Communication Theory-1 Project || Single Side Band Modulation using Filtering Method and Synchronous Demodulation in the Presence of Noise || Using Matlab Code

LAB BASED PROJECT REPORT
On
Single Side Band Modulation using Filtering Method and
Synchronous Demodulation in the Presence of Noise.
Submitted in partial fulfilment of the
Requirements for the award of degree
BachelorofTechnology
In
Electronics andCommunication Engineering
Submitted
By
K. Bhaskar - 160041007
Prathyusha - 160041011
Appaji Babu - 160041034
Under the guidance of
xxxxxxxxxxxxxxxx
(AssistantProfessor)
DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING
KONERU LAKSHMAIAH EDUCATIONAL FOUNDATION
Green Fields, Vaddeswaram, Guntur District

CERTIFICATE
This is to certify that the mini project entitled “Single Side Band Modulation
using Filtering Methodand Synchronous Demodulation in the Presence of Noise”, being
submitted by “K. Bhaskar – 160041007, Prathyusha - 160041011, Appaji Babu -
160041034” in partial fulfillment for the award of degree of Bachelor of Technology (B.
Tech) in Electronics and CommunicationsEngineering is a recordof confideworkcarried out
by them under our guidance during the academic year 2017-2018and it has been found
worthy of acceptance according to the requirements of the university.
Signature of the Project Guide Signature of Headof Department
Departmentof ECE
K L E F

KONERU LAKSHMAIAH EDUCATIONAL FOUNDATION
DEPARTMENTOF ELECTRONICS &COMMUNICATIONENGINEERING
we here by declare that this project based lab report entitled “Single Side Band
Modulation using Filtering Method and Synchronous Demodulation in the Presence of
Noise” has been prepared by us in partial fulfillment of the requirement for the award of
degree “BACHELOR OF TECHNOLOGY IN ELECTRONICS AND
COMMUNICATIONS OF ENGINEERING” during the academic year 2017-2018.
we also declare that this project based lab report is of our own effort and it has not
been submitted to any other university for the award of any degree.
DECLARATION

Acknowledgement
We are greatly indebted to our KL University that has provided a healthy
environment to drive us to achieve our ambitions and goals. We would like to express our
sincere thanks to our project incharge Mr. xxxxxxxxxxx(Assistant professor) sir for the
guidance, supportand assistance they have provided in completing this project.
With immense pleasure, we would like to thank the Head of the Department, Dr. V.
S. V. Prabhakar sir for his valuable suggestions and guidance for the timely completion of
this project.
We are very much glad for having the support given by our principal, K. Subba Rao
sir who inspired us with his words filled with dedication and discipline towards work.
We believe that “Practical Leads A Man Towards Performance”.
Last but not the least, a special thanks goes to the Parents, staff and classmates who are
helpful either directly or indirectly in completion of the Lab Based project

CONTENTS
Abstract
Problem statement
1: Introduction
2: Tasks Simulation Results and Discussion
Task1-single side band modulation by filter shift method
Task2-Synchronus Demodulation
Task 3-Multi Tone Modulating Signal
Task 4-Band limited signal
Task 5-Real Speech Signals
3: Conclusions and References

Project Title: Single Side Band Modulation using Filtering Method
and Synchronous Demodulation in the Presence of Noise
ABSTRACT
In radio communications single side band modulation or single side band suppressed carrier
modulaton is a refinement of amplitude modulation which uses transmission power and bandwidth more
efficiently. Amplitude modulation produces an output signal that has twice the bandwidth of the original
baseband signal. Single-sideband modulation avoids this bandwidth doubling, and the power wasted on a
carrier, at the cost of increased device complexity and more difficult tuning at the receiver . There are two
methods used for SSB and Filter method is the most obvious method to create a local oscillator signal on the
same frequency as the carrier is to use a fixed frequency filter that is tuned to remove only the carrier
frequency. This can be phase shifted, 90°: and entered into the mixer. The phase shift will ensure the DC
component at the output of the mixer is minimised. When looking at the synchronous demodulation of an
AM signal, it is first useful to look at the spectrum of an amplitude modulated signal. It can be seen that it
comprises a carrier with the two sidebands carrying he audio or other information spreading out either side.
These two sidebands are reflections of each other.

