J. Monari 2 nd SKADS Workshop October 2007 BEST-2 test bed: Radio over Fiber experiences Presented by Monari Jader IRA-INAF Radiotelescopio Croce del Nord Villafontana (BO) ITALY

J. Monari 2 nd SKADS Workshop October 2007 Summary 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 link Home made link Collaboration with industry: ANDREW and MITEQ Collaboration with industry: ANDREW and MITEQ

J. Monari 2 nd SKADS Workshop October 2007 The costs of both of them are very similar (hardware and manpower) Which solutions? Coaxials 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. Monari 2 nd SKADS Workshop 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. Monari 2 nd SKADS Workshop October 2007

J. Monari 2 nd SKADS Workshop October 2007 RF Analog Optical Link Vs 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. Monari 2 nd SKADS Workshop October 2007 Connectors APC (Angle Polished Connector) has RL>70dB → increases the performance of the RoF link (Dynamic and NF) DIN/APC SC/APC

J. Monari 2 nd SKADS Workshop October 2007 Which kind of fiber to choose?

J. Monari 2 nd SKADS Workshop October 2007 (extrapolations from the previous measurements) Relative Phase variation among fibers

J. Monari 2 nd SKADS Workshop October 2007

J. Monari 2 nd SKADS Workshop October 2007 Freq=408MHz, Links lenghts = 300mt Relative Phase Stability Vs. Time Stability Vs. Time

J. Monari 2 nd SKADS Workshop October 2007 IRA INAF analog home made link

J. Monari 2 nd SKADS Workshop October 2007 Linee ottiche Linee elettriche The Theoretical model

J. Monari 2 nd SKADS Workshop 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 realization…

J. Monari 2 nd SKADS Workshop October 2007 Link optimised at 16MHz BW Gain -22.9dB Gain Flatness <0.1dB Input Return Loss >28.6dB Output Return Loss >30.9dB Input IP dB m Noise Figure 31dB Link (not optimised) in the MHz band Gain min -23.7dB Gain max -22.1dB Input Return Loss >9.5dB Output Return Loss >24.2dB Input IP3 >+30dBm Noise Figure <31.25dB Measurements

J. Monari 2 nd SKADS Workshop October 2007 Year: 2004 Estimated cost = 500€ for a mass production of 400 pieces (3 years ago quotation) Cost of the optical source

J. Monari 2 nd SKADS Workshop October 2007 Custom product: 1.Electrical specs (<1GHz) 2.Mech. Specs (RX housing) TXRX =1310nm NF=36dBdB Gain=-25dB BW=(0.1-1)GHz IIP3>+33dBm Input RL>15dB Output RL>20dB Power The collaboration with industry industry

J. Monari 2 nd SKADS Workshop October 2007 BEST-2 optical link slides show

J. Monari 2 nd SKADS Workshop October 2007 Collaboration with MITEQ

J. Monari 2 nd SKADS Workshop October 2007

J. Monari 2 nd SKADS Workshop October 2007 Conclusion Fibers are better than coaxials in the array for BEST purposes The Analog Optical link (RoF) simplifies and it is more reliable than the digital optical connection ones Loose fiber and APC connectors could be useful for large arrays Home made links are convenient if: keep in touch directly the factories of laser source to produce them To prepare a lab to test the home made links A collaboration with industry as ANDREW and MITEQ could be an useful and interesting opportunity The experience gained with BEST SKA test best has shown: …thank you for your attention

J. Monari 2 nd SKADS Workshop October 2007

J. Monari 2 nd SKADS Workshop October 2007 First observation of the transit of Cassiopea with BEST-1 1 Rx=¼ of cylinder4 receivers=1 cylinder 5.6 deg. 7.1 deg. (1.7 deg.) Old Cross hardware detector & chart recorder BEST-1 IF

J. Monari 2 nd SKADS Workshop October 2007

J. Monari 2 nd SKADS Workshop October 2007 Future with MITEQ

J. Monari 2 nd SKADS Workshop October 2007

J. Monari 2 nd SKADS Workshop October mt long Dielectric protection against rodens Loose cable construction min (  /  T) The BEST-2 analog optical link