Telecommunication is the transmission of signs, messages, writings and sounds or information of any nature by wire, optical or other electromagnetic systems. Telecommunication occurs when the exchange of information between communication participants includes the use of technology, it is transmitted either electrically over physical media, such as cables, or via electromagnetic radiation. Such transmission paths are divided into communication channels which afford the advantages of multiplexing. Since the Latin term communicatio is considered the social process of information exchange, the term telecommunications is used in its plural form because it involves many different technologies. Early means of communicating over a distance included visual signals, such as beacons, smoke signals, semaphore telegraphs, signal flags, optical heliographs. Other examples of pre-modern long-distance communication included audio messages such as coded drumbeats, lung-blown horns, loud whistles. 20th- and 21st-century technologies for long-distance communication involve electrical and electromagnetic technologies, such as telegraph and teleprinter, radio, microwave transmission, fiber optics, communications satellites.
A revolution in wireless communication began in the first decade of the 20th century with the pioneering developments in radio communications by Guglielmo Marconi, who won the Nobel Prize in Physics in 1909, other notable pioneering inventors and developers in the field of electrical and electronic telecommunications. These included Charles Wheatstone and Samuel Morse, Alexander Graham Bell, Edwin Armstrong and Lee de Forest, as well as Vladimir K. Zworykin, John Logie Baird and Philo Farnsworth; the word telecommunication is a compound of the Greek prefix tele, meaning distant, far off, or afar, the Latin communicare, meaning to share. Its modern use is adapted from the French, because its written use was recorded in 1904 by the French engineer and novelist Édouard Estaunié. Communication was first used as an English word in the late 14th century, it comes from Old French comunicacion, from Latin communicationem, noun of action from past participle stem of communicare "to share, divide out.
Homing pigeons have been used throughout history by different cultures. Pigeon post had Persian roots, was used by the Romans to aid their military. Frontinus said; the Greeks conveyed the names of the victors at the Olympic Games to various cities using homing pigeons. In the early 19th century, the Dutch government used the system in Sumatra, and in 1849, Paul Julius Reuter started a pigeon service to fly stock prices between Aachen and Brussels, a service that operated for a year until the gap in the telegraph link was closed. In the Middle Ages, chains of beacons were used on hilltops as a means of relaying a signal. Beacon chains suffered the drawback that they could only pass a single bit of information, so the meaning of the message such as "the enemy has been sighted" had to be agreed upon in advance. One notable instance of their use was during the Spanish Armada, when a beacon chain relayed a signal from Plymouth to London. In 1792, Claude Chappe, a French engineer, built the first fixed visual telegraphy system between Lille and Paris.
However semaphore suffered from the need for skilled operators and expensive towers at intervals of ten to thirty kilometres. As a result of competition from the electrical telegraph, the last commercial line was abandoned in 1880. On 25 July 1837 the first commercial electrical telegraph was demonstrated by English inventor Sir William Fothergill Cooke, English scientist Sir Charles Wheatstone. Both inventors viewed their device as "an improvement to the electromagnetic telegraph" not as a new device. Samuel Morse independently developed a version of the electrical telegraph that he unsuccessfully demonstrated on 2 September 1837, his code was an important advance over Wheatstone's signaling method. The first transatlantic telegraph cable was completed on 27 July 1866, allowing transatlantic telecommunication for the first time; the conventional telephone was invented independently by Alexander Bell and Elisha Gray in 1876. Antonio Meucci invented the first device that allowed the electrical transmission of voice over a line in 1849.
