Pulse Amplitude Modulation

What Does Pulse Amplitude Modulation Mean?

Pulse amplitude modulation (PAM) is one of several forms of single modulation in which data is transmitted through varying the amplitude of the pulses in regular timed sequence of electrical or electromagnetic pulses. In the case of analog pulse amplitude modulation signals, the number of pulse amplitudes can be infinite. Pulse amplitude modulation is mostly used in digital data transmission with non baseband applications.


Pulse amplitude modulation is used in the popular Ethernet communication standard.

Techopedia Explains Pulse Amplitude Modulation

In pulse amplitude modulation, a signal is sampled at regular intervals and is made proportionate to the magnitude of the signal. Some pulse amplitude modulation systems have the amplitude directly proportional to instantaneous modulating signal. For some systems, the amplitude is inversely proportional to instantaneous modulating signal.The sampled pulses are then sent directly to the receiving end by the channel or are modulated using a carrier wave before transmission.

There are two main types of pulse amplitude modulation:

  • Single Polarity: A fixed direct current level is added to the signal to ensure the pulses are all positive at all times.
  • Double Polarity: This sort of pulse amplitude modulation has both negative and positive pulses going at once.

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Margaret Rouse

Margaret Rouse is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical, business audience. Over the past twenty years her explanations have appeared on TechTarget websites and she's been cited as an authority in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine and Discovery Magazine.Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages. If you have a suggestion for a new definition or how to improve a technical explanation, please email Margaret or contact her…