Cs manual 2021

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JANSONS INSTITUTE OF TECHNOLOGY
Karumathampatti, Coimbatore
Department of Electronics and Communication Engineering
Laboratory Manual
(As per Anna University Regulation 17)
EC 8561 – Communication Systems Laboratory
V Semester

2
Syllabus
(Anna University Regulation 17)
EC 8561 – Communication Systems Laboratory
LIST OF EXPERIMENTS:
1. Signal Sampling and reconstruction
2. Time Division Multiplexing
3. AM Modulator and Demodulator
4. FM Modulator and Demodulator
5. Pulse Code Modulation and Demodulation
6. Delta Modulation and Demodulation
7. Line coding schemes
8. Simulation of ASK, FSK, and BPSK generation schemes
9. Simulation of DPSK, QPSK and QAM generation schemes
10. Simulation of signal constellations of BPSK, QPSK and QAM
11. Simulation of ASK, FSK and BPSK detection schemes
12. Simulation of Linear Block and Cyclic error control coding schemes
13. Simulation of Convolutional coding scheme
14. Communication link simulation

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List of Experiments
S.No EXPERIMENTS MARKS
OBTAINED
PAGE
NO
1 Signal Sampling and reconstruction
1
2 Time Division Multiplexing
6
3 AM Modulator and Demodulator
11
4
FM Modulator and Demodulator
16
5 Pulse Code Modulation and Demodulation
21
6 Delta Modulation and Demodulation
25
7 Observation (simulation) of signal constellations of BPSK, QPSK and
QAM
29
8 Line coding schemes
33
9 FSK and PSK schemes (Simulation)
36
10 Simulation of DPSK 39
11 Error control coding schemes - Linear Block Codes (Simulation)
47
12 Communication link simulation
51
13 Equalization – Zero Forcing & LMS algorithms (simulation)
54

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Exp-No: 01
Date:
AIM:
SIGNAL SAMPLING AND RECONSTRUCTION
To perform the process of sampling for an analog signal and to reconstruct the sampled
signals using pulse modulation techniques.
APPARATUS REQUIRED:
1. Trainer kit
2. Patch Cords with inserting pins
3. Digital Storage Oscilloscope
4. DSO probes, Power chords.
THEORY:
In pulse modulation techniques, the message signal is modulated by some parameters of
pulse train. These parameters are amplitude and width.
Pulse amplitude modulation is defined as an analog modulation technique in which the
signal is sampled at regular intervals such that each sample is proportional to the amplitude
of the signal, at the instant of sampling. Pulse width modulation is defined as an analog
modulation technique in which the width of each pulse is made proportional to the
instantaneous amplitude of the signal at the sampling instant. PWM is also called as PDM/pulse
division modulation.
Sample and Hold circuits are used internally in Analog to Digital conversion. We might
also use them to hold a given signal value from any particular sensor on a robot, for analysis and
later use.The Sample and Hold circuit uses two buffers to keep a voltage level stored in a
capacitor. Excellent Sample and Hold circuits like the LF398 are available on a single chip for
cheap and easy use.
PROCEDURE:
1. Connect the power cord of the trainer unit to AC 220V, 50 Hz supply.
2. Switch ON the trainer kit. The neon lamp will glow indicating that the unit is ready for
operation.
3. Observe the waveforms of Modulating Signal Generator and Clock Signal
Generator in an Oscilloscope.
COMMUNICATION SYSTEMS LAB MANUAL
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4. Using patch cords, connect the Modulating Signal to the sockets marked ‗MOD
INPUT; in the PWM Modulator.
5. Using patch cords, connect the Clock Signal to the sockets marked ‗CLOCK
INPUT‘ in the PWM Modulator.
6. Vary the Modulating Signal & Clock Signal to obtain a Pulse Width Modulated Output
across the sockets marked ‗PWMOUTPUT‘
7. For reconstruction, connect the ‗PWM OUTPUT‘ from the Pulse Width Modulation
to the sockets marked ‗PWM INPUT‗ in the Demodulation.
8. Observe the demodulated output waveform across sockets marked ‗DEMOD OUTPUT‘.
MODEL GRAPH:
PWM:
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KIT DIAGRAM:
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TABULATION:
S.NO SIGNAL AMPLITUDE (V) TIME (s)
1. Modulating signal
2. Sampling Signal
3. Sampled Output
4. Reconstructed output
GRAPH:
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RESULT:
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Exp-No: 2
Date:
AIM:
Simulation of TIME DIVISION MULTIPLEXING
To Perform the simulation of time division multiplexing.
THEORY:
Time division multiplexing (TDM) system, which enables the joint utilization of a
common communication channel by a plurality of independent message sources without mutual
interference among them. The TDM system is highly sensitive to dispersion in the common
channel that is to variations of amplitude with frequency or lack of proportionality of phase with
frequency. Unlike FDM, TDM is immune to non linearity in the channel as a source of cross
talk. The reason for this is, the different message signals are not simultaneously applied to the
channel. The primary advantage of TDM is that several channels of information can be
transmitted simultaneously over a single cable.
