1. KARPAGAM INSTITUTE OF TECHNOLOGY,
COIMBATORE - 105
Course Code with Name : EC8394 Analog and Digital Communication
Staff Name / Designation : Manoj Kumar T AP
Department : ECE
Year / Semester :II/III
Department of Information Technology
2. COURSE SYLLABUS
UNIT I ANALOG COMMUNICATION 9
Introduction to Communication Systems - Modulation β Types - Need for Modulation. Theory of Amplitude
Modulation - Evolution and Description of SSB Techniques - Theory of Frequency and Phase Modulation β
Comparison of Analog Communication Systems (AM β FM β PM).
UNIT II PULSE AND DATA COMMUNICATION 9
Pulse Communication: Pulse Amplitude Modulation (PAM) β Pulse Time Modulation (PTM) β Pulse code
Modulation (PCM) - Comparison of various Pulse Communication System (PAM β PTM β PCM). Data
Communication: History of Data Communication - Standards Organizations for Data Communication- Data
Communication Circuits - Data Communication Codes - Data communication Hardware - serial and
parallel interfaces.
UNIT III DIGITAL COMMUNICATION 9
Amplitude Shift Keying (ASK) β Frequency Shift Keying (FSK)βPhase Shift Keying (PSK) β BPSK β
QPSK β Quadrature Amplitude Modulation (QAM) β 8 QAM β 16 QAM β Bandwidth Efficiencyβ
Comparison of various Digital Communication System (ASK β FSK β PSK β QAM).
UNIT IV SOURCE AND ERROR CONTROL CODING 9
Entropy, Source encoding theorem, Shannon fano coding, Huffman coding, mutual information, channel
capacity, Error Control Coding, linear block codes, cyclic codes - ARQ Techniques.
UNIT V MULTI-USER RADIO COMMUNICATION 9
Global System for Mobile Communications (GSM) - Code division multiple access (CDMA) β Cellular Concept
and Frequency Reuse - Channel Assignment and Handover Techniques - Overview of Multiple Access
Schemes - Satellite Communication - Bluetooth.
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Karpagam Insitute of Technology
3. COURSE OBJECTIVE
β’ Understand analog and digital communication
techniques.
β’ Learn data and pulse communication
techniques.
β’ Be familiarized with source and Error control
coding.
β’ Gain knowledge on multi-user radio
communication.
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Karpagam Insitute of Technology
4. COURSE OUTCOME
At the end of the course, the student should be
able to:
Apply analog and digital communication
techniques
Use data and pulse communication techniques
Analyze Source and Error control coding
Utilize multi-user radio communication
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5. PROGRAM OUTCOMES
ENGINEERING GRADUATES WILL BE ABLE TO:
1. Engineering knowledge: Apply the knowledge of mathematics, science, engineering fundamentals, and
an engineering specialization to the solution of complex engineering problems.
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.
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.
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.
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.
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6. PROGRAM OUTCOMES - CONT
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.
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.
8. Ethics: Apply ethical principles and commit to professional ethics and responsibilities and norms of the
engineering practice.
9. Individual and team work: Function effectively as an individual, and as a member or leader in
diverse teams, and in multidisciplinary settings.
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.
11. Project management and finance: Demonstrate knowledge and understanding of the engineering and
management principles and apply these to oneβs own work, as a member and leader in a team, to manage
projects and in multidisciplinary environments.
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.
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7. PROGRAM SPECIFIC OUTCOMES
1. To create, select, and apply appropriate techniques, resources, modern engineering and IT tools
including prediction and modelling to complex engineering activities with an understanding
of the limitations.
2. To manage complex IT projects with consideration of the human, financial, ethical and
environmental factors and an understanding of risk management processes, and operational
and policy implications.
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8. COURSE OUTCOME Vs. PROGRAM OUTCOMES AND
PROGRAM SPECIFIC OUTCOMES MAPPING
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Course Outcomes PO1 PO2 PO3 PO4 PO5 PO6 PO7 PO8 PO9 PO10 PO11 PO12 PSO2 PSO2 PSO3
CO1
CO2
CO3
CO4
10. UNIT I : SYLLABUS
Introduction to Communication Systems - Modulation β Types -
Need for Modulation. Theory of Amplitude Modulation - Evolution
and Description of SSB Techniques - Theory of Frequency and
Phase Modulation β Comparison of Analog Communication
Systems (AM β FM β PM).
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UNIT I ANALOG COMMUNICATION
11. OBJECTIVES:
β’ Understand analog and digital communication techniques.
