HISTORY OF TELEPHONE

Credit for inventing the electric telephone remains in dispute. As with other great inventions such as radio, television, light bulb, and computer, there were several inventors who did pioneer experimental work on voice transmission over a wire and improved on each other's ideas. Innocenzo Manzetti, Antonio Meucci, Johann Philipp Reis, Elisha Gray, Alexander Graham Bell, and Thomas Edison, among others, have all been credited with pioneer work on the telephone.

The early history of the telephone is a confusing morass of claim and counterclaim, which was not clarified by the huge mass of lawsuits which hoped to resolve the patent claims of individuals. The Bell and Edison patents, however, were forensically victorious and commercially decisive.
Further information: Invention of the telephone and Elisha Gray and Alexander Bell telephone controversy

Early development
Early telephone with hand cranked generator.
• 1844 — Innocenzo Manzetti first mooted the idea of a “speaking telegraph” (telephone).
• 26 August 1854 — Charles Bourseul publishes an article in a magazine L'Illustration (Paris) : "Transmission électrique de la parole".
• 26 October 1861 — Johann Philipp Reis (1834–1874) publicly demonstrated the Reis telephone before the Physical Society of Frankfurt
• 22 August 1865, La Feuille d'Aoste reported “It is rumored that English technicians to whom Mr. Manzetti illustrated his method for transmitting spoken words on the telegraph wire intend to apply said invention in England on several private telegraph lines.”
• 28 December 1871 — Antonio Meucci files a patent caveat (n.3335) in the U.S. Patent Office titled "Sound Telegraph", describing communication of voice between two people by wire.
• 1874 — Meucci, after having renewed the caveat for two years, fails to find the money to renew it. The caveat lapses.
• 6 April 1875 — Bell's U.S. Patent 161,739 "Transmitters and Receivers for Electric Telegraphs" is granted. This uses multiple vibrating steel reeds in make-break circuits.
• 11 February 1876 — Gray invents a liquid transmitter for use with a telephone but does not build one.
• 14 February 1876 — Elisha Gray files a patent caveat for transmitting the human voice through a telegraphic circuit.
• 14 February 1876 — Alexander Bell applies for the patent "Improvements in Telegraphy", for electromagnetic telephones using undulating currents.
• 19 February 1876 — Gray is notified by the U.S. Patent Office of an interference between his caveat and Bell's patent application. Gray decides to abandon his caveat.
• 7 March 1876 — Bell's U.S. patent 174,465 "Improvement in Telegraphy" is granted, covering "the method of, and apparatus for, transmitting vocal or other sounds telegraphically … by causing electrical undulations, similar in form to the vibrations of the air accompanying the said vocal or other sound."
• 10 March 1876 — The first successful telephone transmission of clear speech using a liquid transmitter when Bell spoke into his device, “Mr. Watson, come here, I want to see you.” and Watson heard each word distinctly.
• 30 January 1877 — Bell's U.S. patent 186,787 is granted for an electromagnetic telephone using permanent magnets, iron diaphragms, and a call bell.
• 27 April 1877 — Edison files for a patent on a carbon (graphite) transmitter. The patent 474,230 was granted 3 May 1892, after a 15 year delay because of litigation. Edison was granted patent 222,390 for a carbon granules transmitter in 1879.

Early commercial instruments
Modern emergency telephone powered by sound alone
Early telephones were technically diverse. Some used a liquid transmitter, some had a metal diaphragm that induced current in an electromagnet wound around a permanent magnet, and some were "dynamic" - their diaphragm vibrated a coil of wire in the field of a permanent magnet or the coil vibrated the diaphragm. This dynamic kind survived in small numbers through the 20th century in military and maritime applications where its ability to create its own electrical power was crucial. Most, however, used the Edison/Berliner carbon transmitter, which was much louder than the other kinds, even though it required an induction coil, actually acting as an impedance matching transformer to make it compatible to the impedance of the line. The Edison patents kept the Bell monopoly viable into the 20th century, by which time the network was more important than the instrument.

Early telephones were locally powered, using either a dynamic transmitter or by the powering of a transmitter with a local battery. One of the jobs of outside plant personnel was to visit each telephone periodically to inspect the battery. During the 20th century, "common battery" operation came to dominate, powered by "talk battery" from the telephone exchange over the same wires that carried the voice signals.
Early telephones used a single wire for the subscriber's line, with ground return used to complete the circuit (as used in telegraphs). The earliest dynamic telephones also had only one opening for sound, and the user alternately listened and spoke (rather, shouted) into the same hole. Sometimes the instruments were operated in pairs at each end, making conversation more convenient but were more expensive.

At first, the benefits of an exchange were not exploited. Telephones instead were leased in pairs to the subscriber, who had to arrange telegraph contractors to construct a line between them, for example between his home and his shop. Users who wanted the ability to speak to several different locations would need to obtain and set up three or four pairs of telephones. Western Union, already using telegraph exchanges, quickly extended the principle to its telephones in New York City and San Francisco, and Bell was not slow in appreciating the potential.
Signalling began in an appropriately primitive manner. The user alerted the other end, or the exchange operator, by whistling into the transmitter.
Exchange operation soon resulted in telephones being equipped with a bell, first operated over a second wire, and later over the same wire, but with a condenser (capacitor) in series with the bell coil to allow the AC ringer signal through while still blocking DC (keeping the phone "on hook"). Telephones connected to the earliest Strowger automatic exchanges had seven wires, one for the knife switch, one for each telegraph key, one for the bell, one for the push button and two for speaking.
Rural and other telephones that were not on a common battery exchange had a magneto or hand-cranked generator to produce a high voltage alternating signal to ring the bells of other telephones on the line and to alert the operator.

In the 1890s a new smaller style of telephone was introduced, packaged in three parts. The transmitter stood on a stand, known as a "candlestick" for its shape. When not in use, the receiver hung on a hook with a switch in it, known as a "switchhook." Previous telephones required the user to operate a separate switch to connect either the voice or the bell. With the new kind, the user was less likely to leave the phone "off the hook". In phones connected to magneto exchanges, the bell, induction coil, battery and magneto were in a separate "bell box." In phones connected to common battery exchanges, the bell box was installed under a desk, or other out of the way place, since it did not need a battery or magneto.
Cradle designs were also used at this time, having a handle with the receiver and transmitter attached, separate from the cradle base that housed the magneto crank and other parts. They were larger than the "candlestick" and more popular.

