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EVLA Fiber Selection Critical Design Review

EVLA Fiber Selection Critical Design Review. December 5, 2001. Fiber Selection CDR. Decision about what fiber to install Select cable (Jan 02) Order cable (Jan 02) Receive cable (May 02) Start installation (June 02) Complete install (June 03) . IF Scientific Requirements.

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EVLA Fiber Selection Critical Design Review

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  1. EVLA Fiber Selection Critical Design Review December 5, 2001

  2. Fiber Selection CDR • Decision about what fiber to install • Select cable (Jan 02) • Order cable (Jan 02) • Receive cable (May 02) • Start installation (June 02) • Complete install (June 03)

  3. IF Scientific Requirements • Samplers Dominate the Digital Performance • Input Bandwidth 2-4 GHz • Clock Rate 4096 MHz • Resolution 3 Bits • Aperture Time 50 Ps • Clock Jitter 5 Ps • Clock Rise Time 25 Ps

  4. IF - DTS Specifications • Bit-Error-Rate (End-of-Life) 10-6 • Data Bit rate per Polarization 24 GHz • Data Bit rate per Antenna (12) 96 GHz • Formatted Bit rate per Antenna 120 GHz • Jitter Contribution N/A • Loss of Synchronization <1% Loss of Data

  5. Task at Hand • Select a fiber and a Configuration that can transmit the IF data from the antennas to the correlator. • Identify Optical Requirements • Compare Fibers • Select Fiber

  6. Identify Optical Requirements

  7. Bit Rate / Channel 10 Gbits/s Number WDM Channels 12 or 16 Channels Channel Spacing 200 GHz Spacing Channel Wavelengths C-Band Bit Error Rate 10-9 Initial, 10-6 Final Digital RMS SNR (Q) 6 - Initial, 4.7 - Final Maximum Fiber Length 21.6 km Minimum Fiber Length 625 m Operation Temperature -12 C to 35 C IF Parameters

  8. IF Signal Path

  9. Types of Fiber Analyzed • Corning Products • SMF-28, Standard Single Mode Optical Fiber • MetroCor, Non-Zero Dispersion Shifted Fiber • LEAF, Large Effective Area Fiber • All three fiber types will work for EVLA

  10. Fiber Allocations

  11. Fiber Comparison

  12. Transmission Losses

  13. Erbium Doped Fiber Amplifiers • ( ) • ( ) • ( )

  14. OEM of EDFA

  15. EDFA Performance • All channels will fall in the linear region

  16. Result #1 • Single Mode Fiber with an EDFA will have adequate optical power. • But what about Q ?

  17. Digital SNR (Q) • Q is the ratio of signal current to noise current. • Q = ( I1 - I0 ) / ( i1 + i0 ) • ( I1 – I0 ) is the excess electric signal available for distinguishing between a 1 and a 0. • ( i1 + i0 ) is the RMS electric current induced by noise during a transition.

  18. Transmission Quality • For BER = 10-9 the system requires: • Received Q > 6 • Received power > –20 dBm.

  19. Eye Pattern

  20. Polarization Dependent Loss

  21. Chromatic and Polarization Dispersion

  22. Power Penalty Budget

  23. Q Budget

  24. Result #2 • Achieve a BER of 10-9 • Launch Requirements - 10 Gbits/s @ 0 dBm • Launch Q = 31 • Receiver • Assumes sensitivity -20 dBm • 10-9 , @ 10 Gbits/s

  25. Cost Comparison

  26. Fiber Allocations

  27. System Budget

  28. CDR Recommendation • Single Mode Fiber, SMF • Twelve fibers per pad • Fourteen connectors • Twenty-seven erbium doped fiber amplifiers • Prototype before purchase

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