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75-441: In optical communication , a reconfigurable optical add-drop multiplexer ( ROADM ) is a form of optical add-drop multiplexer that adds the ability to remotely switch traffic from a wavelength-division multiplexing (WDM) system at the wavelength layer. This is achieved through the use of a wavelength selective switching module. This allows individual or multiple wavelengths carrying data channels to be added and/or dropped from

150-551: A limited and asymmetric nature. Naval warfare developed when humans first fought from water-borne vessels. Before the introduction of the cannon and ships with enough capacity to carry them, navy warfare primarily involved ramming and boarding actions. In the time of ancient Greece and the Roman Empire , naval warfare centered on long, narrow vessels powered by banks of oarsmen (such as triremes and quinqueremes ) designed to ram and sink enemy vessels or come alongside

225-473: A mirror to reflect sunlight to a distant observer. When a signaler tilts the mirror to reflect sunlight, the distant observer sees flashes of light that can be used to transmit a prearranged signaling code. Naval ships often use signal lamps and Morse code in a similar way. Aircraft pilots often use visual approach slope indicator (VASI) projected light systems to land safely, especially at night. Military aircraft landing on an aircraft carrier use

300-489: A sister ship of Bismarck , was almost put out of action by miniature submarines known as X-Craft . The X-Craft severely damaged her and kept her in port for some months. A major paradigm shift in naval warfare occurred with the introduction of the aircraft carrier . First at Taranto in 1940 and then at Pearl Harbor in 1941, the carrier demonstrated its ability to strike decisively at enemy ships out of sight and range of surface vessels. The Battle of Leyte Gulf (1944)

375-484: A basic introduction to different forms of optical communication. Visual techniques such as smoke signals , beacon fires , hydraulic telegraphs , ship flags and semaphore lines were the earliest forms of optical communication. Hydraulic telegraph semaphores date back to the 4th century BCE Greece. Distress flares are still used by mariners in emergencies, while lighthouses and navigation lights are used to communicate navigation hazards. The heliograph uses

450-822: A catastrophe for the Russian military in general and the Russian Navy in particular. Although neither party lacked courage, the Russians were defeated by the Japanese in the Battle of Port Arthur, which was the first time in warfare that mines were used for offensive purposes. The warships of the Baltic Fleet sent to the Far East were lost in the Battle of Tsushima. A further step change in naval firepower occurred when

525-564: A focused lamp which can produce a pulse of light. In large versions this pulse is achieved by opening and closing shutters mounted in front of the lamp, either via a manually operated pressure switch or, in later versions, automatically. With hand held lamps, a concave mirror is tilted by a trigger to focus the light into pulses. The lamps are usually equipped with some form of optical sight, and are most commonly deployed on naval vessels and also used in airport control towers with coded aviation light signals . Aviation light signals are used in

600-404: A group, which may be a small squadron of comparable ships, or a larger naval fleet of various specialized ships. The commander of a fleet travels in the flagship , which is usually the most powerful vessel in the group. Before radio was invented, commands from the flagship were communicated by means of flags. At night signal lamps could be used for a similar purpose. Later these were replaced by

675-437: A large number of cannon made oar-based propulsion impossible, and ships came to rely primarily on sails . Warships were designed to carry increasing numbers of cannon and naval tactics evolved to bring a ship's firepower to bear in a broadside , with ships-of-the-line arranged in a line of battle . The development of large capacity, sail-powered ships carrying cannon led to a rapid expansion of European navies, especially

750-591: A major naval power in the mid-17th century in the first Anglo-Dutch war with a technical victory. Successive decisive Dutch victories in the second and third Anglo-Dutch Wars confirmed the Dutch mastery of the seas during the Dutch Golden Age , financed by the expansion of the Dutch Empire . The French Navy won some important victories near the end of the 17th century but a focus upon land forces led to

825-682: A military fleet, although the term " merchant navy " for a commercial fleet still incorporates the non-military word sense . This overlap in word senses between commercial and military fleets grew out of the inherently dual-use nature of fleets; centuries ago, nationality was a trait that unified a fleet across both civilian and military uses. Although nationality of commercial vessels has little importance in peacetime trade other than for tax avoidance , it can have greater meaning during wartime, when supply chains become matters of patriotic attack and defense, and when in some cases private vessels are even temporarily converted to military vessels. The latter

