Pulse amplitude modulation (PAM) is a modulation technique where the amplitude of pulses in a regularly timed sequence is varied according to the amplitude of the modulating signal. There are two types of PAM: single polarity PAM which adds a DC bias to ensure all pulses are positive, and double polarity PAM where pulses can be both positive and negative. PAM is generated by sampling the modulating signal at regular intervals and making each sample proportional to the amplitude of the modulating signal at the time of sampling. The amplitude of the PAM signal then carries the information contained in the modulating signal.

1. SUBMITTED BY
1st BATCH STUDENTS
III – B.Sc, PHYSICS.

2. DEFINITION OF PAM
 Pulse Amplitude Modulation (PAM) is the transmission
of data by varying the amplitude s
( voltage or power levels) of the individual pulses in a
regularly timed sequence of electrical or electromagnetic
pulses.
 The number of possible pulse
amplitudes can be infinite
(in the case of analog PAM),
but it is usually some power
of two so that the resulting
outputsignal can be digital .

4. BLOCK DIAGRAM OF PAM

5. TYPES OF PAM
There are two types of pulse amplitude
modulation:
Single polarity PAM:
In this a suitable fixed DC bias is
added to the signal to ensure that all the
pulses are positive.
Double polarity PAM:
In this the pulses are both positive
and negative.

6. GENERATION OF PAM
 Pulse amplitude modulation is the basic form of pulse
modulation in which the signal is sampled at regular and
each sample is made proportional to the amplitude of the
modulating signal at the sampling instant.
 The Fig shows the generation of PAM signal from the
sampler which has two inputs i.e. modulating signal and
sampling signal or carrier pulse.

7.  Thus the amplitude
of the signal is
proportional to the
modulating signal
through which
information is carried.
This is Pulse amplitude
modulation signal.
 Pulse Modulation may be used to transmitting analog
information, such as continuous speech signal or data.

8. REFERENCES
 http://whatis.techtarget.com/definition/pulse-
amplitude-modulation-PAM
 https://en.wikipedia.org/wiki/Pulse-
amplitude_modulation
 http://www.ques10.com/p/11460/explain-
generation-and-demodulation-of-pam-ppm-
and/