Disadvantages of single wire operation such as crosstalk and hum from nearby AC power wires had already led to the use of twisted pairs and, for long distance telephones, four-wire circuits. Users at the beginning of the 20th century did not place long distance calls from their own telephones but made an appointment to use a special sound proofed long distance telephone booth furnished with the latest technology.

What turned out to be the most popular and longest lasting physical style of telephone was introduced in the early 20th century, including Bell's Model 102. A carbon granule transmitter and electromagnetic receiver were united in a single molded plastic handle, which when not in use sat in a cradle in the base unit. The circuit diagram of the Model 102 shows the direct connection of the receiver to the line, while the transmitter was induction coupled, with energy supplied by a local battery. The coupling transformer, battery, and ringer were in a separate enclosure. The dial switch in the base interrupted the line current by repeatedly but very briefly disconnecting the line 1-10 times for each digit, and the hook switch (in the center of the circuit diagram) permanently disconnected the line and the transmitter battery while the handset was on the cradle.

After the 1930s, the base also enclosed the bell and induction coil, obviating the old separate bell box. Power was supplied to each subscriber line by central office batteries instead of a local battery, which required periodic service. For the next half century, the network behind the telephone became progressively larger and much more efficient, but after the dial was added the instrument itself changed little until touch tone replaced the dial in the 1960s.

Digital telephony
The Public Switched Telephone Network (PSTN) has gradually evolved towards digital telephony which has improved the capacity and quality of the network. End-to-end analog telephone networks were first modified in the early 1960s by upgrading transmission networks with T1 carrier systems. Later technologies such as SONET and fiber optic transmission methods further advanced digital transmission. Although analog carrier systems existed, digital transmission made it possible to significantly increase the number of channels multiplexed on a single transmission medium. While today the end instrument remains analog, the analog signals reaching the aggregation point (Serving Area Interface (SAI) or the central office (CO) ) are typically converted to digital signals. Digital loop carriers (DLC) are often used, placing the digital network ever closer to the customer premises, relegating the analog local loop to legacy status.

IP telephony
Internet Protocol (IP) telephony (also known as Voice over IP), is a disruptive technology that is rapidly gaining ground against traditional telephone network technologies. In Japan and South Korea up to 10% of subscribers, as of January 2005, have switched to this digital telephone service. A January 2005 Newsweek article suggested that Internet telephony may be "the next big thing." As of 2006 many VoIP companies offer service to consumers and businesses.
IP telephony uses an Internet connection and hardware IP Phones or softphone installed on a personal computer to transmit conversations as data packets. In addition to replacing POTS (plain old telephone service), IP telephony is also competing with mobile phone networks by offering free or lower cost connections via WiFi hotspots. VoIP is also used on private wireless networks which may or may not have a connection to the outside telephone network.

Usage
By the end of 2006, there were a total of nearly 4 billion mobile and fixed line subscribers and over 1 billion Internet users worldwide. This included 1.27 billion fixed line subscribers and 2.68 billion mobile subscribers.

HISTORY OF AIRPLANE

To say simply that the Wright brothers invented the airplane would be disrespectful to the long years of scientific research and hard work put in by Orville and Wilbur Wright. Their story reads like the proverbial American dream where two honest, hardworking men, armed with nothing but their intelligence and determination made one of the most significant discoveries of the twentieth century.

Wilbur and Orville were born to Milton and Susan Wright. It was their father who initiated and encouraged the brothers’ interest in airplanes. In 1878 Milton Wright returned from a work related trip with a rubber band powered helicopter. The Wright brothers even at a young age immediately studied the model helicopter and started building replicas.

Around 1896, when the Wright brothers were successfully managing their bicycle company, the newspapers started carrying many stories about the invention of gliders and inventors who were trying to fly. This triggered the imagination of both brothers. They noticed that all the aircrafts developed till then lacked controls.

To start their venture, Wilbur wrote a letter to the Smithsonian Institution requesting for all the information on flight experiments that they had. Subsequently, in 1899 the brothers developed a simple system to warp the wings of a biplane. Warping meant that the plane could be controlled and rolled left or right as required. They tested this system on a series of gliders they developed.
The Wright brothers used Kitty Hawk, North Carolina to test the various models they built. They launched two gliders in 1900 and 1901 but were disappointed with the performance due to lack of lift and control. The brothers went back to the drawing board and spent the winter of 1901-1902 designing a wind tunnel and conducting experiments to figure out the best wing shape. This allowed them to build a glider with plenty of lift. Towards the end of 1902 they launched their third glider with roll, pitch and yaw controls.

The next winter was spent in designing a gasoline engine small and powerful enough to propel an aircraft. Their mechanic Charlie Taylor was a great help in designing the engine. They also designed the first ever airplane propellers and finally built a new, powered aircraft.
However, the road to success was not so easy. They suddenly found themselves competing with Samuel Langley, Secretary of the Smithsonian Institution. He had also built a powered aircraft and had investment funding to help his ventures. Luckily for the Wright brothers, Langley’s two attempts at launching his airplane failed miserably and put him out of competition.

Other problems were not quite so easily resolved. The weather misbehaved and there was nothing much they could do about it. Something in their control however, was the propeller. The propeller shafts broke on the first attempt and the drive sprockets were too loose on the second try. On the third try one of the propeller shafts cracked. Orville finally resolved the problem by using spring steel to make a new set of shafts. The aircraft was ready and they called it the Flyer.
After two unsuccessful attempts, the Wright brothers made aeronautical history on December 17th, 1903. Orville Wright took the Flyer for a 12 second sustained flight covering 120 feet. In the next few hours the brothers made 4 flights the longest of which was 852 feet.
Thus, the Wright brothers invented the airplane and much more!