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900-806: A navy is projection of force into areas beyond a country's shores (for example, to protect sea-lanes , deter or confront piracy , ferry troops, or attack other navies, ports, or shore installations). The strategic defensive purpose of a navy is to frustrate seaborne projection-of-force by enemies. The strategic task of a navy also may incorporate nuclear deterrence by use of submarine-launched ballistic missiles . Naval operations can be broadly divided between riverine and littoral applications ( brown-water navy ), open-ocean applications ( blue-water navy ), and something in between ( green-water navy ), although these distinctions are more about strategic scope than tactical or operational division. First attested in English in

975-436: A similar system to land correctly on a carrier deck. The coloured light system communicates the aircraft's height relative to a standard landing glideslope . As well, airport control towers still use Aldis lamps to transmit instructions to aircraft whose radios have failed. A 'semaphore telegraph', also called a 'semaphore line', 'optical telegraph', 'shutter telegraph chain', ' Chappe telegraph ', or 'Napoleonic semaphore',

1050-458: A single ship or aspect of a ship. However, commodores can also be temporary or honorary positions. For example, during World War II, a Navy captain was assigned duty as a convoy commodore, which meant that he was still a captain, but in charge of all the merchant vessels in the convoy. The most senior rank employed by a navy will tend to vary depending on the size of a navy and whether it is wartime or peacetime, for example, few people have ever held

1125-538: A transport fiber without the need to convert the signals on all of the WDM channels to electronic signals and back again to optical signals. The main advantages of the ROADM are: ROADM functionality originally appeared in long-haul dense wavelength division multiplexing (DWDM) equipment, but by 2005, it began to appear in metro optical systems because of the need to build out major metropolitan networks in order to deal with

1200-465: Is a system used for conveying information by means of visual signals, using towers with pivoting arms or shutters, also known as blades or paddles. Information is encoded by the position of the mechanical elements; it is read when the shutter is in a fixed position. Semaphore lines were a precursor of the electrical telegraph . They were far faster than post riders for conveying a message over long distances, but far more expensive and less private than

1275-484: Is a wireless solar telegraph that signals by flashes of sunlight (generally using Morse code) reflected by a mirror . The flashes are produced by momentarily pivoting the mirror, or by interrupting the beam with a shutter. The heliograph was a simple but effective instrument for instantaneous optical communication over long distances during the late 19th and early 20th century. Its main uses were in military, surveys and forest protection work. They were standard issue in

1350-1233: Is an integral part of the navy but there are variations such as the French Troupes de marine , which is actually part of the French Army . The United States Marine Corps is a separate armed service within the United States Department of the Navy, with its own leadership structure. Naval aviation is the application of military air power by navies, whether from warships that embark aircraft, or land bases. In World War I, several navies used floatplanes and flying boats – mainly for scouting . By World War II, aircraft carriers could carry bomber aircraft capable of attacking naval and land targets, as well as fighter aircraft for defence. Since World War II helicopters have been embarked on smaller ships in roles such as anti-submarine warfare and transport. Some navies have also operated land-based aircraft in roles such as maritime patrol and training . Naval aviation forces primarily perform naval roles at sea. However, they are also used in

1425-482: Is currently building one aircraft carrier, INS  Vikrant , and considering another. France is also looking at a new carrier , probably using a CATOBAR system and possibly based on the British Queen Elizabeth design. A navy typically operates from one or more naval bases . The base is a port that is specialized in naval operations, and often includes housing, a munitions depot , docks for

1500-709: Is that boats are capable of being carried by ships. (Submarines by this rule are ships rather than boats, but are customarily referred to as boats reflecting their previous smaller size.) Navies use many types of boat, ranging from 9-foot (2.7 m) dinghies to 135-foot (41 m) landing craft. They are powered by either diesel engines, out-board gasoline engines, or waterjets. Most boats are built of aluminum, fiberglass, or steel. Rigid-hulled inflatable boats are also used. Patrol boats are used for patrols of coastal areas, lakes and large rivers. Landing craft are designed to carry troops, vehicles, or cargo from ship to shore under combat conditions, to unload, to withdraw from

