SMC291 Albarran and Pitts Reading

11 Pages
119 Views

Department
St. Michael's College Courses
Course Code
SMC103Y1
Professor
Jennifer Harris

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Description
272012 85300 PM y history and development y no single person can be credited with inventing radio y before impossible to simultaneously transmit information yy Electromagnetic Spectrumy wireless communication only theory until Maxwell publish suggestion that signal can be sent electromagneticallyy propagation of signal at various frequencies and level of interference y Hertz 1887 experiments generator to allow spark to be detected by receiving coil measure presence of wireless signals but didnt promote wireless communication y Inspired by telegraph and telephoneprivate citizens experimenting with wireless comm medium y Branlycoherer glass tube filled with metal fillings reacting when detect signal y Lodgeprinciple of resonance tuning to allow transmitter and receiver to operate on same wavelength y Popoffbetter coherer and vertical receiving antenna yy Marconiy Pragmatic view of wireless interested in getting it to work not how it worked y Improve Hertz transmitter and determine that elevated antenna enhanced signal travel increase coherer sensitivity and add telegraph key to control wireless signals y Within 2 years create system to send and detect signal over distance y Italians not interestedEnglish y Market radio as telegraph without Morse code or wires limited to comm tool between ships and shore stations y Transatlantic communications dominate until after WWI noncoded broadcasts followy Didnt invent wireless but recognized its commercial value and improved early operations yy 3 Investors and Innovators y Fessenden first transmission of noncoded radio signals for general reception by listeners poor sound quality and primarily radio operators on ships home experimenters and reporters broadcast programming allow him to read sing and talk y Forest selfpromoter and scientist create radio company improving existing tech and air publicity generating broadcasts to attract listeners and investors invent Audion triode vacuum tube that enable wireless signals to be amplified for improved reception before weak signals not detected well later also build better transmitters y Armstrong discovers principle of regeneration enhance quality of signal amplification and make possible external speaker and constant oscillating signal carrier wave that become founding principle behind new wireless transmitters y Shrink size of transmitters yy Growth of Public Interest in Wireless y WWI Navy take over operation of all high power stations amateurs banned from broadcasting y Demand for reliable transmitters and receiversemergency pooling of patent rights agree to pay for damages if later sued y After war Congress consider maintaining gov control over wireless but changing sentiments make them drop claim y Stations returned y GE and Westinghouse sell partsRCA manufacture radio receiving sets ATT transmitters and station equipment y 3 companies through RCA viewed radio like original Marconi companies as means for maritime and international communication y broadcasting not yet considered y amateurs exchange info magazines trial and error tech growth y boys and encouragement of learning about wireless y parallel between early wireless users and early adopters of all tech computer upgrade software or hardware and internet to share skill level improve and equipment improved early radio share info and obtain full time jobs higher income to buy better receiving equipment wireless tinkerer into radio listener
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