History of radio

The pre- and early history of radio is the history of technology that produced instruments that use radio waves. Later, the history is dominated by programming and contents, which is closer to general history.

Origins and developments

The identity of the original inventor of radio, at the time called wireless telegraphy, is contentious. The key invention for the beginning of "wireless transmission of data using the entire frequency spectrum", known as the spark-gap transmitter, has been attributed to Nikola Tesla, Guglielmo Marconi, and Alexander Popov.

Radio's prehistory (19th century)

In 1820, Hans Christian Ørsted discovered the relationship between electricity and magnetism in a very simple experiment. He demonstrated that a wire carrying a current was able to deflect a magnetized compass needle. In 1831, Michael Faraday began a series of experiments in which he discovered electromagnetic induction. The relation was mathematically modelled by Faraday's law, which subsequently became one of the four Maxwell equations. Faraday proposed that electromagnetic forces extended into the empty space around the conductor, but did not complete his work involving that proposal. Between 1861 and 1865, James Clerk Maxwell made experiments with electromagnetic waves.

On July 30, 1872, Mahlon Loomis was issued U.S. patent 129,971. In 1873, as a result of experiments, Maxwell first described the theoretical basis of the propagation of electromagnetic waves in his paper to the Royal Society A Dynamical Theory of the Electromagnetic Field. Towards end of 1875, while experimenting with the telegraph, Thomas Edison noted a phenomenon that he termed "etheric force", announcing it the press on November 28. He abandoned this research when Elihu Thomson, among others, ridiculed the idea. Between 1893 and 1894, Roberto Landell de Moura, a Brazilian priest and scientist, conducted experiments. He did not publicize his achievement until 1900. In 1878, David E. Hughes was the first to transmit and receive radio waves when he noticed that his induction balance caused noise in the receiver of his homemade telephone. He demonstrated his discovery to the Royal Society in 1880 but was told it was merely induction. In 1880, David E. Hughes demonstrated his discovery to the Royal Society but was told it was merely induction.

In 1884, Temistocle Calzecchi-Onesti at Fermo in Italy invented a tube filled with iron filings, called a "coherer". Between 1884 and 1886, Edouard Branly of France produced an improved versions of the coherer. In 1885, Edison took out a patent on a system of radio communication between ships, which he then sold to Guglielmo Marconi. Between 1886 and 1888, Heinrich Rudolf Hertz validated Maxwell's theory through experiment. He demonstrated that radio radiation had all the properties of waves (now called Hertzian waves), and discovered that the electromagnetic equations could be reformulated into a partial differential equation called the wave equation. Between 1885 and 1892, Claims have been made that Murray, Kentucky farmer Nathan Stubblefield invented radio, but his devices seem to have worked by induction transmission rather than radio transmission. Claims have been made that Nathan Stubblefield invented radio before either Tesla or Marconi, but his device seems to have worked by induction transmission rather than radio transmission.

Wireless beginnings

In the history of radio and development of "wireless telegraphy", there are multiple claims to the invention of radio. Marconi equipped ships with life saving wireless communications and established the first transatlantic radio service. Tesla developed means to reliably produce radio frequencies, publicly demonstrated the principles of radio, and transmitted long distant signals.

In 1893, at St. Louis, Missouri, Tesla gave a public demonstration of "wireless" radio communication. Addressing the Franklin Institute in Philadelphia and the National Electric Light Association, he described in detail the principles of radio communication. _[1] The apparatus that he used contained all the elements that were incorporated into radio systems before the development of the "oscillation valve", the early vacuum tube. Tesla was the first to apply the mechanism of electrical conduction to wireless practices. Also, he initially used sensitive electromagnetic receivers _[2], that were unlike the less responsive coherers later used by Marconi and other early experimenters. Afterwards, the principle of radio communication (sending signals through space to receivers) was publicized widely. Various scientists, inventors, and experimenters begin to investigate wireless methods.

On August 19 of 1894, British physicist Sir Oliver Lodge demonstrated the reception of Morse code signalling using radio waves using a "coherer". In November of 1894, he Indian physicist, Jagdish Chandra Bose, demonstrated publicly the use of radio waves in Calcutta, but he was not interested in patenting his work. _[3] Bose ignited gunpowder and rang a bell at a distance using electromagnetic waves, proving that communication signals can be sent without using wires. in 1894, the Russian physicist Alexander Popov built a coherer. On May 7, 1895, Popov performed a public demonstration of transmission and reception of radio waves used for communication at the Russian Physical and Chemical Society, using his coherer: this day has since been celebrated in the Russian Federation as "Radio Day". Popov was the first to develop a practical communication system based on the coherer, and is usually considered by the Russians to have been the inventor of radio ^[1].

