group 11 final

8/6/2019 Group 11 Final

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Simulation of an Optical Fiber Point

to Point Communication link using

Simulink

By

Nihal Shastry

Uday Madireddy

Nitin Ravi


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Overview of Project

Current scenario

Where our project fits in

Comparison of modulation techniques

QAM

MPSK

EXTERNAL MODULATION

Applications

Future scope


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What is QAM?

QAM can be the expanded as Quadrature

Amplitude Modulation

A popular digital modulation technique in which

both phase and amplitude are varied

It was basically developed to overcome constraints

of complex AM or PM It can transmit more bits per second

It also makes use of minimum Bandwidth


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Block Diagram of QAM Transmitter


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Block Diagram of optical fiber Link

using QAM


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Eye Diagram


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Output Waveform


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Phase Shift Keying Principle - Changes the phase of the carrier in step with the digital

message. Use of a different phase for a 0 and a 1. A 1 signal is denoted by 1. A 0 signal is denoted by 1 + 180.

Quaternary Phase shift keying Binary inputs 00, 01, 10, 11 QPSK output phase -- 0, 90, 180, 270.

Differential Phase Shift Keying Information obtained as the difference in phase between two

successive signals. Modulating signal is not the binary code but the code that records the

changes in the binary code.


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Optical communication link QPSK

modulation

QPSK- Quadrature / Quaternary Phase Shift Keying

Digital modulation technique

M-ary Encoding technique where M = 4 4 different input conditions, 4 output phases possible

for a single carrier frequency.


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QPSK

Four phases:- 0, 90, 180, 270. Two symbols per bit can be transmitted (00, 01,

10, 11). Each symbols phase compared with respect to

the previous symbol.


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Optical link using QPSK


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Signal magnitude with QPSK


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The EYE Diagram


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External Modulation Currently preferred over any other form

of modulation

Done using an MZIM

Phase difference produced in the beam


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DIAGRAM FOR SIMULATION


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DATA GENERATION WITH

MZIM


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Magnitude of signal prior to

entry


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Magnitude of signal after

linear filter


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Magnitude of signal after

parabolic filter


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Eye diagram before fiber entry


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HEAD TO HEAD

QAM: Digital information contained in both amplitude and phase of the

transmitted carrier Susceptible to interfering signals Greater bandwidth efficiency. More bits transferred(4bits/cycle)

QPSK: Digital information - phase of the transmitted signal. Easy to implement and has good resistance to noise. In the receiver end local oscillator to be tuned to the I/P signal. Oscillator experiences drift in freq and phase and hence tuning is tough O

vercome by sending a pilot wave for synchronization Bandwidth Efficiency is around 2 bits per cycle.

DPSK: Simple to implement Larger data transmission capability (40 Gbits/Sec) Has maximum transmission distance when compared to other schemes.


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ADAPTIVE MODULATION


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Applications Can be used for simulating theoretical

systems inexpensively

Any distance, bit rate and data pulsecan be simulated

All parameters are completely user

defined

Completely customizable


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TIME LINEWEEK I WEEK II WEEK III WEEK IV WEEK V WEEK VI WEEK

VIIWEEK

VIII

Research on

Project

X XInitialProject

Design and

QAM

coding

X X XLearning

Simulinkand Initial

Block

diagram X X X X Final Block

Diagram

and

SimulationX X X


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References www.intel.com

Electronic Communications systems Wayne Tomasi

www.ee.buffalo.edu/faculty/paololiu/413/ binary.engin.brown.edu/lecture/Denmark/

Noise analysis for optical fiber communicationsystems -Alper Demir- Istanbul

Transmission Line laser modeling of semi conductor

laser amplified optical communication systems -A.Jlowery-IEE proceedings V 139 #3 June 1992


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Design of analog and digital data transmission filters-Hussein, Baher -IEEE trans on circuits and systems Vol# 40 #7 1993

Frequency chirping in external modulators- FumioKoyama IEEE J of light wave technology Vol #6 #1 Jan 1998

Design of optical communication data links- P.K.Pepeljugoski et all- IBM J of Res. and Dev. Vol #47 No.2/3 2003

A time domain optical transmission system simulationpackage accounting for non linear and polarization-

related effects in a fiber- Andrea Carena et all- IEEE J onselected areas in comm. V #15 #4 May 1997

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