1575-429: Is the branch of a nation's armed forces principally designated for naval and amphibious warfare ; namely, lake -borne, riverine , littoral , or ocean -borne combat operations and related functions. It includes anything conducted by surface ships , amphibious ships, submarines , and seaborne aviation , as well as ancillary support, communications, training, and other fields. The strategic offensive role of

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1650-476: Is the most common type of channel for optical communications. The transmitters in optical fiber links are generally light-emitting diodes (LEDs) or laser diodes . Infrared light is used more commonly than visible light , because optical fibers transmit infrared wavelengths with less attenuation and dispersion . The signal encoding is typically simple intensity modulation , although historically optical phase and frequency modulation have been demonstrated in

1725-588: The Spanish and Portuguese navies that dominated in the 16th and early 17th centuries, and helped propel the age of exploration and colonialism . The repulsion of the Spanish Armada (1588) by the English fleet revolutionized naval warfare by the success of a guns-only strategy and caused a major overhaul of the Spanish Navy , partly along English lines, which resulted in even greater dominance by

1800-614: The Volta Laboratory Association , created and financed by Bell. On June 21, 1880, Bell's assistant transmitted a wireless voice telephone message of considerable distance, from the roof of the Franklin School to the window of Bell's laboratory, some 213 meters (about 700 ft) away. Bell believed the photophone was his most important invention . Of the 18 patents granted in Bell's name alone, and

1875-537: The oiler , minesweeper , patrol boat , hydrographic and oceanographic survey ship and tender . During the age of sail , the ship categories were divided into the ship of the line , frigate, and sloop-of-war . Naval ship names are typically prefixed by an abbreviation indicating the national navy in which they serve. For a list of the prefixes used with ship names ( HMS , USS , LÉ , etc.) see ship prefix . Today's warships are significantly faster than in years past, thanks to much improved propulsion systems. Also,

1950-429: The 12 he shared with his collaborators, four were for the photophone, which Bell referred to as his "greatest achievement", telling a reporter shortly before his death that the photophone was "the greatest invention [I have] ever made, greater than the telephone". The photophone was a precursor to the fiber-optic communication systems which achieved popular worldwide usage starting in the 1980s. The master patent for

2025-471: The 19th century. They are still used during underway replenishment at sea and are acceptable for emergency communication in daylight or, using lighted wands instead of flags, at night. The newer flag semaphore system uses two short poles with square flags, which a signaler holds in different positions to convey letters of the alphabet and numbers. The transmitter holds one pole in each hand, and extends each arm in one of eight possible directions. Except for in

2100-538: The British and Australian armies until the 1960s, and were used by the Pakistani army as late as 1975. In the present day a variety of electronic systems optically transmit and receive information carried by pulses of light. Fiber-optic communication cables are employed to carry electronic data and telephone traffic. Free-space optical communications are also used every day in various applications. Optical fiber

2175-613: The Chappe brothers' contention that angled rods are more visible). In Spain , the engineer Agustín de Betancourt developed his own system which was adopted by that state. This system was considered by many experts in Europe better than Chappe's, even in France. These systems were popular in the late 18th to early 19th century but could not compete with the electrical telegraph, and went completely out of service by 1880. Semaphore flags are

2250-707: The French Navy's relative neglect, which allowed the Royal Navy to emerge with an ever-growing advantage in size and quality, especially in tactics and experience, from 1695. As a response to growing naval influence of the navies of Portuguese, the warrior king of the Marathas, Shivaji laid the foundation of the Maratha navy in 1654. Throughout the 18th century the Royal Navy gradually gained ascendancy over

2325-620: The French Navy, with victories in the War of Spanish Succession (1701–1714), inconclusive battles in the War of Austrian Succession (1740–1748), victories in the Seven Years' War (1754–1763), a partial reversal during the American War of Independence (1775–1783), and consolidation into uncontested supremacy during the 19th century from the Battle of Trafalgar in 1805. These conflicts saw

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2400-485: The French engineer Claude Chappe and his brothers, who succeeded in covering France with a network of 556 stations stretching a total distance of 4,800 kilometres (3,000 mi). It was used for military and national communications until the 1850s. Many national services adopted signaling systems different from the Chappe system. For example, Britain and Sweden adopted systems of shuttered panels (in contradiction to

