fiber optics communications system (1)
TRANSCRIPT
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DIELECTRIC WAVEGUIDE &
FIBER OPTICS TRANSMISSION
MEDIA
COMEC 513 L1
SABILE, s.s.
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DIELECTRIC WAVEGUIDE & OPTICAL FIBER
Index of Refraction
Snells Law
Critical angle
Reflection Coefficient
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Dielectric Waveguide
Let us consider the simpler case of a rectangular
slab of waveguide.
r
i r
1 1 1 2 2 2and
Snells Law of Reflection
1
2
sin
sin
t
i
Snells Law of Refraction
21
1
sinr
i critical
r
Critical Angle:
Case(1): i criticali Case(ii): i criticali
When the incident angle is greater than the critical angle, the wave is totally
reflected back and this phenomenon is known as Total internal reflection.
Total internal
reflectionIncident
waveReflected
wave
Refracted
wave
Incident
wave
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Velocity of light in Free Space
Velocity of light in the mediumu
r r
cn
u
Dielectric Waveguide
The index of refraction, n, is the ratio of the speed of light in a vacuum to the
speed of light in the unbounded medium, or
In nonmagnetic material
rn
1 2
1
sini critical
n
n
1
2
sin
sin
t
i
n
n
1 1 1 1u
o r o r o o r r r r
cu
1
o o
c
1r
Where
Critical Angle:
Snells Law of Refraction:
Snells Law of Refraction can be expressed in terms of refractive index:
Index of refraction:
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A slab of dielectric with index of refraction 3.00 sits in air. What is the relative
permittivity of the dielectric? At what angle from a normal to the boundary willlight be totally reflected within the dielectric? (Ans: 9, 19.5)
Dielectric WaveguideExample
What is the relative permittivity of the dielectric?
1 3n 2 1 (air)n
Criticali
11 rn
2
1 1r n
2
13 9r
At what angle from a normal to the boundary will
light be totally reflected within the dielectric?
1 12
1
1sin sin
319.5
i critical
n
n
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Dielectric WaveguideTE wave
1 2
1 2
cos cos
cos cos
i t
i t
n n
n n
22
2 11sin
2tan
cos
i
TE
i
n n
Ex
Hy
Hz
222 1
22
2 1
cos sin
cos sin
i i
TE
i i
j n n
j n n
TE
Using Snells Law of refraction
The reflection coefficient of a TE plane wave
(See Chapter 5) is given by
22
2 1
1
sincostan
2 2 cos
i
i
i
n na m
TE modes (50 mm thick dielectric ofr= 4 or
n=2 operating at 4.5 GHz)
TE wave
LHS RHS
RHS
LHS
For this example only three TE
modes are possible;
A) TE0 at i = 74.4,
B) TE1 at i = 57.9, and
C) TE2 at i = 39.8.
(A)(B) (C)
Possible modes can be obtained by evaluating
the phase expression for various values of m.
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Dielectric WaveguideTM wave
Ex
Hy
Ez
22
2 1
22
2 1
cos sin
cos sin
i i
TE
i i
j n n
j n n
TE
Using Snells Law of refraction
The reflection coefficient of a TM plane wave
(See Chapter 5) is given by
TM modes (50 mm thick dielectric ofr
= 4 or n=2 operating at 4.5 GHz)
TM wave
1 2
1 2
cos cos
cos cos
t i
TM
t i
n n
n n
22
2 11
2
2 1
sincostan
2 2 cos
ii
i
n na m
n n
For this example only three TM
modes are possible;
A) TM0 at i = 71.6,
B) TM1 at i = 52, and
C) TM2 at i = 33.
RHS
LHS
(A)
(B)(C)
LHS RHS
Possible modes can be obtained by evaluating
the phase expression for various values of m.
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Dielectric Waveguide
A larger ratio of n1/n2 results in
a) a lower critical angle and therefore
b) more propagating modes.
22
2 11
2
2 1
sincos
tan 2 2 cos
ii
i
n na m
n n
LHSRHS for various mRHS
For single mode operation:
2 2
1 2
1 1
2o
a
n n
2 2
1 2
1
2
o
n n
a
(or)
:Slab thicknessa
2 2
1 2
1
2
c
n nf
a
oc
f
Using
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Dielectric Waveguide
D7.6: Suppose a polyethylene dielectric slab of thickness 100 mm exists in
air. What is the maximum frequency at which this slab will support only onemode?