However Meucci's device was of little practical value because it relied upon the electrophonic effect and thus required users to place the receiver in their mouth to "hear" what was being said. The first commercial telephone services were set-up in 1878 and 1879 on both sides of the Atlantic in the cities of New Haven and London. Starting in 1894, Italian inventor Guglielmo Marconi began developing a wireless communication using the newly discovered phenomenon of radio waves, showing by 1901 that they could be transmitted across the Atlantic Ocean; this was the start of wireless telegraphy by radio. Voice and music had little early success. World War I accelerated the development of radio for military communications. After the war, commercial radio AM broadcasting began in the 1920s and became an important mass medium for entertainment and news. World War II again accelerated development of radio for the wartime purposes of aircraft and land communication, radio navigation and radar. Development of stereo FM broadcasting of radio
In telecommunication, a communications system or communication system is a collection of individual communications networks, transmission systems, relay stations, tributary stations, data terminal equipment capable of interconnection and interoperation to form an integrated whole. The components of a communications system serve a common purpose, are technically compatible, use common procedures, respond to controls, operate in union. Telecommunications is a method of communication. Communication is the act of conveying intended meanings from one entity or group to another through the use of mutually understood signs and semiotic rules An optical communication system is any form of telecommunication that uses light as the transmission medium. Equipment consists of a transmitter, which encodes a message into an optical signal, a communication channel, which carries the signal to its destination, a receiver, which reproduces the message from the received optical signal. Fiber-optic communication systems transmit information from one place to another by sending light through an optical fiber.
The light forms a carrier signal, modulated to carry information. A radio communication system is composed of several communications subsystems that give exterior communications capabilities. A radio communication system comprises a transmitting conductor in which electrical oscillations or currents are produced and, arranged to cause such currents or oscillations to be propagated through the free space medium from one point to another remote therefrom and a receiving conductor at such distant point adapted to be excited by the oscillations or currents propagated from the transmitter. Power line communication systems operate by impressing a modulated carrier signal on power wires. Different types of powerline communications use different frequency bands, depending on the signal transmission characteristics of the power wiring used. Since the power wiring system was intended for transmission of AC power, the power wire circuits have only a limited ability to carry higher frequencies; the propagation problem is a limiting factor for each type of power line communications.
A duplex communication system is a system composed of two connected parties or devices which can communicate with one another in both directions. The term duplex is used when describing communication between devices. Duplex systems are employed in nearly all communications networks, either to allow for a communication "two-way street" between two connected parties or to provide a "reverse path" for the monitoring and remote adjustment of equipment in the field. An Antenna is a small length of a qwert conductor, used to radiate or receive electromagnetic waves, it acts as a conversion device. At the transmitting end it converts high frequency current into electromagnetic waves. At the receiving end it transforms electromagnetic waves into electrical signals, fed into the input of the receiver. Several types of antenna are used in communication. Examples of communications subsystems include the Defense Communications System. Telephone Mobile Telegraph Edison Telegraph T. V. Cable Computer A tactical communications system is a communications system, used within, or in direct support of tactical forces is designed to meet the requirements of changing tactical situations and varying environmental conditions, provides securable communications, such as voice and video, among mobile users to facilitate command and control within, in support of, tactical forces, requires short installation times on the order of hours, in order to meet the requirements of frequent relocation.
An Emergency communication system is any system, organized for the primary purpose of supporting the two way communication of emergency messages between both individuals and groups of individuals. These systems are designed to integrate the cross-communication of messages between are variety of communication technologies. An Automatic call distributor is a communication system that automatically queues and connects callers to handlers; this is used in customer service, ordering by telephone, or coordination services. A Voice Communication Control System is an ACD with characteristics that make it more adapted to use in critical situations Sources can be classified as electric or non-electric. Examples of sources include but are not limited to the following: Audio Files Graphic Image Files Email Messages Human Voice Television Picture Electromagnetic Radiation Sensors, like microphones and cameras, capture non-electric sources, like sound and light, convert them into electrical signals; these types of sensors are called input transducers in modern analog and digital communication systems.