PROBLEM STATEMENT
Explore the practical implementation of theoretical concepts like Single Side Band (SSB)
Modulation techniques those are studied in the class room.Investigate the effect of channel noise in the
demodulation and reception of SSB Modulation signals. Exposure to simulation on modulation/demodulation
systems for SSB using MATLAB for synthetic & real signals (such as speech).A base band signal m(t) is
used to generate SSB Modulated signal ( ) by generating DSB-SC modulated signal and then band pass
filtering either LSB or USB frequencies, as shown in the Fig.1. The objective is to explore the theoretical
concepts of SSB signal by modeling and simulation using Matlab and Simulink.
Task1:

Consider a single tone modulating signal m(t) = cos1000πt , and carrier signal c(t) = cos104πt
Determine the expression for SSB Modulated signal in both time domain and frequency domain.
1. Sketch the modulating signal m(t) and its spectrum
.
2. Sketch the carrier signal c(t) and its spectrum.
3. Sketch the SSB Modulated signal (USB/(LSB) ( ) and their spectra.
4. Identify the USB / LSB spectrum.
5. Determine the maximum and minimum amplitudes of the envelope.
6. Find the powers of USB, LSB and modulated signals.
Task 2:
Assume that the demodulation process is synchronous detection as shown in Figure Theobjective is to study
the impact of channel noise in demodulation / reception of SSB Modulated signal. Now consider a single
tone case.
Add the noise variance such that the signal to noise ratio (SNR) of noisy SSB modulated.signal is 20 dB.
1. Use noisy upper side frequency band and lower side frequency bands separately for demodulation
purpose. If necessary use band pass filter.
2. Sketch noisy SSB modulated signal ( ) + n(t) and its spectrum.
3. Sketch the demodulated output mˆ (t) and its spectrum.
4. Find the output SNR and corresponding figure of merit.
5. Repeat the above steps for SNR = 10 dB, 30dB and 40dB and compare. Comment on the results.
Task 3:
Repeat the above Tasks1-2 for multi tone signal m(t) = 2cos1000πt - sin1500πt + 1.5cos2000πt
Task4:
Generate band limited signal for the frequency range 300 to 3400 Hz. Repeat the above Tasks1-2 for this
signal.
Task5:
Repeat above Tasks1-2 for real speech signals.

Introduction to Communication System
The transmission of information-bearing signal over a band pass communication channel, such
as telephone line or a satellite channel usually requires a shift of the range of frequencies contained in the
signal to another frequency range suitable for transmission. A shift in the signal frequency range is
accomplished by modulation. This chapter introduces the definition of modulation, need of modulation, types
of modulation- AM, PM and FM, Various types of AM, spectra of AM, bandwidth requirements, Generation
of AM & DSB-SC, detection of AM & DSB-SC, and power relations.
Communication is a process of conveying message at a distance. If the distance is involved is
beyond the direct communication, the communication engineering comes into the picture. The branch of
engineering which deals with communication systems is known as telecommunication engineering.
Modulation:
Modulation is defined as the process by which some characteristics (i.e. amplitude, frequency, and
phase) of a carrier are varied in accordance with a modulating wave.
Demodulation:
Demodulation is the reverse process of modulation, which is used to get back the original message
signal. Modulation is performed at the transmitting end whereas demodulation is performed at the receiving
end.
In analog modulation sinusoidal signal is used as carrier where as in digital modulation pulse train
is used as carrier.
SSB Modulation:
Single-SideBand modulation (SSB) or Single-SideBandSuppressed-Carrier (SSB-SC) is a
refinement of amplitude modulation which uses transmitter power and bandwidth more efficiently.
Amplitude modulation produces an output signal that has twice the bandwidth of the original baseband
signal.
Standard AM and DSB-SC techniques are wasteful of bandwidth because they both require
transmission bandwidth of 2B Hz, where B is the bandwidth of the baseband modulating signal m(t). In both
cases the transmission bandwidth (BT ) is occupied by the upper sideband (USB) and lower sideband (LSB).

