Sarnoff and RCA did everything possible to interfere with Armstrong’s efforts. I didn't think he'd start a revolution - start up a whole damn new industry to compete with RCA" (Ref 2). Sarnoff is credited with saying, "I thought Armstrong would invent some kind of a filter to remove static from our AM radio. They also had a stake in networks of AM stations. Not only did RCA produce radios, but received substantial royalties for licensing various AM-related patents. RCA was heavily invested in AM radio, which was big business at the time. Armstrong is credited with inventing Frequency Modulation, and received patents to that effect.ĭavid Sarnoff, CEO of RCA, had other ideas. The first mention of Frequency Modulation (FM) occurs in a paper published by Edwin Armstrong in 1936 (Ref 1). The grand floor consoles of the late 1930s leading up to WWII were capable of producing audio that was very good, even by today’s standards, the only exception being that they were monaural, as stereo technology was still a ways off. Receiver design really came of age in the 1930s with the superheterodyne circuit and advancements in loudspeaker design. Nowadays, AM broadcast stations are associated with lower quality audio, but such was not always the case. Thus began the early roots of broadcasting.Įvery vintage consumer radio, be it standard broadcast or shortwave, up to WWII, received amplitude modulated signals. However, amateur operators using Amplitude Modulation (AM) to inject audio into a radio signal, not to mention the general public listening to them, were more interested in audio that they could understand, be it voice or music. Given how robust a Morse signal is, the large commercial traffic companies like Marconi’s were quite satisfied. The receiver would detect these bursts and convert them to audible dashes and dots that the operator could hear. If a transmitter could be switched on and off with a telegraph key, then it could transmit long and short bursts of radio waves corresponding to the long and short dashes and dots of Morse code. After the discovery of radio waves and how to create them, came the question of how to use them for communication. This month, we will look a little deeper into AM, its history, how it works, the corporate politics at its heyday and where it is going. Last month we looked at contributions to the art made by amateur operators, in particular advancements in Amplitude Modulation, or AM, and how it came to give radio its voice.
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