Pulse Amplitude Modulation

Pulse amplitude modulation is defined as the data transmission by altering the amplitudes (power levels or voltage) of every pulse in a regular time sequence of electromagnetic pulses. The possible number of amplitudes can be infinite, but mostly it is some power of two so that the final output signal can be digital. For example, in level-4 PAM there are 22 discrete pulse amplitudes; in level-8 PAM there are 23 discrete pulse amplitudes.

Pulse Amplitude Modulation Circuit

The circuit diagram of PAM looks like :

 

Pulse Amplitude Modulation Circuit

Pulse Amplitude Modulation Circuit

 

Pulse Amplitude Modulation Block Diagram

The block diagram of PAM looks like:

 

Pulse Amplitude Modulation Block Diagram

Pulse Amplitude Modulation Block Diagram

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Types of Pulse Amplitude Modulation


Types of Pulse Amplitude Modulation
There are two major types of PAMs:

  • Single polarity PAM: Here, an appropriate fixed DC bias is integrated with the signal to assure that all pulses are positive.
  • Double polarity PAM: Here, the pulses are both negative and positive.

In some PAMs:

  • The amplitude of every pulse is directly proportional to instantaneous modulating amplitude when the pulse occurs.
  • While in other PAM, the amplitude of every pulse is inversely proportional to instantaneous modulating amplitude when at the occurrence of a pulse.
  • In some other systems, the intensity of every pulse is based on particular characteristics of modulating signal other than strength like instantaneous phase or frequency.

Applications:

PAM is mostly applied in non-based modulating transmission of digital data and applications replaced by pulse-code modulation and pulse-position modulation.

Particularly all phone modems faster than 300 bit/s use quadrature amplitude modulation.

Advantages of Pulse Amplitude Modulation

  • PAM allows data to be transmitted more effectively, efficiently and quickly using conventional copper wires in greater volume.
  • The frequency modulations available are infinite; hence PAM formulas can be developed continually to allow increased data throughput over existing networks.
  • PAM is also the simplest form of modulation.

Pulse Amplitude Modulation Question (FAQs)

Q1: What does PAM stand for?

Ans: PAM is an acronym for Pulse Amplitude Modulation.

Q2: Is pulse amplitude modulation analog or digital?

Ans: PAM can be digital as well as analog.

Q3: What are the two types of PAM?

Ans: Two types of PAM Single polarity PAM and Double polarity PAM.

Hope you have got a brief knowledge of Pulse Amplitude Modulation (PAM). For a better understanding of thermodynamics do read the related articles and refer the practice questions. Stay tuned with BYJU’S for more such interesting articles. Also, download BYJU’S -The Learning App for loads of interactive, engaging physics videos and an unlimited academic assist.


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The process of superimposing signal frequency (i.e. audio wave) on the carrier

wave is known as [AIIMS 1987]