In the circuit diagram the 555 timer is used as a clock generator. This timer is a highly
stable device for generating accurate time delays. In this circuit this timer generates clock signal,
which is of 100 KHz frequency (approximately). This clock signal is connected to the IC 7476.It
divides the clock signal frequency into three parts and those are used as selection lines for
multiplexer. Inbuilt signal generator is provided with sine, square and triangle outputs with
variable frequency. These three signals can be used as inputs to the multiplexer. IC 4052 is a 4 to
1 Analog Multiplexer. It selects one-of-four signal sources as a result of unique three bit binary
code at the select inputs.
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SOFTWARE REQUIRED:
MATLAB
PROCEDURE:
1. Open MATLAB
2. Open new M-file
3. Type the program
4. Save in current directory
5. Compile and Run the program
6. For the output see command window Figure window
PROGRAM:
clc;
closeall;
clearall;
% Signal generation
x=0:.5:4*pi; % siganal taken upto 4pi
sig1=8*sin(x); % generate 1st sinusoidal signal
l=length(sig1);
sig2=8*triang(l); % Generate 2ndtraingularSigal
%DisplayofBothSignal
subplot(2,2,1);
plot(sig1);
title('Sinusoidal Signal');
ylabel('Amplitude--->');
xlabel('Time--->');
subplot(2,2,2);
plot(sig2);
title('Triangular Signal');
xlabel('Time--->');
%DisplayofBothSampledSignal
subplot(2,2,3);
stem(sig1);
title('Sampled Sinusoidal Signal');
xlabel('Time--->');
subplot(2,2,4);
stem(sig2);
title('Sampled Triangular Signal');
xlabel('Time--->');
l1=length(sig1);
l2=length(sig2);
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fori=1:l1
sig(1,i)=sig1(i); %MakingBothrowvectortoamatrix
sig(2,i)=sig2(i);
end
% TDM ofboth quantize signal
tdmsig=reshape(sig,1,2*l1);
%DisplayofTDMSignal
figure
stem(tdmsig);
title('TDM Signal');
xlabel('Time--->');
% Demultiplexing of TDM Signal
demux=reshape(tdmsig,2,l1);
fori=1:l1
sig3(i)=demux(1,i); % Converting The matrix into row vectors
sig4(i)=demux(2,i);
end
% display of demultiplexed signal
figure
subplot(2,1,1)
plot(sig3);
title('Recovered Sinusoidal Signal');
xlabel('Time--->');
subplot(2,1,2)
plot(sig4);
title('Recovered Triangular Signal');
xlabel('Time--->');
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OUTPUT:
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RESULT:
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Exp-No:3
Date:
AIM
AM MODULATION AND DEMODULATION
To transmit a modulating signal after amplitude modulation using AM transmitter and
receive the signal back after demodulating using AM receiver.
APPARATUS REQUIRED:
1. AM transmitter trainer kit
2. AM receiver trainer kit
3. DSO
4. Patch cords
THEORY:
A continuous-wave goes on continuously without any intervals and it is the baseband message signal,
which contains the information. This wave has to be modulated.
According to the standard definition, ―The amplitude of the carrier signal varies in accordance
with the instantaneous amplitude of the modulating signal.‖ Which means, the amplitude of the
carrier signal containing no information varies as per the amplitude of the signal containing information,
at each instant.
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AMPLITUDE MODULATION:
Amplitude Modulation is a process by which amplitude of the carrier signal is
varied in accordance with the instantaneous value of the modulating signal, but frequency and
phase of carrier wave remains constant.
The modulating and carrier signal are given by
Vm(t) = Vm sin�
mt
VC(t) = VC sin�
Ct
The modulation index is given by, ma = Vm / VC.
Vm = Vmax – Vmin and VC = Vmax + Vmin
The amplitude of the modulated signal is given by,
VAM(t) = VC (1+ma sin�
mt) sin�
Ct
Where
Vm = maximum amplitude of modulating signal
VC = maximum amplitude of carrier signal
Vmax = maximum variation of AM signal
Vmin = minimum variation of AM signal
PROCEDURE:
1. The circuit wiring is done as shown in diagram
2. A modulating signal input given to the Amplitude modulator
3. Now increase the amplitude of the modulating signal to the required level.
4. The amplitude and the time duration of the modulating signal are observed using
CRO.
5. Finally the amplitude modulated output is observed from the output of amplitude
modulator stage and the amplitude and time duration of the AM wave are noted
down.
6. Calculate the modulation index by using the formula and verify them. The final
demodulated signal is viewed using an CRO at the output of audio power amplifier
stage. Also the amplitude and time duration of the demodulated wave are noteddown.
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TABULATION:
UNDER MODULATION:
Waveform Amplitude (V) Time Period (sec)
Message
Carrier
Modulated
Demodulated
CRITICAL MODULATION:
Message
Carrier
Modulated
Demodulated
OVER MODULATION:
Message
Carrier
Modulated
Demodulated
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Exp-No: 04
Date:
AIM
FREQUENCY MODULATION AND DEMODULATION
To transmit a modulating signal after frequency modulation using FM transmitter and
receive the signal back after demodulation using FM receiver.
APPARATUS REQUIRED:
1. FM transmitter trainer kit
2. FM receiver trainer kit
3. DSO
4. Patch cords
THEORY:
Frequency modulation (FM) is a form of modulation that represents information as variations in the
instantaneous frequency of a carrier wave. (Contrast this with amplitude modulation, in which the
amplitude of the carrier is varied while its frequency remains constant.) In analog applications, the carrier
frequency is varied in direct proportion to changes in the amplitude of an input signal. Shifting the carrier
frequency among a set of discrete values can represent digital data, a technique known as frequency-shift
keying. FM is commonly used at VHF radio frequencies for high-fidelity broadcasts of music and speech
(see FM broadcasting). Normal (analog) TV sound is also broadcast using FM. A narrowband form is
used for voice communications in commercial and amateur radio settings. The type of FM used in
broadcast is generally called wide-FM, or W-FM. In two-way radio, narrowband narrow-fm (N-FM) is
used to conserve bandwidth. In addition, it is used to send signals into space.