Without input transducers there would not be an effective way to transport non-electric sources or signals over great distances, i.e. humans would have to rely on our eyes and ears to see and hear things despite the distances. Not good! Other examples of input transducers include: Microphones Cameras Keyboards Mouse Force Sensors Accelerometers Once the source signal has been converted into an electric signal, the transmitter will modify this signal for efficient transmission. In order to do
General Services Administration
The General Services Administration, an independent agency of the United States government, was established in 1949 to help manage and support the basic functioning of federal agencies. GSA supplies products and communications for U. S. government offices, provides transportation and office space to federal employees, develops government-wide cost-minimizing policies and other management tasks. GSA employs about 12,000 federal workers and has an annual operating budget of $20.9 billion. GSA oversees $66 billion of procurement annually, it contributes to the management of about $500 billion in U. S. federal property, divided chiefly among 8,700 owned and leased buildings and a 215,000 vehicle motor pool. Among the real estate assets managed by GSA are the Ronald Reagan Building and International Trade Center in Washington, D. C. – the largest U. S. federal building after the Pentagon – and the Hart-Dole-Inouye Federal Center. GSA's business lines include the Federal Acquisition Service and the Public Buildings Service, as well as several Staff Offices including the Office of Government-wide Policy, the Office of Small Business Utilization, the Office of Mission Assurance.
As part of FAS, GSA's Technology Transformation Services helps federal agencies improve delivery of information and services to the public. Key initiatives include FedRAMP, Cloud.gov, the USAGov platform, Data.gov, Performance.gov, Challenge.gov. GSA is a member of the Procurement G6, an informal group leading the use of framework agreements and e-procurement instruments in public procurement. In 1947 President Harry Truman asked former President Herbert Hoover to lead what became known as the Hoover Commission to make recommendations to reorganize the operations of the federal government. One of the recommendations of the commission was the establishment of an "Office of the General Services." This proposed office would combine the responsibilities of the following organizations: U. S. Treasury Department's Bureau of Federal Supply U. S. Treasury Department's Office of Contract Settlement National Archives Establishment All functions of the Federal Works Agency, including the Public Buildings Administration and the Public Roads Administration War Assets AdministrationGSA became an independent agency on July 1, 1949, after the passage of the Federal Property and Administrative Services Act.
General Jess Larson, Administrator of the War Assets Administration, was named GSA's first Administrator. The first job awaiting Administrator Larson and the newly formed GSA was a complete renovation of the White House; the structure had fallen into such a state of disrepair by 1949 that one inspector of the time said the historic structure was standing "purely from habit." Larson explained the nature of the total renovation in depth by saying, "In order to make the White House structurally sound, it was necessary to dismantle, I mean dismantle, everything from the White House except the four walls, which were constructed of stone. Everything, except the four walls without a roof, was stripped down, that's where the work started." GSA worked with President Truman and First Lady Bess Truman to ensure that the new agency's first major project would be a success. GSA completed the renovation in 1952. In 1986 GSA headquarters, U. S. General Services Administration Building, located at Eighteenth and F Streets, NW, was listed on the National Register of Historic Places, at the time serving as Interior Department offices.
In 1960 GSA created the Federal Telecommunications System, a government-wide intercity telephone system. In 1962 the Ad Hoc Committee on Federal Office Space created a new building program to address obsolete office buildings in Washington, D. C. resulting in the construction of many of the offices that now line Independence Avenue. In 1970 the Nixon administration created the Consumer Product Information Coordinating Center, now part of USAGov. In 1974 the Federal Buildings Fund was initiated, allowing GSA to issue rent bills to federal agencies. In 1972 GSA established the Automated Data and Telecommunications Service, which became the Office of Information Resources Management. In 1973 GSA created the Office of Federal Management Policy. GSA's Office of Acquisition Policy centralized procurement policy in 1978. GSA was responsible for emergency preparedness and stockpiling strategic materials to be used in wartime until these functions were transferred to the newly-created Federal Emergency Management Agency in 1979.
In 1984 GSA introduced the federal government to the use of charge cards, known as the GMA SmartPay system. The National Archives and Records Administration was spun off into an independent agency in 1985; the same year, GSA began to provide governmentwide policy oversight and guidance for federal real property management as a result of an Executive Order signed by President Ronald Reagan. In 2003 the Federal Protective Service was moved to the Department of Homeland Security. In 2005 GSA reorganized to merge the Federal Supply Service and Federal Technology Service business lines into the Federal Acquisition Service. On April 3, 2009, President Barack Obama nominated Martha N. Johnson to serve as GSA Administrator. After a nine-month delay, the United States Senate confirmed her nomination on February 4, 2010. On April 2, 2012, Johnson resigned in the wake of a management-deficiency report that detailed improper payments for a 2010 "Western Regions" training conference put on by the Public Buildings Service in Las Vegas.
