STUDENT OBSERVATION MANUALvemu.org/uploads/lecture_notes/20_01_2020_1602341002.pdf · education....

DIGITAL COMMUNICATION SYSTEMS LAB

III/IV B. TECH., I SEMESTER

STUDENT OBSERVATION MANUAL

DEPARTMENT

OF

ELECTRONICS & COMMUNICATION ENGINEERING

VEMU INSTITUTE OF TECHNOLOGY Tirupati - Chittoor Highway Road, P. Kothakota, Chittoor- 517 112.

JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY ANANTAPUR

VEMU INSTITUTE OF TECHNOLOGY

DEPT. OF ELECTRONICS AND COMMUNICATION ENGINEERING

Vision of the institute

To be a premier institute for professional education producing dynamic and vibrant force of

technocrat with competent skills, innovative ideas and leadership qualities to serve the society

with ethical and benevolent approach.

Mission of the institute

Mission_1: To create a learning environment with state-of-the art infrastructure, well equipped

laboratories, research facilities and qualified senior faculty to impart high quality technical

education.

Mission_2: To facilitate the learners to foster innovative ideas, inculcate competent research and

consultancy skills through Industry-Institute Interaction.

Mission_3: To develop hard work, honesty, leadership qualities and sense of direction in rural

youth by providing value based education.

Vision of the Department

To become a centre of excellence in the field of Electronics and Communication Engineering

and produce graduates with Technical Skills, Research & Consultancy Competencies, Life-long

Learning and Professional Ethics to meet the challenges of the Industry and Society.

Mission of the Department

Mission_1: To enrich Technical Skills of students through Effective Teaching and Learning

practices for exchange of ideas and dissemination of knowledge.

Mission_2: To enable the students with research and consultancy skill sets through state-of-the

art laboratories, industry interaction and training on core & multidisciplinary technologies.

Mission_3: To develop and instill creative thinking, Life-long learning, leadership qualities,

Professional Ethics and social responsibilities among students by providing value based

education.

Programme Educational Objectives ( PEOs)

PEO_1: To prepare the graduates to be able to plan, analyze and provide innovative ideas to

investigate complex engineering problems of industry in the field of Electronics and

Communication Engineering using contemporary design and simulation tools.

PEO_2: To provide students with solid fundamentals in core and multidisciplinary domain for

successful implementation of engineering products and also to pursue higher studies.

PEO_3: To inculcate learners with professional and ethical attitude, effective communication

skills, teamwork skills, and an ability to relate engineering issues to broader social context at

work place.

Programme Outcome (POs)

PO_1: Engineering knowledge: Apply the knowledge of mathematics, science, engineering

fundamentals, and an engineering specialization to the solution of complex engineering

problems.

PO_2: Problem analysis: Identify, formulate, review research literature, and analyze complex

engineering problems reaching substantiated conclusions using first principles of mathematics,

natural sciences, and engineering sciences.

PO_3: Design/development of solutions: Design solutions for complex engineering problems

and design system components or processes that meet the specified needs with appropriate

consideration for the public health and safety, and the cultural, societal, and environmental

considerations.

PO_4: Conduct investigations of complex problems: Use research-based knowledge and

research methods including design of experiments, analysis and interpretation of data, and

synthesis of the information to provide valid conclusions.

PO_5: Modern tool usage: Create, select, and apply appropriate techniques, resources, and

modern engineering and IT tools including prediction and modeling to complex engineering

activities with an understanding of the limitations.

PO_6: The engineer and society: Apply reasoning informed by the contextual knowledge to

assess societal, health, safety, legal and cultural issues and the consequent responsibilities

relevant to the professional engineering practice.

PO_7: Environment and sustainability: Understand the impact of the professional engineering

solutions in societal and environmental contexts, and demonstrate the knowledge of, and need

for sustainable development.

PO_8: Ethics: Apply ethical principles and commit to professional ethics and responsibilities

and norms of the engineering practice.