Generation of SSB waves:
1.Filter method
2.Phase shift method
3.Third method (Weaver’s method)
In this Project we discuss only 1&2 methods.we didn’t discuss about third method.
Demodulation of SSB waves:
Coherent detection: it assumes perfect synchronization between the local carrier and that used in the
transmitter both in frequency and phase.
1. Filter Method:
A bandpass filter is an electronic device or circuit that allows signals between two specific frequencies to
pass, but that discriminates against signals at other frequencies.
2. Phase Shift Method:
Phase shift method is one of the methods used for the generation of SSB-SC signals. This method includes
two balanced modulators and two phase shifting networks and avoids the use of filters. Both the balanced
modulators produce side band as an output.It includes two balanced Modulators.Two phase shifting
Networks & Avoids the use of filters.

DEMODULATION
Demodulation is extracting the original information-bearing signal from a modulated carrier wave.
A true SSB demodulator must have the ability to select sidebands. All the methods of SSB
generation so far discussed have their counter parts as demodulators. Demodulating the amplitude of this
auxiliary carrier must be much greater than that of the single-sideband received signal. Too little difference
to phase errors become noticeable in a significantly distorted, no longer sinusoidal envelope. The recovered
information then comprises a large distortion. Single-sideband modulation (SSB) or Single-sideband
suppressed carrier (SSB-SC) is a refinement of amplitude modulation that more efficiently uses electrical
power and bandwidth. Amplitude modulation produces a modulated output signal that has twice the
bandwidth of the original baseband signal. Single-sideband modulation avoids this bandwidth doubling, and
the power wasted on a carrier, at the cost of somewhat increased device complexity and more difficult tuning
at the receiver. The baseband or modulating signal can be recovered from the SSB-SC signal by using the
synchronous detection. Is the subcarrier frequency slightly above the transmitter carrier frequency, so shifts
the recovered information in the direction of lower frequencies. If the subcarrier somewhat too low, the
demodulation signal is too high. The amateur radio on shortwave use, among other SSB. At the receiving
device, the subcarrier frequency is adjustable. A mismatch makes acoustically as caves Mickey Mouse effect.
Advantages:
(1).The modulation signal needed only half the bandwidth.
(2).The entire transmission line will go to the SSB and not divided into 2 sidebands and the carrier signal.
(3).The SSB is insensitive to signal reception loss, because there is no backing, amplitude reductions or
cancellations learns through interference of wave propagation.

Disadvantages:
(1) One of the disadvantages of the SSB modulation include the high demands on the SSB filter to filter
out the desired sideband and the most necessary two-time modulation.
(2) In the receiver, a quartz-accurate subcarrier frequency must be supplied to the demodulation.
(3) Because quartz crystal oscillators are not turn able, the SSB technology has not been enforced in the
normal broadcasting.
NOISE:
Noise is ever present and limits the performance of virtually every system. The presence of noise
degrades the performance of the Analog and digital communication systems. This chapter deals with how
noise affects different Analog modulation techniques. After studying this Chapter the should be familiar with
the following
1. Various performance measures of communication systems
2. SNR calculations for DSB-SC, SSB-SC, Conventional AM, FM (threshold effect, threshold extension,
pre-emphasis and deemphasis) and PM.
3. Figure of merit of All the above systems
4. Comparisons of all Analog modulation systems – Bandwidth efficiency, power efficiency, ease of
implementation.
5. The extent to which the noise affects the performance of communication system is measured by the output
signal-to-noise power ratio or the probability of error.
6. The SNR is used to measure the performance of the Analog communication systems, whereas the
probability of error is used as a performance measure of digital communication systems
7. figure of merit = γ = SNRo/SNRi
The loss or mutilation of the message at low predetection SNR is called as the threshold
effect. The threshold occurs when SNRi is about 10dB or less.
8. Output SNR .
So= output signal power Si = input
signal power
FM = base band signal frequency range