In July 1991 GSA contractors began the excavation of what is now the Ted Weiss Federal Building in New York City. The planning for that buildin
Command and control
Command and control or C2 is a "set of organizational and technical attributes and processes... employs human and information resources to solve problems and accomplish missions" to achieve the goals of an organization or enterprise, according to a 2015 definition by military scientists Marius Vassiliou, David S. Alberts and Jonathan R. Agre, The term refers to a military system. Versions of the United States Army Field Manual 3-0 circulated circa 1999, define C2 in a military organization as the exercise of authority and direction by a properly designated commanding officer over assigned and attached forces in the accomplishment of a mission. A 1988 NATO definition and control is the exercise of authority and direction by a properly designated individual over assigned resources in the accomplishment of a common goal. An Australian Defence Force definition, similar to that of NATO, emphasises that C2 is the system empowering designated personnel to exercise lawful authority and direction over assigned forces for the accomplishment of missions and tasks.
The US Department of Defense Dictionary of Military and Associated Terms defines command and control as: "The exercise of authority and direction by a properly designated commander over assigned and attached forces in the accomplishment of the mission. Called C2. Source: JP 1"; the edition of the Dictionary "As Amended Through April 2010" elaborates, "Command and control functions are performed through an arrangement of personnel, communications and procedures employed by a commander in planning, directing and controlling forces and operations in the accomplishment of the mission." However, this sentence is missing from the "command and control" entry for the edition "As Amended Through 15 August 2014."Commanding officers are assisted in executing these tasks by specialized staff officers and enlisted personnel. These military staff are a group of officers and enlisted personnel that provides a bi-directional flow of information between a commanding officer and subordinate military units; the purpose of a military staff is that of providing accurate, timely information which by category represents information on which command decisions are based.
The key application is that of decisions that manage unit resources. While information flow toward the commander is a priority, information, useful or contingent in nature is communicated to lower staffs and units; this term is in common use within the computer security industry and in the context of cyberwarfare. Here the term refers to the influence an attacker has over a compromised computer system that they control. For example, a valid usage of the term is to say that attackers use "command and control infrastructure" to issue "command and control instructions" to their victims. Advanced analysis of command and control methodologies can be used to identify attackers, associate attacks, disrupt ongoing malicious activity. There are a plethora of derivative terms which emphasise different aspects and sub-domains of C2; these terms come with a plethora of associated abbreviations – for example, in addition to C2, command and control is often abbreviated as C2, sometimes as C&C. Command and control have been coupled with Communication / Communications Intelligence Information / Information Systems Computers / Computing Surveillance Target acquisition Reconnaissance Interoperability Collaboration Electronic warfareand others.
Some of the more common variations include: C2I – Command, Control & Intelligence C2I – Command, Control & Information C2IS – Command and Control Information Systems C2ISR – C2I plus Surveillance and Reconnaissance C2ISTAR – C2 plus ISTAR C3 – Command, Control & Communication C3 – Command, Control & Communications C3 – Consultation and Control C3I – 4 possibilities. Command: The exercise of authority based upon certain knowledge to attain an objective. Control: The process of verifying and correcting activity such that the objective or goal of command is accomplished. Communication: Ability to exercise the necessary liaison to exercise effective command between tactical or strategic units to command. Computers: The computer systems and compatibility of computer systems. Includes data processing. Intelligence: Includes collection as well as distribution of information. A command and control center is a secure room or building in a government, military or prison facility that operates as the agency's dispatch center, surveillance monitoring center, coordination office and alarm monitoring center all in one.
