File:GE FM radio antistatic demonstration 1940.jpg
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[edit]DescriptionGE FM radio antistatic demonstration 1940.jpg |
English: A dramatic public relations demonstration in 1940 by General Electric of the resistance to static (RFI) of its new radio broadcasting technology, frequency modulation (FM). It was held in GE's high voltage lab in New York, with a lightning-like arc from a million volt three phase-transformer as a source of interference behind the radio. The prototype radio, center, had both an AM and FM receiver. The AM receiver was tuned to music from WABC, GE's New York City AM station. The FM receiver was tuned to the same program rebroadcast by Edwin Armstrong's experimental FM radio station, W2XMN, in Alpine, New Jersey. When the AM radio was turned on, only a roar of static from the spark could be heard. When the FM radio was turned on, the music program came through clearly with just a slight amount of static. It took until the 1970s for FM broadcasting to really catch on, but today virtually all serious music broadcasting has moved from AM to FM due to its superior audio quality. Alterations to image: cloned out some text graphics overlaying the image in the upper left corner. |
Date | |
Source | Retrieved October 3, 2015 from E. W. Murtfeldt, "What are the facts about FM?" in Popular Science magazine, Popular Science Publishing Co., New York, Vol. 137, No. 5, November 1940, p. 70 on Google Books |
Author | E. W. Murtfeldt |
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This 1940 issue of Popular Science magazine would have the copyright renewed in 1968. Online page scans of the Catalog of Copyright Entries, published by the US Copyright Office can be found here. Search of the Renewals for Periodicals for 1967, 1968, and 1969 show no renewal entries for Popular Science. Therefore the copyright was not renewed and it is in the public domain. |
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This work is in the public domain because it was published in the United States between 1929 and 1963, and although there may or may not have been a copyright notice, the copyright was not renewed. For further explanation, see Commons:Hirtle chart and the copyright renewal logs.
Note that it may still be copyrighted in jurisdictions that do not apply the rule of the shorter term for US works (depending on the date of the author's death), such as Canada (70 years p.m.a.), Mainland China (50 years p.m.a., not Hong Kong or Macao), Germany (70 years p.m.a.), Mexico (100 years p.m.a.), Switzerland (70 years p.m.a.), and other countries with individual treaties. العربية ∙ Deutsch ∙ English ∙ español ∙ français ∙ galego ∙ italiano ∙ 日本語 ∙ 한국어 ∙ македонски ∙ português ∙ português do Brasil ∙ русский ∙ sicilianu ∙ slovenščina ∙ українська ∙ 简体中文 ∙ 繁體中文 ∙ +/− |
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