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Radio communication


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Radio communication

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  3. 3. b;Sydih fuh mqoa.,hska lsNSmfofkl`f.a iNyd.sJjfhkA ksmojkQ ,enqjls’19 jk ishjfiNs PSj;a jQ fY%aIaV jsohd{hskaf.a uNkaisfha m%;sM,hla f,i /yeka rys; jsoq,s mKsjqv hejSfus l%uh fidhd.kakd ,oS’ fuhg m%uqlJjh oelajq jsoHd{hska} Jagadish Chandra Bose Guglielmo Marconi Alexander Stepanovich Popov Nikola Tesla Ernest Rutherford Alexander PopovGerman troops erecting a wireless fieldtelegraph station during World War I 1901oS m%:u jdksPuh .`jkajsoq,s fiajdj wdrusN jsh’
  4. 4. w;S;fha .`jkajsoq,s mKsjqv hejSfus l%uh Ndjs;d lsrSu isoqjQfhaMORSE CODE NdjS;d lSrsu u.SkS Classic radio receiver dial1jk f,dal hqoaOfhaos kdjsl fin,qka yd hqO fin,qka w;r wdrlaIl f;dr;`re yqjudrelrf.k we;af;ao .`jkajsoq,s mKsjqv hejSfus l%uh Ndjs;d’jrA:udkfha Px.u oQrl:k ;dlaIKh nsNsjs we;af;ao /yeka rys;.`jkajsoq,s mKsjqv hejSfus l%uh Wmfhda.s’
  5. 5. Guglielmo Marconi• Guglielmo Marconi was an electrical engineer and Nobel laureate known for the development of a practical wireless telegraphy system.• In 1896, Guglielmo Marconi was awarded a patent for radio with British Patent 12039, Improvements in Transmitting Electrical Impulses and Signals and in Apparatus There-for. This was the initial patent for the 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 was 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 at Niton, Isle of Wight, England. In 1897, Tesla applied for two key radio patents in the USA. 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.
  6. 6. Jagdish Chandra BoseIn November 1894, the Indian physicist, Jagdish Chandra Bose, demonstrated publicly the use of radio waves in Calcutta, buthe was not interested in patenting his work.[10] Bose ignitedgunpowder and rang a bell at a distance using electromagneticwaves, proving that communication signals can be sent withoutusing wires. He was thus the first to send and receive radiowaves over a significant distance but did not commerciallyexploit this achievement.The 1895 public demonstration by Bose in Calcutta was beforeMarconis wireless signalling experiment on Salisbury Plain inEngland in May 1897.[11][12] In 1896, the Daily Chronicle ofEngland reported on his UHF experiments: "The inventor (J.C.Bose) has transmitted signals to a distance of nearly a mile andherein lies the first and obvious and exceedingly valuableapplication of this new theoretical marvel."
  7. 7. Nikola Tesla Nikola Tesla developed means to reliably produce radio frequencies, publicly demonstrated the principles of radio, and transmitted long distant signals. He holds the US patent for the invention of the radio, as defined as "wireless transmission of data".This box: view • talkNikola Tesla In 1891 Tesla began his research into radio. He later published an article, "The True Wireless", concerning this research.[4] In 1892 he gave a lecture called " Experiments with Alternate Currents of High Potential and High Frequency ", in London (Available at Project Gutenberg).[5] 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.[6] The apparatus that Tesla used contained all the elements that were incorporated into radio systems before the development of the "oscillation valve", the early vacuum tube. Tesla initially used sensitive electromagnetic receivers,[7] that were unlike the less responsive coherers later used by Marconi and other early experimenters. Afterward, the principle of radio communication (sending signals through space to receivers) was publicized widely from Teslas experiments and demonstrations. Various scientists, inventors, and experimenters began to investigate wireless methods. For more information see Teslas wireless work
  8. 8. Oliver Lodge• Oliver Lodge transmitted radio signals on August 14, 1894 (one year after Tesla, five years after Heinrich Hertz and one year before Marconi) at a meeting of the British Association for the Advancement of Science at Oxford University.[8] (In 1995, the Royal Society recognized this scientific breakthrough at a special ceremony at Oxford University. For more information, see Past Years: An Autobiography, New York: Charles Scribners Sons, p231.)• On 19 August 1894 Lodge demonstrated the reception of Morse code signalling via radio waves using a "coherer". He improved Edouard Branlys coherer radio wave detector by adding a "trembler" which dislodged clumped filings, thus restoring the devices sensitivity. [9] In August 1898 he got U.S. Patent 609,154, "Electric Telegraphy", that made wireless signals using Ruhmkorff coils or Tesla coils for the transmitter and a Branly coherer for the detector. This was key to the " syntonic" tuning concept. In 1912 Lodge sold the patent to Marconi.