PO_9: Individual and team work: Function effectively as an individual, and as a member or

leader in diverse teams, and in multidisciplinary settings.

PO_10: Communication: Communicate effectively on complex engineering activities with the

engineering community and with society at large, such as, being able to comprehend and write

effective reports and design documentation, make effective presentations, and give and receive

clear instructions.

PO_11: Project management and finance: Demonstrate knowledge and understanding of the

engineering and management principles and apply these to one’s own work, as a member and

leader in a team, to manage projects and in multidisciplinary environments.

PO_12: Life-long learning: Recognize the need for, and have the preparation and ability to

engage in independent and life-long learning in the broadest context of technological change.

Programme Specific Outcome (PSOs)

PSO_1: Higher Education: Qualify in competitive examinations for pursuing higher education

by applying the fundamental concepts of Electronics and Communication Engineering domains

such as Analog & Digital Electronics, Signal Processing, Communication & Networking,

Embedded Systems, VLSI Design and Control Systems etc..

PSO_2: Employment: Get employed in allied industries through their proficiency in program

specific domain knowledge, specialized software packages and Computer programming or

become an entrepreneur.

JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY ANANTAPUR

III B.Tech. I-Sem (ECE)

(15A04508) DIGITAL COMMUNICATION SYSTEMS LABORATORY

Minimum of Ten Experiments to be conducted (Five from each Part-A & B)

Course Outcomes:

C318.1: Analyze the PCM, DPCM,DM,ADCM using hardware &software

C318.2: Analyze the different shift keying techniques using hardware &software

C318.3: Explain the time division multiplexing technique

C318.4: Analyze the QAM using signal space analysis

HARDWARE EPERIMENTS (PART-A)

1. Time division multiplexing.

2. Pulse code modulation.

3. Differential pulse code modulation.

4. Delta Modulation.

5. Frequency shift keying.

6. Differential Phase shift Keying.

7. QPSK Modulation and Demodulation.

SOFTWARE EXPERIMENTS (PART-B)

Modeling of Digital communications using MATLAB

1. Sampling Theorem-Verification.

2. Pulse code modulation.

3. Differential pulse code modulation.

4. Frequency shift keying.

5. Phase shift keying.

6. Differential Phase shift Keying.

7. QPSK Modulation and Demodulation.

CONTENTS

S. NO. NAME OF THE EXPERIMENT PAGE NO

HARDWARE EXPERIMENTS

1 Time Division Multiplexing 1-4

2 Pulse Code Modulation 5-8

3 Delta Modulation 9-11

4 Frequency Shift Keying 12-13

5 Differential Phase Shift Keying 14-16

SOFTWARE EXPERIMENTS

6 Sampling Theorem Verification 17-20

7 Pulse Code Modulation 21-22

8 Frequency Shift Keying 23-24

9 Phase Shift Keying 25-26

10 QPSK Modulation And Demodulation 27-29

ADDITIONAL EXPERIMENTS

11 Line Codes 30-31

12 Delta Modulation Using MATLAB 32-33

DOS & DONTS IN LABORATORY

1. While entering the Laboratory, the students should follow the dress code

(Wear shoes, White Apron & Female students should tie their hair back).

2. The students should bring their observation note book, practical manual,

record note book, calculator, necessary stationary items and graph sheets if

any for the lab classes without which the students will not be allowed for

doing the practical.

3. All the equipments and components should be handled with utmost care.

Any breakage/damage will be charged.

4. If any damage/breakage is noticed, it should be reported to the instructor

immediately.

5. If a student notices any short circuits, improper wiring and unusual smells

immediately the same thing is to be brought to the notice of technician/lab in

charge.

6. At the end of practical class the apparatus should be returned to the lab

technician and take back the indent slip.

7. Each experiment after completion should be written in the observation note

book and should be corrected by the lab in charge on the same day of the

practical class.

8. Each experiment should be written in the record note book only after getting

signature from the lab in charge in the observation note book.

9. Record should be submitted in the successive lab session after completion of

the experiment.

