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Published byWarren Bond Modified over 8 years ago
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Prof. Alfred J Bird, Ph.D., NBCT http://www.cs.umb.edu/~abird abird@cs.umb.edu Office – Science 3rd floor – S-03-130 Office Hours – Monday and Thursday 3:00PM to 4:00PM
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Seven Levels 7 – Application 6 – Presentation 5 – Session 4 – Transport 3 – Network 2 – Data Link 1 - Physical
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4 – Applications 3 – Transport 2 – Internet 1 – Network Interface
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568-B.1 – Commercial Cabling Standards 568-B.2 – Twisted Pair Media Standards 568-B.3 – Optical Fiber Cabling Standards
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In this field light means any kind of Electromagnetic Radiation What is Electromagnetic Radiation? What radio station do you listen to? WGBH 99.5 means the signal goes up and down about 99500000 times a second. Commercial Power (120v) in the US goes up and down exactly 60 times per second. X-Rays go up and down about 1000000000000000000 times per second.
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Wavelength – the distance between two similar points on the wave. Frequency – The time it takes for a wave to complete one complete cycle of the wave. Wave Speed is equal to the Frequency multiplied by the Wavelength. In symbols: v = f * λ Pay attention to the units.
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It is difficult and confusion to write large and small numbers with a lot of zeros. We have a method called scientific notation to simplify this problem 300000000 = 3x10 8 .0000000000000000000000602 = 6.02X10 -23 In computer sense do this as 3E8 or 6.02E-23
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Speed of light in a vacuum 3x10 8 m/s or 1.86X10 5 mi/s WBZ – 1030kHz λ = v/f : 300000000m/s ÷ 1030000hz ≈ 300m λ = v/f : 300Mm/s ÷ 1.03Mhz ≈ 300m Red Light – 400Thx λ = v/f : 300000000m/s ÷ 4000000000hz ≈.0000000075m λ = v/f : 300Mm/s ÷ 4Tm/s ≈ 750nM
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Extremely wide system bandwidth Immunity to electrostatic interference Elimination of crosstalk Lower signal attenuation Lower costs Safety Corrosion Security
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Speed of Light Varies with the Medium Reflection Refraction Index of Refraction Core Cladding Protective Jacket
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Optical fiber cabling
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The modulator changes the electrical signals into light pulses. There are two primary types of light sources: Diode Lasers (DLs) Distributed Feedback Lasers (DFBs) Dense Wavelength Division Multiplex (DWDMs) Vertical Cavity Surface Emitting Lasers (VCSELs) Tunable Lasers Light Emitting Diodes (LEDs)
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Converts the light back into electrical signals. Important Characteristics: Responsivity Response speed Spectral response
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Fusion splicing Mechanical splices
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Attenuation Scattering Absorption Macrobending Microbending Dispertion
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SONET/SDH – Standards Increase in network reliability Network management Defining methods for synchronous multiplexing of digital signals Defining a set of generic operating/equipment standards Flexible architecture
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You cannot see IR light but it can still hurt you! Lasers concentrate EM radiation! Light beams will fan out from open connections! Light beams will fan out from broken cables!
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