Editing Edwin Howard Armstrong (section)

==Legacy==

It was not until the 1960s that FM stations in the United States started to challenge the popularity of the AM band, helped by the development of FM stereo by General Electric, followed by the FCC's [[FM Non-Duplication Rule]], which limited large-city broadcasters with AM and FM licenses to simulcasting on those two frequencies for only half of their broadcast hours. Armstrong's FM system was also used for communications between [[NASA]] and the [[Apollo program]] astronauts.

A US Postage Stamp was released in his honor in 1983 in a series commemorating American Inventors.<ref>{{cite web| url = https://postalmuseum.si.edu/object/npm_1999.2004.316.1-4| title = American Inventors, September 21, 1983, Smithsonian Postal Museum}}</ref>

Armstrong has been called "the most prolific and influential inventor in radio history".<ref name="Campbell">{{cite book | last = Campbell | first = Richard |author2=Christopher R. Martin |author3=Bettina Fabos | title = Media and Culture: An Introduction to Mass Communication, 8th Ed. | publisher = MacMillan | year = 2011 | pages = 124 | url = https://books.google.com/books?id=WuqjReIZ4TcC&q=%22edwin+armstrong%22&pg=PA124 | isbn = 978-0312644659}}</ref> The superheterodyne process is still extensively used by radio equipment. Eighty years after its invention, FM technology has started to be supplemented, and in some cases replaced, by more efficient digital technologies. The introduction of digital television eliminated the FM audio channel that had been used by analog television, [[HD Radio]] has added digital sub-channels to FM band stations, and, in Europe and Pacific Asia, [[Digital Audio Broadcasting]] bands have been created that will, in some cases, eliminate existing FM stations altogether.<ref>[https://www.hollywoodreporter.com/news/norway-first-country-end-fm-790131 "Norway to Become First Country to Switch Off FM Radio in 2017"] by Scott Roxborough, ''The Hollywood Reporter'', April 20, 2015.</ref> However, FM broadcasting is still used internationally, and remains the dominant system employed for audio broadcasting services.