HISTORY OF FLIGHT

Around 400 BC - Flight in China

The discovery of the kite that could fly in the air by the Chinese started humans thinking about flying. Kites were used by the Chinese in religious ceremonies. They built many colorful kites for fun, also. More sophisticated kites were used to test weather conditions. Kites have been important to the invention of flight as they were the forerunner to balloons and gliders.

Humans Try to Fly like Birds

For many centuries, humans have tried to fly just like the birds and have studied the flight of birds. Wings made of feathers or light weight wood have been attached to arms to test their ability to fly. The results were often disastrous as the muscles of the human arms are not like a birds and cannot move with the strength of a bird.

Hero and the Aeolipile
The ancient Greek engineer, Hero of Alexandria, worked with air pressure and steam to create sources of power. One experiment that he developed was the aeolipile which used jets of steam to create rotary motion. Hero mounted a sphere on top of a water kettle. A fire below the kettle turned the water into steam, and the gas traveled through pipes to the sphere. Two L-shaped tubes on opposite sides of the sphere allowed the gas to escape, which gave a thrust to the sphere that caused it to rotate. The importance of the aeolipile is that it marks the start of engine invention - engine created movement will later prove essential in the history of flight.

1485 Leonardo da Vinci - The Ornithopter and the Study of Flight.
Leonardo Da Vinci made the first real studies of flight in the 1480's. He had over 100 drawings that illustrated his theories on bird and mechanical flight. The drawings illustrated the wings and tails of birds, ideas for man carrying machines, and devices for the testing of wings. The Ornithopter flying machine was never actually created. It was a design that Leonardo da Vinci created to show how man could fly. The modern day helicopter is based on this concept. Leonardo da Vinci's notebooks on flight were reexamined in the 19th century by aviation pioneers.

1783 - Joseph and Jacques Montgolfier - The Flight of the First Hot Air Balloon
The brothers, Joseph Michel and Jacques Etienne Montgolfier, were inventors of the first hot air balloon. They used the smoke from a fire to blow hot air into a silk bag. The silk bag was attached to a basket. The hot air then rose and allowed the balloon to be lighter-than-air. In 1783, the first passengers in the colorful balloon were a sheep, rooster and duck. It climbed to a height of about 6,000 feet and traveled more than one mile.After this first success, the brothers began to send men up in hot air balloons. The first manned flight was on November 21, 1783, the passengers were Jean-Francois Pilatre de Rozier and Francois Laurent.

1799-1850's - George Cayley – Gliders
Sir George Cayley is considered the father of aerodynamics. Cayley experimented with wing design, distinguished between lift and drag, formulated the concepts of vertical tail surfaces, steering rudders, rear elevators, and air screws. George Cayley worked to discover a way that man could fly. Cayley designed many different versions of gliders that used the movements of the body to control. A young boy, whose name is not known, was the first to fly one of Cayley's gliders, the first glider capable of carrying a human.
For over 50 years, George Cayley made improvements to his gliders. Cayley changed the shape of the wings so that the air would flow over the wings correctly. Cayley designed a tail for the gliders to help with the stability. He tried a biplane design to add strength to the glider. George Cayley also recognized that there would be a need for machine power if the flight was to be in the air for a long time. George Cayley wrote "On Ariel Navigation" that showed that a fixed wing aircraft with a power system for propulsion, and a tail to assist in the control of the airplane, would be the best way to allow man to fly.

1891 Otto Lilienthal
German engineer, Otto Lilienthal, studied aerodynamics and worked to design a glider that would fly. Otto Lilienthal was the first person to design a glider that could fly a person and was able to fly long distances.
Otto Lilienthal was fascinated by the idea of flight. Based on his studies of birds and how they fly, he wrote a book on aerodynamics that was published in 1889 and this text was used by the Wright Brothers as the basis for their designs.
After more than 2500 flights, Otto Lilienthal was killed when he lost control because of a sudden strong wind and crashed into the ground.

1891 Samuel Langley
Samuel Langley was physicist and astronomer who realized that power was needed to help man fly. Langley conducted experiments using whirling arms and steam motors. He built a model of a plane, which he called an aerodrome, that included a steam-powered engine. In 1891, his model flew for 3/4s of a mile before running out of fuel.
Samuel Langley received a $50,000 grant to build a full sized aerodrome. It was too heavy to fly and it crashed. He was very disappointed. He gave up trying to fly. His major contributions to flight involved attempts at adding a power plant to a glider. He was also well known as the director of the Smithsonian Institute in Washington, DC.

1894 Octave Chanute
Octave Chanute was a successful engineer who undertook the invention of airplanes as a hobby, after being inspired by Otto Lilienthal. Chanute designed several aircraft, the Herring - Chanute biplane was his most successful design and formed the basis of the Wright biplane design. Octave Chanute published "Progress in Flying Machines" in 1894. It gathered and analyzed all the technical knowledge that he could find about aviation accomplishments. It included all of the world's aviation pioneers. The Wright Brothers used this book as a basis for much of their experiments. Chanute was also in contact with the Wright Brothers and often commented on their technical progress.

1903 The Wright Brothers - First Flight
Orville Wright and Wilbur Wright were very deliberate in their quest for flight. First, they spent many years learning about all the early developments of flight. They completed detailed research of what other early inventors had done. They read all the literature that was published up to that time. Then, they began to test the early theories with balloons and kites. They learned about how the wind would help with the flight and how it could affect the surfaces once up in the air. The next step was to test the shapes of gliders much like George Cayley did when he was testing the many different shapes that would fly. They spent much time testing and learning about how gliders could be controlled.

The Wright Brothers designed and used a wind tunnel to test the shapes of the wings and the tails of the gliders. After they found a glider shape that consistently would fly in the tests in the North Carolina Outer Banks dunes, then they turned their attention to how to create a propulsion system that would create the lift needed to fly. The early engine that they used generated almost 12 horsepower. The "Flyer" lifted from level ground to the north of Big Kill Devil Hill, at 10:35 a.m., on December 17, 1903. Orville piloted the plane which weighed six hundred and five pounds.

