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 Block Diagram

The block diagram of PAM looks like:

 Pulse Amplitude Modulation Block Diagram

You may also want to check out these topics given below!

• Amplitude Modulation and its Applications
• Damped oscillation
• Frequency Modulation vs Amplitude Modulation
• What is Modulation? Why do we need it?
• Frequency And Wavelength
• Frequency Modulations

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 signals other than strength like instantaneous phase or frequency.