Review Perancangan Sistem Komunikasi Optik

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  • 8/13/2019 Review Perancangan Sistem Komunikasi Optik

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    Review Perancangan SKO

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    Power Budget

    TRANSMITTER RECEIVER

    Fibre, connectors and splices

    Power Budget (dB)

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    Fiber Optic Link Power Budget

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    Fiber Optic Connectors & Splices

    Connectors

    Demountable

    terminations for fiber

    Connect to transmitters

    and receivers

    Splices Permanent termination

    of two fibers

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    Fiber Optic Splices

    Permanent terminations for fiber

    Specifications

    Loss

    Repeatability

    Environment

    Reliability

    Back reflection

    Ease of termination

    Cost

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    Cable, Connector & Splice Testing

    Continuity testing with

    visual tracer/fault locator

    Insertion loss with source

    and meter

    OTDR testing

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    Point-to-Point Links

    Key system requirements needed to analyze optical fiber links:

    1. The desired (or possible) transmission distance

    2. The data rate or channel bandwidth

    3. The bit-error rate (BER)

    (a) Core size

    (b) Core index profile

    (c) BW or dispersion

    (d) Attenuation

    (e) NA or MFD

    MMF or SMFLED or laser pin or APD

    (a) Emission wavelength

    (b) Spectral line width

    (c) Output power

    (d) Effective radiating area

    (e) Emission pattern

    (a) Responsivity

    (b) Operating

    (c) Speed

    (d) Sensitivity

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    Selecting the Fiber

    Other factors to consider:attenuation (depends on?)

    and distance-bandwidth product (depends on?)

    cost of the connectors, splicing etc.

    Then decide

    Multimode or single mode

    Step or graded index fiber

    Bit rate and distance are the major factors

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    Selecting the Optical Source

    Emission wavelength depends on acceptable

    attenuation and dispersion

    Spectral line width depends on acceptable

    dispersion (LEDwide, LASERnarrow)

    Output power in to the fiber (LEDlow, LASER

    high)

    Stability, reliability and cost

    Driving circuit considerations

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    Selecting the detector

    Type of detector

    APD:High sensitivity but complex, high bias voltage

    (40V or more) and expensive

    PIN:Simpler, thermally stable, low bias voltage (5V or

    less) and less expensive

    Responsivity (that depends on the avalanche gain

    & quantum efficiency)

    Operating wavelength and spectral selectivity

    Speed (capacitance) and photosensitive area

    Sensitivity (depends on noise and gain)

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    Typical bit rates at different wavelengths

    Wavelength LED Systems LASERSystems.

    800-900 nm

    (TypicallyMultimode Fiber)

    150 Mb/s.km 2500 Mb/s.km

    1300 nm (Lowest

    dispersion)

    1500 Mb/s.km 25 Gb/s.km

    (InGaAsP Laser)

    1550 nm (Lowest

    Attenuation)

    1200 Mb/s.km Up to 500

    Gb/s.km

    (Best demo)

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    Design Considerations

    Link Power Budget

    There is enough power margin in the system to

    meet the given BER

    Rise Time Budget

    Each element of the link is fast enough to meet

    the given bit rate

    These two budgets give necessary conditions

    for satisfactory operation

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    SONET dan SDH

    SONET Bit Rate (Mbps) SDH

    OC-1 51.84 -

    OC-3 155.52 STM-1

    OC-12 622.08 STM-4

    OC-24 1244.16 STM-8

    OC-48 2488.32 STM-16

    OC-96 4976.64 STM-32

    OC-192 9953.28 STM-64

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    Dispersion budget: point-point

    example

    Length of link: 200 km SMF

    PMD: 0.1 ps/nm/km

    Chromatic dispersion: 0.5 ps/nm/km

    Speed of link: OC96~ 5 Gbps Pulse width: ?? ps

    Allowable dispersion with 20% rule: ?? ps

    Amplifiers every 50 km PMD: 1.0 ps

    Spectral width: 0.3 nm

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    Dispersion budgetsame example butat OC48(continued)

    Every eighth link requires repeater

    Item Descr ipt ion Amoun t

    (a) PMD for 50 km, 0.1 ps/nm/km ?? ps

    (b) Material dispersion, 0.5 ps/nm/km ?? ps

    (c) Amplifier ? ps

    (d) Total per link (a+b+c) ?? ps

    (e) After eight links (8xd) ?? ps

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    Design summary: 200 km OC96linkItem Description L ink Loss Dispers ion

    (a)Optical fiber loss at 1310 nm: 250 kmlength at 0.35 db/km; 0.6 ps/nm/km ?? dB ?? ps

    (b)

    Splice loss: 10 splices at 0.1

    db/splice ?? dB

    (c)

    Connection loss: 20 connections at

    0.5 db/connection ?? dB

    (d) 4 amplifiers, gain of 20 dB each ?? dB ?? ps

    (e)

    1 repeater, gain of 20 dB; n equally

    spaced repeaters reduces dispersionby factor of n+1 ?? dB

    (f) Design margin ?? dB

    (g) Total link loss (a)-(f) ?? dB ?? ps

    (h) Transmitter avg. output power ?? dBm

    (I) Receiver input power (h+g) ?? dBm ?? ps

    (j) Receiver dynamic range ?? dBm

    (k) Receiver specs at BER 10-9 ?? dBm ?? ps

    (l) Remaining margin (k-i) ?? dB ?? ps

    OK OK OK

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    Dispersion budget: point-point

    example

    Length of link: 200 km SMF

    PMD: 0.1 ps/nm/km

    Chromatic dispersion: 0.5 ps/nm/km

    Speed of link: OC96~ 5 Gbps Pulse width: 200ps

    Allowable dispersion with 20% rule: 40ps

    Amplifiers every 50 km PMD: 1.0 ps

    Spectral width: 0.3 nm

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    Dispersion budgetsame example but

    at OC96(continued)Item Descr ipt ion Amoun t

    (a) PMD for 50 km, 0.1 ps/nm/km 1.5 ps

    (b) Material dispersion, 0.5 ps/nm/km 7.5 ps

    (c) Amplifier 1 ps

    (d) Total per link (a+b+c) 10 ps

    (e) After four links (4xd) 40 ps

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    Design summary: 200 km OC96link

    (a)

    Optical fiber loss at 1310 nm: 200km

    length at 0.35 db/km; 0.6 ps/nm/km -70 dB 120 ps

    (b) Splice loss: 8splices at 0.1 db/splice -0,8 dB

    (c)

    Connection loss: 16connections at

    0.5 db/connection -8 dB

    (d) 3amplifiers, gain of 20 dB each 60 dB 3 ps

    (e)

    1 repeater, gain of 20 dB; n equally

    spaced repeaters reduces dispersion

    by factor of n+1 20 dB

    (f) Design margin -10 dB

    (g) Total link loss (a)-(f) -8,8 dB 61,5 ps

    (h) Transmitter avg. output power -10 dBm

    (I) Receiver input power (h+g) -18,8 dBm 61,5 ps

    (j) Receiver dynamic range -10 to -25 dBm

    (k) Receiver specs at BER 10-9 -25 dBm 40 ps

    (l) Remaining margin (k-i) 6,2 dB -21,5 ps

    OK OK OK