How did Edwin Armstrong invent the FM radio?

Edwin Armstrong invented FM radio in the 1930s by developing frequency modulation as a method to improve audio quality over AM radio. He discovered that varying the frequency of the carrier wave, rather than its amplitude, reduced noise and static interference, producing clearer sound. His work involved extensive experimentation and the creation of the first FM transmitter and receiver. Armstrong's innovations laid the foundation for modern FM broadcasting and significantly advanced radio technology.