Tasks, Simulation Results and Discussion
Descriptionof Task 1:
Consider a single tone modulating signal m(t) =cos1000 t , and carrier signal with frequency
of 5000 Hz. Determine the expression for Single Side Band (SSB) modulated signal in both time domain and
frequency domain. Sketch the modulating signal m(t), carrier signal c(t) and its spectrums. Sketch the SSB
Modulated signal (USB/ (LSB) ∅ t and their spectra. Identify the USB / LSB spectrum. Determine the
maximum and minimum amplitudes of the envelope. Find the powers of USB / LSB modulated waves.
MATLAB CODE FOR Task 1:
clear all;
close all;
clc;
am=1; %Peak Amplitude of Modulating Signal
ac=1; %Peak Amplitude of Carrier Signal
fm=500; %Modulating Signal Frequency
fc=5000; %Carrier Frequency
fs=100000; %Sampling Frequency
ts=1/fs; %Sampling Interval
N=10000; %Number of Samples
t=(-N/2:1:(N/2-1))*ts; %Time Interval
m=am*cos(2*pi*fm*t); %Modulating Signal
mh=am*sin(2*pi*fm*t); %Hilbert Transform for messagesignal
c=ac*cos(2*pi*fc*t); %Carrier Signal
ch=ac*sin(2*pi*fc*t); %Hilbert Transform for carrier signal
st=m.*c-mh.*ch; %SSB-SC Signal
% TASK - 1
%Time Domain of all signals
subplot(3,2,1);
plot(t,m, 'red', 'LineWidth',1.5);axis([0 0.005 -2.5 2.5]);
xlabel('Time (seconds)');ylabel('Amplitude');title('Modulating Signal signal');
grid on;
subplot(3,2,3);
plot(t,c, 'black', 'LineWidth',1.5);axis([0 0.005 -2.5 2.5]);
xlabel('Time (seconds)');ylabel('Amplitude');title('Carrier Signal signal');
grid on;
subplot(3,2,5);
plot(t,st, 'blue', 'LineWidth',1.5);axis([0 0.005 -2.5 2.5]);
xlabel('Time (seconds)');ylabel('Amplitude(Volts)');title('Modulated signal');
grid on;hold on;
%Spectrums of all Signals
f=(-N/2:1:N/2-1)*fs/N;
M=abs((2/N)*fftshift(fft(m)));
C=abs((2/N)*fftshift(fft(c)));
SF=abs((2/N)*fftshift(fft(st)));

subplot(3,2,2);
plot(f,M/max(M), 'black', 'LineWidth',1.5);axis([-2*fc 2*fc -0.1 1.1]);
xlabel('Frequency (Hz)');ylabel('Amplitude');title('Spectrum of Modulating Signal
signal');
grid on;
subplot(3,2,4);
plot(f,C/max(C), 'black', 'LineWidth',1.5);axis([-2*fc 2*fc -0.1 1.1]);
xlabel('Frequency (Hz)');ylabel('Amplitude');title('Spectrum of Carrier Signal
signal');
grid on;
subplot(3,2,6);
plot(f,SF/max(SF), 'black', 'LineWidth',1.5);axis([-2*fc 2*fc -0.1 1.1]);
xlabel('Frequency (Hz)');ylabel('Amplitude(Volts)');title('Spectrum of Modulated
signal');
grid on;
%Maximum and Minimum amplitudes of the envelope
Amax = ac + am
Amin = ac - am
%Power Calculations
mu=am/ac %Modulation index
Pc=(ac^2)/2 %Carrier Power
Pu=Pc*(mu^2)/4 %USB POWER
Pl=Pc*(mu^2)/4 %LSB POWER
Ps=Pu+Pl %Total Side Band Power
Pt=Pc*(1+((mu^2)/2)) %Total Power of Modulated wave
Assume that the demodulation process is synchronous detection as shown in Figure
Theobjective is to study the impact of channel noise in demodulation / reception of SSB Modulated signal.
Now consider a single tone case.
Add the noise variance such that the signal to noise ratio (SNR) of noisy SSB modulated.signal is 20 dB.