In 1895, Marconi recieves telegraph message without wires, but he did not send voice over the airwaves. In March of 1895, Popov transmitted radio waves between different campus buildings in Saint Petersburg, but did not apply for a patent. In 1895, the New Zealander Ernest Rutherford, 1st Baron Rutherford of Nelson was awarded an Exhibition of 1851 Science Research Scholarship to Cambridge. He was instrumental in the development of radio. He arrived in England with a reputation as an innovator and inventor, and distinguished himself in several fields, initially by working out the electrical properties of solids and then using wireless waves as a method of signalling. Rutherford was encouraged in his work by Sir Robert Ball, who had been scientific adviser to the body maintaining lighthouses on the Irish coast; he wished to solve the difficult problem of a ship’s inability to detect a lighthouse in fog. Sensing fame and fortune, Rutherford increased the sensitivity of his apparatus until he could detect electromagnetic waves over a distance of several hundred metres. Thomson quickly realised that Rutherford was a researcher of exceptional ability and invited him to join in a study of the electrical conduction of gases. The commercial development of wireless technology was thus left for Guglielmo Marconi.

In 1896, Marconi was awarded a patent for radio with British Patent 12039, Improvements in Transmitting Electrical Impulses and Signals and in Apparatus There-for. This is the initial patent for radio, though it used various earlier techniques of various other experimenters (primarily Tesla) and resembled the instrument demonstrated by others (including Popov). During this time spark-gap wireless telegraphy is widely researched. In 1896, Bose went to London on a lecture tour and met Marconi, who was conducting wireless experiments for the British post office. in 1897, Marconi established the radio station on the Isle of Wight, England. In the U.S. during 1897, Tesla applied for two key radio patents. Those two patents were issued in early 1900.

In 1898, Marconi opened a radio factory in Hall Street, Chelmsford, England, employing around 50 people. In 1899, Bose announced his invention of the "iron-mercury-iron coherer with telephone detector" in a paper presented at Royal Society, London. In 1900, Reginald Fessenden made a weak transmission of voice over the airwaves. Around 1900, Tesla opened the Wardenclyffe Tower facility and advertised services. In 1903, Wardenclyffe Tower neared completion. Various theories exist on how Tesla intended to achieve the goals of this wireless system (reportedly, a 200 kW system). Tesla claimed that Wardenclyffe, as part of a World System of transmitters, would have allowed secure multichannel transceiving of information, universal navigation, time synchronization, and a global location system. In 1904, The U.S. Patent Office reversed its decision, awarding Marconi a patent for the invention of radio, possibly influenced by Marconi's financial backers in the States, who included Thomas Edison and Andrew Carnegie. This also allowed the U.S. government (among others) to avoid having to pay the royalties that were being claimed by Tesla for use of his patents.

Spark-gap telegraphy

Using various patents, the company called "British Marconi" was established and began communication between coast radio stations and ships at sea. This company along with its subsidiary American Marconi, had a stranglehold on ship to shore communication. It operated much the way American Telephone and Telegraph operated until 1983, owning all of its own equipment and refusing to communicate with non-Marconi equipped ships. Many inventions improved the quality of radio, and amateurs experimented with uses of radio, thus the first seeds of broadcasting were planted. Around the turn of the century, the Slaby-Arco wireless system was developed by Adolphus Slaby and Georg von Arco (later incorporated into Telefunken).

On Christmas Eve of 1906, Reginald Fessenden used an Alexanderson alternator and rotary spark-gap transmitter to make the first radio audio broadcast, from Brant Rock, Massachusetts. Ships at sea heard a broadcast that included Fessenden playing O Holy Night on the violin and reading a passage from the Bible. In 1909, Marconi and Karl Ferdinand Braun were awarded the Nobel Prize in Physics for "contributions to the development of wireless telegraphy".

