[BC] FM History

[Robert Orban]

At 08:32 AM 11/24/2010, RichardBJohnson at comcast.net wrote:
>Edwin Armstrong invented a new method of encoding audio onto a 
>transmission carrier. It had many advantages, amongst them being 
>that the transmitter could operate in a high efficiency mode (class 
>C) and the noise that often accompanied AM reception was practically 
>non-existent when receiving a station.

There is a lot of misinformation about Armstrong, mostly based on 
Lessing's book "Man of High Fidelity." Armstrong did not invent FM 
per-se. (Carson published "Notes on the theory of modulation", Proc. 
IRE, vol. 10, no. 1 (Feb. 1922), pp. 57-64, but did not conclude that 
FM offered advantages compared to AM, which was true for narrowband 
FM). However, Armstrong was the first to realize the noise reduction 
advantages of wideband FM, receiving a patent in 1933 and publishing 
in 1936. Murray Crosby was first to publish regarding the FM 
threshold effect (in 1937).

http://www.fathom.com/seminars/10701020/session2.html