Modulation
| Amplitude modulation (AM) is a form of modulation in which the amplitude of a carrier wave is varied in direct proportion to that of a modulating signal. AM is commonly used at radio frequencies and was the first method used to broadcast commercial radio. The term "AM" is sometimes used generically to refer to the AM broadcast (mediumwave) band. |
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Frequency modulation (FM) is a form of modulation which the instantaneous frequency of a carrier wave varied in proportion to the amplitude of a modulating signal. Digital data can be represented by shifting the carrier frequency among a set of discrete values, a technique known as frequency-shift keying. FM is commonly used at VHF radio frequencies for high-fidelity broadcasts of music and speech and for the sound in a TV signal. |
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