10. 100% attendance should be maintained for the practical classes.

SCHEME OF EVALUVATION

S

NO NAME OF EXPERIMENT DATE

MARKS AWARDED TOTA

L

(30M)

Record

(10M)

Observat

ion

(10M)

Viva

voce

(10M)

Attenda

nce

(10M)

HARDWARE EXPERIMENTS

1 Time Division Multiplexing

2 Pulse Code Modulation

3 Delta Modulation

4 Frequency Shift Keying

5 Differential Phase Shift

Keying

SOFTWARE EXPERIMENTS

1 Sampling Theorem

Verification

2 Pulse Code Modulation

3 Frequency Shift Keying

4 Phase Shift Keying

5 QPSK Modulation And

Demodulation

Signature of Lab In-charge

DIGITAL COMMUNICATION SYSTEMS LABORATORY III B.Tech I Sem

VEMU INSTITUTE OF TECHNOLOGY, DEPT OF E.C.E Page 1

Exp .No: 1 Date:

TIME DIVISION MULTIPLEXING

Aim:

To demonstrate Time Division Multiplexing and Demultiplexing process using Pulse

Amplitude Modulation signals.

Equipment Required:

1. Experimenter kit DCL-02.

2. Connecting chords.

3. Power supply.

4. 20 MHz dual trace oscilloscope.

Block Diagram:

Procedure:

1. Refer the block diagram and carry out the following connections and switch settings.

2. Connect power supply in proper polarity to the kit DCL-02 & switch it in.



3. Connect 250 Hz, 500 Hz, 1 KHz, and 2 KHz sine wave signal from the function

generator to the multiplexer input channel CH0, CH1, CH2, CH3 by means of the

connecting chords provided.

4. Connect the multiplexer output TXD of the transmitter section to the demultiplexer

input RXD to the receiver section.

5. Connect the output of the receiver section CH0, CH1, CH2, CH3 to the IN0, IN1,

IN2, IN 3 of the filter section.

6. Connect the sampling clock TX CLK and channel identification Clock TXSYNC of

the transmitter section to the corresponding RX CLK and RXSYNC of the receiver

section respectively.

7. Set the amplitude of the input sine wave as desired.

8. Take the observation as mentioned below.

Observations:

Signals Amplitude(V) Time Period(s)

250Hz

500HZ

1 KHz

2 KHz

TX CLK

RX CLK

TXD

RXD

CH0

CH1

CH2

CH3

OUT0

OUT1

OUT2

OUT3



Model Graphs:



Result:



Exp .No: 2 Date:

PULSE CODE MODULATION

Aim:

To study and analyze the performance of Pulse Code Modulation and Demodulation

Process.

Equipment Required:

1. PCM Modulator and Demodulator trainer kit

2. CRO

3. Connecting chords.

4. Power supply.

Block Diagram:

Fig: Block diagram of PCM modulation & Demodulation

Procedure:

1. Refer the block diagram and carry out the following connections.



2. Connect power supply in proper polarity to the kit DCL-03 and DCL-04 & switch it

in.

3. Connect 500 Hz and 1 KHz sine wave signal from the function generator to the input

channel CH0 and CH1of the sample and hold logic.

4. Connect OUT 0 to CH0 IN and OUT 1 to CH1 IN.

5. Set the speed selection switch SW1 to FAST mode.

6. Connect TXDATA, TXCLK and TXSYNC of the transmitter section DCL-03 to the

corresponding RXDATA, RXCLK, and RXSYNC of the receiver section DCL-04.

7. Connect posts DAC OUT to IN post of demultiplexer section on DCL-04.

8. Take the observations as mentioned below.

Observations:

Signals Amplitude(V) Time Period(s)

500 Hz

1 HZ

OUT 0

OUT 1

CLK 1

CLK 2

MUX OUT

DAC OUT

CLK 1

CLK 2

CH 0

CH 1

OUT0

OUT1



Model Graphs:

Fig: Waveforms for PCM modulation



Fig: waveforms for PCM demodulation

Result:



Exp .No: 3 Date:

DELTA MODULATION

Aim:

To study and analyze the performance of delta Modulation and Demodulation Process.