100 mma
2 21 2
1
2
c
n n
f
a
1 1.5n
2 1 (air)n
From Table E.2, for polyethylene
1 2.26 1.5n 1 2.26r
2 1 (air)n
The maximum frequency at which this
slab will support only one mode is
2 2
1 2
8
max2 23
1 1
2 2
3 101.2 GHz
100 10 1.5 1.0
c
n nf
a
Example
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D7.6: Find e and up at 4.5 GHz for the TE0 mode in a 50 mm thick n1 = 2.0
dielectric in air. (Ans: 35 mm and 1.6 x 10
8
m/s)
Example
1 1
8
9sin sin sin sin
3 1035 mm
4.5 10 2 74.4
u o
e
i i i
c
n fn
The effective wavelength in the guide is
1
8
8
sin sin
3 101.6 10 m/s
2 74.4p
e i
cu
n
The propagation velocity is
50 mma
1 2.0n
2 1 (air)n
2 1 (air)n From Fig. 7.16, the critical incident angle for
the TE0 mode
TE0 at i = 74.4
Dielectric Waveguide
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FIBER OPTICS
COMMUNICATIONS SYSTEM
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FIBRE OPTIC COMMUNICATION SYSTEM
Introduction
Fibre optic system is a communication system that
carries information through a guided fibre optic
cable
Light frequencies used in fibre optic systems are
between 1014 and 4x1014 Hz
Thus, the higher the carrier frequency, the wider
the bandwidth and consequently, the greater the
information carrying capacity
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OPTICAL FIBER
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OPTICAL FIBER - BENEFITS
Greater capacity
Data rates of hundreds of Gbps
Smaller size & weight
Lower attenuation
Electromagnetic isolation
Greater repeater spacing
10s of km at least
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OPTICAL FIBER - TRANSMISSION CHARACTERISTICS
Act as wave guide for 1014 to 1015 Hz
Portions of infrared and visible spectrum
Light Emitting Diode (LED)
Cheaper
Wider operating temp range
Last longer
Injection Laser Diode (ILD)
More efficient
Greater data rate
Wavelength Division Multiplexing15
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THE LIGHT SOURCE
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Fibre optics Long thin strand of glass or plastic fibre used to guide light rays from
a point to another point
Fibre-to-detector coupler Interface between fibre and light detector to couple as much light as
possible from the fibre cable into the light detector
Light detector PIN (p-type-intrinsic-n-type) diode / an APD (avalanche photodiode)
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Fibre optic - Basic elements
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FIBER OPTIC TYPES
multimode step-index fiber
the reflective walls of the fiber move the light pulses to the
receiver
multimode graded-index fiber acts to refract the light toward the center of the fiber by
variations in the density
single mode fiber
the light is guided down the center of an extremely narrowcore
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OPTICAL FIBER TRANSMISSION MODES
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FIBER OPTIC SIGNALS
20
fiber optic multimode
step-index
fiber optic multimode
graded-index
fiber optic single mode
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PROPAGATION MODE Monomode fiber (core 8 ~
12 m)
Only one path for the light
to propagatealong fiber
All light rays follow the
same path down
the cable and take the
same time to
travel the length of the
cable
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input pulse output pulse
only one mode, no modal dispersion
Monomode step-index fiber
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PROPAGATION MODE
Multimode step index fiber
(50 ~200 m)
More than one path for lightpropagate along fiber
Light rays are propagated down
the cable in a zig-zag pattern
and all the light rays do notfollow the same path with
different propagation time
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fastest modeslowest mode
input pulse output pulse
Multimode step-index fiber
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PROPAGATION MODE
Multimode graded indexfiber
Light is propagated downthe fiber by refractionwhich result a continuousbending at the light rays
the rays travel near thecenter, so that all the raysarrive at the end point atthe same time
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input pulse output pulse
Multimode graded-index
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FIBEROPTIC - ADVANTAGES
Wider bandwidth: have higher information to carry Lower loss/attenuation: there is less signal attenuation
over long distance
Light weight: higher than copper cable and offer good
benefit where weight is critical (plane) Small size: smaller diameter than electrical cable
Strength: as it has cladding, they offer more strength
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FIBER OPTIC ADVANTAGES
