11EC358
PES INSTITTUE OF TECHNOLOGY
DEPARTMENT OF ELECTRONICS AND COMMUNICATION
DIGITAL COMMUNICATION LABORATORY
11EC358
Session Jan-Jun 2014
6th semester
Total Marks : 50
Lab conduction and Record : 30 Marks
Open Ended Experiment : 20 Marks
Lab conduction : Evaluation will be based on design, implementation , results, inferences , documentation,
answering prelab questions and any modification of the system parameters leading to different results.
Open Ended Experiment could be:
1. Hardware /Matlab/Simulink implementation with results
2. Term Paper
1. Implementation of a digital communication system of your choice. Complete a project which is different
from those taught in class / a part of the curriculum or a similar system with enhancements / improvements
clearly demonstrated . It has to be a working project implemented on Matlab/Simulink / hardware. The
details of the project should be well documented. Codes should be with comments.
2. Term Paper :
(a) Bibliographical survey :Deliverable at the end of the semester . It should be a research paper in
the IEEE format . It should provide a detailed literature survey of a given topic. Some topics
could be OFDM, channel estimation, including error control coding in communication systems,
software defined radio, diversity systems , MIMO , efficient filtering schemes , specific systems
such as spread spectrum etc. Refer to atleast 5 papers from IEEE Transactions, Elsevier, Springer.
Conference papers can also be chosen, however they have to be from IEEE International /
National Conferences . A minimum of 5 papers are to be used to prepare the final submission.
Refer to papers from 2007 onwards.
(b) Research paper: Implement a specific technique or a system given in a paper. Some topics
could be OFDM, channel estimation, including error control coding in communication systems,
software defined radio, diversity systems, MIMO , efficient filtering schemes etc. The
implementation should be clearly stated in the paper and also demonstrated through
appropriate simulation results. Refer to papers from 2007 onwards.
All submissions to be in the IEEE format, max 6 pages.
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Dept of ECE
Staff : GP
11EC358
Plagiarism:
All reports will be run through Plagiarism checkers.
Do not copy figures, tables from papers without referencing them. Complete your documentation in your own words
and quote all references appropriately .
Do not copy material from another project . You can use the results of an earlier project but acknowledge the
previous project and mention details on the content used. Do not directly use codes downloaded from the online
resources available. Develop to suit your requirements and acknowledge the codes used. You may use the codes
developed / given during the course of this laboratory.
Deadlines :
Project Proposal due : 27th Jan 2014
Mid Evaluation : March 12th onwards
Final hard copy of report and demo during the regular lab slots : April 15th onwards
Writing lab records :
1. Use the manual given to you to record the readings.
2. In your record indicate : Title of the experiment , class, prelab questions, results and conclusions. All
components, active devices must be indicated with details on their relevant data from the data sheets.
Emphasize on the results obtained, tabulations ,inferences drawn. Change some parameters and describe
the consequences.
3. All simulations should contain names of students of their respective batches.
4. Indicate units clearly. For manually plotted graphs, indicate scale clearly and label the axes.
5. Compare theoretical results with those obtained practically wherever necessary.
6. Write the Experiment title , date and the experiment number when you write your lab records
Pre lab preparation : Read the manual well. Study the data sheets and make a note of the important specifications of
all components pertaining to that particular experiment. Complete answers to all pre lab questions.
Conducting the experiments :
Verify the power supplies and the inputs to be given to your circuit.
Ensure common ground connections.
Check your circuit before powering it up.
Acknowledgements: Details on the experiment related to Pulse Code Modulation , Delta Modulation were
provided by Darshan Ramakant Bhat , 8th semester, Dept of ECE, PESIT Bangalore. Connecting some of the
hardware experiments and testing them was supported by R Pavan Kumar, 6th semester Dept of ECE, PESIT,
Bangalore.
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Dept of ECE
Staff : GP
11EC358
Expt 1:
To study Time Division Multiplexing (TDM) and demultiplexing
Components required : CD 4051-analog multiplexer.
CD 4051 is an 8 to 1 Analog Multiplexer. It selects one-of-eight signal sources as a result of unique three bit binary
code at the select inputs. CD 4051 is wired as one to eight de-multiplexers. Demux input receives the data source
and transmits the data signals on different channels.
Pre lab questions:
1. What is TDM ? Name some applications of TDM
2. How are TDM transmitters and receivers synchronized ?
3. http://en.wikipedia.org/wiki/File:Telephony_multiplexer_system.gif contains an animation. Look at it and
write what you understand from the animation
4. Compare TDM with other multiplexing schemes /methods. Mention applications of these multiplexing
schemes.
5. Read the data sheet of CD4051 and write some relevant specifications and its pin diagram
Procedure :
1. Connect different signals to the inputs of the Multiplexer as shown in the circuit diagram and observe the
output. Limit all inputs and clock to 4 V p-p and test. Then increase the amplitude to 6 V p-p and test.
2. Connect the multiplexed output as the input to the demultiplexer. Observe the output and compare it with
the original signals
3. Connect different signals to different inputs and tabulate.
4. Draw sample waveforms on the graph sheet. Use the clock signal as your reference to draw multiplexed and
demultiplexed waveforms.
Observations :
Sl No
Input pin
Type of
input signal
Input signal
Amplitude
Multiplexed output
Frequency Time slot
Number
of cycles
Inferences :
1. What did you observe when you changed the amplitude and the frequency of the input signals ?
2. Change the clock input and comment on the output.
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Dept of ECE
Staff : GP
11EC358
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Dept of ECE
Staff : GP