Equipment Required:

1. DCL-07 Kit.

2. Connecting Chords.

3. Power Supply.

4. CRO.

Block Diagram:

Fig: Block diagram for delta modulation

Procedure:

1. Refer to the block diagram and carry out the following connections and switch

techniques.

2. Connect power supply in proper polarity to the kit DCL-07 and switch it ON.

3. Select sine wave input 250Hz of 0V through pot P1 and connects post 250Hz to post

IN of input buffer.

4. Connect output of buffer post OUT to digital sampler input post IN1.



5. Then select clock rate of 8KHz by pressing switch S1 selected clock is indicated by

LED glow.

6. Keep switch S2 in delta position.

7. Connect output of Digital sampler post OUT to input post IN of integrator 1.

8. Connect output of integrator 1 post OUT to input post IN2 of digital sampler.

9. Then observe the delta modulated output at output of digital sampler post OUT and

compare it with the clock rate selected. It is half the frequency of clock rate selected.

10. Observe the integrator output test point. It can be observe that as the clock rate is

increased amplitude of triangular waveform decreases. This is called minimum step

size. These waveforms are as shown below. Then increase the amplitude of 250Hz

sine wave upto 0.5v. signal approximating 250Hz is available at the integrator output.

This signal is obtained by integrating the digital output resulting from delta

modulation.

11. Then go on increasing the amplitude of selected signal through the respective pot

from 0 to 2V. it can be observed that the digital high makes the integrator output to go

upward and digital low makes the integrator output to go downwards. Observe that

the integrator output follow the input signal. The waveforms are as shown in fig.

observe the waveforms at various test-points in the delta modulator section.

12. Increase the amplitude of 250Hz sine wave through pot P1 further high and observe

that the integrator output cannot follow the input signal. state the reason.

13. Repeat the above mention procedures with different signal sources and selecting the

different clock rates and observe the response of delta modulator.

14. Connect delta modulated output post OUT of digital sampler to the input of delta

demodulator section post IN of demodulator.

15. Connect output of Demodulator post OUT to the input of integrator 3 post IN.

16. Connect output of integrator 3 post OUT to the input of output buffer post IN.

17. Connect output of output buffer post OUT to the input of 2nd order filter post IN.

18. Connect output of 2nd order filter post OUT to the input of 4th order filter post IN.

19. Keep switch S4 in HIGH position.

20. Then observed various tests points in delta demodulator section and observe the

reconstructed signal through 2nd order filter and 4th order filter. Observe the

waveforms as shown in fig.



Observations:

Signals Amplitude(v) Time period(s)

250 Hz

Digital Sampler Output

Integrator 3 Output

Filter Output

Model Graphs:

Result:



Exp .No: 4 Date:

FREQUENCY SHIFT KEYING

Aim:

To study and analyze the performance of Frequency Shift Keying Modulation and

Demodulation Process.

Equipment Required:

1. PHYSITECH’S FSK modulation and Demodulation trainer kit.

2. Function Generator

3. CRO

4. Connecting wires and Probes

Circuit Diagram:

Fig: Block diagram for FSK modulation

Procedure:

1. Connect the output of the carrier output provided on kit to the input of the carrier

input 1 terminal.

2. Also connect one of the Data output to the Data input terminal provided on kit.

3. Connect sine wave of certain frequency to the carrier input2 terminal.



4. Switch ON function generator and FSK modulation and demodulation kit.

5. Observe the FSK output by connecting it to CRO. Thus FSK modulation can be

achieved.

6. For FSK demodulation, connect FSK output terminal to the FSK input terminal of

demodulator.

7. Observe the demodulated wave at demodulated output terminal by connecting it to

CRO.

