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Fiber Phase Stability Status. Steven Durand & Jim Jackson September 8, 2003 National Radio Astronomy Observatory a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. OFS BrightWave Cable. Double armor loose tube cable - PowerPoint PPT Presentation
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SJD/JJ Advisory - Sept 2003 1
Fiber Phase Stability Status
Steven Durand & Jim Jackson
September 8, 2003
National Radio Astronomy Observatory
a facility of the National Science Foundation
operated under cooperative agreement by
Associated Universities, Inc.
SJD/JJ Advisory - Sept 2003 2
ArrayDistribution
Panel
I FPatch Panel12 WDM per
Fiber
LOPatch Panel
M & CPatch Panel(TX & RX)
74 Fibers 148 Fibers 148 Fibers
Array FO TerminationRoom
North ArmFiber Entrance
(23 Pads,276 Fibers)
East ArmFiber Entrance
(23 Pads,276 Fibers)
West ArmFiber Entrance
(28 Pads,336 Fibers)
Space ReservedE Array Option
(360 Fibers)
SJD/JJ Advisory - Sept 2003 3
OFS BrightWave Cable
• Double armor loose tube cable
– Corrugated, copolymer coated carbon, steel tape applied longitudinally
• Polyethylene jacket– 1.4 mm Outer, 1.2 mm Middle, 1.0 mm Inner
• Glass/epoxy composite dielectric rod core
SJD/JJ Advisory - Sept 2003 4
Cable Cross Section
SJD/JJ Advisory - Sept 2003 5
OFS Matched Cladding Fiber
• Matched cladding single-mode – Nonzero-dispersion optical fiber
• Gel-filled buffer tubes– Installed in a reverse oscillation lay – 12 fibers per tube
SJD/JJ Advisory - Sept 2003 6
OFS Matched Cladding Specifications @ 1310 nm
• Attenuation coefficient: 0.31-0.35 dB/km• Chromatic dispersion: -9 ps/nm-km• Dispersion slope: 088 ps/nm2-km• Group index of refraction: 1.471• Polarization M dispersion: ≤0.5 ps/(km)1/2 • Rayleigh Backscattering: -49.6 dB• Coefficient of Expansion*: 6 PPM/˚C
* NRAO Estimate
SJD/JJ Advisory - Sept 2003 7
LO Technical RequirementsBased on the Scientific Goals
after all Round-Trip Corrections
• Short Term: < 0.5 ps RMS per second
• Long Term: < 1.4 ps per 30 minutes ~20 degrees at 40 GHz
• Delta Slope: < 0.2 ps change per minute Over 30 minutes
SJD/JJ Advisory - Sept 2003 8
Phase Error Allocation
• Front End 0.4 ps per 30 Min
• LO Converters 0.6 ps per 30 Min
• Fiber System 0.4 ps per 30 Min– RTP measurement accuracy* 0.05 ps
– 512 MHz + 128 Hz jitter* 0.1 ps
– Fiber induced errors 0.25 ps
*NRAO estimates
SJD/JJ Advisory - Sept 2003 9
Round Trip Block Diagram
1310 nm LaserModulator
Optical Receiver-30 dBm
Correlator
PhaseLock Loop
128 HzSignal
512 MHz Signal
Maser
512 MHz Generator128 Hz Generator
5 MHz Generator
512 MHz + 128 HzOffset Generator
Phase Detector
Comparitor
SJD/JJ Advisory - Sept 2003 10
Verification
• Is the magnitude and rate of change of the phase caused by the 22Km tolerable?
• How identical are the two fibers used in the round trip phase measurement system?
Or Is the un-compensated difference in phase uncertainty tolerable?
SJD/JJ Advisory - Sept 2003 11
RTP Test Setup
X
OptTx
OptRx
RTP1
512 MHz
RTP1
DC Out
RTP2
DC Out
Mixers
XOptRx
RTP2
Laser
OpticalSplitter
Test designed and operated byDoug Gerrard and Don Haenichen
SJD/JJ Advisory - Sept 2003 12
RTP Test Hardware
SJD/JJ Advisory - Sept 2003 13
Analog Mixer as a Phase Detector
SJD/JJ Advisory - Sept 2003 14
Temperatures
10
15
20
25
30
35
40
45
8/11/03 18:00 8/11/03 20:00 8/11/03 22:00 8/12/03 0:00 8/12/03 2:00 8/12/03 4:00 8/12/03 6:00 8/12/03 8:00 8/12/03 10:00
Date/Time
Deg
rees C
Inner Temp Room Temp Outer Temp
RTP and Diff
0.00
20.00
40.00
60.00
80.00
100.00
120.00
140.00
160.00
180.00
200.00
8/11/03 18:00 8/11/03 20:00 8/11/03 22:00 8/12/03 0:00 8/12/03 2:00 8/12/03 4:00 8/12/03 6:00 8/12/03 8:00 8/12/03 10:00
Date/Time
Ro
un
d T
rip
Ph
as
e S
hif
t (d
eg
ree
s)
70.00
75.00
80.00
85.00
90.00
95.00
100.00
Dif
f P
ha
se
Sh
ift
(de
gre
es
)
RTP (degrees) Diff (degrees)
