Fiber Allocations Preliminary Design Review

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Fiber Allocations Preliminary Design Review

• December 5, 2001

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Fiber Allocations
IF 120 Gbps WDM 1
LO - 2.048GHz, 512 MHz, 128 MHz 1
MCB Ethernet 2
Battery Back-up communication 1
Telephone Digital System 2
Total Lit Fibers per Antenna 7
12 Fibers Installed per Pad, 5 spares
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Fiber Routing
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Burial Depth

• LO system requires phase stability.
• Stability determined by fiber thermal expansion
• Expansion determined by ground temperature
• Limit fiber expansion to ______ LO cycles / day.
• Highest transmitted LO frequency is 2GHz.
• Wavelength of 2 GHz in fiber is 10 cm.
• Limit fiber expansion to _____cm / day

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Fiber Thermal Expansion

• Average annual temp. variation at 1 m 17.4 C.
• Coefficient of expansion of fiber 18 x 10-7
  /C.
• DL (18 x 10-7 /C)(17.4 C)(22 km)
• 68 cm annually
• Average fiber expansion is estimated to be less
  than the equivalent of 7 cycles over 180 days.

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LO Characteristics_at_ 2.048 GHz
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Fiber InstallationPreliminary Design Review

• December 5, 2001

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Cable Wrap

• Riser Grade Cable

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IF Signal Path
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Cable Cross Section
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Basic Cabling Plan
C5
Splice Box
C6
12 Fibers ea. antenna
60 Fibers
710 m
C7
C8
B5
C9
B6
60 Fibers
2.8 km
B7
B8
B9
A5
A6
60 Fibers
8.1 km
A7
A8
A9
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Fiber Cable Plan

• 13 Trunk Cables from CB out to the Array.
• 60, 72 and 96 fiber cables.
• Triple Jacket/ Double Armor.
• 12-fiber cable from trunks to antennas.
• 17 splice locations
• All standard single-mode fiber.

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EVLA Fiber Cable Plan
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Fiber Acceptance

• Every fiber to be tested at delivery.
• Installation Specification.
• Every fiber to be tested after installation.
• Acceptance specification to be developed.

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Splice Locations
West Arm North Arm East Arm
DW6 DN2 DW1
DW7 CN5 DE4
CW7 BN6 CE5
AW5 AN5 BE5
BetweenAW5/AW9 BetweenAN5/AN9 AE5
Between AE5/AE9
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Splice Box
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Antenna Pad Enclosure
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Antenna Junction Box
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Cable Grounding

• Bonded to ground at every connection.
• Bonded with 6 AWG copper, minimum.
• Bonded to antenna ground, control building
  ground, or a ground rod.

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Cable Burial Plan

• Trenched by NRAO G. Stanzione
• Spliced and terminated by NRAO R. Latasa
• Buried one meter depth, minimum.
• Cable identified with marker tape.
• Splices identified with a concrete monument.
• Armor grounded at each splice or termination.

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Estimated Cable Cost
Double Armor Cable
12 Fiber Cable 0.68 / ft
60 Fiber Cable 1.98 / ft
72 Fiber Cable 2.22 / ft
96 Fiber Cable 2.60 / ft
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Cable Costs( Excluding Grounding and other
miscellaneous parts )
Double Armor Cable 636,000
Splice Boxes 7,000
Antenna Pad Enclosure 27,000
Control Building MDF ( Term. Closet ) 7,000
Total Cost ( excl. misc. ) 677,000
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