The first heavier-than-air flight traveled one hundred twenty feet in twelve seconds. The two brothers took turns during the test flights. It was Orville's turn to test the plane, so he is the brother that is credited with the first flight. Humankind was now able to fly! During the next century, many new airplanes and engines were developed to help transport people, luggage, cargo, military personnel and weapons. The 20th century's advances were all based on this first flight at Kitty Hawk by the American Brothers from Ohio.

HISTORY OF AIRPORT IN UNITED STATES

In the earliest years of civil aviation, no federal money went to build or operate civil landing fields. Federal money was, however, spent to map and catalog the 980 airfields in the United States that had been built by 1918 with private funds. The government's main financial support for aviation came through the purchase of military aircraft and through the military airfields that the government had constructed, especially during World War I. The government also began airmail service in 1918.

As airmail grew, the U.S. government became more involved with airports. The Post Office began investing in air stations to support the transcontinental air route in the early 1920s. The Air Commerce Act, signed by President Calvin Coolidge on May 20, 1926, made it the duty of the Secretary of Commerce to “promote air commerce.” with provisions for: the licensing, inspection, and operation of aircraft; the licensing of pilots and of mechanics engaged in aircraft work; and the operation and extension of the airways system begun by postal authorities. The Act, however, specifically barred the use of federal money for building or maintaining airports. Despite this limitation, the growth of aviation encouraged by the Act led to more private airport development.

During the Great Depression, the Federal Government began massive funding for civil works as part of its effort to create jobs and stimulate the economy. Many of these projects involved airport construction. The Civil Works Administration and later the Federal Emergency Relief Administration spent $11.5 million by the spring of 1934 on labor for 943 airport projects in small cities that established 585 new airports. Aviation regulatory agencies cooperated with these programs. Use of federal funds for constructing landing areas “reasonably necessary for use in air commerce or in the interests of national defense” continued to be allowed.

In September 1939, war broke out in Europe, prompting Congress to appropriate $40 million for Development of Landing Areas for National Defense (DLAND). Under DLAND, the Secretaries of War, Commerce, and the Navy approved expenditures for airports. By 1941, the Army Air Corps had begun directing aid to 986 airports. The Civil Aeronautics Administration (CAA) spent $363 million to construct and repair airfields in the United States, with many designed for civil aviation use after the war. Following World War II, 500 of these airports were declared surplus and turned over to cities, counties, and state sponsors to manage.

For defense purposes, CAA in 1941 extended its air traffic control system to include operation of airport towers. This function became a permanent federal responsibility in the postwar era.
In 1944, CAA submitted a National Airport Plan that helped spark Congressional interest in meeting postwar airport needs. After debating the issue, Congress passed the Federal Airport Act, signed on May 13, 1946, by President Harry S Truman. The Act provided for $500 million in grants for airport projects paid over seven years. The maximum federal grant for an eligible project would provide half of the project's costs. Local airport sponsors would issue bonds to finance the rest of the cost. All projects had to meet CAA standards for location, layout, grading, drainage, paving, and lighting. Further, all tax money collected by local governments for aviation facilities or fuel had to go for airport operations and maintenance.

In 1950, the Federal Airport Act was extended to 1958. Only runways and taxiways were eligible for federal money. Local sponsors were responsible for terminal buildings and equipment. On August 3, 1955, President Dwight Eisenhower signed Public Law 84-211, which included a new four-year program that committed $63 million of federal money each year. At the end of this period, another bill continued the money for two more years. Additional amounts were appropriated annually until 1970 when the Federal Airport Act was repealed, and the Airport and Airway Development Act of 1970, signed by President Richard Nixon on May 21, 1970, became law.

Title I of the Act provided for, among other things, $250 million annually for the “acquisition, establishment, and improvement of air navigational facilities” and security equipment for the next ten years. Title II created what was popularly called the “aviation trust fund,” financed by an eight percent tax on domestic passenger fares, a three-dollar surcharge on passenger tickets originating in the United States, a tax of seven cents per gallon on gasoline and jet fuel, a five percent tax on airfreight waybills, and an annual registration fee and charge per pound for aircraft.

On July 12, 1976, President Gerald Ford signed amendments to the law that increased the taxes levied. Now, eligible projects included snow removal, equipment to reduce aircraft noise, physical barriers and landscaping, and the purchase of land to meet environmental needs. Federal money could now pay for 90 percent of the costs of certain airport projects. This and later amendments also raised the amount of money available to airports.

By 1980, the aviation trust fund had received about $13.8 billion but only $4.1 billion had been spent on the airport system. Many parties were fighting over how the money from the fund should be spent, so most of the money remained unused. The U.S. Treasury on occasion has “tapped” the fund to use the money for projects unrelated to airports.
The Airport and Airway Improvement Act of 1982 raised taxes on aviation fuel and led to the Airport Improvement Program (AIP). It funds the construction of runways, taxiways and parts of terminal buildings and the purchase of land. It also funds automated weather observing systems, various safety-related equipment, and airport planning and noise studies. The AIP was amended several times, including in 1987, to favor small and disadvantaged businesses and individuals.

Around the world, today's airports may be operated by a national airport authority or transportation department, local authorities, airlines, private owners, or contractors. In the United States, most funds for new airports come from the sale of bonds managed by a local authority or sponsor. In the last decade, about $45 billion of AIP money has been spent with about 80 percent going to airports with scheduled air service, though like earlier programs, there continues to be disagreements and even lawsuits over how to spend the aviation trust fund.

References
Bilstein, Roger E. Flight in America, From the Wrights to the Astronauts. Revised edition. Baltimore: Johns Hopkins University Press, 1994.
Greif, Martin. The Airport Book, From Landing Field to Modern Terminal. New York: Main Street Press, Mayflower Books, 1979.
Horonjeff, Robert and McKelvey, Francis. Planning & Design of Airports. New York: McGraw-Hill Book Company, 1983.
Wells, Alexander T. Airport Planning & Management. Blue Ridge Summit, Pa.: Tab Books, 1992.
FAA Airports 50th Anniversary.” http://www.faa.gov/arp/annivers.htm.
“Milestones in Federal Aid to Airports.” http://www.faa.gov/arp/anniv01.htm.

