pulse modulation

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A system of modulation in which pulses are altered and controlled in order to represent the message to be communicated.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun any of a number of techniques whereby a series of information-carrying quantities occurring at discrete instances of time is encoded into a corresponding series of electromagnetic carrier pulses

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun modulation that imposes a signal on a train of pulses