Designing an Optimal SKA

SA Bursary ConferenceDecember 2009 SKA Design

Designing an Optimal SKA

Andrew Faulkner


Designing an optimal SKA around AAs at low

frequencies plus dishes at higher frequencies –

maximising the science output for a fixed cost


..

Sparse AA

Dense AA

..

Mass Storage

TimeStandard

Central Processing Facility - CPF

User interfacevia Internet

...

To 250 AA Stations

...

DSP

...

DSP

To 2400 Dishes

...

12-15m Dishes

Correlator – A

A & D

ish

16 Tb/s

80 Gb/s

Control Processors& User interface

Post Processor

Data

Time

Control

70-450 MHzWide FoV

0.4-1.4 GHzWide FoV

0.8-10 GHzSingle Pixel or Focal planearray

Tile &Station

Processing

SKA Overall Structure


..

Sparse AA

Dense AA

..

Mass Storage

TimeStandard



...

To 250 AA Stations

...

DSP

...

DSP

To 2400 Dishes

...

12-15m Dishes

Correlator – A

A & D

ish

16 Tb/s

80 Gb/s


Post Processor

Data

Time

Control

70-450 MHzWide FoV

0.4-1.4 GHzWide FoV


Tile &Station

Processing



..

Sparse AA

Dense AA

..

Mass Storage

TimeStandard



...

To 250 AA Stations

...

DSP

...

DSP

To 2400 Dishes

...

12-15m Dishes

Correlator – A

A & D

ish

16 Tb/s

80 Gb/s


Post Processor

Data

Time

Control

70-450 MHzWide FoV

0.4-1.4 GHzWide FoV


Tile &Station

Processing



..

Sparse AA

Dense AA

..

Mass Storage

TimeStandard



...

To 250 AA Stations

...

DSP

...

DSP

To 2400 Dishes

...

12-15m Dishes

Correlator – A

A & D

ish

16 Tb/s

80 Gb/s


Post Processor

Data

Time

Control

70-450 MHzWide FoV

0.4-1.4 GHzWide FoV


Tile &Station

Processing



Potential Configuration:

AA Station

Core ~5km dia

Central ProcessingFacility

Comms links

Not to scale!

180km

Dishes spread along spiral

Dishes

AA-hi

AA-lo

~250 Aperture array stations

~2400 Dishes


Parameter name

Unit Range, Value or Calculation

Remarks

PAF:νL MHz 500 – 1000 Lower operational frequency for PAF.

PAF:νH MHz 1500 – 2000 Maximum operational frequency for PAF.

PAF:ΔνMax MHz 700 Maximum instantaneous bandwidth for PAF.

PAF:νNyq MHz Calculated: =PAF:νH Frequency at which PAF antennas are half-wavelength spaced.

PAF:Trec K 30-60 Receiver temperature for PAF receivers.

PAF:ηap % 55-70 Aperture efficiency for the PAFs when placed on the dishes.

PAF:Ageom(νN

yq)m2 Calculated from dish

distribution and aperture efficiency

Total effective area for all the Dishes with PAFS together.

PAF:Bmax km 0 - 500 Maximum baseline (from core) for PAFs. All dishes within this distance are assumed to have a PAF and a WBSPF on them, therefore this parameter determines how many dishes have PAFs.

PAF:Nb,max # 40 Maximum number of beams required from the PAF.

PAF:F Tb/s 0-Max Data rate output from PAF.

Some SKA design parameters.....Parameter name Unit Range, Value or

CalculationRemarks

AAlo:FStn Tb/s 0-100 Data rate transported from each station.

AAlo:νL MHz 70-200 Lower frequency of operation for AAlo. Variable only if we wish to have multiple AAlo element types.

AAlo:νH MHz 200 - 450 Highest frequency of operation for AAlo

AAlo:νNyq MHz 100 - 300 Nyquist frequency for AAlo elements. This will be used to determine the element size (half-wavelength at νNyq), and may differ if we use multiple AAlo element types.

AAlo:ΔνMax MHz calculated: AAlo:νH AAlo:νL

AAlo will be capable of using the full frequency range.

AAlo:Trec(ν) K calculated: (50, 0.1xTsky(ν))

This must be low enough to be unimportant compared to sky noise, but with a limit of 50K

AAlo:Ageom(νNyq

)m2 2-10 x 106 This is the geometric footprint of the all the

antennas – which will be smaller than the area enclosed within a station’s perimeter if the antennas have been sparsed with a filling factor (see below). This quantity is directly proportional to the number of antennas, regardless of any filling factor.