HISTORY OF SATELLITE

Early conceptions

The first fictional depiction of a satellite being launched into orbit is a short story by Edward Everett Hale, The Brick Moon. The story is serialized in The Atlantic Monthly, starting in 1869. The idea surfaces again in Jules Verne's The Begum's Millions (1879).
In 1903 Konstantin Tsiolkovsky (1857–1935) published (The Exploration of Cosmic Space by Means of Reaction Devices), which is the first academic treatise on the use of rocketry to launch spacecraft. He calculated the orbital speed required for a minimal orbit around the Earth at 8 km/s, and that a multi-stage rocket fueled by liquid propellants could be used to achieve this. He proposed the use of liquid hydrogen and liquid oxygen, though other combinations can be used.

In 1928 Slovenian Herman Potočnik (1892–1929) published his sole book, Das Problem der Befahrung des Weltraums - der Raketen-Motor (The Problem of Space Travel — The Rocket Motor), a plan for a breakthrough into space and a permanent human presence there. He conceived of a space station in detail and calculated its geostationary orbit.
He described the use of orbiting spacecraft for detailed peaceful and military observation of the ground and described how the special conditions of space could be useful for scientific experiments. The book described geostationary satellites (first put forward by Tsiolkovsky) and discussed communication between them and the ground using radio, but fell short of the idea of using satellites for mass broadcasting and as telecommunications relays.
In a 1945 Wireless World article the English science fiction writer Arthur C. Clarke (1917-2008) described in detail the possible use of communications satellites for mass communications. Clarke examined the logistics of satellite launch, possible orbits and other aspects of the creation of a network of world-circling satellites, pointing to the benefits of high-speed global communications. He also suggested that thre

History of artificial satellites
The first artificial satellite was Sputnik 1, launched by the Soviet Union on 4 October 1957, and initiating the Soviet Sputnik program, with Sergei Korolev as chief designer and Kerim Kerimov as his assistant. This in turn triggered the Space Race between the Soviet Union and the United States.
Sputnik 1 helped to identify the density of high atmospheric layers through measurement of its orbital change and provided data on radio-signal distribution in the ionosphere. Because the satellite's body was filled with pressurized nitrogen, Sputnik 1 also provided the first opportunity for meteoroid detection, as a loss of internal pressure due to meteoroid penetration of the outer surface would have been evident in the temperature data sent back to Earth. The unanticipated announcement of Sputnik 1's success precipitated the Sputnik crisis in the United States and ignited the so-called Space Race within the Cold War.
Sputnik 2 was launched on November 3, 1957 and carried the first living passenger into orbit, a dog named Laika.
In May, 1946, Project RAND had released the Preliminary Design of an Experimental World-Circling Spaceship, which stated, "A satellite vehicle with appropriate instrumentation can be expected to be one of the most potent scientific tools of the Twentieth Century. The United States had been considering launching orbital satellites since 1945 under the Bureau of Aeronautics of the United States Navy. The United States Air Force's Project RAND eventually released the above report, but did not believe that the satellite was a potential military weapon; rather, they considered it to be a tool for science, politics, and propaganda. In 1954, the Secretary of Defense stated, "I know of no American satellite program."
On July 29, 1955, the White House announced that the U.S. intended to launch satellites by the spring of 1958. This became known as Project Vanguard. On July 31, the Soviets announced that they intended to launch a satellite by the fall of 1957.
Following pressure by the American Rocket Society, the National Science Foundation, and the International Geophysical Year, military interest picked up and in early 1955 the Air Force and Navy were working on Project Orbiter, which involved using a Jupiter C rocket to launch a satellite. The project succeeded, and Explorer 1 became the United States' first satellite on January 31, 1958.
In June 1961, three-and-a-half years after the launch of Sputnik 1, the Air Force used resources of the United States Space Surveillance Network to catalog 115 Earth-orbiting satellites.
The largest artificial satellite currently orbiting the Earth is the International Space Station.

Space Surveillance Network
The United States Space Surveillance Network (SSN) has been tracking space objects since 1957 when the Soviets opened the space age with the launch of Sputnik I. Since then, the SSN has tracked more than 26,000 space objects orbiting Earth. The SSN currently tracks more than 8,000 man-made orbiting objects. The rest have re-entered Earth's turbulent atmosphere and disintegrated, or survived re-entry and impacted the Earth. The space objects now orbiting Earth range from satellites weighing several tons to pieces of spent rocket bodies weighing only 10 pounds. About seven percent of the space objects are operational satellites (i.e. ~560 satellites), the rest are space debris. USSTRATCOM is primarily interested in the active satellites, but also tracks space debris which upon reentry might otherwise be mistaken for incoming missiles. The SSN tracks space objects that are 10 centimeters in diameter (baseball size) or larger.

Non-Military Satellite Services
There are three basic categories of non-military satellite services

1. Fixed Satellite Service
Fixed satellite services handle hundreds of billions of voice, data, and video transmission tasks across all countries and continents between certain points on the earth’s surface.

2. Mobile Satellite Systems
Mobile satellite systems help connect remote regions, vehicles, ships, people and aircraft to other parts of the world and/or other mobile or stationary communications units, in addition to serving as navigation systems.

3. Scientific Research Satellite (commercial and noncommercial)
Scientific research satellites provide us with meteorological information, land survey data (e.g., remote sensing), and other different scientific research applications such as earth science, marine science, and atmospheric research.

Attacks on satellites
In recent times satellites have been hacked by militant organizations to broadcast propaganda and to pilfer classified information from military communication networks.
Satellites in low earth orbit have been destroyed by ballistic missiles launched from earth. Russia, the United States and China have demonstrated the ability to eliminate satellites. In 2007 the Chinese military shot down an aging weather satellite. followed by the US Navy shooting down a defunct spy satellite in February 2008.

