To vary a carrier frequency in relationship to a signal. This is really only useful if you can reverse this procedure or demodulate. This is the basis of a modem.
Some famous uses of this are FM or frequency modulation and AM or amplitude modulation on your car stereo.

One of the goals of modulating are to put many different signals on different carrier frequencies so that they can all use the same medium of delivery. These mediums can be wires (cable TV), air (radio and WLAN), etc. Other common things that use this are Infrared Remote Controls that use light in the Infrared as the carrier frequency.

Mod"u*late (?), v. t. [imp. & p. p. Modulated (?); p. pr. & vb. n. Modulating (?).] [L. modulatus, p.p. of modulari to measure, to modulate, fr. modulus a small measure, meter, melody, dim. of modus. See Mode.]

1.

To form, as sound, to a certain key, or to a certain portion.

2.

To vary or inflect in a natural, customary, or musical manner; as, the organs of speech modulate the voice in reading or speaking.

Could any person so modulate her voice as to deceive so many? Broome.

 

© Webster 1913.


Mod"u*late, v. i. Mus.

To pass from one key into another.

 

© Webster 1913.

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