2475-778: The Spanish. From the beginning of the 17th century the Dutch cannibalized the Portuguese Empire in the East and, with the immense wealth gained, challenged Spanish hegemony at sea. From the 1620s, Dutch raiders seriously troubled Spanish shipping and, after a number of battles that went both ways, the Dutch Navy finally broke the long dominance of the Spanish Navy in the Battle of the Downs (1639). England emerged as

2550-537: The U.S. Navy lifted the ban in April 2010. The major reasons historically cited by the U.S. Navy were the extended duty tours and close conditions which afford almost no privacy. The United Kingdom's Royal Navy has had similar restrictions. Australia, Canada, Norway, and Spain previously opened submarine service to women sailors. A navy will typically have two sets of ranks, one for enlisted personnel and one for officers . Typical ranks for commissioned officers include

2625-567: The United Kingdom launched HMS  Dreadnought in 1906, but naval tactics still emphasized the line of battle. The first practical military submarines were developed in the late 19th century and by the end of World War I had proven to be a powerful arm of naval warfare. During World War II , Nazi Germany 's submarine fleet of U-boats almost starved the United Kingdom into submission and inflicted tremendous losses on U.S. coastal shipping . The German battleship  Tirpitz ,

2700-998: The beach, and to return to the ship. They are rugged, with powerful engines, and usually armed. There are many types in today's navies including hovercraft . They will typically have a power-operated bow ramp, a cargo well and after structures that house engine rooms, pilot houses, and stowage compartments. These boats are sometimes carried by larger ships. Special operations craft are high-speed craft used for insertion and extraction of special forces personnel and some may be transportable (and deployed) by air. Boats used in non-combat roles include lifeboats, mail boats, line handling boats, buoy boats, aircraft rescue boats, torpedo retrievers, explosive ordnance disposal craft, utility boats, dive boats, targets, and work boats. Boats are also used for survey work, tending divers, and minesweeping operations. Boats for carrying cargo and personnel are sometimes known as launches, gigs, barges or shore party boats. Naval forces are typically arranged into units based on

2775-415: The case of a radio failure , an aircraft not equipped with a radio, or in the case of a hearing-impaired pilot. Air traffic controllers have long used signal light guns to direct such aircraft. The light gun's lamp has a focused bright beam capable of emitting three different colors: red, white and green. These colors may be flashing or steady, and provide different instructions to aircraft in flight or on

2850-450: The coastal periphery and along inland waterways, where larger ocean-going naval vessels can not readily enter. Regional powers may maintain a " green water navy " as a means of localized force projection. Blue water fleets may require specialized vessels, such as minesweepers , when operating in the littoral regions along the coast. A basic tradition is that all ships commissioned in a navy are referred to as ships rather than vessels, with

2925-546: The development and refinement of tactics that came to be called the line of battle . The next stage in the evolution of naval warfare was the introduction of metal plating along the hull sides. The increased mass required steam-powered engines, resulting in an arms race between armor and weapon thickness and firepower. The first armored vessels, the French Gloire and British HMS  Warrior , made wooden vessels obsolete. Another significant improvement came with

3000-797: The early 14th century, the word "navy" came via Old French navie , "fleet of ships", from the Latin navigium , "a vessel, a ship, bark, boat", from navis , "ship". The word "naval" came from Latin navalis , "pertaining to ship"; cf. Greek ναῦς ( naus ), "ship", ναύτης ( nautes ), "seaman, sailor". The earliest attested form of the word is in the Mycenaean Greek compound word 𐀙𐀄𐀈𐀗 , na-u -do-mo (* naudomoi ), "shipbuilders", written in Linear B syllabic script. The word formerly denoted fleets of both commercial and military nature. In modern usage "navy" used alone always denotes

3075-465: The efficiency of the engines has improved, in terms of fuel, and of how many sailors it takes to operate them. In World War II, ships needed to refuel very often. However, today ships can go on very long journeys without refueling. Also, in World War II, the engine room needed about a dozen sailors to work the many engines, however, today, only about four or five are needed (depending on the class of

