This mini project to created by Md Halim and it is useful of Communication Coding & Theory Subject of the 4th semester B.tech in CSE branch. thank you

1. Haldia Institute of
Technology , Haldia
PLUSE AMPLITUDE
MODULATION (PAM)
Course Name:- Communication Engg &
Coding Theory
Course Code:- CS401
Dept:- Computer Science & Engineering
Name:- Md. Halim
Class Roll:- L18/CS/154
University Roll:- 103011018015
Date:-

2. 1. INTRODUCTION
➢ Modulation is the process of frequency translation in which any are parameter
(Amplitude, frequency or phase) of high frequency carrier signal is varied in accordance
with instantaneous value of low frequency modulating signal.
➢ Modulation is either analog or digital.
➢ A digital signal is superior to an analog signal because it is more robust to noise and can
easily be recovered, corrected and amplified. For this reason, the tendency today is to
change an analog signal to digital data.
➢ The process of transmitting signals in the form of pulses (discontinuous signals) by using
special techniques.
2. Pulse Amplitude Modulation (PAM)
Fig. 0.1 VPAM must directly proportional with VM
3. Sampling
➢ The process of transmitting signals in the form of pulses (discontinuous signals) by
using special techniques.
➢ The signal is sampled at regular intervals such that each sample is propotional to the
amplitude of signal at that instant.This technique is called “sampling”.
➢ Sampling is common in all pulse modulation techniques Analog signal is sampled
every TS secs.
➢ Ts is referred to as the sampling interval.
➢ fs = 1/Ts is called the sampling rate or sampling frequency.
➢ There are 3 sampling methods:
• Ideal - an impulse at each sampling instant
• Natural - a pulse of short width with varying amplitude
• Flat top - sample and hold, like natural but with single amplitude value
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3. 4. Three different sampling methods
5. Sampling Rate
➢ Nyquist showed that it is possible to reconstruct a band-limited signal from
periodic samples, as long as the sampling rate is at least twice the frequency of the
of highest frequency component of the signal.
i.e. fs ≥ 2fm
where fs is sampling rate
➢ Sampling rates that are too low result in aliasing or foldover
6. BLOCK DIAGRAM FOR PAM
➢ The carrier is in the form of narrow pulses having frequency fs. The uniform sampling
takes place in multiplier to generate PAM signal. Samples are placed Ts sec away from
each other.
Modulating PAM
Signal Signal
➢ Depending upon the shape and polarity of the sampled pulses, PAM is of two types,
LOW PASS
FILTER
M ULTIPLIER
PULSE TRAIN
GENERATOR
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4. 6.1 Natural PAM
➢ sampling occurs when top portion of the pulses are subjected to follow the modulating
wave
6.2 Flat topped PAM
➢ sampling is often used because of the ease of generating the modulated wave. In this
pulses have flat tops after modulation.
➢ The PAM signal can be detected by passing it through a low pass filter
7. Generation and Detection of PAM
Generation of PAM Detection of PAM
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5. 8. Conclusion
➢ The main advantage of the Pulse Amplitude Modulation is better noise
immunity and possibility of use of repeaters which makes communication more reliable
and error free
➢ The formula described by can be used to represent a given set of numerical data on a
pair of variables, by a polynomial. The degree of the polynomial is one less than the
number of pairs of observations. The polynomial that represents the given set of
numerical data can be used for interpolation at any position of the independent variable
6. Reference
1.Jump up^ Stan Gibilisco (2002). Teach yourself electricity and electronics. McGraw-Hill
Professional. p. 477. ISBN 978-0-07-137730-0.
2. Jump up^ B. Boashash, editor, "Time-Frequency Signal Analysis and
Processing – A Comprehensive Reference", Elsevier Science, Oxford, 2003; ISBN 0-08-
044335-4
3. John G. Proakis and Dimitris G. Manalakis, ‘Digital Signal Processing,
principles,algorithms and applications’, Pearson Prentice Hall, 2011.
4.Wikipedia
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