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FM is also used at intermediate frequencies by most analog VCR systems, including VHS,
to record the luminance (black and white) portion of the video signal. FM is the only feasible
method of recording video to and retrieving video from magnetic tape without extreme
distortion, as video signals have a very large range of frequency components — from a few hertz
to several megahertz, too wide for equalizers to work with due to electronic noise below -60 dB.
FM also keeps the tape at saturation level, and therefore acts as a form of noise reduction, and a
simple limiter can mask variations in the playback output, and the FM capture effect removes
print-through and pre-echo. A continuous pilot-tone, if added to the signal — as was done on
V2000 and many Hi-band formats — can keep mechanical jitter under control and assist time
base correction.
PROCEDURE:
1. The circuit wiring is done as shown in diagram
2. A modulating signal input given to the Frequency modulator
3. Now increase the modulated signal to the required level.
4. The amplitude and the time duration of the modulating signal are observed using
CRO.
5. Finally the frequency modulated output is observed from the output of frequency
modulator stage and the amplitude and time duration of the FM wave are noteddown.

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t (sec)
Model Graph:
Frequency Modulation :
Demodulated Signal
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t (sec)
t (sec)
t (sec)
Amplitude
(V)
Amplitude
(V)

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KIT DIAGRAM:
Frequency Modulation :
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FM Demodulation:
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TABULATION:
Message
Carrier
Modulated
Demodulated
GRAPH:
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Exp-No: 05
Date:
AIM
Pulse Code Modulation and Demodulation
To perform the operation of Pulse Code Modulation and demodulation and observe the
output waveforms.
APPARATUS REQUIRED
PCM kit, Power supply, DSO and connecting probes
THEORY
Pulse code modulation is a process of converting an analog signal into digital. The voice
or any data input is first sampled using a sampler (which is a simple switch) and then quantized.
Quantization is the process of converting a given signal amplitude to an equivalent binary
number with fixed number of bits. This quantization can be either midtread or mid-raise and it
can be uniform or non-uniform based on the requirements. For example in speech signals, the
higher amplitudes will be less frequent than the low amplitudes. So higher amplitudes are given
less step size than the lower amplitudes and thus quantization is performed non-uniformly. After
quantization the signal is digital and the bits are passed through a parallel to serial converter and
then launched into the channel serially.
At the demodulator the received bits are first converted into parallel frames and each
frame is de-quantized to an equivalent analog value. This analog value is thus equivalent to a
sampler output. This is the demodulated signal.
PROCEDURE:
1. Make connections as shown in the circuit diagram.
2. Set the input signal and carrier signal.
3. Obtain PCM signal
4. Tabulate the output data and draw the graph.
5. Justify the obtained output
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KIT DIADRAM:
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MODEL GRAPH:
TABULATION:
Message
Carrier
Modulated
Demodulated
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Exp-No: 06
Date:
DELTA MODULATION AND DEMODULATION
AIM
To study and to plot the characteristics of Delta modulation and demodulation.
APPARATUS REQUIRED:
DM kit, Power supply, DSO and connecting probes
THEORY:
Delta modulation is the DPCM technique of converting an analog message signal to a
digital sequence. The difference signal between two successive samples is encoded into a single
bit code. It is a one - bit version of differential pulse code modulation, it provides staircase
approximation for the given input baseband signal. The difference between the input and
staircase approximation is quantized into two levels called, ± ∆.A comparator senses whether or
not the instantaneous level of the analog input signal is greater or less than the feedback signal
(staircase approximation). The comparator output is clocked by a flip flop to form a
continuous NRZ digital data stream. This digital data is converted back to analog staircase
signal using DAC and feed to the comparator. The feedback signal never stands still; it always
travels up or down by a fixed amount (± ∆ ) in any clock period. Because of its fixed
feedback output slope, the linear delta modulator is less than ideal for encoding human
voice, also the accumulator (or) feedback section cannot track large, high frequency signals
with its fixedslope.
The delta demodulator is a simple one which have only feedback system of delta
modulator and a low-pass filter. The demodulator recovers staircase approximation from the
encoded signal and which will be smoothened by a low pass filter to get back original
analog information.
.
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KIT DIAGRAM:
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PROCEDURE:
1. Make connections as shown in the circuit diagram.
2. Set the input signal and carrier signal.
3. Obtain DM signal
4. Tabulate the output data and draw the graph.
5. Justify the obtained output .
MODEL GRAPH:
TABULAR COLUMN:
Name of the signal Amplitude in V Time period in Sec
Modulating Signal
Carrier Signal
Modulated Signal
Demodulated Signal
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GRAPH:
RESULT:
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Exp-No: 07
Date:
LINE CODING SCHEMES
AIM
To study about different line coding schemes.
