Editing Frequency modulation (section)

===Radio===

{{Main|FM broadcasting}}
[[File:FM Broadcast Transmitter High Power.jpg|thumb|An American FM radio transmitter at [[WEDG]] in Buffalo, New York]]
[[Edwin Howard Armstrong]] (1890–1954) was an American electrical engineer who invented wideband frequency modulation (FM) radio.<ref>{{Cite book
 |title = Principles of modern communications technology
 |author = A. Michael Noll
 |publisher = Artech House
 |year = 2001
 |isbn = 978-1580532846
 |page = [https://archive.org/details/principlesofmode0000noll/page/104 104]
 |url = https://archive.org/details/principlesofmode0000noll
|url-access = registration
 }}</ref>
He patented the regenerative circuit in 1914, the superheterodyne receiver in 1918 and the super-regenerative circuit in 1922.<ref>{{patent|US|1342885}}</ref> Armstrong presented his paper, "A Method of Reducing Disturbances in Radio Signaling by a System of Frequency Modulation", (which first described FM radio) before the New York section of the [[Institute of Radio Engineers]] on November 6, 1935. The paper was published in 1936.<ref>{{Cite journal
 |first = E. H.
 |last = Armstrong
 |title = A Method of Reducing Disturbances in Radio Signaling by a System of Frequency Modulation
 |journal = Proceedings of the IRE
 |volume = 24
 |issue = 5
 |pages = 689–740
 |publisher = IRE
 |date= May 1936
 |doi = 10.1109/JRPROC.1936.227383
|s2cid = 43628076
 }}</ref>

As the name implies, wideband FM (WFM) requires a wider [[signal bandwidth]] than [[amplitude modulation]] by an equivalent modulating signal; this also makes the signal more robust against [[Noise (radio)|noise]] and [[Interference (communication)|interference]]. Frequency modulation is also more robust against signal-amplitude-fading phenomena. As a result, FM was chosen as the modulation standard for high frequency, [[high fidelity]] [[radio]] transmission, hence the term "[[FM radio]]" (although for many years the [[BBC]] called it "VHF radio" because commercial FM broadcasting uses part of the [[VHF]] band{{snd}}the [[FM broadcast band]]). FM [[receiver (radio)|receivers]] employ a special [[Detector (radio)|detector]] for FM signals and exhibit a phenomenon known as the ''[[capture effect]]'', in which the [[Tuner (radio)|tuner]] "captures" the stronger of two stations on the same frequency while rejecting the other (compare this with a similar situation on an AM receiver, where both stations can be heard simultaneously). [[Frequency drift]] or a lack of [[selectivity (radio)|selectivity]] may cause one station to be overtaken by another on an [[adjacent channel]]. Frequency [[drift (telecommunication)|drift]] was a problem in early (or inexpensive) receivers; inadequate selectivity may affect any tuner.

A wideband FM signal can also be used to carry a [[stereophonic sound|stereo]] signal; this is done with [[multiplexing]] and demultiplexing before and after the FM process. The FM modulation and demodulation process is identical in stereo and monaural processes.

FM is commonly used at [[VHF]] [[radio frequencies]] for [[high-fidelity]] [[radio broadcasting|broadcasts]] of music and [[Speech communication|speech]]. In broadcast services, where audio fidelity is important, wideband FM is generally used. Analog TV sound is also broadcast using FM. Narrowband FM is used for voice communications in commercial and [[amateur radio]] settings. In [[two-way radio]], narrowband FM (NBFM) is used to conserve bandwidth for land mobile, marine mobile and other radio services.

A high-efficiency radio-frequency [[switching amplifier]] can be used to transmit FM signals (and other [[constant envelope|constant-amplitude signals]]). For a given signal strength (measured at the receiver antenna), switching amplifiers use [[low-power electronics|less battery power]] and typically cost less than a [[linear amplifier]]. This gives FM another advantage over other modulation methods requiring linear amplifiers, such as AM and [[Quadrature amplitude modulation|QAM]].

There are reports that on October 5, 1924, Professor [[Mikhail A. Bonch-Bruevich]], during a scientific and technical conversation in the [[Nizhny Novgorod Radio Laboratory]], reported about his new method of telephony, based on a change in the period of oscillations. Demonstration of frequency modulation was carried out on the laboratory model.<ref>Ф. Лбов. [https://sergeyhry.narod.ru/rl/rl1924_06_09.htm Новая система радиофона] «Радиолюбитель».{{snd}}1924.{{snd}}№ 6.{{snd}}С. 86.</ref>