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AM and FM modulated signals for radio. AM (amplitude modulation) and FM (frequency modulation) are types of modulation.The sound of the program material, usually coming from a radio studio, is used to modulate (vary) a carrier wave of a specific frequency, then broadcast.
Amplitude modulation (AM) is a modulation technique used in electronic communication, most commonly for transmitting messages with a radio wave.In amplitude modulation, the amplitude (signal strength) of the wave is varied in proportion to that of the message signal, such as an audio signal.
AM broadcasting is radio broadcasting using amplitude modulation (AM) transmissions. It was the first method developed for making audio radio transmissions, and is still used worldwide, primarily for medium wave (also known as "AM band") transmissions, but also on the longwave and shortwave radio bands.
The FM modulation and demodulation process is identical in stereo and monaural processes. FM is commonly used at VHF radio frequencies for high-fidelity broadcasts of music and speech. In broadcast services, where audio fidelity is important, wideband FM is generally used. Analog TV sound is also broadcast using FM.
FM radio on the new band had to begin from the ground floor. As a commercial venture, it remained a little-used audio enthusiasts' medium until the 1960s. The more prosperous AM stations, or their owners, acquired FM licenses and often broadcast the same programming on the FM station as on the AM station ("simulcasting"). The FCC limited this ...
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 ...
Most amateur digital modes are transmitted by inserting audio into the microphone input of a radio and using an analog scheme, such as amplitude modulation (AM), frequency modulation (FM), or single-sideband modulation (SSB). Amateur teleprinting over radio (AMTOR) D-STAR (Digital Data) a high speed (128 kbit/s), data-only mode.
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 ...