SOFTWARE USED:
MATLAB
THEORY:
NON-RETURN TO ZERO signal are the easiest formats that can be generated. These signals do
not return to zero with the clock. The frequency component associated with these signals are half
that of the clock frequency. The following data formats come under this category. Non-return to
zero encoding is commonly used in slow speed communications interfaces for both synchronous
and asynchronous transmission. Using NRZ, logic 1 bit is sent as a high value and logic 0 bit is
sent as a low value.
a) NON-RETURN TO ZERO-LEVEL (NRZ-L)
This is the most extensively used waveform in digital logics. All „ones‟ are represented by
„high‟ and all „zeros‟ by „low‟. The data format is directly available at the output of all digital
data generation logics and hence very easy to generate. Here all the transitions take place at the
rising edge of the clock.
b) NON-RETURN TO ZERO-MARK (NRZ-M)
These waveforms are extensively used in tape recording. All „ones‟ are marked by change in
levels and all‟zeros‟ by no transitions, and the transitions take place at the rising edge of the
clock.
c) NON-RETURN TO ZERO-SPACE (NRZ-S)
This type of waveform is marked by change in levels for „zeros‟ and no transition for „ones‟
and the transitions take place at the rising edge of the clock. This format is also used in magnetic
tape recording.
d) UNIPOLAR AND BIPOLAR
Unipolar signals are those signals, which have transition between 0 to +VCC. Bipolar signals are
those signals, which have transition between +VCC to –VCC.
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e) BIPHASE – LINE CODING (BIPHASE -L):
With the Biphase – L one is represented by a half bit wide pulse positioned during the first half
of the bit interval and a zero is represented by a half bit wide pulse positioned during the second
half of the bit interval.
f) BIPHASE MARK CODING(BIPHASE-M):
With the Biphase-M, a transition occurs at the beginning of every bit interval. A „one‟ is
represented by a second transition, half bit later, whereas a zero has no second transition.
g) BIPHASE SPACE CODING(BIPHASE-S):
With a Biphase-S, a transition occurs at the beginning of every bit interval. A „zero‟ is marked
by a second transition, one half bit later; „one‟ has no second transition.
h) RETURN TO ZERO SIGNALS:
These signals are called ―Return to Zero signals‖ since they return to „zero‟ with the clock. In
this category, only one data format, i.e, the unipolar return to zero(URZ); With the URZ a „one‟
is represented by a half bit wide pulse and a „zero‟ is represented by the absence of pulse.
i) MULTILEVEL SIGNALS:
Multilevel signals use three or more levels of voltages to represent the binary digits, „one‟ and
„zero‟ – instead of normal „highs‟ and „lows‟ Return to zero – alternative mark inversion (RZ -
AMI) is the most commonly used multilevel signal. This coding scheme is most often used in
telemetry systems. In this scheme, „one‟ are represented by equal amplitude of alternative
pulses, which alternate between a +5 and -5. These alternating pulses return to 0 volt, after every
half bit interval. The‖Zeros‟ are marked by absence of pulses.
PROCEDURE:
1. Open MATLAB
2. Open new M-file
3. Type the program
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PROGRAM:
clc;
close all;
clear all;
x=[1 0 1 1 0 1];
nx=size(x,2);
sign=1;
i=1;
while i<nx+1
t = i:0.001:i+1-0.001;
if x(i)==1
unipolar_code=square(t*2*pi,100);
polar_code=square(t*2*pi,100);
bipolar_code=sign*square(t*2*pi,100);
sign=sign*-1;
manchester_code=-square(t*2*pi,50);
else
end
unipolar_code=0;
polar_code=-square(t*2*pi,100);
bipolar_code=0;
manchester_code=square(t*2*pi,50);
subplot(4,1,1);
plot(t,unipolar_code);
ylabel('unipolar code');
hold on;
grid on;
axis([1 10 -2 2]);
subplot(4,1,2);
plot(t,polar_code);
ylabel('polar code');
hold on;
grid on;
axis([1 10 -2 2]);
subplot(4,1,3);
plot(t,bipolar_code);
ylabel('bipolar code');
hold on;
grid on;
axis([1 10 -2 2]);
subplot(4,1,4);
plot(t,manchester_code);
ylabel('manchester code');
hold on;
grid on;
axis([1 10 -2 2]);
i=i+1;
end
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Exp-No: 8
Date:
Simulation of ASK, FSK, BPSK generation schemes
AIM :
To study simulation of ASK, FSK, BPSK techniques.
