RTF Test Notes - Structure of the radio industry, genres of...

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Structure of the radio industry, genres of radio programming, role of radio in the lives of its audiences, carry over to television, early radio vitally important to understand TV, also played a big role in cultural lives of many Americans (and others around the world) Social context of radio development -1890s Age of technological experimentation shrinking of time and space telegraph and telephone inventions played a role transmitted code and voice across wires Experimenting with technology-not professional inventors or scientists Regular people, young boys and girls who became fascinated with technological potential Key Inventors Guglielmo Marconi Italian teenager, electronics enthusiast, in 1894 made telegraph technology wireless, code signal through a air (not wires), wireless telegraphy (1894), spark gap device generated radio waves that carried morse code through air, the italian government is not interested in invention, the British government grabs it for naval uses, colonial power (because they holdings in Africa and Asia), set up company called British Marconi in 1897, which makes radio transmitters and receivers for the British government, company expands to US by 1900 and becomes big industry, standard equipment on ships, 400 relay stations on East Coast by 1913, was not a commercial technology Reginald Foessenden invents the heterodyne in 1906, allows for human voice to be transmitted over air instead of coded signals 1st step in process: Transduction: sounds converted to electrical pattern 2nd step: Modulation: electrical pules superimposed onto electromagnetic waves that always exist in atmosphere, waves carry electrical pulses through the air, invented amplitude modulation, means that height of wave changes according to electrical pulses (AM Radio) 3rd step: Reverse Transduction: electrical pulses modulated on waves converted back to sound (through a speaker) Amplitude Modulation (AM) able to carry sound over long distances but susceptible to interference by rain, big building etc. First voice transmission took place on New Years Eve, 1906-quality of voice not
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very good He sold his invention to the United Fruit Company who saw its application to their shipping business Lee DeForest invents the audion tube (1907)- more effective means of transduction and modulation, higher quality of sound transmission, sold invention to AT Edward Armstrong- superheterodyne (1918), increases signal strength, allowed for an alternate form of modulation, developed Frequency Modulation (FM), frequency of waves changes with electrical pulses, clearer signal than AM and less vulnerable to interference, but signal does not travel as far, FM doesn’t get picked up until 1950s because most applications were over long distances over water Early Uses of Radio point to point and broadcasting (singe transmitter to many receivers) once technology developed to carry sound/voice to carry sound/voice across
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This note was uploaded on 04/08/2008 for the course GOV 310L taught by Professor Kieth during the Spring '07 term at University of Texas.

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RTF Test Notes - Structure of the radio industry, genres of...

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