a navigational aid for maritime pilots at sea or on inland waterways.
In navigation, a radio beacon is a kind of beacon, a device which marks a fixed location and allows direction finding equipment to find relative bearing. Radio beacons transmit a radio signal which is picked up by radio direction finding systems on ships, aircraft and vehicles to determine the direction to the beacon.
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.
Information can be thought of as the resolution of uncertainty; it is that which answers the question of "what an entity is" and thus defines both its essence and nature of its characteristics. It is associated with data, as data represents values attributed to parameters, and information is data in context and with meaning attached. Information relates also to knowledge, as knowledge signifies understanding of an abstract or concrete concept.
An aerodrome beacon or rotating beacon is a beacon installed at an airport or aerodrome to indicate its location to aircraft pilots at night.
A weather beacon is a beacon that indicates the local weather forecast in a code of colored or flashing lights. Often, a short poem or jingle accompanies the code to make it easier to remember.
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.
Navigation is a field of study that focuses on the process of monitoring and controlling the movement of a craft or vehicle from one place to another. The field of navigation includes four general categories: land navigation, marine navigation, aeronautic navigation, and space navigation.
Radar is a detection system that uses radio waves to determine the range, angle, or velocity of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. A radar system consists of a transmitter producing electromagnetic waves in the radio or microwaves domain, a transmitting antenna, a receiving antenna and a receiver and processor to determine properties of the object(s). Radio waves from the transmitter reflect off the object and return to the receiver, giving information about the object's location and speed.
A day beacon is an unlighted nautical sea mark. A signboard attached to a day beacon is called a day mark and is used to identify it. Typically, day beacons mark channels whose key points are marked by lighted buoys. Day beacons may also mark smaller navigable routes in their entirety. They are the most common aid to nautical navigation in shallow water as they are relatively inexpensive to install and maintain. Navigation around day beacons is the same as with all other navigational aids.
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.
Aircraft marshalling is visual signalling between ground personnel and pilots on an airport, aircraft carrier or helipad.
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.
A navigational aid is any sort of marker which aids the traveler in navigation, usually nautical or aviation travel. Common types of such aids include lighthouses, buoys, fog signals, and day beacons.
A relay league is a chain of message forwarding stations in a system of optical telegraphs, radio telegraph stations, or riding couriers. Early 19th century methods of this type evolved into the electrical telegraph networks of the mid-to-late 19th century.
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 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.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.
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.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. 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.
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.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.
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.
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.
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 Aeschylus' tragedy Agamemnon ,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.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.
Beacons are sometimes used in retail to send digital coupons or invites to customers passing by.
This section needs expansion. You can help by adding to it.(June 2008)
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.
A contemporary military use of an Infrared beacon is reported in Operation Acid Gambit.
This section needs expansion. You can help by adding to it.(September 2012)
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.
A buoy is a floating device that can have many purposes. It can be anchored (stationary) or allowed to drift with ocean currents. The etymology of the word is disputed.
Optical communication, also known as optical telecommunication, is communication at a distance using light to carry information. It can be performed visually or by using electronic devices. The earliest basic forms of optical communication date back several millennia, while the earliest electrical device created to do so was the photophone, invented in 1880.
A level crossing is an intersection where a railway line crosses a road or path, or in rare situations an airport runway, at the same level, as opposed to the railway line crossing over or under using an overpass or tunnel. The term also applies when a light rail line with separate right-of-way or reserved track crosses a road in the same fashion. Other names include railway level crossing, grade crossing,road through railroad, railroad crossing, train crossing, and RXR (abbreviated).
A siren is a loud noise-making device. Civil defense sirens are mounted in fixed locations and used to warn of natural disasters or attacks. Sirens are used on emergency service vehicles such as ambulances, police cars, and fire trucks. There are two general types: pneumatic and electronic.
Marblehead Lighthouse in Marblehead, Ohio, United States, is the oldest lighthouse in continuous operation on the United States side of the Great Lakes. It has guided sailors safely along the rocky shores of Marblehead Peninsula since 1822, and is an active aid to navigation.
Warning system is any system of biological or technical nature deployed by an individual or group to inform of a future danger. Its purpose is to enable the deployer of the warning system to prepare for the danger and act accordingly to mitigate or avoid it.
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 is one or more visual warning lights fitted to a vehicle for use when the driver wishes to convey to other road users the urgency of their journey, to provide additional warning of a hazard when stationary, or in the case of law enforcement as a means of signalling another driver to stop for interaction with an officer. These lights may be dedicated emergency lights, such as a beacon or a light bar, or may be modified stock lighting, such as a wig-wag or hide-away light, and are additional to any standard lighting on the car such as hazard lights. Often, they are used along with a siren in order to increase their effectiveness. In many jurisdictions, the use of these lights may afford the user specific legal powers, and may place requirements on other road users to behave differently, such as compelling them to pull to the side of the road and yield right of way so the emergency vehicle may proceed through unimpeded.
The Baily Lighthouse is a lighthouse on the southeastern part of Howth Head in County Dublin, Ireland. It is maintained by the Commissioners of Irish Lights.
Emergency vehicle equipment is any equipment fitted to, or carried by, an emergency vehicle, other than the equipment that a standard non-emergency vehicle is fitted with.
The New Presque Isle Light was built in 1870, at Presque Isle, Michigan, east of Grand Lake, and sits on the namesake peninsula. It is one of 149 lighthouses in Michigan, more than any other state. Because of changing shoreline particularly, or alternatively deterioration of the original building, it is not uncommon for a replacement lighthouse to be placed in the vicinity of an earlier light, in this case, the Old Presque Isle Light.
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.
The Hook Lighthouse is a building situated on Hook Head at the tip of the Hook Peninsula in County Wexford, in Ireland. It is one of the oldest lighthouses in the world and the second oldest operating lighthouse in the world, after the Tower of Hercules in Spain. It is operated by the Commissioners of Irish Lights, the Irish Lighthouse Authority, it marks the eastern entrance to Waterford Harbour. The current structure has stood for 846 years as of 2018.
Belgian railway signalling is the signalling in effect on the Belgian rail network currently operated by Infrabel.
Dungeness Lighthouse on the Dungeness Headland started operation on 20 November 1961. Its construction was prompted by the building of Dungeness nuclear power station, which obscured the light of its predecessor which, though decommissioned, remains standing. The new lighthouse is constructed of precast concrete rings; its pattern of black and white bands is impregnated into the concrete. It remains in use today, monitored and controlled from the Trinity House Operations and Planning Centre at Harwich, Essex.
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.
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.