question: How are we able to send information through the air?
comment: There are devices that encode and decode on either side of a transmitted signal. The encoder turns the signal in to a wave form, the decoder reassembles that wave form so the device can play it.
passages: Section::::Key components.:Input transducers (sensors).
  
  Sensors, like microphones and cameras, capture non-electric sources, like sound and light (respectively), and 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 solely on our eyes and ears to see and hear things despite the distances. Not good!
  
  Other examples of input transducers include:
  
  BULLET::::- Microphones
  
  BULLET::::- Cameras
  
  BULLET::::- Keyboards
  
  BULLET::::- Mouse (See Computer Peripherals)
  
  BULLET::::- Force Sensors
   The advancement of media and technology have played the pivotal role in process of globalization and global communication. Cable television, ISDN, digitalization, direct broadcast satellites as well as the Internet have created a situation where vast amounts of information can be transferred around the globe in a matter of seconds.
   During the early 20th century, telegraph, telephony, and radio started the process of global communication. As media technologies developed intensely, they were thought to create, in Marshall McLuhan’ s famous words, a ‘‘global village.’’ The launch of Sputnik, the world’ s first artificial satellite, on October 4, 1957, marked the beginning of technologies that would further interconnect the world. The first live global television broadcast occurred when Neil Armstrong stepped onto the moon in July 1969. In November 1972, pay TV caused expansion of cable when Service Electric offered Home Box Office over its cable system. By 2000, over direct broadcast satellite, a household could receive channels from all over the world. Now with the World Wide Web, smart phones, tablet devices, smart televisions and other digital media devices, billions of people are now able to access media content that was once tied to particular communications media (print, broadcast) or platforms (newspapers, magazines, radio, television, cinema).
   Early means of communicating over a distance included visual signals, such as beacons, smoke signals, semaphore telegraphs, signal flags and optical heliographs. Other examples of pre-modern long-distance communication included audio messages such as coded drumbeats, lung-blown horns, and loud whistles. 20th- and 21st-century technologies for long-distance communication usually involve electrical and electromagnetic technologies, such as telegraph, telephone, and teleprinter, networks, radio, microwave transmission, fiber optics, and communications satellites.
   Data (mainly but not exclusively informational) has been sent via non-electronic (e.g. optical, acoustic, mechanical) means since the advent of communication. Analog signal data has been sent electronically since the advent of the telephone. However, the first data electromagnetic transmission applications in modern time were telegraphy (1809) and teletypewriters (1906), which are both digital signals. The fundamental theoretical work in data transmission and information theory by Harry Nyquist, Ralph Hartley, Claude Shannon and others during the early 20th century, was done with these applications in mind.
   Section::::Electronic media.
  
  In the last century, a revolution in telecommunications has greatly altered communication by providing new media for long distance communication. The first transatlantic two-way radio broadcast occurred in 1906 and led to common communication via analog and digital media:
  
  BULLET::::- Analog telecommunications include some radio systems, historical telephony systems, and historical television broadcasts.
  
  BULLET::::- Digital telecommunications allow for computer-mediated communication, telegraphy, and computer networks.
   The first U.S. satellite to relay communications was Project SCORE in 1958, which used a tape recorder to store and forward voice messages. It was used to send a Christmas greeting to the world from U.S. President Dwight D. Eisenhower. In 1960 NASA launched an Echo satellite; the aluminized PET film balloon served as a passive reflector for radio communications. Courier 1B, built by Philco, also launched in 1960, was the world's first active repeater satellite. Satellites these days are used for many applications such as GPS, television, internet and telephone.
   Section::::History.:Satellite.
  
