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The AM/FM radio combined with a CD player has remained a mainstay of car audio, despite being obsolescent in non-car applications. [17] [18] In the 2010s, internet radio, satellite radio, streaming, and podcasting came into competition with AM/FM radio. By this time some models were offering 5.1 surround sound.
1920s: Radio was first used to transmit pictures visible as television. 1926: Official Egyptian decree to regulate radio transmission stations and radio receivers. [40] Early 1930s: Single sideband (SSB) and frequency modulation (FM) were invented by amateur radio operators. By 1940, they were established commercial modes.
By the end of the 1970s, 50.1% of radio listeners were listening to FM stations, ending AM's historical lead. By 1982, FM commanded 70% of the general audience, and 84% among the 12- to 24-year-old demographic. [17]
The first car radio was introduced in 1922, but it was so large that it took up too much space in the car. [70] The first commercial car radio that could easily be installed in most cars went for sale in 1930. [71] [72]
FM broadcasting is a method of radio broadcasting that uses frequency modulation (FM) of the radio broadcast carrier wave. Invented in 1933 by American engineer Edwin Armstrong , wide-band FM is used worldwide to transmit high-fidelity sound over broadcast radio . [ 1 ]
Radio broadcasting has been used in the United States since the early 1920s to distribute news and entertainment to a national audience. In 1923, 1 percent of U.S. households owned at least one radio receiver, while a majority did by 1931 and 75 percent did by 1937.
The first police radio systems were implemented in Detroit in 1928, when the Detroit Police Department set up a one-way radio system to broadcast crime information to police cars. [2] The frequency was assigned the call sign "KOP" by the Federal Communications Commission .
[58] [59] A few years earlier in 1952, Blaupunkt had been the first company to offer FM radio for automobiles, although AM radio still dominated for years to come. Beginning in 1955, Chrysler offered a small phonograph called the Highway Hi-Fi in its luxury cars, which played proprietary seven-inch records .