A beacon is an intentionally conspicuous device designed to attract attention to a specific location.
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.
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 is the resolution of uncertainty; it is that which answers the question of "what an entity is" and is thus that which specifies the nature of that entity, as well as the essentiality of its properties. Information is associated with data and knowledge, as data is meaningful information and represents the values attributed to parameters, and knowledge signifies understanding of an abstract or concrete concept. The existence of information is uncoupled with an observer, which refers to that which accesses information to discern that which it specifies; information exists beyond an event horizon for example, and in the case of knowledge, the information itself requires a cognitive observer to be accessed.
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 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.
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.
Systems of this kind have existed for centuries over much of the world. The ancient Romans used beacons and 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 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.Beacons are sometimes used for End-to-End Item-Level Monitoring
Denethor II, son of Ecthelion II, is a fictional character in J. R. R. Tolkien's The Return of the King, which is the third and final part of his novel The Lord of the Rings. He is the 26th Ruling Steward of Gondor.
Gondor is a fictional kingdom in J. R. R. Tolkien's writings, described as the greatest realm of Men in the west of Middle-earth by the end of the Third Age. The third volume of The Lord of the Rings, The Return of the King, is largely concerned with the events in Gondor during the War of the Ring and with the restoration of the realm afterward. The history of the kingdom is outlined in the appendices of the book.
In J. R. R. Tolkien's Middle-earth fiction, such as The Hobbit and The Lord of the Rings, the terms Man and Men refer to humankind – in contrast to Elves, Dwarves, Orcs, and other humanoid races – and does not denote gender. Hobbits were a branch of the lineage of Men.
Rohan is a kingdom in J. R. R. Tolkien's fantasy setting of Middle-earth. It is mainly a grassland, and lies north-west of its ally Gondor, and further north-west of Mordor, the realm of Sauron, their enemy. It is inhabited by the Rohirrim, a people of herdsmen and farmers who are well known for their horses and cavalry. Rohan is also referred to as Riddermark or the Mark. The realm is of significant importance in the author's book, The Lord of the Rings. Much of the background of Rohan is grounded in Anglo-Saxon tradition.
The Two Towers is the second volume of J. R. R. Tolkien's high fantasy novel The Lord of the Rings. It is preceded by The Fellowship of the Ring and followed by The Return of the King.
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.
In J. R. R. Tolkien's high fantasy writings, Helm's Deep was a large valley in the north-western White Mountains of Middle-earth. The Battle of Helm's Deep, a major episode in The Lord of the Rings, is set in Helm's Deep.
In J. R. R. Tolkien's legendarium, Isengard is a large fortress in the fictional universe of Middle-earth. It is a translation of the term Angrenost from the fictional language of Sindarin. Both terms mean "iron fortress". Additionally, Isengard can mean "West Guard".
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.
The White Mountains are a fictional mountain range in J. R. R. Tolkien's Middle-earth, where they lie primarily in the Kingdom of Gondor, but partly also in the Kingdom of Rohan. The name White Mountains is a loose translation of Ered Nimrais, meaning "mountains of white horns" in Sindarin, one of the languages created by Tolkien. The mountains are named after the glaciers and snowcaps of their highest peaks.
Leading lights are a pair of light beacons, used in navigation to indicate a safe passage for vessels entering a shallow or dangerous channel; and may also be used for position fixing. At night, the lights are a form of leading line that can be used for safe navigation. The beacons consist of two lights that are separated in distance and elevation, so that when they are aligned, with one above the other, they provide a bearing. Range lights are often illuminated day and night.
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.
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.
Aircraft warning lights are high-intensity lighting devices that are attached to tall structures and are used as collision avoidance measures. Such devices make structures more visible to passing aircraft and are usually used at night, although they may be used during the day as well. These lights need to be of sufficient brightness in order to be visible for miles around the structure.
Meriadoc Brandybuck, usually referred to as simply Merry, is a fictional character from J. R. R. Tolkien's Middle-earth legendarium, featured throughout his most famous work, The Lord of the Rings.
Aragorn II, son of Arathorn is a fictional character from J. R. R. Tolkien's legendarium. He is one of the main protagonists of The Lord of the Rings. Aragorn was a Ranger of the North, first introduced with the name Strider at Bree, as the Hobbits continued to call him throughout The Lord of the Rings. He was eventually revealed to be the heir of Isildur and rightful claimant to the thrones of Arnor and Gondor. He was also a confidant of Gandalf and an integral part of the quest to destroy the One Ring and defeat the Dark Lord Sauron.
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.