Jamming
Due to the low received signal strength of satellite transmissions they are prone to jamming by land-based transmitters. Such jamming is limited to the geographical area within the transmitter's range. GPS satellites are potential targets for jamming, but satellite phone and television signals have also been subjected to jamming.
Satellite Services
* Satellite Internet access
* Satellite phone
* Satellite radio
* Satellite television
* Satellite navigation

Source : http://en.wikipedia.org/

HISTORY OF INTERNET

Prior to the widespread internetworking that led to the internet, most communication networks were limited by their nature to only allow communications between the stations on the network, and the prevalent computer networking method was based on the central mainframe computer model. Several research programs began to explore unicorn homes and articulate principles of networking between separate physical networks. This led to the development of the packet switching model of digital networking. These research efforts included those of the laboratories of Donald Davies (NPL), Paul Baran (RAND Corporation), and Leonard Kleinrock’s MIT and UCLA.

1957
The USSR launches Sputnik, the first artificial earth satellite. In response,the United States forms the Advanced Research Projects Agency (ARPA) within theDepartment of Defense (DoD) to establish US lead in science and technology applicable to the military.

1962
RAND Paul Baran, of the RAND Corporation (a government agency), was commissioned by the U.S. Air Force to do a study on how it could maintain its command and control over its missiles and bombers, after a nuclear attack. This was to be a military research network that could survive a nuclear strike, decentralized so that if any locations (cities) in the U.S. were attacked, the military could still have control of nuclear arms for a counter-attack.

Baran's finished document described several ways to accomplish this. His final proposal was a packet switched network.

"Packet switching is the breaking down of data into datagrams or packets that are labeled to indicate the origin and the destination of the information and the forwarding of these packets from one computer to another computer until the information arrives at its final destination computer. This was crucial to the realization of a computer network. If packets are lost at any given point, the message can be resent by the originator."

ARPA awarded the ARPANET contract to BBN. BBN had selected a Honeywell minicomputer as the base on which they would build the switch. The physical network was constructed in 1969, linking four nodes: University of California at Los Angeles, SRI (in Stanford), University of California at Santa Barbara, and University of Utah. The network was wired together via 50 Kbps circuits.

1960-1970
The research led to the development of several packet-switched networking solutions in the late 1960s and 1970s, including ARPANET and the X25 protocols. Additionally, public access and hobbyist networking systems grew in popularity, including unix to unix copy (UUCP) and Fido Net. They were however still disjointed separate networks, served only by limited gateways between networks. This led to the application of packet switching to develop a protocol for inter-networking, where multiple different networks could be joined together into a super-framework of networks. By defining a simple common network system, the Internet protocol suite, the concept of the network could be separated from its physical implementation. This spread of inter-network began to form into the idea of a global inter-network that would be called “The Internet” , and this began to quickly spread as existing networks were converted to become compatible with this. This spread quickly across the advanced telecommunication networks of the western world, and then began to penetrate into the rest of the world as it became the de-facto international standard and global network. However, the disparity of growth led to a digital divide that is still a concern today.

ARPA awarded the ARPANET contract to BBN. BBN had selected a Honeywell minicomputer as the base on which they would build the switch. The physical network was constructed in 1969, linking four nodes: University of California at Los Angeles, SRI (in Stanford), University of California at Santa Barbara, and University of Utah. The network was wired together via 50 Kbps circuits
The first e-mail program was created by Ray Tomlinson of BBN.
The Advanced Research Projects Agency (ARPA) was renamed The Defense Advanced Research Projects Agency (or DARPA)
ARPANET was currently using the Network Control Protocol or NCP to transfer data. This allowed communications between hosts running on the same network.

Development began on the protocol later to be called TCP/IP, it was developed by a group headed by Vinton Cerf from Stanford and Bob Kahn from DARPA. This new protocol was to allow diverse computer networks to interconnect and communicate with each other.

1980-1990
Following commercialisation and introduction of privately run Internet Service Providers in the 1980s, and its expansion into popular use in the 1990s, the Internet has had a drastic impact on culture and commerce. This includes the rise of near instant communication by e-mail, text based discussion forums, and the World Wide Web. Investor speculation in new markets provided by these innovations would also lead to the inflation and collapse of the Dot-Com Buble, a major market collapse. But despite this, the Internet continues to grow.

HISTORY OF MOBILE PHONE

The introduction of cells for mobile phone base stations, invented in 1947 by Bell Labs engineers at AT&T, was further developed by Bell Labs during the 1960s. Radiophones have a long and varied history going back to the Second World War with military use of radio telephony links and civil services in the 1950s, while hand-held cellular radio devices have been available since 1983. Due to their low establishment costs and rapid deployment, mobile phone networks have since spread rapidly throughout the world, outstripping the growth of fixed telephony.

In 1945, the zero generation (0G) of mobile telephones was introduced. 0G mobile telephones, such as Mobile Telephone Service, were not officially categorized as mobile phones, since they did not support the automatic change of channel frequency during calls, which allows the user to move from one cell (the base station coverage area) to another cell, a feature called "handover".

In 1970, Bell Labs invented such a "call handoff" feature, which allowed mobile-phone users to travel through several cells during the same conversation. Motorola is widely considered to be the inventor of the first practical mobile phone for handheld use in a non-vehicle setting. Using a modern, if somewhat heavy portable handset, Motorola manager Martin Cooper made the first call on a handheld mobile phone on April 3, 1973.

The first commercial cellular network was launched in Japan by NTT in 1979. Fully automatic cellular networks were first introduced in the early to mid 1980s (the 1G generation) with the Nordic Mobile Telephone (NMT) system in 1981. This was followed by a boom in mobile telephone usage, particularly in Northern Europe.

The first "modern" network technology on digital 2G (second generation) cellular technology was launched by Radiolinja (now part of Elisa Group) in 1991 in Finland on the GSM standard which also marked the introduction of competition in mobile telecoms when Radiolinja challenged incumbent Telecom Finland (now part of TeliaSonera) who ran a 1G NMT network. A decade later, the first commercial launch of 3G (Third Generation) was again in Japan by NTT DoCoMo on the WCDMA standard.[citation needed] Until the early 1990s, most mobile phones were too large to be carried in a jacket pocket, so they were typically installed in vehicles as car phones. With the miniaturization of digital components, mobile phones have become increasingly handy over the years.