Command and control centers are operated by a government or municipal agency. Various branches of the US military such as the US Coast Guard and Navy have command and control centers. T
Video is an electronic medium for the recording, playback and display of moving visual media. Video was first developed for mechanical television systems, which were replaced by cathode ray tube systems which were replaced by flat panel displays of several types. Video systems vary in display resolution, aspect ratio, refresh rate, color capabilities and other qualities. Analog and digital variants exist and can be carried on a variety of media, including radio broadcast, magnetic tape, optical discs, computer files, network streaming. Video technology was first developed for mechanical television systems, which were replaced by cathode ray tube television systems, but several new technologies for video display devices have since been invented. Video was exclusively a live technology. Charles Ginsburg led an Ampex research team developing one of the first practical video tape recorder. In 1951 the first video tape recorder captured live images from television cameras by converting the camera's electrical impulses and saving the information onto magnetic video tape.
Video recorders were sold for US $50,000 in 1956, videotapes cost US $300 per one-hour reel. However, prices dropped over the years; the use of digital techniques in video created digital video, which allows higher quality and much lower cost than earlier analog technology. After the invention of the DVD in 1997 and Blu-ray Disc in 2006, sales of videotape and recording equipment plummeted. Advances in computer technology allows inexpensive personal computers and smartphones to capture, store and transmit digital video, further reducing the cost of video production, allowing program-makers and broadcasters to move to tapeless production; the advent of digital broadcasting and the subsequent digital television transition is in the process of relegating analog video to the status of a legacy technology in most parts of the world. As of 2015, with the increasing use of high-resolution video cameras with improved dynamic range and color gamuts, high-dynamic-range digital intermediate data formats with improved color depth, modern digital video technology is converging with digital film technology.
Frame rate, the number of still pictures per unit of time of video, ranges from six or eight frames per second for old mechanical cameras to 120 or more frames per second for new professional cameras. PAL standards and SECAM specify 25 frame/s. Film is shot at the slower frame rate of 24 frames per second, which complicates the process of transferring a cinematic motion picture to video; the minimum frame rate to achieve a comfortable illusion of a moving image is about sixteen frames per second. Video can be progressive. In progressive scan systems, each refresh period updates all scan lines in each frame in sequence; when displaying a natively progressive broadcast or recorded signal, the result is optimum spatial resolution of both the stationary and moving parts of the image. Interlacing was invented as a way to reduce flicker in early mechanical and CRT video displays without increasing the number of complete frames per second. Interlacing retains detail while requiring lower bandwidth compared to progressive scanning.
In interlaced video, the horizontal scan lines of each complete frame are treated as if numbered consecutively, captured as two fields: an odd field consisting of the odd-numbered lines and an field consisting of the even-numbered lines. Analog display devices reproduce each frame doubling the frame rate as far as perceptible overall flicker is concerned; when the image capture device acquires the fields one at a time, rather than dividing up a complete frame after it is captured, the frame rate for motion is doubled as well, resulting in smoother, more lifelike reproduction of moving parts of the image when viewed on an interlaced CRT display. NTSC, PAL and SECAM are interlaced formats. Abbreviated video resolution specifications include an i to indicate interlacing. For example, PAL video format is described as 576i50, where 576 indicates the total number of horizontal scan lines, i indicates interlacing, 50 indicates 50 fields per second; when displaying a natively interlaced signal on a progressive scan device, overall spatial resolution is degraded by simple line doubling—artifacts such as flickering or "comb" effects in moving parts of the image which appear unless special signal processing eliminates them.
A procedure known as deinterlacing can optimize the display of an interlaced video signal from an analog, DVD or satellite source on a progressive scan device such as an LCD television, digital video projector or plasma panel. Deinterlacing cannot, produce video quality, equivalent to true progressive scan source material. Aspect ratio describes the proportional relationship between the width and height of video screens and video picture elements. All popular video formats are rectangular, so can be described by a ratio between width and height; the ratio width to height for a traditional television screen is 4:3, or about 1.33:1. High definition televisions use an aspect ratio of 16:9, or about 1.78:1. The aspect ratio of a full 35 mm film frame with soundtrack is 1.375:1. Pixels on computer monitors are square, but pixels used in digital video have non-square aspect ratios, such as those used in the PAL and NTSC variants of the CCIR 601 digital video
Military tactics encompasses the art of organising and employing fighting forces on or near the battlefield. They involve the application of four battlefield functions which are related – kinetic or firepower, protection or security, shock action. Tactics are a separate function from control and logistics. In contemporary military science, tactics are the lowest of three levels of warfighting, the higher levels being the strategic and operational levels. Throughout history, there has been a shifting balance between the four tactical functions based on the application of military technology, which has led to one or more of the tactical functions being dominant for a period of time accompanied by the dominance of an associated fighting arm deployed on the battlefield, such as infantry, cavalry or tanks. Beginning with the use of melee and missile weapons such as clubs and spears, the kinetic or firepower function of tactics has developed along with technological advances so that the emphasis has shifted over time from the close-range melee and missile weapons to longer-range projectile weapons.
