Editing Amplitude modulation (section)

===Continuous waves===
The first AM transmission was made by Canadian-born American researcher [[Reginald Fessenden]]<ref name="t786">{{cite web | title=Reginald Fessenden (U.S. National Park Service) | website=NPS.gov Homepage (U.S. National Park Service) | date=1932-07-22 | url=https://www.nps.gov/people/reginaldfessenden.htm | access-date=2024-12-16}}</ref> on December 23, 1900<ref name="t779">{{cite web | last=Reel | first=Monte | title=Island Is Birthplace of Broadcast | website=Washington Post | date=2000-12-17 | url=https://www.washingtonpost.com/archive/local/2000/12/17/island-is-birthplace-of-broadcast/61d6fb5e-ecd2-4db4-b9ba-8b89e5c167b0/ | access-date=2024-12-16}}</ref> using a spark gap transmitter with a specially designed high frequency 10&nbsp;kHz [[induction coil|interrupter]],<ref name="AGARD_1992">{{cite report |author=Advisory Group for Research and Development (AGARD) |date=October 2, 1992 |title=ELF/VLF/LF Radio Propagation and Systems Aspects |url=https://apps.dtic.mil/sti/tr/pdf/ADA267991.pdf |publisher=North Atlantic Treaty Organization (NATO) |access-date=2024-12-16}}</ref> over a distance of {{convert|1|mi|km|spell=in}} at Cobb Island, Maryland, US. His first transmitted words were, "Hello. One, two, three, four. Is it snowing where you are, Mr. Thiessen?".<ref name="t779" /> Though his words were "perfectly intelligible", the spark created a loud and unpleasant noise.<ref name="AGARD_1992" />

Fessenden was a significant figure in the development of AM radio. He was one of the first researchers to realize, from experiments like the above, that the existing technology for producing radio waves, the spark transmitter, was not usable for amplitude modulation, and that a new kind of transmitter, one that produced [[sinusoidal]] ''[[continuous wave]]s'', was needed. This was a radical idea at the time, because experts believed the impulsive spark was necessary to produce radio frequency waves, and Fessenden was ridiculed. He invented and helped develop one of the first continuous wave transmitters – the [[Alexanderson alternator]], with which he made what is considered the first AM public entertainment broadcast on Christmas Eve, 1906. He also discovered the principle on which AM is based, [[heterodyne|heterodyning]], and invented one of the first [[detector (radio)|detector]]s able to [[rectifier|rectify]] and receive AM, the [[electrolytic detector]] or "liquid baretter", in 1902. Other radio detectors invented for wireless telegraphy, such as the [[Fleming valve]] (1904) and the [[crystal detector]] (1906) also proved able to rectify AM signals, so the technological hurdle was generating AM waves; receiving them was not a problem.