β’ Learn data and pulse communication techniques.
β’ Be familiarized with source and Error control coding.
β’ Gain knowledge on multi-user radio communication.
12. UNIT I ANALOG COMMUNICATION
Introduction to Communication Systems
οΆ Communication is the process of establishing connection (or link) between
two points for information exchange
οΆ The Two basic types of communication systems are
(i) Analog β Transmitted signals are analog in nature
(ii) Digital - Transmitted signals are 0βs and 1βs or discrete levels in nature
Analog
Digital
13. Introduction to Communication Systems
Advantages of Analog communications
ο§ Transmitters and Receivers are simple
ο§ Low bandwidth requirement
ο§ Frequency Division Multiplexing can be used
Disadvantages of Analog communication
ο§ Noise affects the signal quality
ο§ It is not possible to separate noise and signal
ο§ Repeaters canβt be used between transmitter
ο§ Coding is not possible
ο§ It is not suitable for the transmission of secret information
UNIT I ANALOG COMMUNICATION
14. UNIT I ANALOG COMMUNICATION
Introduction to Communication Systems
General Communication Systems:
15. Introduction to Communication Systems
Transmitter:
A collection of one or more electronic devices or circuits that converts the original
source information to a form more suitable for transmission over a particular
transmission medium.
Transmission Medium:
Provides a means of transporting signals between a transmitter and a receiver.
Receiver:
A collection of electronic devices and circuits that accepts the transmitted signals fro the
transmission medium and then converts those signals back to their original form.
System Noise:
Is any unwanted electrical signals that interfere with the information signal.
UNIT I ANALOG COMMUNICATION
16. Introduction to Communication Systems
Drawbacks of Baseband Transmission
οΆ Excessively large antenna heights.
οΆ Signals get mixed up.
οΆ Short range of communication.
οΆ Multiplexing is not possible.
οΆ Poor quality of reception.
UNIT I ANALOG COMMUNICATION
18. UNIT I ANALOG COMMUNICATION
Modulation
Process of changing characteristics of the carrier signal with respect to the
instantaneous change in message signal
In the modulation process some properties of the high frequency carrier wave is
varied in accordance with the modulating or message signal
Message Signal - Original message Carrier Signal - A high frequency
analog signal
Frequency = 1/time
23. Need for Modulation
οΆ Reduction in antenna height
οΆ Long distance communication
οΆ Avoid mixing up of other signals
οΆ Multiplexing
οΆ Ease of radiation
οΆ Improve the quality of reception
UNIT I ANALOG COMMUNICATION
24. Theory of Amplitude Modulation
Amplitude of the carrier signal is changed with respect to the instantaneous
change in message signal.
UNIT I ANALOG COMMUNICATION
Message Signal : em = Em sin Οmt
Carrier Signal : ec = Ec sin Οct
Em β Maximum amplitude of message signal
Ec - Maximum amplitude of Carrier signal
Οm - Frequency of message signal 2Οfm
Οc - Frequency of carrier signal 2Οfc
eAM = (Em sin Οmt + Ec )sin Οct
25. Theory of Amplitude Modulation
Modulation Index
The ratio of maximum amplitude of modulating signal to maximum
amplitude carrier signal is called modulation index.
Value of Em must be less than value of Ec to avoid any distortion in the
modulated signal . 0<=m=>1
Maximum value of modulation index will be equal to 1 when Em= Ec
When modulation index is expressed in percentage , it is called as
Percentage Modulation or Depth of modulation.
