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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. - PowerPoint PPT Presentation
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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
• 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
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
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
Identify Optical Requirements
IF Parameters
-12 C to 35 COperation Temperature
625 mMinimum Fiber Length
21.6 kmMaximum Fiber Length
6 - Initial, 4.7 - FinalDigital RMS SNR (Q)
10-9 Initial, 10-6 FinalBit Error Rate
C-BandChannel Wavelengths
200 GHz SpacingChannel Spacing
12 or 16 ChannelsNumber WDM Channels
10 Gbits/sBit Rate / Channel
IF Signal Path
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
Fiber Allocations
IF 120 Gbps WDM 1
LO - 2.048GHz, 512 MHz, 128 MHz 1
MCB Ethernet 2
Emergency Communication 1
Telephone Digital System 2
Total Lit Fibers per Antenna 7
12 Fibers Installed per Pad with 5 spares
Fiber Comparison
Parameter LEAF MetroCor SMF-28
Attenuation (22 km) 5.5 dB 5.5 dB 6.6 dB Maximum Bit Rate w/o Penalty 16.4 Gbits/s 20.8 Gbits/s 8.2 Gbits/s Dispersion Power Penalty (22 km) 0.5 dB 0.3 dB 2 dB Max. Launch Power 3.8 dBm 2.5 dBm 4.3 dBm Cost Relative to SMF-28 >200% 167% 100%
Transmission Losses
Fiber Attenuation -6.6 dBConnectors, Splices, Bends -6.3 dBMUX, DMUX -12.5 dBTotal Transmission Losses -24.5 dB
Elements No. Units Loss/Unit (dB) Loss (dBm) Q (linear)IF Rack to Vertex Room Bulkhead
Launch Power 0.00 31.2016ch WDM MUX 1 -6.00 -6.00Connector 3 -0.30 -0.90Fiber (km) 0.004 -0.30 0.00
Vertex Room Bulkhead to Antenna Pad Pv tx bulkhead = -6.90
Connector 1 -0.30 -0.30Fiber (km) 0.02 -0.30 -0.01
Farthest Antenna Pad to CB Termination Panel Plast antenna pad = -7.21
MIL Connector 2 -0.50 -1.00Connector 1 -0.30 -0.30Fiber (km) 0.7 -0.30 -0.21Splice 2 -0.10 -0.20Bends 18 -0.10 -1.80
CB Termination Panel to Patch Panel Ptermination panel = -10.72
Connector 3 -0.30 -0.90Fiber (km) 22 -0.30 -6.60EDFA Gain 1 12.00
Correlator Patch Panel to Correlator Receiver PIF patch panel = -6.22
Fiber (km) 0.004 -0.30 0.00Connector 3 -0.30 -0.9016ch WDM DMUX 1 -6.50 -6.50
Received Power -13.62 -25.20Receiver Sensitivity -20.00 6.00Margin 6.38 0.00
Erbium Doped Fiber Amplifiers
— ( )
— ( )
— ( )
OEM of EDFA
EDFA Performance
• All channels will fall in the linear region
Result #1
• Single Mode Fiber with an EDFA will have adequate optical power.
•But what about Q ?
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.
Transmission Quality
For BER = 10-9 the system requires:
• Received Q > 6
• Received power > –20 dBm.
Eye Pattern
Polarization Dependent Loss
No. Units Loss/Unit PDL (dB) (dB)
Connectors[6] 13 0.1 1.3 Multiplexers 2 0.1 0.2
Receiver 1 0.12 0.12 Amplifier 1 0.5 0.5
Total PDL 2.12
Chromatic and Polarization Dispersion
SMF-28 MetroCor LEAF tD when L = 22 km 43 ps 17 ps 21.6 ps
PD at 10 Gbits/s 2 dB 0.3 dB 0.5 dB
Power Penalty Budget
EVLA IF System Power Penalties (in dB)Extinction Ratio -1.86Crosstalk -2.00Chromatic Disp. (SMF-28) -2.00PMD -0.04Nonlinearities 0.00PDL -2.12Component Aging -3.00Margin -3.00
Total Power Penalties (dB) -14.02Total Power Penalties (Linear) -25.23
Q Budget
Description Last Pad First Pad
Reciever (10-9) 6 ()Power Penalties 25.23 ()Transmitter Q 31.2 ()
Result #2
Achieve a BER of 10-9
— Launch Requirements - 10 Gbits/s @ 0 dBm
— Launch Q = 31Receiver
— Assumes sensitivity -20 dBm
— 10-9 , @ 10 Gbits/s
Cost Comparison
SMF 28 MetroCor LEAF100% 167% 200%
Fiber Allocations
IF 120 Gbps WDM 1LO - 2.048GHz, 512 MHz, 128 MHz 1MCB Ethernet 2Battery Back-up Communication 1Telephone Digital System 2Total Lit Fibers per Antenna 712 Fibers Installed per Pad, 5 spares
System Budget
Double Armor Cable, SMF-28 $636,000EDF Amplifier (27) $300,000Total $936,000
CDR Recommendation
• Single Mode Fiber, SMF
• Twelve fibers per pad
• Fourteen connectors
• Twenty-seven erbium doped fiber amplifiers
• Prototype before purchase