greater capacity (bandwidth of up to 2 Gbps)
smaller size and lighter weight
lower attenuation
immunity to environmental interference
highly secure due to tap difficulty and lack of signalradiation (Security: cannot be tapped easily aselectrical cable)
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FIBER OPTIC DISADVANTAGES
expensive over short distance
requires highly skilled installers
adding additional nodes is difficult
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ATTENUATION
The attenuation in fiber optics are due mainly to:
Scattering losses
Absorption losses
Bending losses Splicing loss
Coupling losses
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ATTENUATIONSTANDARDFIBER
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1st window wavelength :0.85 um The lowest minimum loss: 5 to 10 db/km
2nd window 1.30 um 0.5 to 2 dB/km
3rd window 1.55 um 01. to 0.5 dB/km
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FIBREOPTIC - BASICELEMENTS
The main elements are:
Driving circuitry:
Serves as an electrical interface between the inputcircuitry and light source and to drive the light source
Light source
LED / LASER
Convert electrical energy to optical energy, where theamount of light emitted is proportional to the amount ofdrive current
Light source-to-fiber coupler
An interface to couple the light emitted by the sourceinto the optical fibre cable
Fibre optics
Long thin strand of glass or plastic fibre used to signalin a form of light from a point to another point
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FIBRE OPTIC COMMUNICATION SYSTEM
Elements in an optical fibre communication link
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OPTICAL TRANSMISSION MULTIPLEX SYSTEM
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APPLICATIONOFFIBEROPTICCABLE
Some of the applications of fiber optic
Long haul, backbone public and private networks
Local loop networks
Fiber backbone networks (LAN connectivity)
High resolution image and digital video Computer networks, wide area and local area
Shipboard communications
Aircraft communications and controls
Interconnection of measuring and monitoringinstruments in plants and laboratories
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Fiber to the node / neighborhood(FTTN) / Fiber to the cabinet
(FTTCab)
Fiber to the curb (FTTC) / Fibre to the
kerb (FTTK)- Also sometimes called
FTTP for "to the pole", which usage
conflicts with use of the "P" to mean
"to the premises".
Fiber to the building (FTTB) which
does not imply any fiber actually
inside a home.
Fiber to the home (FTTH) which
actually means "into the home" to
internal fiber optic outlets.
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Numerical Aperture
Wavelength
Acceptance angle
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Optical FiberA typical optical fiber is shown in Figure. The fibercore iscompletely encased in a fibercladdingthat has a slightly
lesser value of refractive index. Signals propagate along the
core by total internal reflection at the core-cladding boundary.
f cn n
A cross section of the fiber with rays traced for two
different incident angles is shown. If the phase matching
condition is met, these rays each represent propagating
modes.
The abrupt change in n is a characteristic of a step-index
fiber. Optical fiber designed to support only one
propagating mode is termed single-mode fiber. More
than one mode propagates in multi-mode fiber.
2 2
01
2f c
a n n
k
In step-index optical fiber, a single mode will propagate so long as the
wavelength is big enough such that
where k01 is the first root of the zeroth order
Bessel function, equal to 2.405
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Optical Fiber
For step-index multi-mode fiber, the total number of propagating modes is
approximately
2
2 22
f c
aN n n
Example 7.3: Suppose we have an optical fiber core of index 1.465 sheathed in
cladding of index 1.450. What is the maximum core radius allowed if only one mode
is to be supported at a wavelength of 1550 nm?
01
2 22 f c
ka
n n
2 2
01
2f c
a n n
k
How many modes are supported at this maximum radius for a source wavelength of
850 nm?
9
2 2
2.405 1550 10or 2.84
2 (1.465) (1.450)
x ma a m
2
6
2 2
9
(2.84 10 )2 (1.465) (1.450) 9.6
850 10
x mN
x m
The fiber supports 9 modes!
O i l Fib
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Optical FiberNumerical Aperture
Light must be fed into the end of the fiber to initiate
mode propagation. As Figure shows, upon incidence
from air (no) to the fiber core (nf) the light is refracted
by Snells Law:
FiberLaser Source
sin sino a f b
n n
cos cos 90 sinb c c
2 2sin cos 1
b b
2sin 1 cos
o a f bn n
2
sin 1 sino a f cn n
90 180c b
90b c
The sum of the internal angles in a
triangle is 180 deg.
