Memo from David Sarnoff titled "Radio Music Box." In the "radio music box" message, he purportedly suggested that radio receivers be mass-produced for public use and that music, news, and information be broadcast to households that owned the apparatus.
He proposed suggestions for making radio a "home utility." Despite the fact that David Sarnoff was employed by American Marconi in 1916, which the Radio Corporation of America eventually bought, In 1919, the Radio Corporation of America was established.
Shortwave radio, cellular telephony, air-traffic control, conventional broadcast radio and television, and even remote-controlled toys all use them. (For more information, see radio waves and electromagnetic radiation.)
Today, AM, FM, Shortwave, Longwave, Satellite, Ham, DAB, Walkie-Talkies, and HD radio are the most popular. They all employ various technologies or bands.
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