In April of 1909, Charles David Herrold, an electronics instructor in San Jose, California constructed a broadcasting station. It used spark gap technology, but modulated the carrier frequency with the human voice, and later music. The station "San Jose Calling" (there were no call letters), continued in an unbroken lineage to eventually become today's KCBS in San Francisco. Herrold, the son of a Santa Clara Valley farmer, coined the terms "narrowcasting" and "broadcasting", respectively to identify transmissions destined for a single receiver such as that on board a ship, and those transmissions destined for a general audience. (The term "broadcasting" had been used in farming to define the tossing of seed in all directions.) Charles Herrold did not claim to be the first to transmit the human voice, but he claimed to be the first to conduct "broadcasting". To help the radio signal to spread in all directions, he designed omni-directional antennas, which he mounted on the rooftops of various buildings in San Jose. Herrold also claims to be the first broadcaster to accept advertising, although advertising generally involves paid announcements. He exchanged publicity for a local record store for records to play on his station.

In 1912, the RMS Titanic sank. After this, wireless telegraphy using spark-gap transmitters quickly became universal on large ships. In 1913, the International Convention for the Safety of Life at Sea was convened and produced a treaty requiring shipboard radio stations to be manned 24 hours a day. A typical high-power spark gap was a rotating commutator with six to twelve contacts per wheel, nine inches to a foot wide, driven by about 2000 volts DC. As the gaps made and broke contact, the radio wave was audible as a tone in a crystal set. The telegraph key often directly made and broke the 2000 volt supply. One side of the spark gap was directly connected to the antenna. Receivers with thermionic valves became commonplace before spark-gap transmitters were replaced by continuous wave transmitters.

Audio broadcasting (1915 to 1950s)

In the 1920s, Westinghouse bought DeForest's and Armstrong's patent. Westinghouse engineers developed a more modern vacuum tube. In 1920, Regular wireless broadcasts for entertainment began in Argentina, pioneered by the group around Enrique Telémaco Susini. Also in 1920, Spark-gap telegraphy stops. On August 31 of 1920, the first known radio news program was broadcast by station 8MK, the unlicensed predecessor of WWJ (AM) in Detroit, Michigan. In 1922, regular wireless broadcasts for entertainment began in the UK from the Marconi Research Centre at Writtle near Chelmsford, England. Early radios ran the entire power of the transmitter through a carbon microphone.

During the mid 1920s, Amplifying vacuum tubes revolutionized radio receivers and transmitters. Before that, the commonest type of receiver was the crystal set, although some early radios used some type of amplification through electric current or battery. Inventions of the triode amplifier, generator, and detector enabled audio radio. The invention of amplitude-modulated (AM radio), so that more than one station can send signals (as opposed to spark-gap radio, where one transmitter covers the entire bandwidth of spectra) was pioneered by Fessenden and Lee de Forest.

In October of 1920, Westinghouse in Pittsburgh, Pennsylvania became the first US licensed commercial broadcasting station when it was granted call letters KDKA. (Their engineer Frank Conrad had been broadcasting from his own station since 1916.) On August 20 of 1920, E.W. Scripps's WWJ in Detroit received its commercial broadcasting license and started broadcasting. It has carried a regular schedule of programming to the present. Broadcasting was not yet supported by advertising. The stations owned by manufacturers and department stores were established to sell radios and those owned by newspapers to sell papers and express the opinions of the owners. In the 1920s, Radio was first used to transmit pictures visible as television. During the early 1930s, single sideband (SSB) and frequency modulation (FM) were invented by amateur radio operators. By 1940, they were established commercial modes.

Westinghouse was brought into the patent allies group, General Electric, American Telephone and Telegraph, and Radio Corporation of America, and became a part owner of RCA. All radios made by GE and Westinghouse were sold under the RCA label 60% GE and 40% Westinghouse. ATT's Western Electric would build radio transmitters. The patent allies attempted to set up a monopoly, but they failed due to successful competition. Much to the dismay of the patent allies, several of the contracts for inventor's patents held clauses protecting "amateurs" and allowing them to use the patents. Whether the competing manufacturers were really amateurs was ignored by these competitors.

These features arose:-

Commercial (United States) or governmental (Europe) station networks
Federal Radio Commission
Federal Communications Commission
Birth of the soap opera
Race towards shorter waves and FM

In 1933, FM radio was patented; Edwin H. Armstrong invented it. FM uses frequency modulation of the radio wave to minimize static and interference from electrical equipment and the atmosphere, in the audio program. In 1937, W1XOJ, the first experimental FM radio station, was granted a construction permit by the FCC. In the 1940s, standard analog television transmissions started in North America and Europe.