UNIT I ANALOG COMMUNICATION
26. Theory of Amplitude Modulation
Calculation of modulation index from AM waveform:
UNIT I ANALOG COMMUNICATION
πΈπ =
πΈπππ₯ β πΈπππ
2
πΈπ = πΈπππ₯ β πΈπ
= πΈπππ₯ β (
πΈπππ₯ β πΈπππ
2
)
=
2πΈπππ₯ β (πΈπππ₯ β πΈmin β‘
β‘
)
2
=
2πΈπππ₯ βπΈπππ₯ + πΈπππ
2
=
πΈπππ₯ + πΈπππ
2
π =
πΈπ
πΈπ
=
πΈπππ₯ β πΈπππ
2
πΈπππ₯ + πΈπππ
2
π =
πΈπππ₯ β πΈπππ
πΈπππ₯ + πΈπππ
27. Theory of Amplitude Modulation
Calculation of modulation index from AM waveform:
UNIT I ANALOG COMMUNICATION
ππ΄π = (πΈπ + πΈπ sinππ π‘) sinππ π‘
ππ΄π = (πΈπ + ππΈπ sinππ π‘) sin ππ π‘ π =
πΈπ
πΈπ
ππ ππΈπ = πΈπ
ππ΄π = (πΈπ sinππ π‘ + ππΈπ sin ππ π‘ sinππ π‘)
ππ΄π = πΈπ sin ππ π‘ +
ππΈπ
2
cos ππ π‘ β πππ‘ β
ππΈπ
2
cos(ππ π‘ + πππ‘)
sinπ΄ sin π΅ = 1/2 cos π΄ β π΅ β 1/2 cos(π΄ + π΅)
ππ΄π = πΈπ sin ππ π‘ +
ππΈπ
2
cos πππ‘ β ππ π‘ β
ππΈπ
2
cos(πππ‘ + ππ π‘) cos π΄ β π΅ = cos(π΅ β π΄)
ππ΄π = πΈπ sin ππ π‘ +
ππΈπ
2
cos ππ β ππ π‘ β
ππΈπ
2
cos(ππ + ππ )π‘
ππ = 2π±ππ πππ ππ = 2π±ππ
ππ΄π = πΈπ sin 2π±πππ‘ +
ππΈπ
2
cos 2π±ππ β 2π±ππ π‘ β
ππΈπ
2
cos(2π±ππ + 2π±ππ ) π‘
ππ΄π = πΈπ sin 2π±πππ‘ +
ππΈπ
2
cos 2π± ππ β ππ π‘ β
ππΈπ
2
cos2π±(ππ + ππ ) π‘
ππ΄π = πΈπ sin 2π±πππ‘ +
ππΈπ
2
cos 2π±πππ π π‘ β
ππΈπ
2
cos2π± ππ’π π π‘
28. Theory of Amplitude Modulation
(i) Amplitude of the carrier signal remains unaltered after modulation
(ii) Amplitude of upper side and lower side frequencies depends on both amplitude
of carrier and modulation index
(iii) At the beginning of each cycle of envelope, carrier is out of phase with the upper
and lower side frequencies
(iv) Upper and lower side frequencies are 1800 out of phase with each other
UNIT I ANALOG COMMUNICATION
π
πππ₯ = πΈπ +
πΈπ
2
+
πΈπ
2
=
2πΈπ+πΈπ+πΈπ
2
=
4πΈπ
2
= 2πΈπ
ππππ = πΈπ β
πΈπ
2
β
πΈπ
2
=
2πΈπβπΈπβπΈπ
2
= 0
29. Theory of Amplitude Modulation
Calculation of modulation index from AM waveform:
UNIT I ANALOG COMMUNICATION
Bandwidth of the
signal can be obtained
by taking the difference
between highest and
lowest frequencies
Frequency domain Representation of AM Wave
30. Theory of Amplitude Modulation
AM Time Domain Analysis
UNIT I ANALOG COMMUNICATION
If π
π = 5 π»π§ , π
π = 25 π»π§ , π = 1 πππ πΈπ = 1 π
ππ΄π = πΈπ sin 2π±π
ππ‘ +
ππΈπ
2
cos 2π± π
π β π
π π‘ β
ππΈπ
2
cos2π±(π
π + π
π ) π‘
ππ΄π = sin 2π±25π‘ +
1
2
cos 2π± 20 π‘ β
1
2
cos2π±(30) π‘
31. Theory of Amplitude Modulation
AM Power Distribution:
AM signal has three components : Unmodulated carrier, lower sideband and upper sideband. Hence total
power of AM wave is the sum of carrier power and powers in the two sidebands .
UNIT I ANALOG COMMUNICATION
ππ‘ππ‘ππ = ππ + πππ π + ππ’π π πππ€ππ =
ππππ‘πππ 2
π ππ ππ π‘ππππ
ππππ‘πππ =
πΈ
2
ππ =
(
πΈπ
2
)2
π
πππ π =
(
πΈπ
2 2
)2
π
ππ’π π =
(
πΈπ
2 2
)2
π
πΈπ = ππΈπ
ππ‘ππ‘ππ =
πΈπ
2
2π
+
(
π πΈπ
2 2
)2
π
+
(
π πΈπ
2 2
)2
π
ππ‘ππ‘ππ =
πΈπ
2
2π
+
π2πΈπ
2
8π
+
π2πΈπ
2
8π
ππ‘ππ‘ππ =
πΈπ
2
2π
+ 2(
π2πΈπ
2
8π
)
ππ‘ππ‘ππ =
πΈπ
2
2π
+
π2πΈπ
2
4π
ππ‘ππ‘ππ =
πΈπ
2
2π
(1 +
π2
2
)
ππ‘ππ‘ππ = ππ(1 +
π2
2
)
ππ‘ππ‘ππ
ππ
= (1 +
π2
2
) ;
ππ‘ππ‘ππ
ππ
β 1 =
π2
2
; 2
ππ‘ππ‘ππ
ππ
β 1 = π2
π = 2(
ππ‘ππ‘ππ
ππ
β 1)
32. Evolution and Description of SSB Techniques
Single sideband, SSB modulation is basically a derivative of amplitude
modulation, AM. By removing some of the components of the ordinary AM
signal it is possible.
