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8/6/2019 OPTICALCOMMUNICATIONPPT BHUVANA
http://slidepdf.com/reader/full/opticalcommunicationppt-bhuvana 1/22
8/6/2019 OPTICALCOMMUNICATIONPPT BHUVANA
http://slidepdf.com/reader/full/opticalcommunicationppt-bhuvana 2/22
Presented by,
R.BHUVANESHWARI S.S.MANOVIDHYAA
3RD ECE 3RD ECE
8/6/2019 OPTICALCOMMUNICATIONPPT BHUVANA
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ABSTRACT Underwater Monitoring, Observing systems -
underwater wireless comm. , sensor n/w.
Providing high data rate.
Communication performance with absorption
Alternative to overcome acoustic comm. The link models
8/6/2019 OPTICALCOMMUNICATIONPPT BHUVANA
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INTRODUCTION
PROPERTIES OF UNDERWATER W/L OPTICAL
COMMUNICATION
COMMUNICATION LINK MODELS
BER CALCULATION
NUMERICAL EXAMPLES CONCLUSION
8/6/2019 OPTICALCOMMUNICATIONPPT BHUVANA
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Acoustic underwater communication.
Data rates.
Speed of acoustic waves in ocean-1500 m / s.
Distresses to marine mammals due to acoustic waves.
alternative means of underwatercommunication.
Examples- UUVs and other network controlsystems.
8/6/2019 OPTICALCOMMUNICATIONPPT BHUVANA
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8/6/2019 OPTICALCOMMUNICATIONPPT BHUVANA
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Light pulse-attenuation-wavelength
The extinction co-eff icient[e.o.e]
c(e) = (a) + 3(s)
extinction coeff icient c(e)
Absorption(a) Scattering coeff icients3(s)
8/6/2019 OPTICALCOMMUNICATIONPPT BHUVANA
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Absorption, scattering, and extinction
coeff icients for four types of water such as pure sea water,
clean ocean water,
coastal ocean water, and
turbid harbor water at
520-nm wavelength.
Turbidity e.o.e
The propagation loss
8/6/2019 OPTICALCOMMUNICATIONPPT BHUVANA
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The line-of -sight communication
linkThe modulating retro ref lector
communication link
T
he ref le
cti
on
communi
cati
on link
8/6/2019 OPTICALCOMMUNICATIONPPT BHUVANA
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8/6/2019 OPTICALCOMMUNICATIONPPT BHUVANA
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� Most common link btwn two pts.
� Light beam from transmitter to receiver
� Signal reaching receiver
PR los = PT T RLpr .,(d/ cosx) ( ARec cos x)/{ 2 d 2(1 cos x}
PT Avg. transmitter optical power
T,R-Optical efficiency of the transmitter, receiverd- perpendicular distance btwn. receiver
transmitter
x- laser beam divergence angle
8/6/2019 OPTICALCOMMUNICATIONPPT BHUVANA
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One has high resources than other
e.g.: submarine, diver Interrogator illuminates modulating retro
ref lector by continuous wave beam
Receiver Ref lects with modulatedinformation
8/6/2019 OPTICALCOMMUNICATIONPPT BHUVANA
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If LOS not available
Transmitter emits light wave by 0min, 0max,0i,0t
light reaching ocean-air surf ace bounce back
Ref ractive index<waterTIR
Anular area
Aann = 2 (h + x ) 2(1 cos 0max 1+
cos0min)= 2 (h + x )2(cos 0min cos 0max) Received power
P R ref(0) ARec f Rref(0)
8/6/2019 OPTICALCOMMUNICATIONPPT BHUVANA
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simple, widespread technology
intensity modulation, OOK Receiver based on SiMPs
photo detector f abricated- form of
arrays of photodiodes operated inGeiger mode to create a photon-
counting device.
8/6/2019 OPTICALCOMMUNICATIONPPT BHUVANA
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Accoding to poisson,gaussian distribution
BER = 1/ 2 erfc r1T-r0T
Ertc ( j) =2/j exp (-2)d
Where,r 1 = r d + r bg + r s
r 0 = r d + r bg
rd,rbg-sources of additive noise due to dark
counts and background illumination
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LINK PHOTONS
LOS 8000
REFLECTIVE 10RETRO
REFLECTIVE
2
8/6/2019 OPTICALCOMMUNICATIONPPT BHUVANA
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LINK DISTANCEREFLECTIVE 40m
RETRO
REFLECTIVE
50m
LOS 60m
8/6/2019 OPTICALCOMMUNICATIONPPT BHUVANA
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(a) when only
absorption isconsiderers
(b) when absorptionand scattering are
considered
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High data rate
Mesg. transmission long distance-multiple relaynode
Hybrid An improvement
Acoustic-low data rate-high turbidity,distance
Optic-high data rate
Complexity ,cost increases In Future more accurate numerical results
Design multiple access, WDM, CDMA
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S. Arnon and D. Kedar, Non-line-of sight underwater optical wire-lesscommunication network, J. Opt.
Soc. Am. A 26(3), 530539(2009)
B. Cochenour, L. Mullen, and A. Laux,Spatial and temporal dispersion in
high bandwidth underwater lasercommunication links, inPr oc. IEEE
Military Communications Conf ., pp.17 (2008).
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