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3150-431: The electrical telegraph lines which would later replace them. The maximum distance that a pair of semaphore telegraph stations can bridge is limited by geography, weather and the availability of light; thus, in practical use, most optical telegraphs used lines of relay stations to bridge longer distances. Each relay station would also require its complement of skilled operator-observers to convey messages back and forth across

3225-614: The enemy vessel so its occupants could be attacked hand-to-hand. Naval warfare continued in this vein through the Middle Ages until the cannon became commonplace and capable of being reloaded quickly enough to be reused in the same battle. In ancient China , large naval battles were known since the Qin dynasty ( also see Battle of Red Cliffs , 208), employing the war junk during the Han dynasty . However, China's first official standing navy

3300-500: The era of the Roman empire , naval forces included marine legionaries for maritime boarding actions . These were troops primarily trained in land warfare, and did not need to be skilled at handling a ship. Much later during the age of sail, a component of marines served a similar role, being ship-borne soldiers who were used either during boarding actions, as sharp-shooters, or in raids along shorelines. The Spanish Infantería de Marina

3375-417: The exception of destroyers and submarines, which are known as boats. The prefix on a ship's name indicates that it is a commissioned ship. An important tradition on board naval vessels of some nations has been the ship's bell . This was historically used to mark the passage of time, as warning devices in heavy fog, and for alarms and ceremonies. The ship's captain, and more senior officers are "piped" aboard

3450-456: The following, in ascending order ( Commonwealth ranks are listed first on each line; USA ranks are listed second in those instances where they differ from Commonwealth ranks): "Flag officers" include any rank that includes the word "admiral" (or commodore in services other than the US Navy), and are generally in command of a battle group , strike group or similar flotilla of ships, rather than

3525-509: The ground (for example, "cleared to land" or "cleared for takeoff"). Pilots can acknowledge the instructions by wiggling their plane's wings, moving their ailerons if they are on the ground, or by flashing their landing or navigation lights during night time. Only 12 simple standardized instructions are directed at aircraft using signal light guns as the system is not utilized with Morse code. A heliograph ( Greek : Ἥλιος helios , meaning "sun", and γραφειν graphein , meaning "write")

3600-543: The invention of the rotating turrets, which allowed the guns to be aimed independently of ship movement. The battle between CSS  Virginia and USS  Monitor during the American Civil War (1861–1865) is often cited as the beginning of this age of maritime conflict. The Russian Navy was considered the third strongest in the world on the eve of the Russo-Japanese War , which turned to be

3675-412: The lab. The need for periodic signal regeneration was largely superseded by the introduction of the erbium-doped fiber amplifier , which extended link distances at significantly lower cost. The commercial introduction of dense wavelength-division multiplexing (WDM) in 1996 by Ciena Corp was the real start of optical networking. WDM is now the common basis nearly every high-capacity optical system in

3750-513: The line. The modern design of semaphores was first foreseen by the British polymath Robert Hooke , who first gave a vivid and comprehensive outline of visual telegraphy in a 1684 submission to the Royal Society . His proposal (which was motivated by military concerns following the Battle of Vienna the preceding year) was not put into practice during his lifetime. The first operational optical semaphore line arrived in 1792, created by

3825-493: The most widely used. ROADMs were first introduced in 2002 with the introduction of DWDM. ROADMs can be directionless, colorless, contentionless, and gridless. Directionless means that any wavelength can be dropped from any fiber, and any wavelength or signal can be sent to any port in the ROADM. Colorless implies every port in the ROADM can handle or accept any wavelength or color of light. Contentionless means several identical wavelengths or signals can be dropped from several ports at

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3900-458: The number of ships included, a single ship being the smallest operational unit. Ships may be combined into squadrons or flotillas , which may be formed into fleets . The largest unit size may be the whole Navy or Admiralty . A task force can be assembled using ships from different fleets for an operational task. Despite their acceptance in many areas of naval service, female sailors were not permitted to serve on board U.S. submarines until

3975-479: The numerous United States carrier battle groups . Only two nations, the United States and France , presently operate CATOBAR carriers of any size, while Russia , China and India operate sizeable STOBAR carriers (although all three are originally of Russian design). The United Kingdom is also operating two Queen Elizabeth -class carriers, which are the largest STOVL vessels in service, and India