AAlo:ff % 50-100 AAlo filling factor: a value of 80% would denote that only 80% of the area within a station’s perimeter is taken up with antenna footprints.

AAlo:N # 50 - 350 The number of AAlo stations in total. All are assumed to be the same size.

AAlo:DStn m calculated: π×DStn

2/4=Ageom/(ff×N)The diameter of each AAlo station. This is calculated from the geometric area of antennas, the filling factor and the number of stations. Need to check this against constraints from calibration.

AAlo:fcore % 67 The fraction of AAlo collectors which are within the close-packed core.

AAlo:Dcore km calculated: π×Dcore

2/4=(Ageom× fcore )/(ff×0.91)

The diameter of the close-packed core. Calculated, assuming a station packing density of 91% within the core (theoretical max for abutting circles).

AAlo:Bmax km Dcore/2 - 400 The maximum baseline (distance from core) that the AAlo stations are placed out to.

AAlo:Bmid km Dcore/2 - 100 Break baseline (radius) for AAlo distribution.

AAlo:fmid % 95 Fraction of AAlo collectors within Bmid.

AAlo:ηap % 80 The aperture efficiency for the AAlo antennas. Taken as fixed for now – we will use values from LOFAR, but ultimately this will depend on the antenna design.

AAlo:S(ν) m2/K calculated Calculated sensitivity of the AAlo collectors, as a whole.

AAlo:BpS # 2-8 Bits per Sample for the AAlo data.

Parameter name Unit Range, Value or Calculation

Remarks

AAhi:FStn Tb/s 0-100 Data rate transported from each station.

AAhi:νL MHz Minimum operational frequency for AAhi

AAhi:νH MHz1000 – 3000 (AA only)

700 – 1450 (for SKA designs

with Dishes)

Maximum operational frequency for AAhi. The range of values needed depends upon the telescope being designed: for the AA-only telescope we will need to model the costs of an Aperture array that can perform at high frequency (up to 3GHz), whilst for the SKA designs which include dishes with SPFs/PAFs we will not need to consider such high operational frequencies for the AAhi as they will be covered by these other receivers.

AAhi:νNyq MHz calculated: 0.7×AAhi:νH Frequency at which AAhi antennas meet Nyquist sampling criterion.

AAhi:ΔνMax MHz 700 Maximum instantaneous bandwidth for AAhi.

AAhi:Trec K 30-60 Receiver temperature for AAhi antennas.AAhi:Ageom(νNyq) m2 0-10 x 105 Total effective area, on boresight and at AAhi:νNyq

for all the AAhi stations together.AAhi:DStn m calculated:

π×DStn2/4=Ageom/(N)

Diameter of each AAhi station (assumed to all be the same)

AAhi:fcore % 67 Fraction of the AAhi collectors that are within the core.

AAhi:Dcore km calculated: π×Dcore

2/4=(Ageom× fcore )/0.91

Diameter of the core for the AAhi. Calculated from collecting area and core fraction assuming close-packing circles.

AAhi:Bmax km Dcore/2 - 500 Maximum baseline (from core) for AAhi.AAhi:N # 150 - 350 Number of AAhi stations.AAhi:Bmid km 10 - 100 Baseline (radius) of AAhi distribution break.

AAhi:fmid % 95 Fraction of total AAhi collectors within Bmid.

AAhi:BpS # 2-8 Bits per Sample for the AAhi data.AAhi:RFinput # 1-25 Number of RF inputs into analogue beam-forming

unit (see Figure 1) .AAhi:RFoutput # 1-AAhi:RFinput Number of RF beams output from analogue beam-

forming unit (see Figure 1) .

Parameter name Unit Range, Value or Calculation

Remarks

DISH:D m 6-25 Dish diameter.

DISH:fcore % 50 The fraction of Dishes that are within the core.

DISH:Dcore km calculated The diameter of the core. The core is assumed to be close-packed with its size determined by shadowing requirements and the number of dishes in the core, which is determined from the core fraction.

DISH:Bmax km 3000 The maximum baseline (distance from core) that dishes are placed out to.

DISH:Bmid km 100 - 500 Break distance for dish distribution (see next).

DISH:fmid % 75 Fraction of dishes that are within the Bmid distance (including the fraction in the core).

DISH:Aeff m2 0-10 x 105 Total effective area of the all the dishes.