90
The numerical aperture, NA, is defined as
21 sin
sinf c
a
o
nNA
n
O ti l Fib
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Optical FiberNumerical Aperture
The incident light make an angle c with a normal to
the corecladding boundary. A necessary condition
for propagation is that c exceed the critical angle(i)critical, where
sin ci critf
n
n
2 2
f c
o
n nNA
n
Therefore, the numerical aperture, NA, can bewritten as
21 sin
f c
o
nNA
n
FiberLaser Source
sin ci critf
n
n
O ti l Fib
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Example 7.4: Lets find the critical angle within the fiber described in Example
7.3. Then well find the acceptance angle and the numerical aperture.
1 1.450sin sin 81.8 .
1.465
c
c
f
n
n
2 2
1 (1.465) (1.450)sin 12.1 .
1a
The critical angle is
The acceptance angle
Finally, the numerical aperture is
sin 0.209.a
NA
Optical FiberNumerical Aperture
O ti l Fib
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Optical FiberSignal Degradation
Intermodal Dispersion: Let us consider the case when a single-frequency source (called a
monochromaticsource) is used to excite different modes in a multi-mode fiber. Each mode
will travel at a different angle and therefore each mode will travel at a different propagationvelocity. The pulse will be spread out at the receiving end and this effect is termed as the
intermodal dispersion.
Waveguide Dispersion: The propagation velocity is a function of frequency. The spreading
out of a finite bandwidth pulse due to the frequency dependence of the velocity is termed as
the waveguide dispersion.
Material Dispersion: The index of refraction for optical materials is generally a function of
frequency. The spreading out of a pulse due to the frequency dependence of the refractive
index is termed as the material dispersion.
Attenuation
Electronic Absorption: The photonic energy at short wavelengths may have the right amount
of energy to excite crystal electrons to higher energy states. These electrons subsequently
release energy by photon emission (i.e., heating of the crystal lattice due to vibration).
Vibrational Absorption: If the photonic energy matches the vibration energy (at longer
wavelengths), energy is lost to vibrational absorption.
O ti l Fib
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Optical FiberGraded-Index Fiber
One approach to minimize dispersion in a
multimode fiber is to use a graded index fiber (or
GRIN, for short).
The index of refraction in the core has an
engineered profile like the one shown in Figure.
Here, higher order modes have a longer path to
travel, but spend most of their time in lower index
of refraction material that has a faster propagationvelocity.
Lower order modes have a shorter path, but travel
mostly in the slower index material near the center
of the fiber.
The result is the different modes all propagate
along the fiber at close to the same speed. The
GRIN therefore has less of a dispersion problem
than a multimode step index fiber.
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FIBER LINK BUDGET
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LINK BUDGET
A link budgetis the accounting of all of the gains and
losses from the transmitter, through the medium (freespace, cable, waveguide, fiber, etc.) to the receiver in atelecommunication system.
It accounts for the attenuation of the transmitted signal due topropagation, as well as the antenna gains, feedline andmiscellaneous losses.
Randomly varying channel gains such as fading are taken intoaccount by adding some margin depending on the anticipatedseverity of its effects. The amount of margin required can be reducedby the use of mitigating techniques such as antenna diversity orfrequency hopping, in case of a wireless media.
A simple link budget equation looks like this:
Received Power (dBm) = Transmitted Power (dBm) + Gains(dB) Losses (dB)
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Cable Plant Link Loss Budget Analysis
In fiber optic comm. System, loss budget
analysis is the calculation and verification of
a fiber optic system's operating
characteristics.
This encompasses items such as routing,
electronics, wavelengths, fiber type, and
circuit length.
Attenuation and bandwidth are the key
parameters for budget loss analysis.
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Prior to designing or installing a fiber optic system, a loss
budget analysis is recommended to make certain the system
will work over the proposed link.
Both the passive and active components of the circuit have to
be included in the budget loss calculation.
Passive loss is made up of fiber loss, connector loss, splice
loss, and couplers or splitter loss.
Active components are system gain, wavelength, transmitter
power, receiver sensitivity, and dynamic range.
Prior to system turn up, test the circuit with a source and FO
power meter to ensure that it is within the loss budget.
Analysis of Link Loss In The Design Stage
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The idea of a loss bud get is to insu re the network
equipment w i l l work o ver the instal led f iber opt ic l ink .
It is normal to be cons ervat ive over the specif icat ions!
Don't use the best pos sible specs fo r f iber attenuat ion
or con nector loss - give you rself som e margin!
Analysis of Link Loss In The Design Stage
For example, we have a 2 km multimode link with 5 connections (2
connectors at each end and 3 connections at patch panels in the
link) and one splice in the middle.