HISTORY OF COMPUTER

Before 1900
People have been using mechanical devices to aid calculation for thousands of years. For example, the abacus probably existed in Babylonia (present-day Iraq) about 3000 B.C.E. The ancient Greeks developed some very sophisticated analog computers. In 1901, an ancient Greek shipwreck was discovered off the island of Antikythera. Inside was a salt-encrusted device (now called the Antikythera mechanism) that consisted of rusted metal gears and pointers. When this c. 80 B.C.E. device was reconstructed, it produced a mechanism for predicting the motions of the stars and planets. (More Antikythera info here.)

John Napier (1550-1617), the Scottish inventor of logarithms, invented Napier's rods (sometimes called "Napier's bones") c. 1610 to simplify the task of multiplication.
In 1641 the French mathematician and philosopher Blaise Pascal (1623-1662) built a mechanical adding machine. Similar work was done by Gottfried Wilhelm Leibniz (1646-1716). Leibniz also advocated use of the binary system for doing calculations.
Recently it was discovered that Wilhelm Schickard (1592-1635), a graduate of the University of Tübingen (Germany), constructed such a device in 1623-4, before both Pascal and Leibniz. A brief description of the device is contained in two letters to Johannes Kepler. Unfortunately, at least one copy of the machine burned up in a fire, and Schickard himself died of bubonic plague in 1635, during the Thirty Years' War.
Joseph-Marie Jacquard (1752-1834) invented a loom that could weave complicated patterns described by holes in punched cards. Charles Babbage (1791-1871) worked on two mechanical devices: the Difference Engine and the far more ambitious Analytical Engine (a precursor of the modern digital computer), but neither worked satisfactorily. (Babbage was a bit of an eccentric -- one biographer calls him an "irascible genius" -- and was probably the model for Daniel Doyce in Charles Dickens' novel, Little Dorrit. A little-known fact about Babbage is that he invented the science of dendrochronology -- tree-ring dating -- but never pursued his invention. In his later years, Babbage devoted much of his time to the persecution of street musicians (organ-grinders).) The Difference Engine can be viewed nowadays in the Science Museum in London, England.
One of Babbage's friends, Ada Augusta Byron, Countess of Lovelace (1815-1852), sometimes is called the "first programmer" because of a report she wrote on Babbage's machine. (The programming language Ada was named for her.)
William Stanley Jevons (1835-1882), a British economist and logician, built a machine in 1869 to solve logic problems. It was "the first such machine with sufficient power to solve a complicated problem faster than the problem could be solved without the machine's aid." (Gardner) It is now in the Oxford Museum of the History of Science.
Herman Hollerith (1860-1929) invented the modern punched card for use in a machine he designed to help tabulate the 1890 census.

1900 - 1939: The Rise of Mathematics
Work on calculating machines continued. Some special-purpose calculating machines were built. For example, in 1919, E. O. Carissan (1880-1925), a lieutenant in the French infantry, designed and had built a marvelous mechanical device for factoring integers and testing them for primality. The Spaniard Leonardo Torres y Quevedo (1852-1936) built some electromechanical calculating devices, including one that played simple chess endgames.
In 1928, the German mathematician David Hilbert (1862-1943) addressed the International Congress of Mathematicians. He posed three questions: (1) Is mathematics complete; i.e. can every mathematical statement be either proved or disproved? (2) Is mathematics consistent, that is, is it true that statements such as "0 = 1" cannot be proved by valid methods? (3) Is mathematics decidable, that is, is there a mechanical method that can be applied to any mathematical assertion and (at least in principle) will eventually tell whether that assertion is true or not? This last question was called the Entscheidungsproblem.
In 1931, Kurt Gödel (1906-1978) answered two of Hilbert's questions. He showed that every sufficiently powerful formal system is either inconsistent or incomplete. Also, if an axiom system is consistent, this consistency cannot be proved within itself. The third question remained open, with 'provable' substituted for 'true'.
In 1936, Alan Turing (1912-1954) provided a solution to Hilbert's Entscheidungsproblem by constructing a formal model of a computer -- the Turing machine -- and showing that there were problems such a machine could not solve. One such problem is the so-called "halting problem": given a Pascal program, does it halt on all inputs?

1940's: Wartime brings the birth of the electronic digital computer
The calculations required for ballistics during World War II spurred the development of the general-purpose electronic digital computer. At Harvard, Howard H. Aiken (1900-1973) built the Mark I electromechanical computer in 1944, with the assistance of IBM.
Military code-breaking also led to computational projects. Alan Turing was involved in the breaking of the code behind the German machine, the Enigma, at Bletchley Park in England. The British built a computing device, the Colossus, to assist with code-breaking.
At Iowa State University in 1939, John Vincent Atanasoff (1904-1995) and Clifford Berry designed and built an electronic computer for solving systems of linear equations, but it never worked properly.
Atanasoff discussed his invention with John William Mauchly (1907-1980), who later, with J. Presper Eckert, Jr. (1919-1995), designed and built the ENIAC, a general-purpose electronic computer originally intended for artillery calculations. Exactly what ideas Mauchly got from Atanasoff is not complely clear, and whether Atanasoff or Mauchly and Eckert deserve credit as the originators of the electronic digital computer was the subject of legal battles and ongoing historical debate. The ENIAC was built at the Moore School at the University of Pennsylvania, and was finished in 1946.
In 1944, Mauchly, Eckert, and John von Neumann (1903-1957) were already at work designing a stored-program electronic computer, the EDVAC. Von Neumann's report, "First Draft of a Report on the EDVAC", was very influential and contains many of the ideas still used in most modern digital computers, including a mergesort routine. Eckert and Mauchly went on to build UNIVAC.
Meanwhile, in Germany, Konrad Zuse (1910-1995) built the first operational, general-purpose, program-controlled calculator, the Z3, in 1941. More information about Zuse can be found here.
In 1945, Vannevar Bush published a surprisingly prescient article in the Atlantic Monthly about the ways information processing would affect the society of the future. (Another copy of the Bush article appears here.)
Maurice Wilkes (b. 1913), working in Cambridge, England, built the EDSAC, a computer based on the EDVAC. F. C. Williams (b. 1911) and others at Manchester University built the Manchester Mark I, one version of which was working as early as June 1948. This machine is sometimes called the first stored-program digital computer.
The invention of the transistor in 1947 by John Bardeen (1908-1991), Walter Brattain (1902-1987), and William Shockley (1910-1989) transformed the computer and made possible the microprocessor revolution. For this discovery they won the 1956 Nobel Prize in physics. (Shockley later became notorious for his racist views.)
Jay Forrester (b. 1918) invented magnetic core memory c. 1949. More about Forrester here.