1. Use noisy upper side frequency band and lower side frequency bands separately for demodulation
purpose. If necessary use band pass filter.
2. Sketch noisy SSB modulated signal ( ) + n(t) and its spectrum.
3. Sketch the demodulated output mˆ (t) and its spectrum.
4. Find the output SNR and corresponding figure of merit.
Repeat the above steps for SNR = 10 dB, 30dB and 40dB and compare. Comment on the results
MATLAB CODE FOR TASK 2:
clear all; close all; clc;
fc=5000; %%%% carrier frequency
fs=30000; %%%% Sample frequency
N=5000; %%%% Number of samples
Ts=1/fs; %%%% Sampling interval
t=(0:Ts:(N*Ts)- Ts); %%%% Time interval
f=(-N/2:1:N/2-1)*fs/N; %%%% Frequency interval
fm = 500; %%%% Modulating frequency
am=1; %Peak Amplitude of Modulating Signal
m=am*cos(2*pi*fm*t); %Modulating Signal
mh=am*sin(2*pi*fm*t); %Hilbert Transform for messagesignal
st=m.*c-mh.*ch; %SSB-SC Signal
%NOISE ADDED
%DSB-SC signal with 10db noise
y3=awgn(st,10);
figure();
subplot(4,2,1);
plot(t,y3/max(y3), 'black', 'LineWidth',1.5);axis([0 0.005 -1.2 1.2]);
xlabel('Time (seconds)');ylabel('Amplitude');title('s(t) +10dB noise');
grid on;
%Spectrum of DSB-SC 10db noise added
Y3F=abs((2/N)*fftshift(fft(y3)));
subplot(4,2,2);
plot(f,Y3F/max(Y3F), 'black', 'LineWidth',1.5);axis([-2*fc 2*fc -0.1 1.1]);
xlabel('Frequency (Hz)');ylabel('Amplitude(Volts)');title('Spectrum of 10db Noise
Modulated signal');
grid on;
y4=awgn(st,20);
subplot(4,2,3);
grid on;
subplot(4,2,4);
Modulated signal');
grid on;
y5=awgn(st,30);
subplot(4,2,5);

grid on;
subplot(4,2,6);
Modulated signal');
grid on;
y6=awgn(st,40);
subplot(4,2,7);
grid on;
subplot(4,2,8);
Modulated signal');
grid on;
%Time domain of Demodulated signal
md1=y3.*cos(2*pi*fc*t);
[b,a]=butter(2,0.01);
mf1=filter(b,a,md1);
md2=y4.*cos(2*pi*fc*t+(pi/4));
[b,a]=butter(2,0.1);
md4=y6.*cos(2*pi*fc*t+(3*pi/4));
figure();
subplot(1,2,1);
plot(t,mf4);title('Demodulated signal');
axis([0 0.005 -2.5 2.5]);
xlabel('Time');ylabel('Amplitude');
%frequency domain of Demodulated signal
MF4=abs((2/N)*fftshift(fft(mf4)));
subplot(1,2,2);
plot(f,MF4/max(MF4), 'black', 'LineWidth',1.5);axis([-2*fc 2*fc -0.1 1.1]);
xlabel('Frequency (Hz)');ylabel('Amplitude');title('Spectrum of Demodulated signal');
grid on;

Repeat the above Tasks1-2 for multi tone signal m(t) = 2cos1000πt - sin1500πt + 1.5cos2000πt

MATLAB CODE for Task-3:
am1=2; %Peak Amplitude of Modulating Signal
am2=1.5; %Peak Amplitude of Modulating Signal
m = am1.*cos(1000*pi*t)-sin(1500*pi*t)+am2.*cos(2000*pi*t);% Message signal
mh= am1.*sin(2*pi*500*t)-cos(2*pi*750*t)+am2.*sin(2*pi*1000*t); %Hilbert Transform for
messagesignal
st=m.*c-mh.*ch; %s SB-SC Signal
subplot(3,2,1);
grid on;
subplot(3,2,3);
grid on;
subplot(3,2,5);
grid on;hold on;
f=(-N/2:1:N/2-1)*fs/N;
subplot(3,2,2);
xlabel('Frequency (Hz)');ylabel('Amplitude');title('Spectrum of Modulating Signal
signal');
grid on;
subplot(3,2,4);
xlabel('Frequency (Hz)');ylabel('Amplitude');title('Spectrum of Carrier Signal
signal');
grid on;
subplot(3,2,6);