65 Km Spool Test
5 cycles X 360° / 13° = 137 Ratio
6 ppm / °C
SJD/JJ Advisory - Sept 2003 15
Calculated Temperature Effects on Phase
• 22 Km Length Change per (6 ppm / °C)– 30 minutes = 5.4 um → 0.028 ps– 6 months = 1.4 m → 6677 ps (3.4 cycles)
• 30 meters in Control Building per– 30 minutes = 10.4 mm → 49 ps
• 28 meters up the Antenna per– 30 minutes = 10.7 mm → 51 ps
Total ~ 100 ps/30 min (EVLA Memo – 44)
(100 ps / 30 min) / (137 Ratio ) = ~.73 ps / 30 min
SJD/JJ Advisory - Sept 2003 16
Master Pad Fiber Enclosure
SJD/JJ Advisory - Sept 2003 17
Fiber Enclosure Temperature
SJD/JJ Advisory - Sept 2003 18
Master Pad Fiber EnclosureSlope represents 0.5 ps / 30 minutes½ for 2 way trip = 0.25 ps / 30 minutes
1° Phase Shift = 5.4 ps
SJD/JJ Advisory - Sept 2003 19
Master Pad Fiber Enclosurewith Insulation
SJD/JJ Advisory - Sept 2003 20
Insulated Fiber Box Temperatures
SJD/JJ Advisory - Sept 2003 21
RTP1 and RTP2
62.0
64.0
66.0
68.0
70.0
72.0
74.0
76.0
78.0
80.0
82.0
84.0
8/29/0312:00
8/29/0318:00
8/30/030:00
8/30/036:00
8/30/0312:00
8/30/0318:00
8/31/030:00
8/31/036:00
8/31/0312:00
8/31/0318:00
9/1/030:00
9/1/036:00
9/1/0312:00
9/1/0318:00
9/2/030:00
9/2/036:00
9/2/0312:00
Date/Time
RT
P1
an
d R
TP
2 P
ha
se
Sh
ift
(de
gre
es
)
-4.0
-3.0
-2.0
-1.0
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
Dif
fere
nc
e P
ha
se
Sh
ift
(de
gre
es
)
RTP1 (degrees) RTP2 (degrees) Difference (degrees)
Insulated CB to MP
1° Phase Shift = 5.4 ps
Test Apparatus drift is +/- 0.5 ° per day
~ 0.22 ps per 30 minutes
SJD/JJ Advisory - Sept 2003 22
Cable Wrap Test Fixture
• Antenna – 540 ° Total
– 40 ° / minute
• Test Fixture test results:
< 0.5 ° shift
@ 1.2 GHz
SJD/JJ Advisory - Sept 2003 23
Conclusion
• The magnitude and rate of change of the phase shift caused by the buried 22Km is tolerable.
6 ppm / °C or Total ~ 0. 028 ps / 30 min
~ 3.4 cycles per 6 months
May have a problem with CB and Antenna fiber• The un-compensated difference of two fibers is
Measured less than ~.73 ps / 30 min• The cable wrap may also work.
SJD/JJ Advisory - Sept 2003 24
Elevation Cable Bend
SJD/JJ Advisory - Sept 2003 25
LO Block Diagram
512 MHzVCO
512 MHzVCXO
ZEROCROSSINGDETECTOR
PLL
512 MHz + 128 Hz
PHASEMONITOR
PLL
MASTER LOGENERATOR
MASTER LO128 Hz TO
DCSSYSTEM
MASTER LO128 Hz 5 MHz
MASTEROFFSETGENERATOR
ROUND TRIPPHASE
MEASUREMENT
MOD LASER
DEMOD
512 MHzDEMOD
512 MHzVCXO
PLLCLEAN
UP
LOREFERENCE
RECEIVER
512 MHz
ANTENNAFO
SYSTEM
CENTRALFOSYSTEM
OPTICALSplitter
SJD/JJ Advisory - Sept 2003 26
LO Optical Loss Budget
1310 nm LaserModulator
-6.2 dB6 dBm
Optical Receiver-30 dBm
22 km Fiber
-8.8 dBm
-6.2 dB22 km Fiber
OpticalReceiver-30 dBm
-25 dBm
Connectionsand Splices
Connectionsand Splices
Splitter
5%95%
-23 dBm
-8.8 dBm
-1 dB -14 dB
SJD/JJ Advisory - Sept 2003 27
Existing 6" Waveguide Conduit
1 5/8" Unitstrut
2" Liquid-Tight FMC
6" X 2" Threaded PVC45 degree ‘Y’
Track Level
Unistrut set inConcrete to 18" depth
SS Splice EnclosureAntennaUmbilicalJumper
Connector
8.5in. 14.5in.
17.0in.
19.0in. (min)
36.0in.(max)
SJD/JJ Advisory - Sept 2003 28
EVLA Fiber
DN2 DN3 DN4 DN5 DN6 DN7 DN8 DN9 CN5
TDN
CN6 CN7 CN8 CN9
TCN
BN5BN6BN7BN8BN9AN5AN6AN7AN8AN9
TBN
TANb
TANc
EVLA North Arm FiberCable Plan
Control Building
TANa
96 f iber2,604 f t
60 f iber4,173 f t
60 f iber12,965 f t
60 f iber12,965 f t
60 f iber13,642 f t
36 f iber20,709 f t
STCN.01STDN.01
STBN.01
STAN.01
STAN.02STAN.03
Splice
Manhole
Trunk Cable
Homerun Cable
Symbol Key
STAN.03
TANc
AN9
SJD/JJ Advisory - Sept 2003 29
Base SpliceEnclosure
SamplerRACK
LO System
Vertex Room
Lower PedRoom
Upper PedRoom
MCBRACK
ElevationCableBend
AzimuthCable Wrap
12:1 Mux
Vertex SpliceEnclosure
12 SingleMod Fiber
2
2
1
~92ToMIBs Multi
PedestalSplice
Enclosure
12 Single Mode Fibers to Control Building
24Multi
ToMIBs
24Multi
HybridCable
12
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