SOFTWARE USED:
MATLAB
PROCEDURE:
7. Open MATLAB
8. Open new M-file
9. Type the program
PROGRAM:
ASK generation:
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clc;
clear all;
close all;
%GENERATE CARRIER SIGNAL
Tb=1; fc=10;
t=0:Tb/100:1;
c=sqrt(2/Tb)*sin(2*pi*fc*t);
%generate message signal
N=8;
m=rand(1,N);
t1=0;t2=Tb
for i=1:N
t=[t1:.01:t2]
if m(i)>0.5
m(i)=1;
m_s=ones(1,length(t));
else
m(i)=0;
m_s=zeros(1,length(t));
end
message(i,:)=m_s;
%product of carrier and message
ask_sig(i,:)=c.*m_s;
t1=t1+(Tb+.01);
t2=t2+(Tb+.01);
%plot the message and ASK signal
subplot(5,1,2);
axis([0 N -2 2]);
plot(t,message(i,:),'r');
title('message signal');
xlabel('t--->');
ylabel('m(t)');grid on
hold on
subplot(5,1,4);
plot(t,ask_sig(i,:));
title('ASK signal');
xlabel('t--->');
ylabel('s(t)');
grid on
hold on
end
hold off
%Plot the carrier signal and input binary data
subplot(5,1,3);plot(t,c);
title('carrier signal');
xlabel('t--->');ylabel('c(t)');
grid on
subplot(5,1,1);stem(m);
title('binary data bits');
xlabel('n--->');ylabel('b(n)');
grid on
BPSK MODULATION
clc;
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clear all;
close all;
Tb=1;
t=0:Tb/100:Tb;
fc=2;
c=sqrt(2/Tb)*sin(2*pi*fc*t);
N=8;
m=rand(1,N);
t1=0;t2=Tb
for i=1:N
t=[t1:.01:t2]
if m(i)>0.5
m(i)=1;
else
m(i)=0;
m_s=-1*ones(1,length(t));
end
message(i,:)=m_s;
%product of carrier and message signal
bpsk_sig(i,:)=c.*m_s;
%Plot the message and BPSK modulated signal
subplot(5,1,2);
axis([0 N -2 2]);
title('message signal(POLAR form)');
xlabel('t--->');
ylabel('m(t)');
grid on;
hold on;
subplot(5,1,4);
plot(t,bpsk_sig(i,:));
title('BPSK signal');
xlabel('t--->');
ylabel('s(t)');
grid on; hold on;
t1=t1+1.01; t2=t2+1.01;
end
hold off
%plot the input binary data and carrier signal
title('binary data bits');
grid on;
subplot(5,1,3);plot(t,c);
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title('carrier signal');
xlabel('t--->');ylabel('c(t)');
grid on;
FSK Modulation
clc;
clear all;
close all;
Tb=1; fc1=2;fc2=5;
t=0:(Tb/100):Tb;
c1=sqrt(2/Tb)*sin(2*pi*fc1*t);
c2=sqrt(2/Tb)*sin(2*pi*fc2*t);
N=8;
m=rand(1,N);
t1=0;t2=Tb
for i=1:N
t=[t1:(Tb/100):t2]
if m(i)>0.5
m(i)=1;
invm_s=zeros(1,length(t));
else
m(i)=0;
m_s=zeros(1,length(t));
invm_s=ones(1,length(t));
end
message(i,:)=m_s;
%Multiplier
fsk_sig1(i,:)=c1.*m_s;
fsk_sig2(i,:)=c2.*invm_s;
fsk=fsk_sig1+fsk_sig2;
%plotting the message signal and the modulated signal
subplot(3,2,2);
axis([0 N -2 2]);
title('message signal');
xlabel('t --->');ylabel('m(t)');
grid on;hold on;
subplot(3,2,5);plot(t,fsk(i,:));
title('FSK signal');
xlabel('t --->');ylabel('s(t)');
grid on;hold on;
t1=t1+(Tb+.01); t2=t2+(Tb+.01);
end
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hold off
%Plotting binary data bits and carrier signal
title('binary data');
xlabel('n --->'); ylabel('b(n)');grid on;
subplot(3,2,3);plot(t,c1);
title('carrier signal-1');
xlabel('t --->');ylabel('c1(t)');grid on;
title('carrier signal-2');
xlabel('t --->');ylabel('c2(t)');grid on;
OUTPUT:
ASK modulation
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BPSK modulation
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FSK modulation
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RESULT:
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Exp-No: 09
Date:
Simulation of DPSK, QPSK AND QAM generation schemes
AIM:
To write a program in MATLAB for design of DPSK, QPSK, QAM.
SOFTWARE USED:
MATLAB
PROCEDURE:
1. Open MATLAB
2. Open new M-file
3. Type the program
PROGRAM:
DPSK:
clear all;
close all;
i=10;
j=5000;
a=round(rand(1,i));
t=linspace(0,10,j);
fc=5;
SNR=10;
st1=t;
for n=1:10
for m=j/i*(n-1)+1:j/i*n
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if a(n)<1
st1(m)=0;
else
st1(m)=1;
end
end
end
figure(1)
subplot(211)
plot(t,st1);
title('Original Input Bit');
axis([0,10,-1,2]);
b=zeros(1,i);
b(1)=a(1);
for n=2:10
if a(n)==1
if b(n-1)==1
b(n)=0;
else
b(n)=1;
end
else
b(n)=b(n-1);
end
end
st2=t;
for n=1:10
if b(n)==0
st2(m)=0;
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else
st2(m)=1;
end
end
end
subplot(212);
plot(t,st2);
title('Differentially Encoded Bitstream');
axis([0,10,-1,2]);
st3=t;
for n=1:j
if st2(n)==1
st3(n)=0;
else
st3(n)=1;
end
end
figure(2)
subplot(311);
plot(t,st3);
title('Inverse of Differentially Encoded Bitstream')
axis([0,10,-1,2]);
s1=sin(2*pi*fc*t);