4050-457: The photophone ( U.S. patent 235,199 Apparatus for Signalling and Communicating, called Photophone ), was issued in December 1880, many decades before its principles came to have practical applications. Free-space optics (FSO) systems are employed for ' last mile ' telecommunications and can function over distances of several kilometers as long as there is a clear line of sight between

4125-432: The prow of the ship. Firing a cannon salute partially disarms the ship, so firing a cannon for no combat reason showed respect and trust. As the tradition evolved, the number of cannons fired became an indication of the rank of the official being saluted. Historically, navy ships were primarily intended for warfare. They were designed to withstand damage and to inflict the same, but only carried munitions and supplies for

4200-418: The radio transmitter, or the flashing light when radio silence was needed. A " blue water navy " is designed to operate far from the coastal waters of its home nation. These are ships capable of maintaining station for long periods of time in deep ocean, and will have a long logistical tail for their support. Many are also nuclear powered to save having to refuel. By contrast a " brown water navy " operates in

4275-645: The rank of Fleet Admiral in the U.S. Navy, the chief of the Royal Australian Navy holds the rank of Vice Admiral, and the chief of the Irish Naval Service holds the rank of Commodore. Naval infantry, commonly known as marines , are a category of infantry that form part of a state's naval forces and perform roles on land and at sea, including amphibious operations , as well as other, naval roles. They also perform other tasks, including land warfare, separate from naval operations. During

4350-576: The rest position, the flags cannot overlap. The flags are colored differently based on whether the signals are sent by sea or by land. At sea, the flags are colored red and yellow (the Oscar flags ), while on land, they are white and blue (the Papa flags ). Flags are not required, they just make the characters more obvious. Signal lamps (such as Aldis lamps), are visual signaling devices for optical communication (typically using Morse code). Modern signal lamps are

4425-408: The same time. Gridless means that the ROADM can handle frequencies or signals that aren't precisely 50 GHz apart from each other. This is relevant because 50 GHz spacing has been traditionally used in fiber optic communications. Optical communication An optical communication system uses a transmitter , which encodes a message into an optical signal , a channel , which carries

4500-715: The seafaring local people (either Malays of Srivijaya or Javanese of Mataram ) to attack as far as the coast of Tanzania and Mozambique with 1000 boats and attempted to take the citadel of Qanbaloh, about 7,000 km to their West, in 945–946 AD. In 1350 AD Majapahit launched its largest military expedition, the invasion of Pasai , with 400 large jong and innumerable smaller vessels. The second largest military expedition, invasion of Singapura in 1398, Majapahit deployed 300 jong with no less than 200,000 men. The average jong used by Majapahit would be about 76.18–79.81 m LOA , carrying 600–700 men, with 1200–1400 tons deadweight . The mass and deck space required to carry

4575-423: The several hundred to thousand satellites effectively creating a space-based optical mesh network . More generally, transmission of unguided optical signals is known as optical wireless communications (OWC). Examples include medium-range visible light communication and short-distance IrDA , using infrared LEDs. Navy A navy , naval force , military maritime fleet , war navy , or maritime force

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4650-501: The ship using a Boatswain's call . In the United States, the First Navy Jack is a flag that has the words, "Don't Tread on Me" on the flag. By English tradition, ships have been referred to as a "she". However, it was long considered bad luck to permit women to sail on board naval vessels. To do so would invite a terrible storm that would wreck the ship. The only women that were welcomed on board were figureheads mounted on

4725-507: The ship). Today, naval strike groups on longer missions are always followed by a range of support and replenishment ships supplying them with anything from fuel and munitions, to medical treatment and postal services. This allows strike groups and combat ships to remain at sea for several months at a time. The term "boat" refers to small craft limited in their use by size and usually not capable of making lengthy independent voyages at sea. The old navy adage to differentiate between ships and boats

4800-718: The signal to its destination, and a receiver , which reproduces the message from the received optical signal. When electronic equipment is not employed the 'receiver' is a person visually observing and interpreting a signal, which may be either simple (such as the presence of a beacon fire ) or complex (such as lights using color codes or flashed in a Morse code sequence). Modern communication relies on optical networking systems using optical fiber , optical amplifiers , lasers , switches, routers , and other related technologies. Free-space optical communication use lasers to transmit signals in space, while terrestrial forms are naturally limited by geography and weather. This article provides