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Cable Length 2.0 2.0 2.0
Fiber Type Multimode Single mode
Wavelength (nm) 850 1300 1300 1550
Fiber Atten. dB/km 3 - 3.5 1 -1.5 0.4 -1/0.5 0.3 - 1/0.5
Total Fiber Loss 6.0 - 7.0 2.0 - 3.0
Cable Plant Passive Component Loss
Step 1. Fiber loss at the operating wavelength
(All specs in brackets are maximum values perEIA/TIA 568 standard. For
single mode fiber, a higher loss is allowed for premises applications. )
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Step 2. Connector Loss
Multimode connectors will have losses of 0.2- 0.5 dB typically. Single
mode connectors, which are factory made and fusion spliced havelosses of 0.1- 0.2 dB. Field terminated single mode connectors may
have losses as high as 0.5-1.0 dB.
Let's calculate it at both typical and worst case values.
Connector Loss0.3 dB (typical
adhesive/polish conn)
0.75 dB (TIA-568 max
acceptable)
Total # of Connectors 5 5
Total Connector Loss 1.5 dB 3.75 dB
(All connectors are allowed 0.75 max perEIA/TIA 568 standard)
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Step 3. Splice Loss
Multimode splices are usually made with mechanical splices, although
some fusion splicing is used. The larger core and multiple layers makefusion splicing about the same loss as mechanical splicing, but fusion is
more reliable in adverse environments. 0.1-0.5 dB is for multimode
splices, 0.3 being a good average for an experienced installer. Fusion
splicing of single mode fiber will typically have less than 0.05 dB (that's
right, less than a tenth of a dB!)
Typical Splice Loss 0.3 dB
Total # splices 1
Total Splice Loss 0.3 dB
(All splices are allowed 0.3 max perEIA/TIA 568 standard)
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Best Case TIA 568 Max
850 nm 1300 nm 850 nm 1300 nm
Total Fiber Loss (dB) 6.0 2.0 7.0 3.0
Total Connector Loss (dB) 1.5 1.5 3.75 3.75
Total Splice Loss (dB) 0.3 0.3 0.3 0.3Other (dB) 0 0 0 0
Total Link Loss (dB) 7.8 3.8 11.05 7.05
Step 4. Total Passive System Attenuation
Add the fiber loss, connector and splice losses to get the link loss.
Remember these should be the criteria for testing. Allow +/- 0.2 -0.5dB for measurement uncertainty and that becomes your pass/fail
criterion.
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Equipment Link Loss Budget Calculation:
Link loss budget for network hardware depends
on the dynamic range, the difference between the
sensitivity of the receiver and the output of the
source into the fiber.
You need some margin for system degradation
over time or environment, so subtract that margin
(as much as 3dB) to get the loss budget for thelink.
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Step 5. Data From Manufacturer's Specification for Active
Components (Typical 100 Mb/s link)
Operating Wavelength (nm) 1300
Fiber Type MM
Receiver Sens. (dBm@ required BER) -31
Average Transmitter Output (dBm) -16
Dynamic Range (dB) 15
Recommended Excess Margin (dB) 3
St 6 L M i C l l ti
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Step 6. Loss Margin Calculation
Dynamic Range (dB) (above) 15 15
Cable Plant Link Loss (dB) 3.8 (Type) 7.05 (TIA)
Link Loss Margin (dB) 11.2 7.95
As a general rule, the Link Loss Margin should be greater than
approximately 3 dB to allow for link degradation over time.
LEDs in the transmitter may age and lose power, connectors or splicesmay degrade or connectors may get dirty if opened for rerouting or
testing.
If cables are accidentally cut, excess margin will be needed to
accommodate splices for restoration.
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CRITERIA & CALCULATION FACTORS
Basic Items Used To Determine General
Transmission System Performance
Fiber Loss Factor
Type of fiber
Transmitter
Receiver Sensitivity
Number and type of splices
Margin
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TRANSMISSIONDISTANCECLASSIFICATIONS
Very Short Reach : 300-600 m or less
Short: 2Km
Intermediate: 10-40 Km
Long: 40- 80 Km
Very Long Reach: 120 Km
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EXAMPLE:
Two operation centers are located about 8 miles apart based on
map distance. Assume that the primary communication devices ateach center are a wide area network capable router with fiber opticcommunication link modules, and that the centers are connected bya fiber optic cable. The actual measured distance based on walkingthe route , is a total measured length (including slack coils) of 9miles. There are no additional devices installed along the cable path.