subplot(312)
plot(t,s1);
axis([0,10,-2,2]);
title('Carrier for Differentially Encoded Bitstream ')
s2=-s1;
subplot(313)
plot(t,s2);
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axis([0,10,-2,2]);
title('Carrier for Inverse of Differentially Encoded Bitstream ')
d1=st2.*s1;
d2=st3.*s2;
figure(3);
subplot(311);
plot(t,d1);
axis([0,10,-2,2]);
title('DPSK of Differentially Encoded Bitstream')
subplot(312)
plot(t,d2);
axis([0,10,-2,2]);
title('DPSK of Inverse of Differentially Encoded Bitstream')
e_dpsk=d1+d2;
subplot(313)
plot(t,e_dpsk);
axis([0,10,-2,2]);
title('DPSK Waveform')
awgn_dpsk=awgn(e_dpsk,SNR,'measured','dB');
figure(4)
subplot(311)
plot(t,awgn_dpsk);
axis([0,10,-2,2]);
title('DPSK waveform with AWGN')
[B1,A1]=butter(1,[3/(500/2) 7/(500/2)]);
awgn_dpsk1=filter(B1,A1,awgn_dpsk);
subplot(312);
plot(t,awgn_dpsk1);
axis([0,10,-2,2]);
title('Bandpass matched Filter output');
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dem_dpsk=awgn_dpsk1.*sin(2*pi*fc*t);
subplot(313)
plot(t,dem_dpsk);
axis([0,10,-2,2]);
title('Demodulated DPSK Waveform')
[b1,a1]=butter(1,2/(500/2),'low');
al_dpsk=filter(b1,a1,dem_dpsk);
figure(5)
subplot(311)
plot(t,al_dpsk);
axis([0,10,-2,2]);
title('Low Pass Filter Output')
st=zeros(1,i);
for m=0:i-1
for j=m*500+1:(m+1)*500
if al_dpsk(1,m*500+250)<0
st(m+1)=0;
else
st(m+1)=1;
end
end
end
dpsk=zeros(1,j);
for m=0:i-1
for j=m*500+1:(m+1)*500
if al_dpsk(1,j)<0
dpsk(1,j)=0;
else
dpsk(1,j)=1;
end
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end
end
subplot(312);
plot(t,dpsk);
axis([0,10,-1,2]);
title('Differentially Decoded Bitstream')
error=dpsk-st2;
error=abs(error);
errorrate=sum(error)/5000
dt=zeros(1,i);
dt(1)=st(1);
for n=2:10
if (st(n)-st(n-1))<=0&&(st(n)-st(n-1))>-1
dt(n)=0;
else
dt(n)=1;
end
end
st=t;
for n=1:10
if dt(n)<1;
st(m)=0;
end
else
st(m)=1;
end
end
end
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subplot(313)
plot(t,st);
title('Retrieved Bitstream');
axis([0,10,-1,2])
QPSK:
QPSK
clc;
clear all;
close all;
%GENERATE QUADRATURE CARRIER SIGNAL
Tb=1;t=0:(Tb/100):Tb;fc=1;
c1=sqrt(2/Tb)*cos(2*pi*fc*t);
c2=sqrt(2/Tb)*sin(2*pi*fc*t);
N=8;m=rand(1,N);
t1=0;t2=Tb
for i=1:2:(N-1)
t=[t1:(Tb/100):t2]
if m(i)>0.5
m(i)=1;
else
m(i)=0;
end
%odd bits modulated signal
odd_sig(i,:)=c1.*m_s;
if m(i+1)>0.5 21
m(i+1)=1;
else
m(i+1)=0;
end
%even bits modulated signal
even_sig(i,:)=c2.*m_s;
%qpsk signal
qpsk=odd_sig+even_sig;
%Plot the QPSK modulated signal
subplot(3,2,4);plot(t,qpsk(i,:));
title('QPSK signal');xlabel('t --- >');ylabel('s(t)');grid on; hold on;
t1=t1+(Tb+.01); t2=t2+(Tb+.01);
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end
hold off
%Plot the binary data bits and carrier signal
title('binary data bits');xlabel('n --->');ylabel('b(n)');grid on;
title('carrier signal-1');xlabel('t --->');ylabel('c1(t)');grid on;
% QPSK Demodulation
t1=0;t2=Tb
for i=1:N-1
t=[t1:(Tb/100):t2]
%correlator
x1=sum(c1.*qpsk(i,:));
x2=sum(c2.*qpsk(i,:));
%decision device
if (x1>0&&x2>0)
demod(i)=1;
demod(i+1)=1;
elseif (x1>0&&x2<0)
demod(i)=1;
demod(i+1)=0;
elseif (x1<0&&x2<0)
demod(i)=0;
demod(i+1)=0;
elseif (x1<0&&x2>0)
demod(i)=0;
demod(i+1)=1;
end
t1=t1+(Tb+.01); t2=t2+(Tb+.01);
end
subplot(3,2,5);stem(demod);
title('qpsk demodulated bits');xlabel('n --- >');ylabel('b(n)');grid on;
QAM code
t=0:0.0001:1;
%Message 1
m1=cos(2*pi*50*t);
%Message 2
m2=sin(2*pi*100*t);
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%Carrier
c1=cos(2*pi*1000*t);
%Quadrature Carrier
c2=sin(2*pi*1000*t);
mod1=m1.*c1;
mod2=m2.*c2;
mod=mod1+mod2;
subplot(5,1,1)
plot(t,m1);
title('Message 1');
subplot(5,1,2)
plot(t,m2);
title('Message 2');
subplot(5,1,3)
plot(t,mod);
title('Modulated Signal');
%Demodulation with Carrier
demod1=mod.*c1;
%Demodulation with Quadrature Carrier
demod2=mod.*c2;
[a b]=butter(5,2*55*0.0001);
msg1=filter(a,b,demod1);
[a b]=butter(5,2*105*0.0001);
msg2=filter(a,b,demod2);
subplot(5,1,4)
plot(t,msg1);
title('Message 1 retrieved');
subplot(5,1,5)
plot(t,msg2);
title('Message 2 retrieved');
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OUTPUT:
DPSK:
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QAM:
RESULT:
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Exp-No: 10
Date:
SIMULATION OF SIGNAL CONSTELLATIONS OF BPSK, QPSK AND
QAM
AIM:
To write a program in MATLAB for design of BPSK, QPSK, QAM.