Kinetic effects were delivered by the sword, spear and bow until the introduction of artillery by the Romans. Until the mid 19th century, the value of infantry-delivered missile firepower was not high, meaning that the result of a given battle was decided by infantry firepower alone relying on artillery to deliver significant kinetic effects; the development of disciplined volley fire, delivered at close range, began to improve the hitting power of infantry, compensated in part for the limited range, poor accuracy and low rate of fire of early muskets. Advances in technology the introduction of the rifled musket, used in the Crimean War and American Civil War, meant flatter trajectories and improved accuracy at greater ranges, along with higher casualties; the resulting increase in defensive firepower meant infantry attacks without artillery support became difficult. Firepower became crucial to fixing an enemy in place to allow a decisive strike. Machine guns added to infantry firepower at the turn of the 20th century, the mobile firepower provided by tanks, self-propelled artillery and military aircraft rose in the century that followed.
Along with infantry weapons and other armoured vehicles, self-propelled artillery, guided weapons and aircraft provide the firepower of modern armies. Mobility, which determines how a fighting force can move, was for most of human history limited by the speed of a soldier on foot when supplies were carried by beasts of burden. With this restriction, most armies could not travel more than 32 kilometres per day, unless travelling on rivers. Only small elements of a force such as cavalry or specially trained light troops could exceed this limit; this restriction on tactical mobility remained until the latter years of World War I when the advent of the tank improved mobility sufficiently to allow decisive tactical manoeuvre. Despite this advance, full tactical mobility was not achieved until World War II when armoured and motorised formations achieved remarkable successes. However, large elements of the armies of World War II remained reliant on horse-drawn transport, which limited tactical mobility within the overall force.
Tactical mobility can be limited by the use of field obstacles created by military engineers. Personal armour has been worn since the classical period to provide a measure of individual protection, extended to include barding of the mount; the limitations of armour have always been weight and bulk, its consequent effects on mobility as well as human and animal endurance. By the 18th and 19th centuries, personal armour had been discarded, until the re-introduction of helmets during World War I in response to the firepower of artillery. Armoured fighting vehicles proliferated during World War II, after that war, body armour returned for the infantry in Western armies. Fortifications, which have been used since ancient times, provide collective protection, modern examples include entrenchments, barbed wire and minefields. Like obstacles, fortifications are created by military engineers. Shock action is as much a psychological function of tactics as a physical one, can be enhanced by the use of surprise.
It has been provided by charging infantry, well as by chariots, war elephants and armoured vehicles which provide momentum to an assault. It has been used in a defensive way, for example by the drenching flights of arrows from English longbowmen at the Battle of Agincourt in 1415 which caused the horses of the French knights to panic. During early modern warfare, the use of the tactical formations of columns and lines had a greater effect than the firepower of the formations alone. During the early stages of World War II, the combined effects of German machine gun and tank gun firepower, enhanced by accurate indirect fire and air attack broke up Allied units before their assault commenced, or caused them to falter due to casualties among key unit leaders. In both the early modern and World War II examples, the cumulative psychological shock effect on the enemy was greater than the actual casualties incurred; the development of tactics has involved a shifting balance between the four tactical functions since ancient times, changes in firepower and mobility have been fundamental to these changes.
Various models have been proposed to explain the interaction between the tactical functions and the dominance of individual fighting arms during different periods. J. F. C. Fuller proposed three "tactical cycles" in each of the classical and Chri