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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
The radio spectrum is the part of the electromagnetic spectrum with frequencies from 3 Hz to 3,000 GHz (3 THz). Electromagnetic waves in this frequency range, called radio waves , are widely used in modern technology, particularly in telecommunication .
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]
The frequency spectrum of a typical radio signal from an AM or FM radio transmitter. The horizontal axis is frequency; the vertical axis is signal amplitude or power. It consists of a signal (C) at the carrier wave frequency f C, with the modulation contained in narrow frequency bands called sidebands (SB) just above and below the carrier.
The frequency deviation of a radio is of particular importance in relation to bandwidth, because less deviation means that more channels can fit into the same amount of frequency spectrum. The FM broadcasting range between 87.5 and 108 MHz uses a typical channel spacing of 100 or 200 kHz, with a maximum frequency deviation of +/-75 kHz, in some ...
Therefore, in effect, the FM broadcast band comprises only FM channels 201 (88.1 MHz) through 300 (107.9 MHz). Originally, FM stations in a market were generally spaced four channels (800 kHz) apart. This spacing was developed in response to problems perceived on the original FM band, mostly due to deficiencies in receiver technology of the time.
A spectrum analyzer is a standard instrument used for RF sweep. It includes an electronically tunable receiver and a display. The display presents measured power (y axis) vs frequency (x axis). The power spectrum display is a two-dimensional display of measured power vs. frequency. The power may be either in linear units, or logarithmic units ...
Spectrum of an FM broadcast signal. The pilot tone is the orange vertical line on the right of the spectrogram. In FM stereo broadcasting, a pilot tone of 19 kHz indicates that there is stereophonic information at 38 kHz (the second harmonic of the pilot tone). The receiver doubles the frequency of the pilot tone and uses it as a frequency and ...