L a rg e Ante nna Arra y Re moting using RoF T e c hnique s - PowerPoint PPT Presentation

L a rg e Ante nna Arra y Re moting using RoF T e c hnique s for Ra dioa stronomic a l Applic ation E mb ra c e Me e ting , Bo lo g na 23 Se pte mb e r 2005

Outline � T he BE ST Pro je c t fo r the No rthe rn Cro ss � Ro FT e c hno lo g ie s Sig nific a nt Aspe c t � Ro FT e sting � T he F ie ld T ria l � Co nc lusio ns

T he S.K.A. Hybr id Conc e pt � We pro po se a L o w F re q ue nc y Arra y re mo ting via Ro Flinks[BW 0.1-2.5GHz; L e ng th fro m 2.5 to 10K m]: – T he la st te c hno lo g y pa pe rs (SK A me mo s o n Hyb rid so lutio n b y Va n Arde nne &L a zio a nd Va n Arde nne &Bunto n) indic a te a n a ppro xima te numb e r b e twe e n 200,000 a nd 800,000 links!!!!! � L OW COST is F UNDAME NT AL

Why use RoF L ink for Radioastr onomy L a rg e T e le sc ope s? � Dig ita l Ra dio e q uipme nts lo c a te d in a n I ndo o r Ce ntra l Are a � Simplific a tio n o f the L O a nd sync hro nism sig na ls distrib utio n � Pro te c tio n fro m L ig htning Strike s � RFI s I so la tio n � MT BF I mpro ve me nt � Ma inte na nc e Co st Re duc tio n � L a rg e Ba nd Ava ila b ility

Options for the BE ST pr oje c t � 48 c ylindric a l re fle c to rs o f the No rth/ So uth a rm a nd 6 se g me nts o f the E a st/ We st a rm (216 F ro nt E nds) to b e linke d to the c e ntra l pro c e ssing ro o m (a lmo st 700 m): whic h so lutio ns? A. Co a xia l Ca b le s to e xte rna l Ca b ins whe re sig na ls c a n b e dig itize d a nd se nt via F a st E the rne t L inks to the Pro c e ssing Ro o m B. Ana lo g ue Optic a l L inks dire c tly fro m F o c a l L ine s to the Pro c e ssing Ro o m

Ante nna Re moting : Case A F oc al line N/ S Coa xia l Ca ble L NA Amp Ze r o IF RX I Q Coa xia l Ca ble L .O. L L L .O. .O. .O. ADC Me dia Ma nc he ste r ADC PPS PPS PPS PPS Conv . Ma nc he ste r Ma nc he ste r Ma nc he ste r de c ode r Ma nc he ste r E E E le t./ Opt. le t./ Opt. le t./ Opt. Me dia ADC ADC ADC e nc ode r CK e nc o de r e nc o de r e nc o de r CK CK CK Co nv. Co nv. Co nv. Conv. Dig ita l 160 Mbit/ s 80 MHz 80 MHz 80 MHz 80MHz CK Pro c e ssing PPS PC PC PC PC PC PC BACK E ND Me dia. CPU Conv. 10 Mbit/ s E the rne t pro to c o l E the rne t I nte rfa c e Me dia PC PC PC SWI T CH Conv. Othe r F rom othe r e xte rna l RXs Proc e ssing room Proc e ssing room c abins 1.0 Gbit/ s E xte rna l Ca bin Pr oc e ssing Room

Ante nna Re moting : Case B Focal line N/S RoF LNA Amp Amp TX Processing Room RoF RX L.O. Zero IF PPS I RX Q CK 80MHz ADC BACK END ADC Digital Processing From other RXs

Ante nna Re moting : Case B Focal line N/S External Cabin Processing Room

MT BF sig nific a ntly impro ve s mo ving fro m c o a xia l c a b le s so lutio n to a na lo g ue o ptic a l links o ne

IM- DD RoF L IM- DD RoF L ink ink RoF T ra nsmitte r RF Pa ra me te rs Me a sure d @ 450MHz -25 ° C 20 ° C 65 ° C E IN (dBm/ Hz) -137,99 -136,02 -133,19 NF (dB) 36,01 37,98 40,81 DR (dB · Hz 2/ 3 ) SF 119,24 117,54 117,14 IIP3 (dBm) 40,81 40,34 42,65 +Vcc C out C in I 0 w out P RX P TX R PIN General Structure of an IM-DD RoF Link

IM- DD RoF L ink

T opic Que stion Co nside r impo rta nt ra dio a stro no mic re q uire me nts b o th c o nne c te d with te mpe ra ture c ha ng e s: � Phase Stab ility � Gain Stab ility How will a RoF link be have ?

Ma in T a rg e t T o pe rfo rm a se rie s o f me a sure me nts to de te rmine ho w the pa ra me te rs o f Ro Flinks c ha ng e fro m link to link due to te mpe ra ture c ha ng e s. T his will e na b le us to unde rsta nd if Ro F te c hno lo g ie s a re suita b le to Ra dio a stro no my.