Observations:

Signals Amplitude(v) Time period(s)

Data input

Carrier signal 1

Carrier signal 2

FSK output

Demodulated output

Model Graphs:

Result:



Exp .No: 5 Date:

DIFFERENTIAL PHASE SHIFT KEYING

Aim:

To study and analyze the performance of Differential Phase Shift Keying Modulation and

Demodulation Process.

Equipment Required:

1. Experimental kit ADCL-01.

2. Connecting wires.

3. Power supply.

4. 20MHz dual trace oscilloscope

Block Diagram:

Procedure:

1. Refer to the block diagram and carry out the following connections and switch

techniques.

2. Connect power supply in proper polarity to the kit ADCL-01 and switch it on.



3. Select data pattern of simulated data using switch SW1.

4. Connect SDATA generated to DATA IN of NRZ-L CODER.

5. Connect the NRZ-L DATA output to the DATA IN of the DIFFERENTIAL

ENCODER.

6. Connect the clock generated SCLOCK to CLK IN of the DIFFERENTIAL

ENCODER.

7. Connect differentially encoded data to control input C1 of CARRIER

MODULATOR.

8. Connect carrier component SIN1 to IN 1 and SIN 2 to IN 2 of the carrier modulator

logic.

9. Connect DPSK modulated signal MOD OUT to MOD IN of the BPSK

DEMODULATOR.

10. Connect output of BPSK demodulator b(t) OUT to input of DELAY SECTION b(t)

IN and one input b(t) IN of decision device.

11. Connect the output of delay section b(t-Tb) OUT to the input b(t-Tb) IN of decision

device.

12. Compare the DPSK decoded data at DATA OUT with respect to input SDATA.

13. Observe various waveforms as mentioned below, if recovered data mismatches with

respect to the transmitter data, then use RESET switch for clear observation of data

output.

Observations:

Signal Amplitude(v) Time period(s)

SDATA

SCLOCK

NRZ-L DATA

Differentially encoded data

SIN 1

SIN 2

DPSK MOD OUT

Recovered differentially encoded

data

Delayed data

Recovered data (NRZ-L DATA)

DPSK Demodulation



Model Graph:

Result:



Exp .No: 5 Date:

SAMPLING THEOREM VERIFICATION

Aim: To generate a MATLAB Program to verify sampling theorem.

Software Required:

➢ PC and MATLAB software

Procedure:

• Open MATLAB Software

• Open new M-file

• Type the program

• Save in current directory

• Run the program

• For the output see command window\ Figure window.

Program:

clc;

close all;

clear all;

f1=3;

f2=23;

t=-0.4:0.0001:0.4;

x=cos(2*pi*f1*t)+cos(2*pi*f2*t);

figure(1);

plot(t,x,'-.r');

xlabel('time-----');

ylabel('amp---');

title('The original signal');

%case 1: (fs<2fm)

fs1=1.4*f2;

ts1=1/fs1;

n1=-0.4:ts1:0.4;

xs1=cos(2*pi*f1*n1)+cos(2*pi*f2*n1);

figure(2);

stem(n1,xs1);

hold on;

plot(t,x,'-.r');

hold off;

legend('fs<2fm');

%case 2: (fs=2fm)

fs2=2*f2;

ts2=1/fs2;

n2=-0.4:ts2:0.4;




figure(3);

stem(n2,xs2);

hold on;

plot(t,x,'-.r');

hold off;

legend('fs=2fm');

%case 3: (fs>2fm)

fs3=7*f2;

ts3=1/fs3;

n3=-0.4:ts3:0.4;


figure(4);

stem(n3,xs3);

hold on;

plot(t,x,'-.r');

hold off;

legend('fs>2fm');

Output:



Result:



Exp .No: 7 Date:

PULSE CODE MODULATION

Aim:

To write a MATLAB program for Pulse Code Modulation and to observe the output wave

forms.

