- Timeline of radio
The timeline of radio lists within the
history of radio, the technologyand events that produced instruments that use radiowaves and activities that people undertook. 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 (
1820: Hans Christian Ørsteddiscovered the relationship between electricityand magnetismin a very simple experiment. He demonstrated that a wire carrying a current was able to deflect a magnetized compassneedle.
1831: Michael Faradaybegan 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.
1861to 1865: James Clerk Maxwellmade experiments with electromagnetic waves.
1872: Mahlon Loomiswas issued US patent|129971.
1873: Maxwell, as a result of experiments, 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".
1875: Thomas Edisonannounced to the press that while experimenting with the telegraph, he had noted a phenomenon that he termed " etheric force". He abandoned this research when Elihu Thomson, among others, ridiculed the idea.
1878: David E. Hugheswas the first to transmit and receive radio waves when he noticed that his induction balance caused noise in the receiver of his homemade telephone.
*1880: David Hughes demonstrated his discovery to the Royal Society, but was told it was merely induction.
1884: Temistocle Calzecchi-Onestiat Fermoin Italy invented a tube filled with ironfilings, called a " coherer".
*1884 to 1886:
Edouard Branlyof France produced an improved version of the coherer.
1886to 1888: Heinrich Rudolf Hertzvalidated 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 equationcalled the wave equation.
1885to 1892: Claims have been made that Murray, Kentuckyfarmer Nathan Stubblefieldinvented radio, but his devices seem to have worked by induction transmission rather than radio transmission.
*1893 to 1894:
Roberto Landell de Moura, a Brazilian priest and scientist, conducted experiments. He did not publicize his achievement until 1900.
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.
1893: At St. Louis, Missouri, Teslagave a public demonstration of " wireless" radio communication. Addressing the " Franklin Institute" in Philadelphiaand the " National Electric Light Association", he described in detail the principles of radio communication. [http://www.ieee-virtual-museum.org/collection/people.php?taid=&id=1234597&lid=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 conductionto "wireless practices". Also, he initially used sensitive electromagneticreceivers [http://www.teslasociety.com/teslarec.pdf] , 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.
1894: Heinrich Rudolf Hertzdied.
1894: British physicist Sir Oliver Lodgedemonstrated the reception of Morse code signalling using radio waves using a "coherer".
1894: The Indian physicist, Jagdish Chandra Bose, demonstrated publicly the use of radio waves in Calcutta, but he was not interested in patenting his work. [http://www.ieee-virtual-museum.org/collection/people.php?taid=&id=1234735&lid=1] Bose ignited gunpowder and rang a bell at a distance using electromagnetic waves, proving that communication signals can be sent without using wires.
1894: The Russian physicist Alexander Popov built a coherer.
*7 May 1895: Popov demonstrated in public 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
Russiaas " 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 [ [http://www.ieee.org/organizations/history_center/milestones_photos/popov.html IEEE - IEEE History Center ] ] .
cohererto detect radio signals in wireless telegraphy.]
1895: Marconi received telegraph message without wires, but he did not send voice over the airwaves.
*Beginning of 1895: Tesla detected signals from his New York lab's transmissions at
West Point(a distance of 50 miles).
1895: Popov transmitted radio waves between different campus buildings in Saint Petersburg, but did not apply for a patent. This features in the case against Marconi in radio's invention.
1895: The New Zealander Ernest Rutherford, 1st Baron Rutherford of Nelsonwas 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. Thomsonquickly 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 others (such as Guglielmo Marconi).
1896: Marconi was awarded a patent for radio with British Patent12039, "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.
1896: Bose went to London on a lecture tour and met Marconi, who was conducting wireless experiments for the British post office.
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.
1898: Marconi opened the first radio factory, on Hall Street, Chelmsford, England, employing around 50 people.
1899: Bose announced his invention of the "iron-mercury-iron coherer with telephone detector" in a paper presented at Royal Society, London.
1900: Reginald Fessendenmade a weak transmission of voice over the airwaves.
1900: Tesla opened the Wardenclyffe Towerfacility and advertised services.
1901: Marconiclaims to have received in St. John's, Newfoundland a radio signal transmitted from Poldhuin Cornwall(UK), but this is disputed. The claims of Marconi's signal and case against it are still discussed.
1903: Wardenclyffe Towerneared 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.
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 Edisonand 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.
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 Telegraphoperated 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 Adolf Slabyand Georg von Arco(later incorporated into Telefunken).
