DescripciónGE 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.
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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Este archivo se encuentra en el dominio público en los Estados Unidos porque fue publicado en ese país entre los años 1929 y 1963, y, teniendo un aviso de derechos de autor, no se renovó su protección. A menos que su autor haya fallecido años antes, se mantiene bajo propiedad intelectual en los países o zonas que no aplican la regla del plazo más corto para las obras estadounidenses, como China continental (50 años p.m.a., a excepción de Hong Kong o Macao), Alemania (70), Canadá (70), Suiza (70), México (100) y otros países con reglas particulares. Vea Commons:Hirtle chart como referencia e información.