Requirements:


Procedure:

1. Open MATLAB Software

2. Open new M-file

3. Type the program

4. Save in current directory

5. Run the program

6. For the output see command window\ Figure window

MATLAB Program:

clc;

clear all;

close all;

t=0:.01:3;

a=sin(2*pi*t);

p=square(2*pi*10*t);

p(p<0)=0;

s=a.*p;

figure(1);

subplot(3,1,1);

plot(a);

xlabel('time');

ylabel('amplitude');

title('analog signal');

subplot(3,1,2);

plot(p);

xlabel('time');


title('square signal');

subplot(3,1,3);

plot(s);

xlabel('time');


title('sampled signal');

n=3;

y=uencode(s,n,1);

r=udecode(y,n,1);

figure(2);



subplot(2,1,1);

plot(y);

xlabel('time');


title('encoded signal');

subplot(2,1,2)

plot(r);

xlabel('time');


title('decoded signal');

MODEL GRAPHS:

Result:

0 50 100 150 200 250 300 350-1

-0.5

0

0.5

1

time

am

plitu

de

analog signal

0 50 100 150 200 250 300 3500

0.5

1

time

am

plitu

de

square signal

0 50 100 150 200 250 300 350-1

-0.5

0

0.5

1

time

am

plitu

de

sampled signal

0 50 100 150 200 250 300 3500

1

2

3

4

5

6

7

time

ampl

itude

encoded signal

0 50 100 150 200 250 300 350-1

-0.5

0

0.5

1

time

ampl

itude

decoded signal



Exp .No: 8 Date:

FREQUENCY SHIFT KEYING

Aim:

To write a MATLAB program for Frequency Shift Keying and to observe the output

waveforms.

Requirements:

PC and MATLAB software

Procedure:


2. Open new M-file

3. Type the program


5. Run the program


MATLAB Program:

clc;

close all;

clear all;

fc1=input('Enter the freq of 1st Sine Wave carrier:');

fc2=input('Enter the freq of 2nd Sine Wave carrier:');

fp=input('Enter the freq of Periodic Binary pulse (Message):');

amp=input('Enter the amplitude (For Both Carrier & Binary Pulse Message):');

amp=amp/2;

t=0:0.001:1;

c1=amp.*sin(2*pi*fc1*t);% For Generating 1st Carrier Sine wave

c2=amp.*sin(2*pi*fc2*t);% For Generating 2nd Carrier Sine wave

subplot(4,1,1); %For Plotting The Carrier wave

plot(t,c1);

xlabel('Time');

ylabel('Amplitude');

title('Carrier 1 Wave');

subplot(4,1,2) ;%For Plotting The Carrier wave

plot(t,c2);

xlabel('Time');


title('Carrier 2 Wave');

m=amp.*square(2*pi*fp*t)+amp;%For Generating Square wave message

subplot(4,1,3); %For Plotting The Square Binary Pulse (Message)

plot(t,m);



0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1-2

02

Time

Am

plit

ude Carrier 1 Wave

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1-2

02

Time

Am

plit

ude Carrier 2 Wave

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10

24

Time

Am

plit

ude Binary Message Pulses

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1-2

02

Time

Am

plit

ude Modulated Wave

xlabel('Time');


title('Binary Message Pulses');

for i=0:1000 %here we are generating the modulated wave

if m(i+1)==0

mm(i+1)=c2(i+1);

else

mm(i+1)=c1(i+1);

end

end

subplot(4,1,4) ;%For Plotting The Modulated wave

plot(t,mm);

xlabel('Time');


title('Modulated Wave');

The Following Inputs Given To Generate FSK Modulated Wave:

Enter the freq of 1st Sine Wave carrier: 10

Enter the freq of 2nd Sine Wave carrier: 30

Enter the freq of Periodic Binary pulse (Message):5

Enter the amplitude (For Both Carrier & Binary Pulse Message):4

Wave Forms:

Result:



Exp .No: 9 Date:

PHASE SHIFT KEYING

Aim: To write a MATLAB program for phase Shift Keying and to observe the output

waveforms

Experimental requirements:

➢ PC loaded with MATLAB software

Procedure:


