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A History on tuners


The identity of the original inventor of radio, at the time called wireless telegraphy , is contentious. 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.

In 1893 in St. Louis , Missouri , Nikola Tesla made the first public demonstration of radio communication. Addressing the Franklin Institute in Philadelphia and the National Electric Light Association , he described and demonstrated in detail the principles of radio communication. The apparatus that he used contained all the elements that were incorporated into radio systems before the development of the vacuum tube . He initially used magnetic receivers [1] ( http://www.teslasociety.com/teslarec.pdf ) , unlike the coherers used by Marconi and other early experimenters.

In 1894 British physicist Sir Oliver Lodge demonstrated the possibility of signalling using radio waves using a detecting device called a coherer , a tube filled with iron filings which had been invented by Temistocle Calzecchi-Onesti at Fermo in Italy in 1884 . Edouard Branly of France and Alexander Popov of Russia later produced improved versions of the coherer. Popov, who was the first to develop a practical communication system based on the coherer, is usually considered by his own countrymen to have been the inventor of radio. The Indian physicist, Jagdish Chandra Bose , demonstrated publicly the use of radio waves in November of 1894 in Calcutta , but he was not interested in patenting his work (see IEEE Virtual Museum ( http://www.ieee-virtual-museum.org/collection/people.php?taid=&id=1234735&lid=1 ) ).

In 1896 Guglielmo Marconi was awarded what is sometimes recognised as the world's first patent for radio with British Patent 12039, Improvements in transmitting electrical impulses and signals and in apparatus there-for . In 1897 he established the world's first Radio Station on the Isle of Wight , England . The same year in the USA, some key developments in radio's early history were created and patented by Nikola Tesla. The US Patent Office reversed its decision in 1904 , awarding Guglielmo 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 . Some believe this was done to allow the US Government to avoid having to pay the royalties that were being claimed by Nikola Tesla for use of his patents.

The first voice radio transmission, broadcast in December, 23, 1906, by Reginald Fessendon, was "One, two, three, four. Is it snowing where you are?"

In 1909 Marconi, with Karl Ferdinand Braun , was also awarded the Nobel Prize in Physics for "contributions to the development of wireless telegraphy". However, Tesla's patent (number 645576 ) was reinstated in 1943 by the US Supreme Court, shortly after his death. This decision was based on the fact that there was prior work existing before the establishment of Marconi's patent. Some believe it was apparently made for financial reasons, to allow the US Government to avoid having to the pay damages that were being claimed by the Marconi Company for use of its patents during World War I (ignoring the prior establish work). Some posit, the government's initial granting to Marconi the patent right in order to nullify any claims Tesla had for compensation.

Marconi opened the world's first "wireless" factory in Hall Street, Chelmsford, England in 1898 , employing around 50 people. Around 1900, Tesla opened the Wardenclyffe Tower facility and advertised services. By 1903, the tower structure 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.

The next great invention was the vacuum tube detector, invented by a team of Westinghouse engineers.

On Christmas Eve , 1906 , Reginald Fessenden (using his heterodyne principle ) transmitted the first radio audio broadcast in history from Brant Rock, Massachusetts . Ships at sea heard a broadcast that included Fessenden playing the song O Holy Night on the violin and reading a passage from the Bible . The world's first radio news programme was broadcast August 31st 1920 by station 8MK in Detroit, Michigan . The world's first regular wireless broadcasts for entertainment commenced in 1922 from the Marconi Research Centre at Writtle near Chelmsford, England , which was also the location of the world's first "wireless" factory.

The controversy over who invented the radio, with the benefit of hindsight, can be broken down as follows: Q1: who invented 'wireless transmission of data using the entire frequency spectrum' (Spark-Gap Radio)? A1: Tesla, Marconi, Popov, possibly in that order. Q2: who invented 'AM radio' (amplitude modulated), so that more than one station can send signals (as opposed to spark-gap radio, where one transmitter covers the entire bandwidth of spectrums)? A2: Reginald Fessenden ( [2] ( http://www.invent.org/hall_of_fame/59.html ) Q3: who invented 'FM radio' (frequency modulated), so that a signal can carry more than a couple of hundred miles? A3: Edwin H. Armstrong

Early radios ran the entire power of the transmitter through a carbon microphone. While some early radios used some type of amplification through electric current or battery, through the mid 1920s the most common type of receiver was the Crystal set . In the 1920s, amplifying vacuum tubes revolutionized both radio receivers and radio transmitters .


Developments in the 20th century

In the early 1930s , single sideband and frequency modulation were invented by amateur radio operators. By the end of the decade, they were established commercial modes.

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.

The Sansui TU-X1, considered by many "the mother of all stereo FM tuners".