Ste p :1 T he SMF Contr ibution T he c o ntrib utio n o f the I T U-T G.652 SMF is summa rize d b y the T he rma l Co e ffic ie nt o f De la y ∆ ∆ φ 6 6 10 t 10 = = TCD ∆ φ ∆ t T T nom nom

SMF T he r mal Coe ffic ie nt of De lay 80 70 loose fiber 1 loose fiber 2 loose fiber 3 60 loose fiber 4 tight fiber 1 tight fiber 2 50 TCD [ppm/°C] 40 30 20 10 0 -20 -10 0 10 20 30 40 50 Temperature [°C]

Ste p 2: T he Optic al T X T e mpe r atur e Stability

Ste p 2: T he Optic al T X T e mpe r atur e Stability

Ste p 2: T he Optic al T X T e mpe r atur e Stability

Ste p 2: T he Optic al T X T e mpe r atur e Stability

Ste p 2: Nar r owband RoF L ink S 21 Stability • S 21 re la tive va ria tio n, wo rst c a se : � a rg (S 21 ) = 0.4 de g re e � |S 21 | = 0.3 dB @ 408MHz, in a ste p o f 15 ° C • S 21 a b so lute va ria tio n, wo rst c a se : � a rg (S21) = 0.7 de g re e � |S21| = 1.4 dB @ 408MHz, in a ste p o f 15 ° C

Ste p 2: Br oadband RoF L ink S21 Stability • S 21 re la tive va ria tio n, wo rst c a se : � a rg (S 21 ) = 1.4 de g re e � |S 21 | = 0.4 dB 0.1-2.2 GHz [A.2 & A.3 SK A Ba nd], in a ste p o f 15 ° C • S 21 a b so lute va ria tio n, wo rst c a se : � a rg (S21) = 1.6 de g re e � |S21| = 1.5 dB 0.1-2.2 GHz [A.2 & A.3 SK A Ba nd], in a ste p o f 15 ° C

T he F ie ld T ria l: BE ST - 1

T he F ie ld T ria l: BE ST - 1

T he F ie ld T ria l: BE ST - 1 � I F RSSI sig na l tra c e s o f the fir st de te c te d tra nsit (3C405 “Cyg nus-A”)

First observation of the transit of Cassiopea with BEST-1 Old Cross hardware 5.6 deg. detector & 7.1 deg. (1.7 deg.) IF chart recorder BEST-1 1 Rx=¼ of cylinder 4 receivers=1 cylinder

Re c e ive r |S 21 | Var iation ove r T e mpe r atur e

Coax- F ibe r Optic on- fie ld c ompar ison

Coax- Optic a l L ink L a b c ompa rison

T he pr e se nt situation � T he te sts a re g o ing o n to unde rsta nd de e ply the c a use s o f the o sc illa tio n fo und o ut. � T o impro ve o ur kno wle dg e a b o ut the b e ha vio r o f Optic a l T ra nsmitte rs c o mpa riso ns a mo ng diffe re nt c irc uita l so lutio ns (e ve n with the rmo -c o ntro lle d la se rs) a re b e ing pe rfo rme d.

T he COST fac tor � Ro FT e c hno lo g y is still to o e xpe nsive fo r ma ssive de plo yme nt like S.K .A. a nd BE ST � A ma ss pro duc tio n c o uld no t a llo w a suffic ie nt pric e de c re a se (I n the BE ST pro je c t DF B la se r b a se d tra nsmitte rs we re e mplo ye d, b e c a use o f the de e p kno wle dg e o f the pe rfo rma nc e o f this te c hno lo g y) � Ne w kno wle dg e a b o ut e le c tro -o ptic a l de vic e s ha s to b e a c q uire d, b o th fo r impro ve me nts o f the c urre nt te c hno lo g y a nd fo r ne w lo w c o st te c hno lo g ie s de ve lo pme nt (like VCSE L )

T o ac quir e knowle dge : the IRA L ink link optimized at 408MHz @ 16MHz BW Gain -22.9dB Gain Flatness <0.1dB Input Return Loss >28.6dB Output Return >30.9dB Loss Input IP3 +32.8dBm 31dB Noise Figure link (not optimized) in the 300-600MHz band Gain min -23.7dB Gain max -22.1dB Input Return Loss >9.5dB Output Return >24.2dB Loss Planned cost: 500 € Input IP3 >+30dBm Noise Figure <31.25dB

Conc lusions � A ne w r e c e iving c hain, using 4 R oF links, has be e n de signe d, simulate d, te ste d and installe d on a single c ylindr ic al ante nna of the Nor th- South ar m of the Nor the r n Cr oss � T hanks to Analog Optic al L ink it was possible to install 4 F r ont E nds de signe d at the IRA L abs dir e c tly in the F oc al L ine s of the ante nna: – Ove ra ll Syste m T e mpe ra ture impro ve me nt – A ra ise in Re lia b ility, MT BF , ma inta ina b ility � It has be e n de monstr ate d that RoF te c hnology c an be c onside r e d ve r y pr omising in the futur e de ployme nt of S.K.A. proje c t

F utur e De ve lopme nts � Ne w F ie ld tria ls will b e pe rfo rme d to c he c k the F ib e r T he rma l Sta b ility o ve r dista nc e s up to 2km � T he b e ha vio r o f the re c e iving c ha ins in re la tio n with te mpe ra ture va ria tio ns is b e ing de e ply a na lyze d to unde rsta nd c le a rly e ve ry c ha ng ing fa c to r � Ne w L o w Co st Ro FT e c hno lo g ie s a re c o ntinuo usly unde r e va lua tio n (VCSE L a nd multimo de fib e r)