  The first U.S. satellite to relay communications was Project SCORE in 1958, which used a tape recorder to store and forward voice messages. It was used to send a Christmas greeting to the world from U.S. President Dwight D. Eisenhower. In 1960 NASA launched an Echo satellite; the aluminized PET film balloon served as a passive reflector for radio communications. Courier 1B, built by Philco, also launched in 1960, was the world's first active repeater satellite. Satellites these days are used for many applications such as uses in GPS, television, internet and telephone uses.
   After World War 2, microwaves were rapidly exploited commercially. Due to their high frequency they had a very large information-carrying capacity (bandwidth); a single microwave beam could carry tens of thousands of phone calls. In the 1950s and 60s transcontinental microwave relay networks were built in the US and Europe to exchange telephone calls between cities and distribute television programs. In the new television broadcasting industry, from the 1940s microwave dishes were used to transmit backhaul video feed from mobile production trucks back to the studio, allowing the first remote TV broadcasts. The first communications satellites were launched in the 1960s, which relayed telephone calls and television between widely separated points on Earth using microwave beams. In 1964, Arno Penzias and Robert Woodrow Wilson while investigating noise in a satellite horn antenna at Bell Labs, Holmdel, New Jersey discovered cosmic microwave background radiation.
   Thus, the work of many researchers enabled the use of electronics to convert signals into high frequency oscillating currents, and via suitably shaped conductors, electricity permits the transmission and reception of these signals via radio waves over very long distances.
  
  Section::::Production and uses.
  
  Section::::Production and uses.:Generation and transmission.
   BULLET::::- The radio station Witzleben begins in Germany with the regular broadcasting of television test broadcasts, initially on long wave with 30 lines (= 1,200 pixels) at 12.5 image changes per second. It appear first blueprints for television receiver.
  
  BULLET::::- John Logie Baird starts in the UK on behalf of the BBC with regular experimental television broadcasts to the public.
  
  BULLET::::- Frederic Eugene Ives transmits a color television from New York to Washington.
  
  BULLET::::- 1930
  
  BULLET::::- Manfred von Ardenne invented and developed the flying-spot scanner, Europe's first fully electronic television camera tube.
   The invention of the rectenna in the 1960s made long distance wireless power transmission feasible. The rectenna was invented in 1964 and patented in 1969 by US electrical engineer William C. Brown, who demonstrated it with a model helicopter powered by microwaves transmitted from the ground, received by an attached rectenna. Since the 1970s, one of the major motivations for rectenna research has been to develop a receiving antenna for proposed solar power satellites, which would harvest energy from sunlight in space with solar cells and beam it down to Earth as microwaves to huge rectenna arrays. A proposed military application is to power drone reconnaissance aircraft with microwaves beamed from the ground, allowing them to stay aloft for long periods. In recent years, interest has turned to using rectennas as power sources for small wireless microelectronic devices. The largest current use of rectennas is in RFID tags, proximity cards and contactless smart cards, which contain an integrated circuit (IC) which is powered by a small rectenna element. When the device is brought near an electronic reader unit, radio waves from the reader are received by the rectenna, powering up the IC, which transmits its data back to the reader.
   [[Optical communication]] has played an important role in [[communication network]]s.
  
  Optical communication provided the hardware basis for [[internet]] technology, laying the foundations for the [[Digital Revolution]] and Information Age.
  
  In 1953, Bram van Heel demonstrated image transmission through bundles of [[optical fiber]]s with a transparent cladding. The same year, [[Harold Hopkins (physicist)|Harold Hopkins]] and [[Narinder Singh Kapany]] at [[Imperial College]] succeeded in making image-transmitting bundles with over 10,000 optical fibers, and subsequently achieved image transmission through a 75 cm long bundle which combined several thousand fibers.
   The history of communication stretches from prehistoric forms of art and writing through modern communication methods such as the Internet. Mass communication began when humans could transmit messages from a single source to multiple receivers. Mass communication has moved from theories such as the hypodermic needle model (or magic bullet theory) through more modern theories such as computer-mediated communication.
   In the present day a variety of electronic systems optically transmit and receive information carried by pulses of light. Fiber-optic communication cables are now employed to send the great majority of the electronic data and long distance telephone calls that are not conveyed by either radio, terrestrial microwave or satellite. Free-space optical communications are also used every day in various applications.
  