SOFTWARE USED:
MATLAB
PROCEDURE:
1. Open MATLAB
2. Open new M-file
3. Type the program
6. For the output see command window Figure winDOW
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PROGRAM:
% Setting up parameters for modulation type
data = randint(1000,1,[1,0]); % generating binary data of 1000 bits with ones
and zeros
mod_type=input('Enter the modulation type[1 for BPSK,2 for QPSK,3 for 16QAM,4
for 64QAM]: ');
norm_factor=[1.0;0.7071;0.3162;0.1543]; % normalization factors,
1.0:BPSK,0.7071:QPSK,0.3162:16QAM,0.1543:64QAM
nc=[1;2;4;6]; % number of bits per subcarrier, 1:BPSK,2:QPSK,4:16QAM,6:64QAM
input_seq = data;
k=norm_factor(mod_type);
mode=nc(mod_type);
% Selecting constellation point as per modulation type
switch mode
case 1
b=k*[1 -1];
case 2
b=k*[1+1i -1+1i 1-1i -1-1i];
case 4
b=k*[1+1i 1+3i 1-1i 1-3i 3+1i 3+3i 3-1i 3-3i -1+1i -1+3i -1-1i -1-3i -3+1i -
3+3i -3-1i -3-3i];
end
count=1;
count1=1;
for i=1:(ceil(length(input_seq)/mode))
temp=0;
for j=1:mode
temp=bitor(temp,bitshift(input_seq(count),(j-1)));
count=count+1;
if(count>length(input_seq))
break;
end
end
map_out(count1)=b(temp+1);
count1=count1+1;
end
figure;plot(real(map_out),imag(map_out),'r.');title('constellation');
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OUTPUT:
BPSK:
QPSK:
QAM:
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Exp-No:
11 Date:
AIM :
Simulation of ASK, FSK, BPSK detection schemes
To study simulation of ASK, FSK, BPSK detection techniques.
SOFTWARE USED:
MATLAB
PROCEDURE:
1. Open MATLAB
2. Open new M-file
3. Type the program
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PROGRAM:
ASK DEMODULATION
t1=0;t2=Tb
for i=1:N
t=[t1:Tb/100:t2]
%correlator
x=sum(c.*ask_sig(i,:));
%decision device
if x>0
demod(i)=1;
else
demod(i)=0;
end
t1=t1+(Tb+.01);
t2=t2+(Tb+.01);
end
%plot demodulated binary data bits
title('ASK demodulated signal');
grid on
BPSK Demodulation
t1=0;t2=Tb
for i=1:N
t=[t1:.01:t2]
%correlator
x=sum(c.*bpsk_sig(i,:));
%decision device
if x>0
demod(i)=1;
else
demod(i)=0;
end
t1=t1+1.01;
t2=t2+1.01;
end
%plot the demodulated data bits
subplot(5,1,5);
stem(demod);
title('demodulated data');
grid on
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FSK Demodulation
t1=0;t2=Tb
for i=1:N
t=[t1:(Tb/100):t2]
%correlator
x1=sum(c1.*fsk_sig1(i,:));
x2=sum(c2.*fsk_sig2(i,:));
x=x1-x2;
%decision device
if x>0
demod(i)=1;
else
demod(i)=0;
end
t1=t1+(Tb+.01);
t2=t2+(Tb+.01);
end
%Plotting the demodulated data bits
title(' demodulated data');
xlabel('n --->');ylabel('b(n)');
grid on;
OUTPUT:
ASK demodulation
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PSK demodulation
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FSK demodulation
RESULT:
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Exp-No: 12
Date:
SIMULATION OF LINEAR BLOCK AND CYCLIC ERROR CONTROL CODING
SCHEMES
AIM :
To study simulation of error control coding schemes - linear block and cyclic code
techniques.