1950's
Grace Murray Hopper (1906-1992) invented the notion of a compiler, at Remington Rand, in 1951. Earlier, in 1947, Hopper found the first computer "bug" -- a real one -- a moth that had gotten into the Harvard Mark II. (Actually, the use of ``bug'' to mean defect goes back to at least 1889.)
John Backus and others developed the first FORTRAN compiler in April 1957. LISP, a list-processing language for artificial intelligence programming, was invented by John McCarthy about 1958. Alan Perlis, John Backus, Peter Naur and others developed Algol.
In hardware, Jack Kilby (Texas Instruments) and Robert Noyce (Fairchild Semiconductor) invented the integrated circuit in 1959.
Edsger Dijkstra invented an efficient algorithm for shortest paths in graphs as a demonstration of the ARMAC computer in 1956. He also invented an efficient algorithm for the minimum spanning tree in order to minimize the wiring needed for the X1 computer. (Dijkstra is famous for his caustic, opinionated memos. For example, see his opinions of some programming languages).
In a famous paper that appeared in the journal Mind in 1950, Alan Turing introduced the Turing Test, one of the first efforts in the field of artificial intelligence. He proposed a definition of "thinking" or "consciousness" using a game: a tester would have to decide, on the basis of written conversation, whether the entity in the next room responding to the tester's queries was a human or a computer. If this distinction could not be made, then it could be fairly said that the computer was "thinking".
In 1952, Alan Turing was arrested for "gross indecency" after a burglary led to the discovery of his affair with Arnold Murray. Overt homosexuality was taboo in 1950's England, and Turing was forced to take estrogen "treatments" which rendered him impotent and caused him to grow breasts. On June 7, 1954, despondent over his situation, Turing committed suicide by eating an apple laced with cyanide.

1960's
In the 1960's, computer science came into its own as a discipline. In fact, the term was coined by George Forsythe, a numerical analyst. The first computer science department was formed at Purdue University in 1962. The first person to receive a Ph. D. from a computer science department was Richard Wexelblat, at the University of Pennsylvania, in December 1965.
Operating systems saw major advances. Fred Brooks at IBM designed System/360, a line of different computers with the same architecture and instruction set, from small machine to top-of-the-line. Edsger Dijkstra at Eindhoven designed the THE multiprogramming system.
At the end of the decade, ARPAnet, a precursor to today's Internet, began to be constructed.
Many new programming languages were invented, such as BASIC (developed c. 1964 by John Kemeny (1926-1992) and Thomas Kurtz (b. 1928)).
The 1960's also saw the rise of automata theory and the theory of formal languages. Big names here include Noam Chomsky and Michael Rabin. Chomsky later became well-known for his theory that language is "hard-wired" in human brains, and for his criticism of American foreign policy.
Proving correctness of programs using formal methods also began to be more important in this decade. The work of Tony Hoare played an important role. Hoare also invented Quicksort.
Douglas C. Englebart invents the computer mouse c. 1968, at SRI.
Ted Hoff (b. 1937) and Federico Faggin at Intel designed the first microprocessor (computer on a chip) in 1969-1971.
A rigorous mathematical basis for the analysis of algorithms began with the work of Donald Knuth (b. 1938), author of 3-volume treatise entitled The Art of Computer Programming.

1970's
The theory of databases saw major advances with the work of Edgar F. Codd on relational databases. Codd won the Turing award in 1981.
Unix, a very influential operating system, was developed at Bell Laboratories by Ken Thompson (b. 1943) and Dennis Ritchie (b. 1941). Brian Kernighan and Ritchie together developed C, an influential programming language.
Other new programming languages, such as Pascal (invented by Niklaus Wirth) and Ada (developed by a team led by Jean Ichbiah), arose.
The first RISC architecture was begun by John Cocke in 1975, at the Thomas J. Watson Laboratories of IBM. Similar projects started at Berkeley and Stanford around this time.
The 1970's also saw the rise of the supercomputer. Seymour Cray (b. 1925) designed the CRAY-1, which was first shipped in March 1976. It could perform 160 million operations in a second. The Cray XMP came out in 1982. Cray Research was taken over by Silicon Graphics.
There were also major advances in algorithms and computational complexity. In 1971, Steve Cook published his seminal paper on NP-completeness, and shortly thereafter, Richard Karp showed that many natural combinatorial problems were NP-complete. Whit Diffie and Martin Hellman published a paper that introduced the theory of public-key cryptography, and a public-key cryptosystem known as RSA was invented by Ronald Rivest, Adi Shamir, and Leonard Adleman.
In 1979, three graduate students in North Carolina developed a distributed news server which eventually became Usenet.

1980's
This decade also saw the rise of the personal computer, thanks to Steve Wozniak and Steve Jobs, founders of Apple Computer.
The first computer viruses are developed c. 1981. The term was coined by Leonard Adleman, now at the University of Southern California.
In 1981, the first truly successful portable computer was marketed, the Osborne I. In 1984, Apple first marketed the Macintosh computer.
In 1987, the US National Science Foundation started NSFnet, precursor to part of today's Internet.

1990's and Beyond
Parallel computers continue to be developed.
Biological computing, with the recent work of Len Adleman on doing computations via DNA, has great promise. The Human Genome Project is attempting to sequence all the DNA in a single human being.
Quantum computing gets a boost with the discovery by Peter Shor that integer factorization can be performed efficiently on a (theoretical) quantum computer.
The "Information Superhighway" links more and more computers worldwide.
Computers get smaller and smaller; the birth of nano-technology.