  Section::::Forms.:Semaphore line.
   In terms of communication, information is expressed either as the content of a message or through direct or indirect observation. That which is perceived can be construed as a message in its own right, and in that sense, information is always conveyed as the content of a message.
  
  Information can be encoded into various forms for transmission and interpretation (for example, information may be encoded into a sequence of signs, or transmitted via a signal). It can also be encrypted for safe storage and communication.
   BULLET::::- 1958: The first communication satellite, Project SCORE, was developed in 1958. Launched on December 18, Project SCORE (Signal Communications via Orbiting Relay Experiment) broadcast President Eisenhower's Christmas greeting, proving that voice and code signals could be relayed over vast distances using satellite communication technology developed at Fort Monmouth.
  
  BULLET::::- 1959: The first Weather Satellite, the Vanguard 2, was launched on 19 February 1959, equipped to map the earth's cloud patterns by a varying infrared scanning device. The electronics for the satellite were developed at Fort Monmouth.
   Microwave transmission is the transmission of information by microwave radio waves. Although an experimental microwave telecommunication link across the English Channel was demonstrated in 1931, the development of radar in World War II provided the technology for practical exploitation of microwave communication. In the 1950s, large transcontinental "microwave relay" networks, consisting of chains of repeater stations linked by line-of-sight beams of microwaves were built in Europe and America to relay long distance telephone traffic and television programs between cities. Communication satellites which transferred data between ground stations by microwaves took over much long distance traffic in the 1960s. In recent years, there has been an explosive increase in use of the microwave spectrum by new telecommunication technologies such as wireless networks, and direct-broadcast satellites which broadcast television and radio directly into consumers' homes.
   "One can walk through the spiral-like tunnel. At the end of that tunnel is a black sphere (the somewhere). A small TV transmitter transmits the information (in the form of a flame) to the carrier, the spiral, and the receivers (TVs). Information always moves through time and space in the same form. It always has the form of the spiral. The sounds of human language move through space in the same way as our solar system moves through the universe. We store information on a computer disc in a spiral form, as we do on a videotape.
   On an otherwise ordinary day in Los Angeles, air traffic controllers in contact with American Airlines Flight 117 have the flight appear on a radar screen. The air traffic controllers instruct the McDonnell Douglas DC-10 airliner to make an emergency landing at Los Angeles International Airport. 
   BULLET::::- Through mass communication, information can be transmitted quickly to a large number of people who generally stay far away from the sources of information. Mass communication is being done through many mediums, such as radio, television, social networking, billboards, and newspapers.
  
  Section::::Field of study.
   In a 1959 paper, Cornell University physicists Philip Morrison and Giuseppe Cocconi had speculated that any extraterrestrial civilization attempting to communicate via radio signals might do so using a frequency of megahertz ( centimeters), which is naturally emitted by hydrogen, the most common element in the universe and therefore likely familiar to all technologically advanced civilizations.
   Communicating data from one location to another requires some form of pathway or medium. These pathways, called communication channels, use two types of media: cable (twisted-pair wire, cable, and fiber-optic cable) and broadcast (microwave, satellite, radio, and infrared). Cable or wire line media use physical wires of cables to transmit data and information. Twisted-pair wire and coaxial cables are made of copper, and fiber-optic cable is made of glass.
   According to Brower; "That was wireless telephony, then and there, but we didn't know it. We didn't know whether we were talking through the ground, but thought so, and I still think that may have been possible, for who knows yet whether these radio waves of today are carrying sounds by that means or through the air? I'm asking who knows this for certain. Signals from California were heard in New York recently below ground in a subway car."
   It was recognized that developing audio-capable transmitters would be a significant advance, but it took many years of research before quality audio transmissions became possible. In 1904 Valdemar Poulsen developed an arc converter transmitter, which, although still somewhat limited, would be the most commonly used transmitter employed for early audio experimentation. Initially the main objective for most inventors was developing devices usable for individual point-to-point communication, and the fact that radio signals could be overheard by others was at first seen as a defect that limited secure communication. Thus, it took awhile before the potential of "sending signals broadcast" was recognized.
  