  9. 9. Alexander Popov Popov was the first man to demonstrate the practical applications of radio waves. In 1895, 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:[13] this day has since been celebrated in Russia as " Radio Day". He did not apply for a patent for this invention. Popovs early experiments were transmissions of only 600 yards (550 m). 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.[14][15] Around March 1896 Popov demonstrated in public the transmission of radio waves, between different campus buildings, to the Saint Petersburg Physical Society. (This was before the public demonstration of the Marconi system around September 1896). Per other accounts, however, Popov achieved these results only in December, 1897; that is, after publication of Marconis patent.[16] In 1898 his signal was received 6 miles (9.7 km) away, and in 1899 30 miles away. In 1900, Popov stated at the Congress of Russian Electrical Engineers that, "the emission and reception of signals by Marconi by means of electric oscillations was nothing new, as in America Nikola Tesla did the same experiments in 1893."[17][18] Later Popov experimented with ship-to-shore communication. Popov died in 1905 and his claim was not pressed by the Russian government until 1945. Around 1895: 3-way near photofinish for first use of radio In March 1895, Popov transmitted radio waves between campus buildings in Saint Petersburg, but did not apply for a patent.
  10. 10. Ernest Rutherford• The New Zealander Ernest Rutherford, 1st Baron Rutherford of Nelson was instrumental in the development of radio. In 1895 he was awarded an Exhibition of 1851 Science Research Scholarship to Cambridge. 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 meters. The commercial development, though, of wireless technology was left for others, as Rutherford continued purely scientific research. 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.
  11. 11. Telephone Herald in Donald Manson working as an employeeBudapest, Hungary (1901).of the Marconi Company (England, 1906)
  12. 12. .`jka jsoq,sfha jsldYkh A Fisher 500 AM/FM hi-fi receiver from 1959.American girl listens to radioduring the Great Depression.
  13. 13. Pure One Classic- DAB Amateur radio station withDigital Radio from 2008 multiple receivers and transceivers
  14. 14. Bush House, homeof the BBC WorldService.
  15. 15. YS% ,xldfjs .`jkajsoq,s wdh;kLakhand 87.9 MHz88.5 North, North Central, North Western Wickramasinghapura MHz97.6 MHz (Karagahatenna)Island Wide (Nayabedda, aBattaramullaWorld Yatiyantota)Kandy & Southern (Deniyaya, Service transmitted Hunasgiriya) via APSTAR 2R satellite (76.5°E) 3.652 GHz Transponder 2 A Horizontal-Linear 6.5 Ms/SecHIRU 94.7 MHz94.7 Kandy (Hunasgiriya)Rajarata (Gammaduwa)Island MHz95.3 Wide (Nuwara Eliya)ColomboRuhuna (Gongala) MHz96.7 MHz96.7 MHzSHAKTH 91.2 MHz91.5 Bandarawelle (Nayabedda)Kandy Braybrooke PlaceI FM MHz103.8 (Hunasgiriya)Upcountry & Islandwide (Mt Oliphant, Colombo MHz105.1 Nuwara Eliya)ColomboMatale MHz105.1 (Karagahatenna/Gammaduwa)Southern Sri Lanka MHz105.1 MHz (Gongala)SIRASA 88.8 MHz101.7 Central Sri Lanka (Mt Oliphant, Nuwara Eliya 4 PO Box 25FM MHz106.2 kW)Rajarata, Northern & Eastern Sri Lanka Araliya Uyana MHz106.2 (Gammaduwa)Kandy (Hunasgiriya, 2 kW)Southern Pannipitiya MHz106.5 Sri Lanka (Gongala)Colombo (Union Place, 2 MHz106.5 MHz kW)Uva (Nayabedda)Y FM 91.2 MHz92.6 KandyColombo (Araliya Uyana, Depanama, Pannipitiya)North Formerly Classic FM MHz99.1 MHz101.3 Central (Gammaduwa)Southern Sri Lanka (Gongala)Uva 7 Braybrooke Place MHz101.3 MHz (Nayabedda) Colombo 2