Parameter name Unit Range, Value or

Calculation Remarks

SPF:νL MHz Lowest frequency of operation for the Wide-band feeds.

SPF:ν H MHz 10,000 Highest frequency of operation for the Wide-band feeds.

SPF:ΔνMax GHz 1-8 Maximum instantaneous bandwidth for the Wide-band feeds.

SPF:Trec K 15-50

Receiver temperature for the Wide-band feeds (no consideration will be taken of how this varies across the band). This range needs to be checked against current international expectations.

SPF:ηap % 55-70 Aperture efficiency for the Wide-band feeds when placed on the dishes.


SKA implementation analysis

Instrument Technical

Specification:

• Sensitivity• Survey speed• Configuration• Stability

PotentialDesigns:

• Collector type• Frequency

range• Data rates• etc

OperationalConstraints:

• Time allocation• Storage• Power• Operations

budget

PhysicalParameters:

• Flux• Area of sky• Polarisation• Dynamic range• etc

KeyScience

Experiments

SKADesign

Modelling:

• Variants• Performance• Cost• Power• Risk


Science Requirements....

The Design Reference mission

http://www.skatelescope.org/PDF/091001_DRM_v0.4.pdf


Design Reference Mission

2. Resolving AGN and Star Formation in Galaxies3. Pre-biotic molecules in and around Protoplanetary Disks4. Cosmic Magnetism Deep Field Component5. Wide Field Polarimetry

6. Tracking Cosmic Star Formation: Continuum Deep Field7. Neutral Gas in Galaxies: Deep HI Field8. Epoch of Reionization HI Imaging Tomography9. Spacetime Env. of the Galactic Center with Radio Pulsars

10a. Theories of Gravity using Ultra-relativistic Binaries: Survey

13a. Pulsar Timing Array for Gravitational Wave Study: Survey

10b. Theories of Gravity using Ultra-relativistic Binaries: Timing

13b. Pulsar Timing Array for Gravitational Wave Study: Timing

11. Galaxy Evolution over Cosmic Time via H I Absorption12. H I Baryon Acoustic Oscillations

14a. Exploration of the Unknown: The Transient Radio Sky14b. Exploration of the Unknown: The Transient Radio Sky

15. Probing AGN via HI absorption

Science Experiments


0

2,500

5,000

7,500

10,000

Sen

sitiv

ity A

eff/T

sys

m2 K

−1

0.3 1.0 3.0 10.0

Frequency GHz

0.1 0.14 1.4

2. Resolving AGN and Star Formation in Galaxies

39,000 5. Wide Field Polarimetry - 2

11. Galaxy Evolution via H I Absorption

12. HI BAO

3. Protoplanetary disks

6. Continuum deep field7. Deep HI Field

9. Galactic centre pulsars

10a, 13a. Pulsar search

10b, 13b. Pulsar timing

4. Cosmic Magnetism

8. HI EoR

Sensitivity Requirements

12,500

15,000

Specified sensitivity

Derived from survey speed

5. Wide Field Polarimetry - 1

Huge....

DRM 0.4

15. Probing AGN via HI abs’n


1e2

1e4

1e6

1e8

1e10

Sur

vey

Spe

ed m

4 K−2

deg

2

0.3 1.0 3.0 10.0

Frequency GHz

0.1 0.14 1.4

2. Resolving AGN & Star Form’n

5. Wide Field Polarimetry

11. Galaxy Ev. via HI Abs’n

12. HI BAO


7. Deep HI Field

9. Galactic centre pulsars10b, 13b. Pulsar timing

4. Cosmic Magnetism

8. HI EoR

Survey SpeedRequirements

1e1

Specified survey speed

Derived from sensitivity

13a. Pulsar search

DRM 0.4

6. Continuum deep field


10

30

100

300

1,000

Bas

elin

e le

ngth

, km

0.3 1.0 3.0 10.0

Frequency GHz

0.1 0.14 1.4

>3000 2. Resolving AGN and Star Formation in Galaxies


11. Galaxy Evolution via HI Absorption

12. HI BAO



7. Deep HI Field




4. Cosmic Magnetism8. HI EoR

Baseline Requirements

3

1

Stated in DRM

Unstated in DRM - assumed DRM 0.4

3000 15. Probing AGN via HI abs’n


Comments on Science reqts

• Major surveys are <1.4 GHz: below HI line

• Only AGN experiments are >500km baseline

• Interesting how many want 10,000 m2/K......

