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Frequency modulation
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Frequency modulation is a signal modulation technique used in electronic communication, originally for transmitting messages with a radio wave. In frequency modulation a carrier wave is varied in its
FM has better noise (RFI) rejection than AM, as shown in this dramatic New York publicity demonstration by General Electric in 1940. The radio has both AM and FM receivers. With a million-volt electric arc as a source of interference behind it, the AM receiver produced only a roar of static, while the FM receiver clearly reproduced a music program from Armstrong's experimental FM transmitter W2XMN in New Jersey.
FM has better noise (RFI) rejection than AM, as shown in this dramatic New York publicity demonstration by General Electric in 1940. The radio has bot
Frequency spectrum and waterfall plot of a 146.52 MHz carrier, frequency modulated by a 1,000 Hz sinusoid. The modulation index has been adjusted to a
Frequency spectrum and waterfall plot of a 146.52 MHz carrier, frequency modulated by a 1,000 Hz sinusoid. The modulation index has been adjusted to around 2.4, so the carrier frequency has small amplitude. Several strong sidebands are apparent; in principle an infinite number are produced in FM but the higher-order sidebands are of negligible magnitude.
An American FM radio transmitter at WEDG in Buffalo, New York
An American FM radio transmitter at WEDG in Buffalo, New York
FM broadcasting
Videos
FM broadcasting is a radio broadcasting method that uses frequency modulation transmissions. In November 1919, Hans Idzerda began broadcasts, using narrow-band FM, over station PCGG, located at The Ha
Frequency modulation
…fax modems), telephone caller-ID systems, garage-door openers, remote keyless entry systems, and radioteletype. Frequency modulation is widely used for FM broadcasting. It is also used in telemetry, radar, seismic prospecting, and monitoring newborns for seizures via EEG, two-way radio systems, sound synthesis, magnetic…
A commercial 35 kW FM radio transmitter built in the late 1980s. It belongs to FM radio station KWNR, in Henderson, Nevada, and broadcasts on 95.5 MHz
A commercial 35 kW FM radio transmitter built in the late 1980s. It belongs to FM radio station KWNR, in Henderson, Nevada, and broadcasts on 95.5 MHz.
Crossed-dipole antenna array of station KENZ's 94.9 MHz, 48 kW transmitter on Lake Mountain, Utah. It radiates circularly polarized radio waves.
Crossed-dipole antenna array of station KENZ's 94.9 MHz, 48 kW transmitter on Lake Mountain, Utah. It radiates circularly polarized radio waves.
Armstrong's first prototype FM broadcast transmitter, located in the Empire State Building, New York City, which he used for secret tests of his syste
Armstrong's first prototype FM broadcast transmitter, located in the Empire State Building, New York City, which he used for secret tests of his system between 1934 and 1935. Licensed as experimental station W2XDG, it transmitted on 41 MHz at a power of 2 kW.