PULSE AMPLITUDE MODULATION

1. PULSE AMPLITUDE
MODULATION
Presented
By
SOBIR MECH
M.TECH (ECE) 1st Year
PONDICHERRY UNIVERSITY

2. • Pulse-amplitude modulation (PAM), is a form of
signal modulation where the message information is
encoded in the amplitude of a series of signal pulses.
• It is an analog pulse modulation scheme in which the
amplitudes of a train of carrier pulses are varied
according to the sample value of the message signal.
• Demodulation is performed by detecting the
amplitude level of the carrier at every symbol period.

3. There are two types of pulse amplitude modulation:
1 Single polarity PAM: In this a suitable fixed DC
bias is added to the signal to ensure that all the
pulses are positive.
2 Double polarity PAM: In this the pulses are both
positive and negative.
• Pulse-amplitude modulation is widely used in
modulating signal transmission of digital data,
with non-baseband applications having been
largely replaced by pulse-code modulation, and,
more recently, by pulse-position modulation.
TYPES

4. Principle of PAM: (1) original signal, (2) PAM signal, (a) amplitude of signal, (b) time

5. Construction of PAM signal
Time Domain Frequency Domain

6. Sampling Methods in PAM
Ideal and natural sampling signal can eliminate noise.
Ideal sampling signal is difficult to generate

7. Detection of PAM Sample Signal
fo for the LPF must within the
range of fm < fo < fs - fm
fs = 2fm but usually fs > 2fm
GUARDBAND
fm = fs / 2 = 1 / 2T
ms(t) = VPAM

8. Generation and Detection of PAM
Generation of PAM
Detection of PAM

9. Signal shown of PAM Signal
In the noise aspect, this type of signal is EASILY EFFECTED
by noise.This is type of flat-top sampling signal

10. Effect of Noise:
• Since the information is contained in the amplitude
variations, the noise will contaminate the
information.

11. Advantages:
• Better SNR due to increased signal Power.
• Generation is easy.
Disadvantages:
• Aperture effect introduces distortion.

12. THANK YOU…