SOFTWARE USED:
MATLAB
PROGRAM:
LINEAR CODE:
clc;
clear all;
% Input Generator Matrix
g=input('Enter The Generator Matrix: ')
disp ('G = ')
disp ('The Order of Linear block Code for given Generator Matrix is:')
[n,k] = size(transpose(g))
for i = 1:2^k
for j = k:-1:1
if rem(i-1,2^(-j+k+1))>=2^(-j+k)
u(i,j)=1;
else
u(i,j)=0;
end
end
end
u;
disp('The Possible Codewords are :')
c = rem(u*g,2)
disp('The Minimum Hamming Distance dmin for given Block Code is= ')
d_min = min(sum((c(2:2^k,:))'))
% Code Word
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r = input('Enter the Received Code Word:')
p = [g(:,n-k+2:n)];
h = [transpose(p),eye(n-k)];
disp('Hammimg Code')
ht = transpose(h)
disp('Syndrome of a Given Codeword is :')
s = rem(r*ht,2)
for i = 1:1:size(ht)
if(ht(i,1:3)==s)
r(i) = 1-r(i);
break;
end
end
disp('The Error is in bit:')
i
disp('The Corrected Codeword is :')
r
CYCLIC ERROR CONTROL CODE:
clc;
clear all;
close all;
n=7;
k=4;
genpoly=cyclpoly(n,k,'max');
berf=[];
for i=1:10
b=0;
for j=1:50
msg=randint(500,k,[0,1]);
code=encode(msg,n,k,'cyclic/binary',genpoly);
t=0:0.1:10;
snr=0;
y=awgn(code,i);
y(find(y>0))=1;
y(find(y<0))=1;
msgop=decode(y,n,k,'cyclic/binary',genpoly);
[number,b1]=biterr(msgop,msg);
b=b+b1;
end
berf(i)=b/50;
end
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semilogy(1:10,berf);
title('performance analysis in awgn for cyclic codes');
xlabel ('snr (db)');
ylabel ('BER');
OUTPUT:
Enter The Generator Matrix: [1 0 0 0 1 0 1;0 1 0 0 1 1 1;0 0 1 0 1 1 0;0 0 0 1 0 1 1]
g =
1 0 0 0 1 0 1
0 1 0 0 1 1 1
0 0 1 0 1 1 0
0 0 0 1 0 1 1
G = The Order of Linear block Code for given Generator Matrix is:
n =7
k =4
The Possible Codewords are :
c =
0 0 0 0 0 0 0
0 0 0 1 0 1 1
0 0 1 0 1 1 0
0 0 1 1 1 0 1
0 1 0 0 1 1 1
0 1 0 1 1 0 0
0 1 1 0 0 0 1
0 1 1 1 0 1 0
1 0 0 0 1 0 1
1 0 0 1 1 1 0
1 0 1 0 0 1 1
1 0 1 1 0 0 0
1 1 0 0 0 1 0
1 1 0 1 0 0 1
1 1 1 0 1 0 0
1 1 1 1 1 1 1
The Minimum Hamming Distance dmin for given Block Code is=
d_min =3
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Enter the Received Code Word:[1 0 0 0 1 0 0]
r =1 0 0 0 1 0 0
Hammimg Code
ht =1 0 1
1 1 1
1 1 0
0 1 1
1 0 0
0 1 0
0 0 1
Syndrome of a Given Codeword is :
s = 0 0 1
The Error is in bit:
i = 7
The Corrected Codeword is :
r = 1 0 0 0 1 0 1
OUTPUT FOR CYCLIC CODE:
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Exp.No:13
Date:
AIM:
Simulation of Convolutional coding scheme
To study the simulation of convolutional coding scheme.
JANSONS INSTITUE OF TECHNOLOGY
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SOFTWARE REQUIRED:
MATLAB
PROCEDURE:
1. Open MATLAB
2. Open new M-file
3. Type the program
PROGRAM:
function [Conv_out] = conv_encoder(Conv_In)
Conv_In= [1 1 0 1 0 1 1 0 1 1 0 1 0 1 1 0 1 0 1 0]; % x=[1 0 1 1 0 0 0];
m1=0;
m2=0;
m3=0;
m4=0;
%m_in m1 m2 m3 m4
%[1 0 1 0 1] =x0
%[1 1 0 1 1] =x1
%[1 1 1 1 1] =x2;
for k = 1:length(Conv_In)
% 1st polynomial
% x0= [1 0 1 0 1]
m_in = Conv_In(k);
temp1 = bitxor(m_in,m2);
x0 = bitxor(temp1,m4);
% 2nd polynomial
temp2 = bitxor(temp1,m3);
%3rd polynomial
Conv_out((3*k)-2) = x0;
Conv_out((3*k)-1) = x1;
Conv_out(3*k) = x2;
%%%Shifiting
m4=m3;
m3=m2;
m2=m1;
m1=m_in;
end

72
OUTPUT:
ans =
Columns 1 through 15
1 1 1 1 0 0 1 1 0 0 0 1 1 1 1
1 0 1 1 1 1 0 0 1 0 0 1 0 0 0
0 0 1 0 0 1 1 1 1 1 0 1 1 1 1
0 0 1 0 0 1 1 1 1 1 0 1 0 0 0

73
RESULT:
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Exp-No: 14
Date:
AIM:
COMMUNICATION LINK SIMULATION
To design a Model for establishing communication link using Simulink.
SOFTWARE USED:
MATLAB
PROCEDURE:
1. Open the MATLAB Software.
2. Click on the Simulink icon. In that window select File -new Model to create your model
3. Select the components required for your design from the Simulink library.
4. After saving the design, click on the Run button to view the output.
CIRCUIT DIAGRAM:
THEORY:
A Communication can be established by the transmission of signals between two entities
through a communication channel. A binary generator is used as a source of signal which will be
producing signals in terms of ones and zeros. Here Hamming encoder is used for encoding the
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signal and the encoded signal is further modulated by using the QPSK modulator, after which the
signal is transmitted through a channel, where there are the possibilities of addition of noise. By
selecting a Hamming decoder and QPSK demodulator the source signal without any distortion is
recovered back, which is shown at the output.
OUTPUT:
Source Signal Signal before Transmission
Signal After Passing Through Signal Received
Communication Channel
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RESULT:
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