J. Monari 2 nd SKADS Workshop 10-11 October 2007 BEST-2 test BEST-2 test bed bed : : Radio over Fiber Radio over Fiber experiences experiences Presented by Monari Jader IRA-INAF Radiotelescopio Croce del Nord Villafontana (BO) ITALY Email : [email protected]
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J. Monari 2 nd SKADS Workshop 10-11 October 2007 BEST-2 test bed: Radio over Fiber experiences Presented by Monari Jader IRA-INAF Radiotelescopio Croce.
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J. Monari2nd SKADS Workshop 10-11 October 2007
BEST-2 test BEST-2 test bedbed: : Radio over Fiber Radio over Fiber
experiencesexperiences
Presented by Monari Jader IRA-INAF Radiotelescopio Croce del Nord Villafontana (BO) ITALY Email : [email protected]
J. Monari2nd SKADS Workshop 10-11 October 2007
SummarySummary
• Introduction: Coax Cables Vs. Fibers Introduction: Coax Cables Vs. Fibers
• Digital Optical link Vs. Analog Optical link Digital Optical link Vs. Analog Optical link
• Which kind of Fibers or connectors?Which kind of Fibers or connectors?
• Home made linkHome made link
• Collaboration with industry: ANDREW and Collaboration with industry: ANDREW and MITEQMITEQ
J. Monari2nd SKADS Workshop 10-11 October 2007
The costs of both of them are very similar (hardware and manpower)
Which solutions?
Coaxials vs FibersCoaxials vs Fibers
Coaxial cables to external cabins where
signals can be digitized and sent via Fast Ethernet links to the processing room
Analogue Optical Links directly from Focal Lines to the Processing Room
J. Monari2nd SKADS Workshop 10-11 October 2007
Coaxial solution:
MTBF: 10624h -> ~1.2y
RoF solution:
MTBF: 37137h -> ~4.2y
• MIL-HDBK-217-FN2 data base
• series reliability model
• 100% duty cycle
• operating temperature: 30°C
• environments:
• GM (Ground Mobile) for antenna equipment
• GF (Ground Fixed Uncontrolled) for cabin equipment
• GB (Ground Benign Controlled) for processing room equipment
J. Monari2nd SKADS Workshop 10-11 October 2007
J. Monari2nd SKADS Workshop 10-11 October 2007
RF Analog Optical Link Vs RF Analog Optical Link Vs digital link….digital link….
Big efforts are spent to design low cost analog links because they offer several benefits:
1) The electronic move from the outside cabins to the processing room in the central building.
2) More Reliable, less risks and easier maintenance.
3) No Sync, LO and PPS distribution from the main building to cabins.
4) Fibers are cheaper, lighter and more flexible than coaxial cables.
5) Fibers have more phase stability vs temperature and amplitude equalization in wide bandwidth than coaxial.
J. Monari2nd SKADS Workshop 10-11 October 2007
ConnectorsConnectors
APC (Angle Polished Connector) has RL>70dB → increases the performance of the RoF link (Dynamic and NF)
DIN/APC
SC/APC
J. Monari2nd SKADS Workshop 10-11 October 2007
Which kind of fiber to Which kind of fiber to choose?choose?
Tnom
T
t
nomt
TCD
610610
0
10
20
30
40
50
60
70
80
-20 -10 0 10 20 30 40 50
Temperature [°C]
TC
D [
pp
m/°
C]
loose fiber 1loose fiber 2
loose fiber 3loose fiber 4
tight fiber 1tight fiber 2
J. Monari2nd SKADS Workshop 10-11 October 2007
(extrapolations from the previous measurements)
Relative Phase variation Relative Phase variation among fibers among fibers
J. Monari2nd SKADS Workshop 10-11 October 2007
J. Monari2nd SKADS Workshop 10-11 October 2007
Freq=408MHz, Links lenghts = 300mt
Relative PhaseRelative Phase Stability Vs. TimeStability Vs. Time
J. Monari2nd SKADS Workshop 10-11 October 2007
IRA INAF analog home IRA INAF analog home made linkmade link
J. Monari2nd SKADS Workshop 10-11 October 2007
in
outopta R
RkkgdBG
4log10
221
2
10
21
2
2
221
21024
2log10kgTk
IIeRINIR
Rkkg
RdBNF
opt
DarkDDin
outopt
in
Linee ottiche
Linee elettriche
The Theoretical modelThe Theoretical model
J. Monari2nd SKADS Workshop 10-11 October 2007
Direct modulation of the laser
Optical source: Laser DFB 1310nm
Resistive matching
Utilizzo di un fotodiodo di monitor per realizzare un controllo in retroazione sul livello di potenza ottica emessa
Circuito di accensione lenta
Direct detection by photodiode PIN
Passive optical RX (No post-amplification)
From the idea to the From the idea to the realization…realization…
J. Monari2nd SKADS Workshop 10-11 October 2007
Link optimised at408MHz @ 16MHz BW
Gain -22.9dB
Gain Flatness
<0.1dB
Input Return Loss
>28.6dB
Output Return Loss
>30.9dB
Input IP3 +32.8dBm
Noise Figure 31dB
Link (not optimised) in the
300-600MHz band
Gainmin-23.7dB
Gainmax-22.1dB
Input Return Loss
>9.5dB
Output Return Loss
>24.2dB
Input IP3 >+30dBm
Noise Figure <31.25dB
MeasurementsMeasurements
J. Monari2nd SKADS Workshop 10-11 October 2007
0
100
200
300
400
500
600
1 10 100 1000
Quantity
Las
er (
DF
B)
cost
[eu
ro]
Year: 2004
Estimated cost = 500€ for a mass production of 400 pieces (3 years ago quotation)
Cost of the optical sourceCost of the optical source