Advantages of SSB
(i) Carrier is removed - it can be re-introduced in the receiver
(ii) Secondly one sideband is removed - both sidebands are mirror images
of one another and the carry the same information.
UNIT I ANALOG COMMUNICATION
33. Evolution and Description of SSB Techniques
SSB β Single Side Band
SSBFC - Single Side Band Full Carrier
Half of the side band is transmitted
Requires less bandwidth than DSBFC
Power in the AM modulated wave is also halved
Repetition rate is equal to the frequency of the message signal
UNIT I ANALOG COMMUNICATION
34. Evolution and Description of SSB Techniques
SSBSC - Single Side Band Suppressed Carrier
One sideband and carrier is removed
Requires only half of the bandwidth
Requires even less power
UNIT I ANALOG COMMUNICATION
35. Evolution and Description of SSB Techniques
SSBRC - Single Side Band Reduced Carrier or Single Side Band reinserted Carrier
One side band is completely removed
Carrier voltage is reduced by 10 % of its unmodulated wave ie 0.1Ec
Carrier is totally suppressed and then reinserted at reduced voltage or
amplitude
Main purpose is for demodulation purpose
Carrier amplitude must be elevated to its original amplitude at receiver
Requires only half of the bandwidth
Also called as Exalted carrier transmission
UNIT I ANALOG COMMUNICATION
36. Evolution and Description of SSB Techniques
ISB- Independent Side Band
Single carrier frequency is independently modulated by two different
message signal
Consists of two independent side band signals
Conserves both power and bandwidth
UNIT I ANALOG COMMUNICATION
37. Evolution and Description of SSB Techniques
VSB β Vestigial Side Band
Part of side band is suppressed
One side band, Full carrier, part of side band is transmitted
UNIT I ANALOG COMMUNICATION
38. Evolution and Description of SSB Techniques
Advantages
Power Conservation
Bandwidth Conservation
Selective Fading
Noise Reduction
Disadvantages
Complex Receivers
Tuning difficulties
UNIT I ANALOG COMMUNICATION
39. Evolution and Description of SSB Techniques
Single sideband, SSB modulation is basically a derivative of amplitude
modulation, AM. By removing some of the components of the ordinary AM
signal it is possible.
Advantages of SSB
(i) Carrier is removed - it can be re-introduced in the receiver
(ii) Secondly one sideband is removed - both sidebands are mirror images
of one another and the carry the same information.
UNIT I ANALOG COMMUNICATION
40. Theory of Frequency and Phase Modulation
Deviation ratio: Deviation ratio is the worst case modulation index and is
equal to the maximum peak frequency deviation divided by the maximum
modulating signal frequency.
Carsonβs rule : Carsonβs rule states that the bandwidth required to transmit an
angle modulated wave as twice the sum of the peak frequency deviation
and the highest modulating signal frequency.
B=2(Ξ΄ +fm) Hz
UNIT I ANALOG COMMUNICATION
41. Theory of Frequency and Phase Modulation
UNIT I ANALOG COMMUNICATION
Angle modulation can be expressed as e(t) = πΈπ sin( ππ π‘ + ππ‘)
(i) For FM signal, the maximum frequency deviation takes place when
modulating signl is at positive and negative peaks.
(ii) For PM signal the maximum requency deviation takes place near zero
crossings of the modulating signal.
(iii) Both FM and PM waveforms are identical except the phase shit.
