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An American FM radio transmitter in Buffalo, NY at WEDG. Edwin Howard Armstrong (1890–1954) was an American electrical engineer who invented wideband frequency modulation (FM) radio. [12] He patented the regenerative circuit in 1914, the superheterodyne receiver in 1918 and the super-regenerative circuit in 1922. [13]
Position of FM radio in the electromagnetic spectrum A commercial 35 kW FM radio transmitter built in the late 1980s. It belongs to FM radio station KWNR, in Henderson, Nevada, and broadcasts at 95.5 MHz. FM broadcasting is a method of radio broadcasting that uses frequency modulation (FM) of the radio broadcast
Wide FM, 20.0 kHz width, ±5 kHz deviation, still widely used for amateur radio, NOAA weather radio, marine, and aviation users and land mobile users below 50 MHz [2] 11K2 F3E Narrow FM, 11.25 kHz bandwidth, ±2.5 kHz deviation – In the United States, all Part 90 Land Mobile Radio Service (LMRS) users operating above 50 MHz were required to ...
The power of an AM radio signal plotted against frequency. fc is the carrier frequency, fm is the maximum modulation frequency. In radio communications, a sideband is a band of frequencies higher than or lower than the carrier frequency, that are the result of the modulation process. The sidebands carry the information transmitted by the radio ...
The FM bandwidth is wider because of the many sidebands. The power output from an FM transmitter is constant with modulation, so as power goes into the sidebands, the carrier power is reduced. A balanced modulator mixes the audio signal and the radio frequency carrier, but suppresses the carrier, leaving only the sidebands. The output from the ...
Narrow band Frequency Modulation was developed and demonstrated by Hanso Idzerda in 1919. Wide band Frequency modulation radio originated in the United States during the 1930s; the system was developed by the American electrical engineer Edwin Howard Armstrong. However, FM broadcasting did not become widespread, even in North America, until the ...
A low-frequency message signal (top) may be carried by an AM or FM radio wave. Waterfall plot of a 146.52 MHz radio carrier, with amplitude modulation by a 1,000 Hz sinusoid. Two strong sidebands at + and - 1 kHz from the carrier frequency are shown.
Frequency modulation is widely used for FM broadcasting of radio programming, and largely supplanted amplitude modulation for this purpose starting in the 1930s, with its invention by American engineer Edwin Armstrong in 1933. [4] FM also has many other applications, such as in two-way radio communications, and in FM synthesis for music ...