xlabel('Frequency (Hz)');ylabel('Amplitude(Volts)');title('Spectrum of Modulated
signal');
grid on;
%Power Calculations
mu1=am1/ac;
mu2=am2/ac;
mu=sqrt((mu1^2)+(mu2^2)) %Modulation index
%NOISE ADDED
y3=awgn(st,10);
figure();
subplot(4,2,1);
grid on;
subplot(4,2,2);
Modulated signal');
grid on;
y4=awgn(st,20);
subplot(4,2,3);
grid on;
subplot(4,2,4);
Modulated signal');
grid on;
y5=awgn(st,30);
subplot(4,2,5);
grid on;
subplot(4,2,6);
Modulated signal');
grid on;
y6=awgn(st,40);
subplot(4,2,7);
grid on;

subplot(4,2,8);
Modulated signal');
grid on;
md1=y3.*cos(2*pi*fc*t);
[b,a]=butter(2,0.01);
md4=y6.*cos(2*pi*fc*t+(3*pi/4));
figure();
subplot(1,2,1);
plot(t,mf4);title('Demodulated signal');
axis([0 0.005 -2.5 2.5]);
xlabel('Time');ylabel('Amplitude');
%frequency domain of Demodulated signal
MF4=abs((2/N)*fftshift(fft(mf4)));
subplot(1,2,2);
plot(f,MF4/max(MF4), 'black', 'LineWidth',1.5);axis([-2*fc 2*fc -0.1 1.1]);
xlabel('Frequency (Hz)');ylabel('Amplitude');title('Spectrum of Demodulated signal');
grid on;

Generate band limited signal for the frequency range 300 to 3400 Hz. Repeat the above Tasks1-
2 for this signal
MATLAB CODE for Task-4
clc;
clear all;
close all;
am=1;

am=1;
ac=1;
%%%% Generation of message signal
m1=
cos(2*pi*300*t)+cos(2*pi*500*t)+cos(2*pi*700*t)+cos(2*pi*1000*t)+cos(2*pi*1500*t)+cos(2*pi*2000*
t)+cos(2*pi*3000*t)+cos(2*pi*34000*t);
[b,a] = butter(5,fc*2/fs);
m = filtfilt(b,a,m1);
mh = imag(hilbert(m));
M= abs((2/N)*fftshift(fft(m))); %%%% Spectrum of Message signal
%Carrier Signal
c=ac*cos(2*pi*fc*t);
ch = imag(hilbert(c)); %%%% Generation of carrier signal
C=abs((2/N)*fftshift(fft(c))); %%%% Spectrum of Carrier signal
st=m.*c-mh.*ch; %%%% Representation of the SSBSC Signal
SF=abs((2/N)*fftshift(fft(st))); %%%% Spectrum of the SSBSC Signal
subplot(3,2,1);
grid on;
subplot(3,2,3);
grid on;
subplot(3,2,5);
grid on;hold on;
f=(-N/2:1:N/2-1)*fs/N;

subplot(3,2,2);
xlabel('Frequency (Hz)');ylabel('Amplitude');title('Spectrum of Modulating Signal signal');
grid on;
subplot(3,2,4);
xlabel('Frequency (Hz)');ylabel('Amplitude');title('Spectrum of Carrier Signal signal');
grid on;
subplot(3,2,6);
xlabel('Frequency (Hz)');ylabel('Amplitude(Volts)');title('Spectrum of Modulated signal');
grid on;
Amax = ac + am
Amin = ac - am
%Power Calculations
%NOISE ADDED
%SSB-SC signal with 10db noise
y3=awgn(st,10);
figure();
subplot(4,2,1);
grid on;
%Spectrum of SSB-SC 10db noise added
subplot(4,2,2);
xlabel('Frequency (Hz)');ylabel('Amplitude(Volts)');title('Spectrum of 10db Noise Modulated signal');
grid on;
y4=awgn(st,20);
subplot(4,2,3);
grid on;

