Major Edwin Armstrong, the pioneering inventor of wideband FM radio, showcased his revolutionary FM receiver technology in the late 1930s and early 1940s. Despite initial resistance and skepticism, Armstrong’s wideband FM system offered superior audio quality, resistance to interference, and noise-free transmission compared to traditional AM radio. The Federal Communications Commission (FCC) eventually authorized commercial FM broadcasting in 1940, marking a turning point in the radio industry. Early FM stations, like WTMJ in Milwaukee and W2XOY in New York, emerged with high-powered transmitters and sought to capitalize on the new technology. The transition from AM to FM broadcasting was met with enthusiasm and excitement, shaping the future of radio transmission.
http://www.theradiohistorian.org/fm/fm.html