A lot vs. Alot: 9 Grammatical Pitfalls
1610s, in music, back-formation from modulation, or else from Latin modulatus, past participle of modulari. General sense from 1620s. In telecommunications from 1908. Related: Modulated; modulating.
To vary the amplitude, frequency, or some other characteristic of a signal or power source. See also amplitude modulation, frequency modulation.