subplot(4,2,4);
grid on;
y5=awgn(st,30);
subplot(4,2,5);
grid on;
subplot(4,2,6);
grid on;
y6=awgn(st,40);
subplot(4,2,7);
grid on;
subplot(4,2,8);
grid on;
%demodulation%
md=y3.*cos(2*pi*(fc+50)*t);
[b,a]=butter(2,0.004);
mf=filter(b,a,md);
figure();
subplot(1,1,1);
plot(t,mf); title('Demodulated Signal');
xlabel('Time'); ylabel('Demodulated Signal');

Repeat above Tasks1-2 for real speechsignals.
MATLAB CODE for Task-5
clc;
clear all;
close all;
am=1;
am=1;
ac=1;
% Speech signal
[m, fs] = audioread('speech.wav');
m = m(35001:40000); m = m';m = m/max(m);
M=abs((2/N)*fftshift(fft(m))); %%% Spectrum of Message signal
mh = imag(hilbert(m));
M= abs((2/N)*fftshift(fft(m))); %%%% Spectrum of Message signal
%Carrier Signal
c=ac*cos(2*pi*fc*t);
ch = imag(hilbert(c)); %%%% Generation of carrier signal
C=abs((2/N)*fftshift(fft(c))); %%%% Spectrum of Carrier signal
st=m.*c-mh.*ch; %%%% Representation of the SSBSC Signal
SF=abs((2/N)*fftshift(fft(st))); %%%% Spectrum of the SSBSC Signal
subplot(3,2,1);
xlabel('Time (seconds)');ylabel('Amplitude');title('Modulating speech signal');
grid on;
subplot(3,2,3);

grid on;
subplot(3,2,5);
grid on;hold on;
f=(-N/2:1:N/2-1)*fs/N;
subplot(3,2,2);
xlabel('Frequency (Hz)');ylabel('Amplitude');title('Spectrum of Modulating Signal signal');
grid on;
subplot(3,2,4);
xlabel('Frequency (Hz)');ylabel('Amplitude');title('Spectrum of Carrier Signal signal');
grid on;
subplot(3,2,6);
xlabel('Frequency (Hz)');ylabel('Amplitude(Volts)');title('Spectrum of Modulated signal');
grid on;
Amax = ac + am
Amin = ac - am
%Power Calculations
%NOISE ADDED
y3=awgn(st,10);
figure();
subplot(4,2,1);
grid on;

subplot(4,2,2);
grid on;
y4=awgn(st,20);
subplot(4,2,3);
grid on;
subplot(4,2,4);
grid on;
y5=awgn(st,30);
subplot(4,2,5);
grid on;
subplot(4,2,6);
grid on;
y6=awgn(st,40);
subplot(4,2,7);
grid on;
subplot(4,2,8);
grid on;
%demodulation%
md=y3.*cos(2*pi*(fc+50)*t);
[b,a]=butter(2,0.004);
mf=filter(b,a,md);
figure();
subplot(1,1,1);
plot(t,mf); title('Demodulated Signal');
xlabel('Time'); ylabel('Demodulated Signal');

CONCLUSION
This project mainly concerned with SSB modulation and de-modulation. Modulation
using filtering method and demodulation using synchronous detector . An illustration of noise affected signal
is not presented over this report. modulation and demodulation techniques are implemented practically using
matlab. This project can be extended to real time applications.
REFERENCES
 Advanced Electronic Communications Systems by Wayne Tomasi
 https://in.mathworks.com/matlabcentral/fileexchange/32956-costas-
loop?focused=5200142&tab=function
 https://en.wikipedia.org/wiki/Costas_loop
 Modern Digital and Analog Communication Systems B. P. Lathi

Communication Theory-1 Project || Single Side Band Modulation using Filtering Method and Synchronous Demodulation in the Presence of Noise || Using Matlab Code

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