4875-476: The source and the destination, and the optical receiver can reliably decode the transmitted information. Other free-space systems can provide high-data-rate, long-range links using small, low-mass, low-power-consumption subsystems which make them suitable for communications in space. Various planned satellite constellations intended to provide global broadband coverage take advantage of these benefits and employ laser communication for inter-satellite links between

4950-419: The system for conveying information at a distance by means of visual signals with hand-held flags, rods, disks, paddles, or occasionally bare or gloved hands. Information is encoded by the position of the flags, objects or arms; it is read when they are in a fixed position. Semaphores were adopted and widely used (with hand-held flags replacing the mechanical arms of shutter semaphores ) in the maritime world in

5025-411: The traffic driven by the increasing demand for packet -based services. The switching or reconfiguration functions of a ROADM can be achieved using a variety of switching technologies including microelectromechanical systems (MEMS), liquid crystal , thermo optic and beam-steering switches in planar waveguide circuits, and tunable optical filter technology. MEMS and liquid crystal technologies are

5100-400: The vessels, and various repair facilities. During times of war temporary bases may be constructed in closer proximity to strategic locations, as it is advantageous in terms of patrols and station-keeping. Nations with historically strong naval forces have found it advantageous to obtain basing rights in other countries in areas of strategic interest. Navy ships can operate independently or with

5175-701: The voyage (rather than merchant cargo). Often, other ships that were not built specifically for warfare, such as the galleon or the armed merchant ships in World War II , did carry armaments. In more recent times, navy ships have become more specialized and have included supply ships, troop transports, repair ships, oil tankers and other logistics support ships as well as combat ships. Modern navy combat ships are generally divided into seven main categories: aircraft carriers , cruisers , destroyers , frigates , corvettes , submarines , and amphibious assault ships . There are also support and auxiliary ships, including

5250-667: The world The first optical communication systems were designed and delivered to the U.S. Army and Chevron by Optelecom, Inc., the venture co-founded by Gordon Gould, the inventor of the optical amplifier and the laser. The photophone (originally given an alternate name, radiophone ) is a communication device which allowed for the transmission of speech on a beam of light . It was invented jointly by Alexander Graham Bell and his assistant Charles Sumner Tainter on February 19, 1880, at Bell's 1325 'L' Street laboratory in Washington, D.C. Both were later to become full associates in

5325-644: The world's total numbers and total tonnage of naval vessels of 1,000 tons or greater. Throughout the rest of the 20th century, the United States Navy would maintain a tonnage greater than that of the next 17 largest navies combined. During the Cold War , the Soviet Navy became a significant armed force, with large numbers of large, heavily armed ballistic missile submarines and extensive use of heavy, long-ranged antisurface missiles to counter

5400-465: Was arguably the largest naval battle in history ; it was also the last battle in which battleships played a significant role. By the end of World War II , the carrier had become the dominant force of naval warfare. World War II also saw the United States become by far the largest naval power in the world. In the late 20th and early 21st centuries, the United States Navy possessed over 70% of

5475-482: Was especially important, and common, before 20th-century military technology existed, when merely adding artillery and naval infantry to any sailing vessel could render it fully as martial as any military-owned vessel. Such privateering has been rendered obsolete in blue-water strategy since modern missile and aircraft systems grew to leapfrog over artillery and infantry in many respects; but privateering nevertheless remains potentially relevant in littoral warfare of

5550-411: Was formed in 1537, making it the oldest, current marine force in the world. The British Royal Marines combine being both a ship-based force and also being specially trained in commando frogman -style operations and tactics, operating in some cases separately from the rest of the Royal Navy. The Royal Marines also have their own special forces unit . In the majority of countries, the marine force

5625-609: Was not established until the Southern Song dynasty in the 12th century, a time when gunpowder was a revolutionary new application to warfare. The Chola Dynasty in Southern India had a navy composed of trade ships transporting armies overseas. The Chola Navy reached its peak under Rajendra I , and was most notably used in invasions of Sri Lanka and Southeast Asia . Nusantaran thalassocracies made extensive use of naval power and technologies. This enabled

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