Future planning provides for the inclusion of a freeway managementsystem communication link within 5 years.
Note:
All distance measurements must be converted to kilometers. Fiber
cable is normally shipped with a maximum reel length of 15,000 feet(or 4.5km). 9 miles is about 46,000 feet or 14.5km. Assume that thissystem will have at least 4 mid-span fusion splices.
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From the Table: Fiber Loss Budget Calculation
Fiber Loss: 14.5 km 0.35 dB = -5.075 Fusion splice Loss: 4 0.2 dB = - 0.8
Terminating Connectors: 2 1.0 dB = -2.0
Margin: -5.0
Total Fiber Loss = -12.875
The manufacturer of the router offers threetransmitter/receiver options for single mode fiber:
REACH TRANSMIT POWER RECEIVER SENSITIVITY
Short: -3 dBm -18 dBm
Intermediate: 0 dBm -18 dBm
Long: +3 dBm -28 dBm
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To determine the correct power option add the transmit
power to the fiber loss calculation.
REACH TRANSMIT POWER FIBER LOSS LOSS BUDGET
Short: -3 dBm -12.875 -15.875 dBm
Intermediate: 0 -12.875 -12.875 dBm
Long: +3 dBm -12.875 -9.875 dBm
Compare this to the receiver sensitivity specification
REACH RCVR SENSITIVITY LOSS BUDGET DIFFERENCE
Short: -18 dBm -15.875 +3.0
Intermediate: -18 dBm -12.875 +6.0
Long: -28 dBm -9.875 +19.0
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Because a loss margin of 5.0dB was included in the
fiber loss calculation, the short reach option will
provide sufficient capability for this system.
In fact, the total margin is 8.0db because the
difference between the loss budget and receiver
sensitivity is 3.0 db.
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Problem: Assume a system with the following specifications:
Light transmitter LED output power: 30 W
Light receiver sensitivity: 1 W
Cable Length: 6 km
Cable attenuation: 3 dB/Km, 3X6 = 18 dB total
Four connectors: attenuation 0.8 dB = 3.2 dB total
LED-to-connector loss: 2 dB Cable dispersion: 8 ns/km
Data rate: 3 Mbps
1. Calculate for all the losses.2. What power gain is needed to overcome this loss?
S
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SOLUTION:
First calculate all the losses; add all the dB loss factors.
Total Loss, dB = 18 + 3.2 + 2 + 2 = 25.2 dB
If we add 4-dB contingency factor, making the total loss:
25.2 + 4 = 29.2 dB
What power gain is needed to overcome this loss? dB = 10 log Pt/Pr
where Pt is the transmit power; Pr is the received power
29.2 dB = 10 log Pt/Pr
Pt/Pr = 831.8
Pt = 30/831.8 = 0.036 W
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Note that if the receiver sensitivity is 1 W, 0.036 W is
below the threshold of the receiver.
The problem may be solved in one of the three ways:
Increase transmitter power
1.
Get a more sensitive receiver2. Add repeater.
If the transmitter power is increased to 1 mW or 1000 W:
The Pr= 1000 831.8 = 1.2 W this value is > 1 W
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PERFORMANCE CONSIDERATION:
The performance of a cable is indicated by the bitrate-distance product.
This rating is the fastest bit rate that can be
achieved over a 1 km cable.
R = 1/5dD (s/km)
R maximum data bit rate in Mbps for a given
distance D in Km of the cable with dispersion factor ofd, given in s/km.
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Problem :
A measurement is made on a fiber-optic cable 1200 ft long.
Its upper frequency limit is determined to be 43 Mbps. What
is the dispersion factor D?
1 km = 3274 ft.
D = 1200 ft or 1200/3,274 = 0.367 km
R = 1/5dD
D = 1/5Rd = 1/ [5(43 x 106)(0.367)] = 12.7 ns/km
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HOW TO ESTIMATE TOTAL LINK LOSS
HOW TO ESTIMATE TOTAL LINK LOSS
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Example:
Assume a 40km single mode link at 1310 nm with 2connector pair and 5 splices. Calculate the link loss.
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HOW TO ESTIMATE FIBER DISTANCE
E l
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Example:
Assume a Fast Ethernet Single mode link at 1310nm with 2 connector pairs and 5
splices. Estimate the possible distance of the fiber before dissipating the optical
power to a value below the receiver sensitivity. What are the factors that will
determine the maximum distance of the fiber?
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THANKYOU