Beacon
Visual beacons range from small, single-pile structures to large lighthouses or light stations and can be located on land or on water.
[citation needed] In the United States, a series of beacons were constructed across the country in the 1920s and 1930s to help guide pilots delivering air mail.
[citation needed] Historically, 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.
But when enemies, led by the Marquess of Shen really arrived at the wall, although the towers were lit, no defenders came, leading to King Yōu's death and the collapse of the Western Zhou dynasty.
In England the authority to erect beacons originally lay with the King and later was delegated to the Lord High Admiral.
[7] In the Scottish borders country, a system of beacon fires was at one time established to warn of incursions by the English.
[8] 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.
[9] Due to the progressive advance of the borders throughout the process of the Reconquista, the entire Spanish geography is full of defensive lines of castles, towers and fortifications, visually connected to each other, which served as fortified beacons.
Soldiers will typically affix them to their helmets or other gear so they are easily visible to others using night vision including other infantry, ground vehicles, and aerial platforms (drones, helicopters, planes, etc.).
As time went on, more sophisticated options began to emerge with electronically powered infrared strobes with specific mounting solutions for attaching to helmets or load bearing equipment.
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.
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.
[15] 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.
[19] 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.