(iv) From modulated waveform it is difficult to know, whether the
modulation is FM or PM
Message Signal - ππ = πΈπ sin ππ π‘
Carrier Signal - ππ = πΈπ sin ππ π‘
42. Theory of Frequency and Phase Modulation
UNIT I ANALOG COMMUNICATION
PM wave : πππ π‘ = πΈπ sin[ππ π‘ + πΎπππ ]
PM wave : πππ π‘ = πΈπ sin[ππ π‘ + πΎππΈπ sin ππ π‘]
Modulation Index for PM: KπΈπ
PM wave : πππ π‘ = πΈπ sin[ππ π‘ + π sin ππ π‘]
FM wave : ππΉπ π‘ = πΈπ sin[ππ π‘ + πΎπ ππ ]
FM wave : ππΉπ π‘ = πΈπ sin[ππ π‘ + πΎπ πΈπ sin ππ π‘]
FM wave : πππ π‘ = πΈπ sin[ππ π‘ + πΎππΈπ
cos ππ π‘
ππ
.]
Modulation Index for FM:
πΎπΈπ
ππ
or
πΎπΈπ
2π±ππ
FM wave : πππ π‘ = πΈπ sin[ππ π‘ + mcos ππ π‘ .]
Modulation Index for FM:
Modulation Index for PM
2π±ππ
Maximum Frequency deviation (Ξ΄):
Modulation Index for PM
2π±
Modulation Index for FM :
πΏ
ππ
Bandwidth : 2(Ξ΄+ππ πππ₯ )
43. Advantages of FM
Resilience to noise
Easy to apply modulation at a low power stage of the transmitter
It is possible to use efficient RF amplifiers with frequency modulated signals
Disadvantages of FM
Requires more complicated demodulator
Sidebands extend to infinity either side
UNIT I ANALOG COMMUNICATION
44. Comparison of Analog Communication Systems
(AM β FM β PM)
UNIT I ANALOG COMMUNICATION
AM FM PM
Amplitude gets
varied
Frequency gets
varied
Phase gets varied
Bandwidth: 2fm Bandwidth :
2(Ξ΄+fm)
Bandwidth :
2(Ξ΄+fm)
High noise
distortion
Lesser noise
distortion
Less noise
distortion
Multiplexing is not
possible
Multiplexing is
possible
Multiplexing is
possible
High complexity in
design
Low complexity in
design
Low complexity is
design
45. β’ Communication
Process of Exchanging Information Between Transmitter and Receiver
β’ Types of Communication β Analog and Digital
β’ Components of Communication β Source, Transmitter, Channel, Receiver,
Destination
β’ Modulation and Demodulation
β’ Need for modulation
β’ Amplitude Modulation β Changing amplitude of carrier with respect to the
message signal
β’ SSB Techniques β SSBFC, SSBSC, SSBRC, ISB, VSB
β’ Angle Modulation β Frequency and Phase Modulation
UNIT I ANALOG COMMUNICATION
48. To a conventional AM modulator, one input is a 500KHz carrier with an
amplitude of 20 V (peak). The other input is a 10KHz modulating signal
that is of sufficient amplitude to cause a change in the output wave of
Β±7.5V (peak). Determine
(i) Upper and lower side frequencies.
(ii) Modulation coefficient and percent modulation.
(iii) Peak amplitude of the modulated carrier and the upper and lower side
frequency voltages.
(iv) Maximum and minimum amplitudes of the envelope.
(v) The expression for the modulated wave.
(vi) Draw the output spectrum.
(vii) Sketch the output envelope. (14)
ASSIGNMENT QUESTIONS
51. Assignment Answers
Calculate the modulation index and percent modulation if the instantaneous
voltage of modulating signal and carrier are 40 sin Οmt and 50 sin Οct
respectively
53. A 400 W carrier is modulated to a depth of 80 %. Calculate the total power in
modulated wave
54. A broadcast transmitter radiates 20 kW when the modulation percentage is 75.
Calculate the carrier power and power of each sideband.
55. If a10V carrier is amplitude modulated by two different frequencies with
amplitudes 2V and 3V respectively, find the modulation index.
56. To a conventional AM modulator, one input is a 500KHz carrier with an amplitude of 20 V (peak).
The other input is a 10KHz modulating signal that is of sufficient amplitude to cause a change
in the output wave of Β±7.5V (peak). Determine
(i) Upper and lower side frequencies.
(ii) Modulation coefficient and percent modulation.
(iii) Peak amplitude of the modulated carrier and the upper and lower side frequency voltages.
(iv) Maximum and minimum amplitudes of the envelope.
(v) The expression for the modulated wave.
(vi) Draw the output spectrum.
(vii) Sketch the output envelope.
57.
58. What is the bandwidth required for PM and FM signal in which the
modulating signal is 2 KHz and maximum deviation is 10 KHz.
Given : Ξ΄ = 10000 Hz fm = 2000 Hz
B=2(Ξ΄ +fm) Hz
B= 2(10000+2000)
=2(12000)
= 24000Hz