2. Open new M-file

3. Type the program


5. Run the program


MATLAB Program:

clc;

clear all;

close all;

b = input('Enter the Bit stream \n '); %b = [0 1 0 1 1 1 0];

n = length(b);

t = 0:0.01:n;

x = 1:1:(n+1)*100;

for i = 1:n

if (b(i) == 0)

b_p(i) = -1;

else

b_p(i) = 1;

end

for j = i:.1:i+1

bw(x(i*100:(i+1)*100)) = b_p(i);

end

end

bw = bw(100:end);

sint = sin(2*pi*t);

st = bw.*sint;

subplot(3,1,1)

plot(t,bw)

gridon ;

axis([0 n -2 +2]) ;



subplot(3,1,2) ;

plot(t,sint) ;

grid on ;

axis([0 n -2 +2]) ;

subplot(3,1,3) ;

plot(t,st);

gridon ;

axis([0 n -2 +2]) ;

Wave forms:

Result:



Exp .No: 10 Date:

QPSK MODULATION AND DEMODULATION

Aim:

To write a MATLAB program for QPSK Modulation and Demodulation and to observe the

output wave forms.

Experimental Requirements:


Procedure:


2. Open new M-file

3. Type the program


5. Run the program


MATLAB Program:

clear;

clc;

b = input('Enter the bit stream = ');

n = length(b);

t = 0:0.01:n;

x = 1:1:(n+2)*100;

for i = 1:n

if (b(i) == 0)

u(i) = -1;

else

u(i) = 1;

end

for j = i:0.1:i+1

bw(x(i*100:(i+1)*100)) = u(i);

if (mod(i,2) == 0)

bw_e(x(i*100:(i+1)*100)) = u(i);

bw_e(x((i+1)*100:(i+2)*100)) = u(i);

else

bw_o(x(i*100:(i+1)*100)) = u(i);

bw_o(x((i+1)*100:(i+2)*100)) = u(i);

end

if (mod(n,2)~= 0)

bw_e(x(n*100:(n+1)*100)) = -1;

bw_e(x((n+1)*100:(n+2)*100)) = -1;

end

end

end



bw = bw(100:end);

bw_o = bw_o(100:(n+1)*100);

bw_e = bw_e(200:(n+2)*100);

cost = cos(2*pi*t);

sint = sin(2*pi*t);

x = bw_o.*cost;

y = bw_e.*sint;

z = x+y;

subplot(3,2,1);

plot(t,bw);

xlabel('n ---->');

ylabel('Amplitude ---->');

title('Input Bit Stream');

grid on ;

axis([0 n -2 +2]);

subplot(3,2,5);

plot(t,bw_o);

xlabel('n ---->');


title('Odd Sequence');

grid on ;

axis([0 n -2 +2]);

subplot(3,2,3);

plot(t,bw_e);

xlabel('n ---->');


title('Even Sequence');

grid on ;

axis([0 n -2 +2]);

subplot(3,2,4);

plot(t,x);

xlabel('Time ---->');


title('Odd Sequence BPSK Modulated Wave');

grid on ;

axis([0 n -2 +2]);

subplot(3,2,2);

plot(t,y);



title('Even Sequence BPSK Modulated Wave');

grid on ;

axis([0 n -2 +2]);

subplot(3,2,6);

plot(t,z);



title('QPSK Modulated Wave');

grid on ;

axis([0 n -2 +2]);



Output:

Enter the bit stream = [0 1 1 0 1 0 0 0]

Model wave forms:

Result:



Exp .No: 11 Date:

LINE CODES

Aim:

To study the time and frequency domain characteristics of various line coding

signal formats.

Equipment:

1. TIMS system with modules

2 Channel 100MHz DSO

Background:

The TIMS line coder will accept a baseband TTL pulse stream and perform the

appropriate level and timing conversions to produce a number of unit-polar and bi-polar

analog level line codes. In this lab we will look at the characteristics of the following codes:

NRZ-L, NRZ-M, and RZ-AMI. and Biphase-L. The bit pattern for the experiment will be

generated by the TIMS sequence generator. In order to make time domain comparisons of the

line coder input and the decoder output, you’ll have to use the single acquisition mode of the

scope to capture frames of waveform data.

