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WHAT IF I TRANSMIT LIGHT WITHOUT OPTICAL FIBRE?. Powerpoint Templates. FREE SPACE OPTICS (F.S.O.). PRESENTED BY :- VIVEK SHRIVASTAV BRANCH/YEAR :- E&c ENGG.,4 TH YEAR SECTION :- ‘B’. Contents :-. Introduction Various configurations
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WHAT IF I TRANSMIT LIGHT WITHOUT OPTICAL FIBRE? Powerpoint Templates
FREE SPACE OPTICS (F.S.O.) PRESENTED BY :- VIVEK SHRIVASTAV BRANCH/YEAR :- E&c ENGG.,4TH YEAR SECTION :- ‘B’
Contents :- • Introduction • Various configurations • Indoor and outdoor implementations • Various attenuation factors • Advantages and Disadvantages • Present usages of technology • future scope with technology • Conclusion • references
\ INTRODUCTION:- In F.S.O. • FIBRE REPLACED BY FREE SPACE • INFORMATION TARNSMISSION BY LIGHT BEAMS THROUGH THE ATMOSPHERE
‘Ofc’ v/s ‘fso’ ‘Wireless’ does not imply roaming
Various config. :- • Mainly Three types of configuration is there:- • Line of site(LOS) config. • Directed-non LOS config.Hybrid config. • Non Directed-non LOS config.Diffused config.
Indoor implementation:- • Interference:- • Incandescent light(~2800 K) max. attenuation. • Sunlight (~6000K) • Florescent lamp • Attenuation :- • Free space loss(due to beam divergence) –impo. • Atmospheric loss (not much in indoors) • Eye safety:-most important • should be class 1 safe(< 0.5 mW, 880 nm, LASER) • restricts system power (though LEDs can be used at higher powers, but Bandwidth limited)
Outdoor implementation :- • Attenuation – Most Important • Atmospheric Loss (varies with weather) • 0.2 dB/km in exceptionally clear weather • 300 dB/km in very dense fog • Restricts the range (~500m in most commercial systems) • May need low capacity back-up RF links • Scintillation Noise (atmospheric turbulence induced intensity fluctuations) – speckled pattern • Alignment Issues – Line of sight • Interference • Sunlight (~ 6000 K)
Attenuation factors ….contd. PR= PT . Areceiver . e –σ.R/(Div-range)2 • PR ~ PT e –σ.R WHERE σ IS ATTENUATION FACTOR FOR TRANSMISSION • Free Space losses-beam divergence • Atmospheric losses exponential term– dominates • Scattering + Absorption
Attenuation :: Scattering Depends on particle size • Size parameter α = 2π r/λ • ‘ r ’ varies with atmospheric composition r << λ => σ ~ λ-4 Rayleigh Scattering-fog r ~ λ => σ ~ λ-1.6 to 0Mie Scattering r >> λ => σ ~ λ0 Geometric Scattering Thus, larger λ => lower attenuation
Scintillation noise :- Inhomogenities in Temp. and Pressure Variations in Refractive Index along the transmission path Speckled pattern (both in time and space) at the receiver
Advantages of FSO :- • Link capacity:- • capable of sending up to 1.25 Gbps of data, voice, and video communications simultaneously through the air • enables optical communications at the speed of light • full-duplex Gigabit Ethernet throughout • WDM(wavelength division multiplexing) leading upto 10Gbps connectivity.
Advantages …….. Contd. • Economical :- • Uses optical transceiver-cheaper • No licensing for spectrum-bandwidth allocation is free • Requires no software upgradation –for particular device • Immune to radio frequency interference and saturation.
Advantages …….. Contd. • Simpler to install-just connecting the to transceiver. • Highbit rates. • lowbit error rates • Protocol transparency-using highly directional beam. • easy to encrypt any data travelling across the FSO connection
Disadvantages of FSO :- • Beam dispersion-atmospheric effect. • Atmospheric absorption • Fog -one of major cause. • Scintillation • Sun at opposite side to receiver-swamp signals. • Shadowing .
Disadvantage…….. Contd. • Requires a compatible area for installation. • Devices require maintenance.
Application-FSO :- • LAN-to-LAN connections on campuses at Fast Ethernet or Gigabit Ethernet speeds • LAN-to-LAN connections in a city-Metropolitan area network. • Converged Voice-Data-Connection • Temporary network installation (for events or other purposes). • Re-establish high-speed connection quickly (disaster recovery).
Application-FSO :- ..Contd. • For communications between spacecraft, including elements of a satellite constellation. • As option for intra connectivity in companies.
Future scope of technology:- • Deep space exploration. • High speed switching systems. • Analogous to satellite communication link. • Will reduce the effective cost of means of communications.
Conclusions :- • Short distance connectivity. • Atmospheric condition dependency. • Higher speed and bandwidth. • Immune to data loss. • Highly secure. • Fast temporary installation. • Free of cost spectrum.
Every technologies have short comes But its merits are the reason they are being used in various technologies “Reveals a new world to be explored”.
References :- An Introduction to Free-space Optical Communications Hennes HENNIGER1, Otakar WILFERT2,1 Institute of Communications and Navigation, German Aerospace Center (DLR), 82230 Wessling, Germany,2University of Technology Purkynova 118, CZ-61200 Brno, Czech Republic. www.wikkipedia.com www.freespaceoptics.com Free-Space Optical Communications at JPL/NASA H. Hemmati. Integration Scenarios for Free Space Optics in Next Generation (4G) Wireless Networks Waqar Hameed*, S. Sheikh Muhammad** and Noor Muhammad Sheikh*. Experimental Performance Study of a Very High Speed Free Space Optic Link at the University of Beira Interior Campus: a Case Study. An Intra-Chip Free-Space Optical Interconnection, Jing Xue, Alok Garg, Berkehan Ciftcioglu, ShangWang, Jianyun Hu, Ioannis Savidis, yManish Jain,Michael Huang, Hui Wu, Eby G. Friedman, yGary W. Wicks, yDuncan Moore. Google search-images.
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