1906: Reginald Fessendenused an Alexanderson alternatorand rotary spark-gap transmitterto 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 violinand reading a passage from the Bible.
1907: Marconi established the first permanent transatlantic wireless service from Clifden, Ireland to Glace Bay, Nova Scotia.
1909: Marconi and Karl Ferdinand Braunwere awarded the Nobel Prize in Physicsfor "contributions to the development of wireless telegraphy".
Charles David Herrold, an electronics instructor in San Jose, Californiaconstructed a broadcasting station. It used spark gaptechnology, 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 Valleyfarmer, 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 omnidirectional 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.
1912: The RMS "Titanic" sank. After this, wireless telegraphy using spark-gap transmitters quickly became universal on large ships.
1913: Marconiinitiated duplex transatlantic wireless communication between North America and Europe for the first time, using receiver stations in LetterfrackIreland, and Louisbourg, Nova Scotia.
1913: The International Convention for the Safety of Life at Seawas 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)
1916: First regular broadcasts on 9XM (now WHA) - Wisconsin state weather, delivered in Morse Code
1919: First clear transmission of human speech, (on 9XM) after experiments with voice ( 1918) and music ( 1917).
1920: Regular wireless broadcasts for entertainment began in Argentina, pioneered by the group around Enrique Telémaco Susini.
1920: Spark-gap telegraphystopped.
*20 August 1920:
E.W. Scripps's WWJ in Detroitreceived 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.
1920: The first known radio news program was broadcast by station 8MK, the unlicensed predecessor of WWJ (AM)in Detroit, Michigan.
1920: Westinghouse in Pittsburgh, Pennsylvaniabecame the first US commercial broadcasting station to be licensed when it was granted call letters KDKA. (Their engineer Frank Conradhad been broadcasting from his own station since 1916.)
*1922: Regular wireless broadcasts for entertainment began in the
UKfrom the Marconi Research Centre at Writtlenear Chelmsford, England. Early radios ran the entire power of the transmitter through a carbon microphone.
vacuum tubes revolutionized radio receivers and transmitters; Westinghouse engineers improved them. (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 detectorenabled audio radio.
Fessendenand Lee de Forestpioneered the invention of amplitude-modulated radio (AM radio), so more than one station can send signals (as opposed to spark-gap radio, where one transmitter covers the entire bandwidth of spectra). Westinghouse bought DeForest's and Armstrong's patent.
1920s: Radio was first used to transmit pictures visible as television.
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
* Race towards shorter waves and FM
1933: FM radiowas patented; Edwin H. Armstrong invented it. FM uses frequency modulationof the radio wave to minimize static and interference from electrical equipment and the atmosphere, in the audio program.
1937: W1XOJ, the first experimental FM radio station, was granted a construction permit by the FCC.
1940s: Standard analog television transmissions started in North America and Europe.
1943: Tesla's patent (number "645576") was reinstated by the U.S. Supreme Court shortly after Tesla's death, because prior artexisted before Marconi's patent was established. Ignoring Tesla's prior art, the decision may have let the U.S. government avoid paying damages that the Marconi Company was claiming for use of its patents during World War I; it is speculated that the U.S. government initially refused to grant Marconi the patent right, to nullify any claims Tesla had for compensation.
World War II: The FM radio broadcast was introduced in Germany.
1948: A new wavelength plan was set up for Europeat 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 modulationexperience with VHF, it was realized that FM radio was a much better alternative for VHF radio than AM.
Later 20th century developments
1960s: VOR systems finally became widespread; before that, aircraftused commercial AM radio stations for navigation. (AM stations are still marked on U.S. aviationcharts).
1954: Regency introduced a pocket transistorradio, the TR-1, powered by a "standard 22.5V Battery".
1960: Sonyintroduced 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.
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.
1970s: LORANbecame the premier radio navigation system. Soon, the U.S. Navy experimented with satellite navigation.
1987: The GPSconstellation of satellites was launched.
1990s: Amateur radioexperimenters began to use personal computers with audio cards to process radio signals.
1994: The U.S. Army and DARPAlaunched an aggressive successful project to construct a software radiothat could become a different radio on the fly by changing software.
*Late 1990s: The
digitaltransmissions began to be applied to broadcasting.
Telex on Radio
Telegraphydid 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 radioconsists of sending radio-style audio programming over streaming Internetconnections: no radio transmitters need be involved at any point in the process.
* Oldest radio station
Birth of public radio broadcasting
* [http://ns1763.ca/radio30/radio-first-30yrs.html Timeline of the First Thirty Years of Radio 1895 – 1925]
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