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

• 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 COSTis F

UNDAME NT AL

Why use RoF L ink for Radioastr

• nomy

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

• je c t
• 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

• c a l L

ine s to the Pro c e ssing Ro o m

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?

ADC CK 80 MHz

PC PC PC

Proc e ssing room

PC PPS

E le t./ Opt. Co nv. Ma nc he ste r e nc o de r

L .O.

ADC CK 80 MHz

PC PC PC

Proc e ssing room

PC PPS

E le t./ Opt. Co nv. Ma nc he ste r e nc o de r

L .O.

ADC CK 80 MHz

PC PPS

E le t./ Opt. Co nv. Ma nc he ste r e nc o de r

L .O.

1.0 Gbit/ s Coa xia l Ca ble

Me dia. Conv.

Pr

• c e ssing Room

L .O.

160 Mbit/ s

L NA Amp

F

• c al line N/ S

E xte rna l Ca bin

BACK E ND

10 Mbit/ s

Dig ita l Pro c e ssing

ADC ADC

CK PPS Coa xia l Ca ble

Me dia Conv. Me dia Conv.

Othe r RXs E the rne t pro to c o l

Ma nc he ste r de c ode r

SWI T CH CPU

Ze r

• IF

RX

Ma nc he ste r e nc ode r

PPS CK 80MHz

E the rne t I nte rfa c e

I Q

F rom othe r e xte rna l c abins

Me dia Conv.

Ante nna Re moting : Case A

LNA Amp

BACK END

Digital Processing

ADC ADC From other RXs I Q

Amp

RoF TX

Zero IF RX

RoF RX L.O. PPS CK 80MHz

Focal line N/S Processing Room

Ante nna Re moting : Case B

Focal line N/S External Cabin Processing Room

Ante nna Re moting : Case B

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

• ptic a l links o ne

RPIN

+Vcc

Cout wout PRX PTX

I0

Cin

General Structure of an IM-DD RoF Link

42,65 40,34 40,81 IIP3 (dBm) 117,14 117,54 119,24 SF DR (dB·Hz2/ 3) 40,81 37,98 36,01 NF (dB)

• 133,19
• 136,02
• 137,99

E IN (dBm/ Hz) 65°C 20°C

• 25°C

RoF T ra nsmitte r RF Pa ra me te rs Me a sure d @ 450MHz

IM- DD RoF L ink IM- DD RoF L ink

IM- DD RoF L ink

T

• pic 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

• 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.

T T t t TCD

nom nom

∆ ∆ = ∆ ∆ = φ φ

6 6

10 10

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

Ste p :1 T he SMF Contr ibution

SMF T he r mal Coe ffic ie nt of De lay

10 20 30 40 50 60 70 80

• 20
• 10

10 20 30 40 50

Temperature [°C] TCD [ppm/°C]

loose fiber 1 loose fiber 2 loose fiber 3 loose fiber 4 tight fiber 1 tight fiber 2

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

• 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

• S

21 re la tive va ria tio n, wo rst c a se :

• a rg (S21) = 0.4 de g re e
• |S

21| = 0.3 dB

@ 408MHz, in a ste p o f 15°C

Ste p 2: Nar r

• wband RoF L

ink S21 Stability

• 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

• S

21 re la tive va ria tio n, wo rst c a se :

• a rg (S21) = 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

Ste p 2: Br

• adband RoF L

ink S21 Stability

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”)

T he F ie ld T ria l: BE ST

• 1

First observation of the transit of Cassiopea with BEST-1

1 Rx=¼ of cylinder 4 receivers=1 cylinder

5.6 deg. 7.1 deg. (1.7 deg.) Old Cross hardware detector & chart recorder BEST-1 IF

Re c e ive r |S21| 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

• ut.

T

• 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.

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

• 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 he COST fac tor

Planned cost: 500 €

<0.1dB

Gain Flatness

+32.8dBm

Input IP3

31dB

Noise Figure

>30.9dB

Output Return Loss

>28.6dB

Input Return Loss

• 22.9dB

Gain link optimized at 408MHz @ 16MHz BW

• 22.1dB

Gainmax

>+30dBm

Input IP3

<31.25dB

Noise Figure

>24.2dB

Output Return Loss

>9.5dB

Input Return Loss

• 23.7dB

Gainmin link (not optimized) in the 300-600MHz band

T

• ac quir

e knowle dge : the IRA L ink

A ne w r

e c e iving c hain, using 4 R

• F 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

• ss

T

hanks to Analog Optic al L ink it was possible to install 4 F r

• nt E

nds de signe d at the IRA L abs dir e c tly in the F

• c 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

• mising in the futur

e de ployme nt of S.K.A. proje c t

Conc lusions

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

• 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)

F utur e De ve lopme nts