Procedure:

TIMS setup:

Refer to Figure 2 in the attached Lab Sheet. Configure the modules as shown, note

that the Buffer Amplifier is not inserted in the data path at the beginning of the lab. Note

that the Beginning of Sequence output of the Sequence Generator is used to trigger the

scope.

Measurements:

Time domain:

1) Connect channel 1 of the oscilloscope to the data input of the Line Encoder module.

Capture a screen of data, adjusting the time base of the scope so that you can easily

identify one bit time in the data input.

2) Observe the NRZ-L output with the second oscilloscope channel. Sketch a representative

portion of the input bit pattern and the NRZ-L output, a number of 0-1-0 transitions are

required. Verify that the coding is correct. From your observations, estimate the

fundamental frequency of the spectrum that the NRZ-L waveform would produce. (Hint:

Think square waves..)

3) Set the scope to free run, you won’t be able to see a synchronized output but you won’t



need to. While observing the NRZ-L output, switch the scope input coupling between DC

and AC. Is there a vertical shift in the waveform display? If so, record the change in

voltage.

4) Repeat steps 2 and 3 for the NRZ-M, RZ-AMI, and Biphase-L outputs.

Frequency Domain:

1. Use the FFT function of the scope to observe the signal spectrum of the NRZ-L output.

The spectrum will conform to your knowledge of the sinx/x function. Using the FFT

analyzer, determine:

a) The center frequencies of the sinx/x lobes (maximums)

b) The frequencies of the sinx/x nulls (minimums)

c) If possible, the frequencies of the components within each lobe envelope

2. Repeat step 5 for the NRZ-M, RZ-AMI, and Biphase-L outputs.

Polarity Reversal:

1. Connect the NRZ-L output of the Line Encoder to one input of the Buffer Amplifier.

Adjust the Buffer

2. Connect the NRZ-L output of the Line Encoder to the NRZ-input of the Line

Decoder. Observe the data input of the Line Encoder and the data output of Line

Decoder using the scope. The signals should be the same.

3. Insert the Buffer Amplifier into the circuit between the Line Encoder output and the

Line Decoder input and observe the data input and output again. Has the inversion

on the communication channel produced an inversion in the received data?

4. Repeat steps 8 and 9 for the NRZ-M, RZ-AMI, and Biphase-L outputs.

RESULT:

Code Offset (V) Maximums Nulls Components Polarity Sensitive?

(Hz) (Hz) (Hz) (Yes/No)

NRZ-L

NRZ-M

RZ-AMI

Bi∅-L



Exp .No: 12 Date:

DELTA MODULATION

Aim: To perform delta modulation in MATLAB

Experimental Requirements:

➢ PC loaded with MATLAB

Procedure:

1. 1. Open MATLAB Software

2. Open new M-file

3. Type the program


5. Run the program


MATLAB Program:

clc;

clear all;

close all;

t=[0:0.01:1];

m=sin(2*pi*t);

hold on;

plot(m,'black');

title('sinc pulse');

xlabel('time');


d=2*pi/100;

for n=1:1:100

if n==1

e(n)=m(n);

eq(n)=d*sign(e(n));

mq(n)=eq(n);

else

e(n)=m(n)-mq(n-1);



eq(n)=d*sign(e(n));

mq(n)=mq(n-1)+eq(n);

end

end

stairs(mq,'black');

hleg=legend('original signal','stair case approximated signal');

Wave forms:

Result:

0 20 40 60 80 100 120-1.5

-1

-0.5

0

0.5

1

1.5sinc pulse

time

am

plitu

de

original signal

stair case approximated signal

STUDENT OBSERVATION MANUALvemu.org/uploads/lecture_notes/20_01_2020_1602341002.pdf · education....

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