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Programme Course Name Course Code Semester Session

The document discusses a lecture on principles of electronic communication. It provides details of the lecture such as the course name, code, semester, faculty name and institute. The topics discussed in the previous lecture included pulse code modulation, sampling and quantization. The topics to be discussed in the current lecture are listed as line coding or data formatting and digital modulation techniques including amplitude shift keying, frequency shift keying, phase shift keying and quadrature phase shift keying. Line coding and different digital modulation techniques such as amplitude shift keying generation and detection are explained.

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81 views12 pages

Programme Course Name Course Code Semester Session

The document discusses a lecture on principles of electronic communication. It provides details of the lecture such as the course name, code, semester, faculty name and institute. The topics discussed in the previous lecture included pulse code modulation, sampling and quantization. The topics to be discussed in the current lecture are listed as line coding or data formatting and digital modulation techniques including amplitude shift keying, frequency shift keying, phase shift keying and quadrature phase shift keying. Line coding and different digital modulation techniques such as amplitude shift keying generation and detection are explained.

Uploaded by

yash
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as PDF, TXT or read online on Scribd
You are on page 1/ 12

Programme : RTU- B.Tech.

in EE
Course Name : Principle of Electronic Communication
(Open-Elective)
Course Code : 7EC6.60.1
Semester : VII
Session : 2020-2021

Faculty Name: : J.P. Vijay (Associate Professor-Department of


Electronics & Communication Engineering

Swami Keshvanand Institute of Technology, Management &


Gramothan
Ramnagaria, Jagatpura, Jaipur-302017, INDIA
Approved by AICTE, Ministry of HRD, Government of India,
Recognized by UGC under Section 2(f) of the UGC Act, 1956
E-mail: info@skit.ac.in Web: www.skit.ac.in
Lecture-10
Principle of Electronic Communication

Topics discussed in the Topics to be discussed in today’s


previous Lecture Lecture

Pulse code Modulation Line Coding or Data Formatting


(PCM)
Digital Modulation techniques
Sampling
ASK – Generation and Detection
Quantization

Numericals

2
Line Coding
Line Coding: In telecommunication, a line code is a pattern of
voltage or current used to represent digital data transmitted by a
transmission line.
Eg. Input digital stream: 101001110

3
Digital Modulation Techniques
Modulation is the process where some characteristics of periodic
waveform, called the carrier signal, is varied according with a
modulating signal that typically contains information to be
transmitted.

If the modulating signal is in digital form, then the modulation is


known as digital modulation.

Carrier signal C(t) = A cos ( ωct+ θ )

A= Amplitude of carrier signal (volts)


ωc = Frequency of carrier signal (radian /sec) = 2 π f
θ = Phase of the carrier signal (degree)
4
Digital Modulation Techniques
A= Amplitude of carrier signal (volts)
ωc = Frequency of carrier signal (radian /sec) = 2 π f
θ = Phase of the carrier signal (degree)
Carrier signal C(t) = A cos ( ωct+ θ )

Modulating Signal: Digital (1010101)

Type of Digital Modulation techniques

Amplitude Shift Key (ASK)

Frequency Sift Key (FSK)

Phase Shift Key (PSK)

Quadrature Phase Shift Key (QPSK) 5


Amplitude Shift Key (ASK)
In ASK, amplitude of carrier wave shift according to digital
modulating signal, if digital signal is binary encoded (1 & 0) that
type of modulation is called binary amplitude shift key.

The simplest way of achieving amplitude shift keying is by


switching ‘On’ the carrier whenever the data bit is '1' &
switching off the carrier whenever the data bit is '0'. This
technique is also known as ‘On-Off’ key.

Thus, Data = 1 carrier transmitted, Data = 0 carrier not


transmitted.

In ASK, Frequency and Phase of carrier remain


Constant
6
ASK (Binary)
Amplitude modulation equation:

Carrier equation- C(t) = A cos ( ωct+ θ )

Modulation Signal (0 & 1)

When input is ‘1’ the equation of ASK

S(t)= C(t) = A cos ( ωct+ θ )

When input is ‘0’ the equation of ASK

S(t) =0

7
ASK Generation (Modulator)

Stream of 1 and 0
(Unipolar)
When input is ‘1’ the ASK

S(t)= C(t) = A cos ( ωct+ θ )


C(t) = A cos ( ωct+ θ )
When input is ‘0 the ASK

S(t) =0

Figure. ASK Modulator


8
ASK Waveform
Carrier C(t) = A cos ωct
Modulating or information Signal (0 &1)= ‘10010’

9
ASK Waveform
Carrier C(t) = A cos ωct
Modulating or information Signal (0 &1)= ‘01010’

10
ASK Detection (Demodulator)
Demodulation: To get back original modulating signal
To remove the carrier signal from the modulated signal

The modulated ASK signal is given to the half-wave rectifier, which


delivers a positive half output. The low pass filter suppresses the higher
frequencies and gives an envelope detected output from which the
comparator delivers a digital output.
11
Query-Session

12

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