Transcript Simulation of an Optical Fiber Point to Point

Simulation of an Optical Fiber Point
to Point Communication link using
Simulink
By
Nihal Shastry
Uday Madireddy
Nitin Ravi
Overview of Project
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Current scenario
Where our project fits in
Comparison of modulation techniques
QAM
MPSK
EXTERNAL MODULATION
Applications
Future scope
What is QAM?
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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
Block Diagram of QAM Transmitter
Block Diagram of optical fiber Link
using QAM
Eye Diagram
Output Waveform
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Phase Shift Keying
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Quaternary Phase shift keying
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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 φ1.
A “0” signal is denoted by φ1 + 180°.
Binary inputs – 00, 01, 10, 11
QPSK output phase -- 0°, 90°, 180°, 270°.
Differential Phase Shift Keying
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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.
Optical communication link – QPSK
modulation
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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.
QPSK
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Four phases:- 0°, 90°, 180°, 270°.
Two symbols per bit can be transmitted (00, 01,
10, 11).
Each symbol’s phase compared with respect to
the previous symbol.
Optical link using QPSK
Signal magnitude with QPSK
The EYE Diagram
External Modulation
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Currently preferred over any other form
of modulation
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Done using an MZIM
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Phase difference produced in the beam
DIAGRAM FOR SIMULATION
DATA GENERATION WITH
MZIM
Magnitude of signal prior to
entry
Magnitude of signal after
linear filter
Magnitude of signal after
parabolic filter
Eye diagram before fiber entry
HEAD TO HEAD
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QAM:
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QPSK:
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DPSK:
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Digital information contained in both amplitude and phase of the
transmitted carrier
Susceptible to interfering signals
Greater bandwidth efficiency. More bits transferred(4bits/cycle)
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
Overcome by sending a pilot wave for synchronization
Bandwidth Efficiency is around 2 bits per cycle.
Simple to implement
Larger data transmission capability (40 Gbits/Sec)
Has maximum transmission distance when compared to other schemes.
ADAPTIVE MODULATION
Applications
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Can be used for simulating theoretical
systems inexpensively
Any distance, bit rate and data pulse
can be simulated
All parameters are completely user
defined
Completely customizable
TIME LINE
WEEK I
Research on
Project
Initial
Project
Design and
QAM
coding
Learning
Simulink
and Initial
Block
diagram
Final Block
Diagram
and
Simulation
WEEK II
WEEK III
WEEK IV
WEEK V
WEEK VI
WEEK
VII
WEEK
VIII
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References
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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 communication
systems -Alper Demir- Istanbul
Transmission Line laser modeling of semi conductor
laser amplified optical communication systems -A.J
lowery-IEE proceedings V 139 #3 June 1992
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Design of analog and digital data transmission filters-
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Frequency chirping in external modulators-
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Design of optical communication data links- P.K.
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Hussein, Baher -IEEE trans on circuits and systems Vol# 40 #7 1993
Fumio
Koyama IEEE J of light wave technology Vol #6 #1 Jan 1998
Pepeljugoski et all- IBM J of Res. and Dev. Vol #47 No.2/3 2003
A time domain optical transmission system simulation
package accounting for non linear and polarizationrelated effects in a fiber- Andrea Carena et all- IEEE J on
selected areas in comm. V #15 #4 May 1997