• Continuum & Pulsars want as much sensitivity as

possible

• Transients requirements are not shown

• Would like the parameters as a function of frequency


Some design trade-offs......


Tailoring the AA system

100

10

1

100

1000

Frequency (MHz)

Sky

Brig

htne

ss T

empe

ratu

re (K

)

Aeff

Aeff/Tsys

Fully sampled AA-hi

Sparse AA-lo

TskyBecoming sparse

Aeff / T

sys (m2 / K

)

AA frequency overlap

Dishoperation

f AA f max


Ae

Ae

Ae

…..

…..

….. Tile

Processor- hi

TH_0

TH_1

TH_n

…..

…..

….. Tile

Processor- lo

TL_0

TL_1

TL_m

StationProcessor

0e/oe/o

e/oe/o

…..

…..

o/eo/eo/eo/e

o/eo/eo/eo/e

……

.

e/oe/o

e/oe/o

Station Processor n…

….

Long distance drivers…

..o/eo/eo/eo/eo/eo/e

e/oe/oe/oe/o

e/oe/oe/oe/o

Long distance drivers…

..Long distance drivers

…..

....

…..1.0-1.4GHz

analogue

1.0 GHzanalogue

12 fibre lanes @10Gb/s each

……

…...

12 fibre lanes @10Gb/s each

10Gb/s fibre

…..

Max 4 Station Processors

Local Processinge.g. Cal; pulsars

To Correlator

Inputs #: 1296Channel rate:120Gb/s

(raw)Total i/p rate: 1.5 Pb/s

Typical:AA-hi tiles: 300AA-lo tiles: 45Total: 345I/p data rate:42Tb/s

Notes:1. No control network shown2. Up to 4 station processor systems

can be implemented in parallel3. Data shown are raw, typ. get 80%

data

…..

AA Station Configuration


62%

28%

10%

AA System Cost

AA-hi arrays

AA-lo arrays

Station processors

AA Station performance costsCost for Field of View, FoV: 10%

Cost for Aeff/Tsys: 90%

Sensitivity: Aeff/Tsys

Survey Speed: (Aeff/Tsys)2 x FoV


Frequency

AA – Dish Frequency X-over

Dish+feedAA

• Cost increases as ftop2

• Can reduce Aeff at high f• Cover main survey reqts.

• low flow implies large dia.• Large feed for low freq• Costs high for low freq


Central Processing Facility


Central Processing Facility

... AA slice

... AA slice

... AA slice

... D

ish & A

A+D

ish Correlation

......

ProcessorBuffer

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Data sw

itch ......

AA S

tationsD

ishes

Data Archive

ScienceProcessors

Correlator UV Processors Image formation

Science analysis, user interface & archive

Beams Visibilities UV data Images

250 x 16Tb/s~4.8 Pb/s

2400 x 80Gb/s

Tb/s Gb/s Gb/sPb/s

...

...

Imaging P

rocessors

~10 Pflop


The central processing problem…..

Data rate, R, from the correlator

• Each pair of antennas are multiplied together R Nc2

• For each beam R Nb

• Must avoid chromatic aberration – need to split bandwidth Df into

Nch channels of width df < f D / B R f / df

• Longest integration time must sample changing sky due to rotation

of the earth dt < 2600 qmax / qD R 1 / dt

222 1

21

D

DBNN

tffNNN

samplesR

cbpolcb dd

Linear for no. of beams

Quadratic for no. of collectors

Quadratic for baseline

lengthInverse

Quadratic for collector

diameter


The central processing problem…..

Data rate, R, from the correlator

• Each pair of antennas are multiplied together R Nc2

• For each beam R Nb

• Must avoid chromatic aberration – need to split bandwidth Df into

Nch channels of width df < f D / B R f / df

• Longest integration time must sample changing sky due to rotation

of the earth dt < 2600 qmax / qD R 1 / dt

222 1

21

D

DBNN

tffNNN

samplesR

cbpolcb dd

Linear for no. of beams

Quadratic for no. of collectors

Quadratic for baseline

lengthInverse

Quadratic for collector

diameter

Processing cost....