In 1943, Tesla's patent (number 645576) was reinstated by the U.S. Supreme Court shortly after Tesla's death. This decision was based on the fact that prior art existed before the establishment of Marconi's patent. Ignoring Tesla's prior art, the decision may have enabled the U.S. government to avoid having to pay damages that were being claimed by the Marconi Company for use of its patents during World War I (as, it is speculated, the government's initial reversal to grant Marconi the patent right in order to nullify any claims Tesla had for compensation).

After World War II, the FM radio broadcast was introduced in Germany. In 1948, a new wavelength plan was set up for Europe at a meeting in Copenhagen. Because of the recent war, Germany (which was not even invited) was only given a few medium-wave frequencies, which are not very good for broadcasting. For this reason Germany began broadcasting on USW, "ultra short wave" (nowadays called VHF). After some amplitude modulation experience with VHF, it was realized that FM radio was a much better alternative for VHF radio than AM.

Later 20th century developments

In the early 1960s, VOR systems finally became widespread; before that, aircraft used commercial AM radio stations for navigation. (AM stations are still marked on U.S. aviation charts). in 1954, Regency introduced a pocket transistor radio, the TR-1, powered by a "standard 22.5V Battery". In 1960, Sony introduced their first transistorized radio, small enough to fit in a vest pocket, and able to be powered by a small battery. It was durable, because there were no tubes to burn out. Over the next twenty years, transistors displaced tubes almost completely except for very high power, or very high frequency, uses.

In 1963, Color television was commercially transmitted, and the first (radio) communication satellite, TELSTAR, was launched. In lLate 1960s, the U.S. long-distance telephone network began to convert to a digital network, employing digital radios for many of its links. in the 1970s, LORAN became the premier radio navigation system. Soon, the U.S. Navy experimented with satellite navigation. In 1987, the GPS constellation of satelliotes was launched in 1987. In the early 1990s, amateur radio experimenters began to use personal computers with audio cards to process radio signals. In 1994, the U.S. Army and DARPA launched an aggressive successful project to construct a software radio that could become a different radio on the fly by changing software. During the late 1990s, the digital transmissions began to be applied to broadcasting.

Telex on Radio

Telegraphy did not go away on radio. Instead, the degree of automation increased. On land-lines in the 1930s, Teletypewriters automated encoding, and were adapted to pulse-code dialing to automate routing, a service called telex. For thirty years, telex was the absolute cheapest form of long-distance communication, because up to 25 telex channels could occupy the same bandwidth as one voice channel. For business and government, it was an advantage that telex directly produced written documents.

Telex systems were adapted to short-wave radio by sending tones over single sideband. CCITT R.44 (the most advanced pure-telex standard) incorporated character-level error detection and retransmission as well as automated encoding and routing. For many years, telex-on-radio (TOR) was the only reliable way to reach some third-world countries. TOR remains reliable, though less-expensive forms of e-mail are displacing it. Many national telecom companies historically ran nearly pure telex networks for their governments, and they ran many of these links over short wave radio.

21st century development

Internet radio

Internet radio consists of sending radio-style audio programming over streaming Internet connections: no radio transmitters need be involved at any point in the process.

Early technology wars: Push or pull, streaming media or multicast
Run your own station with live365 or almost like Geocities or Hotmail

Digital audio broadcasting

Digital audio broadcasting (DAB): appears to be set to grow in importance relative to FM radio for airborne broadcasts in several countries.

iTrip

iTrip is an FM transmitter and accessory for Apple's popular iPod and Playstation Portable that can get all FM stations on an iPod or Playstation Portable that is made by Griffin Technology.

Only works with fourth and fifth generation iPods
Different iTrips are for different iPods
Not suitable for large urban areas

Exotic technologies

References

Belrose, John S., "Fessenden and Marconi: Their Differing Technologies and Transatlantic Experiments During the First Decade of this Century". International Conference on 100 Years of Radio (5-7 September 1995).

External andticles and references

Citations

^ http://www.ieee.org/organizations/history_center/milestones_photos/popov.html

Websites

[1] ttp://www.ieee.org/organizations/history_center/milestones_photos/popov.html

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