Nb FoV: cheapB resolution: expensiveD-1 FoV: very expensive

Fewer big stations + more beams is much cheaper


Data rates out of Correlator

Experiment 3000 Dishes + SPF 250 AA stations

DescriptionBmax

(km)

Δf(MHz)

fmax

(MHz)Achieved FoV Data rate (Tb/s) Achieved

FoV1 Data rate (Tb/s)

Survey: High surface brightness continuum 5 700 1400 0.78 0.055 108 0.03

Survey: Nearby HI high res. 32000 channels 5 700 1400 0.78 1.0 108 2.6

Survey: Medium spectral resolution; resolved imaging (8000)

30 700 1400 0.78 1.2 108 5.4

Survey: Medium resolution continuum 180 700 1400 0.78 33.1 108 14.1

Pointed: Medium resolution continuum deep observation 180 700 1400 0.78 33.1 0.78 0.15

High resolution with station beam forming2 1000 2000 8000 0.0015 33.4

High resolution without station beam forming3 1000 2000 8000 0.0015 429

Highest resolution for deep imaging2 3000 4000 10000 0.001 391

1. For the AA the data rate assumes constant FoV across the band.2. Assuming that for the dynamic range the FoV of the station only has to be imaged3. Assuming that for the dynamic range the FoV of the dish must be imaged


Subtract current sky model from visibilities using current calibration model

Grid UV data to form e.g. W-projection

Major cycle

Image gridded data

Deconvolve imaged data (minor cycle)

Solve for telescope and image-plane calibration model

Update current sky model

Update calibration model

Astronomicalquality data

UV data store

UV processors

Imaging processors

Processing model


Model for UV processor

• Highly parallel – 20 TFlop promised in 2 years – assume 50 Tflop in 2018

• Operations/sample reqd.: ~20,000/calibration loop• Processor: €1000, 5 calibration loops, 50% efficiency, • Each processor can operate on ~ 1 GB/s of data • Requirement: 100 PFlop (AA) 2 EFlop (dishes)• Buffer 1 hr of data 7.2 TB in a fast store • Memory est. €200 per TB.

• Total UV-processing : Cost = €2.5m per TB/s

AA < €10mDishes ~ €125m

ProcessorBuffer

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......

UV Processors

UV data

Gb/s


From Bruce Elmegreen, IBM

Processing

Technology Roadmapping


Modelling: Design and Costing Tool

Also tracks Power & data rate


Hierarchical designs..


Data link cost vs length (16Tbit/s)• Large data rate

link costs from tool show the combine effect of distance break points for different technologies.

• These break have strong implications for cost savings if we change the layout of the Aperture Arrays

Change from short range to

mid range lasers

Introduction of first pre-

amplifiers

Change from short range to

mid range lasers

Introduction of first amplifiers

(80km)

Introduction second

amplifiers (160km)


Changing the collector distribution

• Does this matter? Yes. Look at the estimated costs for 250 AA station links, each with 16 Tbit/s. Vary Bmid – distance within which 95% of all stations are placed, cost implications of the order 100 Million EUR.

• 95% within 10km, very few stations out to 180km

• 95% within 100km, remainder out to 180km


Impact of changing the distribution

• Does this matter? Yes. Look at the estimated costs for 250 AA station links, each with 16 Tbit/s. Vary Bmid – distance within which 95% of all stations are placed, cost implications of the order 100 Million EUR.

• 95% within 10km, very few stations out to 180km: 60M Euros

• 95% within 100km, remainder out to 180km: 140M Euros


Consider a possible SKA....

Freq. Range Collector Sensitivity Number / size Distribution

70 MHz to 450 MHz

Sparse Aperture array (AA-lo)

4,000 m2/K at 100 MHz

250 arrays, Diameter 180 m 66% within core 5 km

diameter, rest along 5 spiral arms out to 180 km radius300 MHz to

1.4 GHzDense Aperture array (AA-hi)

10,000 m2/K at 800 MHz

250 arrays, Diameter 56 m

1 GHz to 10 GHz

Dishes with single pixel feed

5,000 m2/K at 1 GHz

1,200 dishes Diameter 15 m

50% within core 5 km diameter, 25% between the core and 180 km, 25% between 180 km and 500 km radius.


0

2,500

5,000

7,500

10,000

Sen

sitiv

ity A

eff/T

sys

m2 K

−1

0.3 1.0 3.0 10.0

Frequency GHz

0.1 0.14 1.4

2. Resolving AGN and Star Formation in Galaxies

39,000 5. Wide Field Polarimetry - 2

11. Galaxy Evolution via H I Absorption

12. HI BAO


6. Continuum deep field7. Deep HI Field




4. Cosmic Magnetism

8. HI EoR

Sensitivity Requirements

12,500

15,000

Specified sensitivity

Derived from survey speed

5. Wide Field Polarimetry - 1

Huge....

DRM 0.4

15. Probing AGN via HI abs’n

AA-lo

AA-hi

Dish

Can this reqt.be 5000 m2K-1?

This reqt. is ~16 Km2 AA!!


1e2

1e4

1e6

1e8

1e10

Sur

vey

Spe

ed m

4 K−2

deg

2

0.3 1.0 3.0 10.0

Frequency GHz

0.1 0.14 1.4

2. Resolving AGN & Star Form’n


11. Galaxy Ev. via HI Abs’n

12. HI BAO


7. Deep HI Field

9. Galactic centre pulsars10b, 13b. Pulsar timing

4. Cosmic Magnetism

8. HI EoR

Survey SpeedRequirements

1e1

Specified survey speed

Derived from sensitivity

13a. Pulsar search

DRM 0.4


AA-lo

AA-hi

Dish

Does the science require this?


10

30

100

300

1,000

Bas

elin

e le

ngth

, km

0.3 1.0 3.0 10.0

Frequency GHz

0.1 0.14 1.4

>3000 2. Resolving AGN and Star Formation in Galaxies


11. Galaxy Evolution via HI Absorption

12. HI BAO



7. Deep HI Field




4. Cosmic Magnetism8. HI EoR

Baseline Requirements

3

1

Stated in DRM

Unstated in DRM - assumed DRM 0.4

3000 15. Probing AGN via HI abs’n

AA-lo

AA-hi

Dish

These baselines are very expensive!Fibre & computing

A few large low freq dishes?


SKA Cost RemarksQuantity Each Total € 2011 NPV Aperture Arrays: AA-hi arrays 250 1,467,065 366,766,150 165 core and 85 outer arraysAA-lo arrays 250 648,876 162,218,926 Station processors 250 227,004 56,750,988 Processing for station beamforming

Total AA 585,736,064 Dishes:

Antenna + feed 1200 219,175 263,010,000 Includes Antenna, feed, electronics and cooling

Total dish 263,010,000 Communications:

AA core 64,313,900 AA outer 57,951,575 Dishes 28,130,166 Trenching - all 92,457,741 Total comms 242,853,382

Central Processing Includes control and clock distribution

Correlator 62,749,341 Includes correlation facilities for both AA and dish collectors

Post processing 34,000,000 Includes processing and storageClock distribution 9,263,217 Total central proc. 106,012,558

Total SKA 1,197,612,004

Costs for ‘this’ SKA

Costs not Included:

Development workNon-recoverable expensesCivil worksPower installationOperational CostsProject Management

Collectors250 x 57m dia AA-hi250x220m dia AA-lo1200 x 15m dishesWideband SP Feeds


SKA Cost RemarksQuantity Each Total € 2011 NPV Aperture Arrays: AA-hi arrays 250 1,467,065 366,766,150 165 core and 85 outer arraysAA-lo arrays 250 648,876 162,218,926 Station processors 250 227,004 56,750,988 Processing for station beamforming

Total AA 585,736,064 Dishes:

Antenna + feed 1200 219,175 263,010,000 Includes Antenna, feed, electronics and cooling

Total dish 263,010,000 Communications:

AA core 64,313,900 AA outer 57,951,575 Dishes 28,130,166 Trenching - all 92,457,741 Total comms 242,853,382

Central Processing Includes control and clock distribution

Correlator 62,749,341 Includes correlation facilities for both AA and dish collectors

Post processing 34,000,000 Includes processing and storageClock distribution 9,263,217 Total central proc. 106,012,558

Total SKA 1,197,612,004

Costs for ‘this’ SKA

Costs not Included:

Development workNon-recoverable expensesCivil worksPower installationOperational CostsProject Management

Collectors250 x 57m dia AA-hi250x220m dia AA-lo1200 x 15m dishesWideband SP Feeds

~€1.2 Bn

49%

22%

20%

9%

SKA Overall

AA lo & hi

Dish+SPF

Wide area comms

Processing+correlator

62%

28%

10%

AA System Cost

AA-hi arrays

AA-lo arrays

Station processors


AA-hi Arrays (not inc. station processing)

28%

27%

30%

15%

0%

Core AA-hi Breakdown

Element costAnalogue data transportInfrastructureSignal ProcessingCalibration source

Infrastructure:Cover membraneSteels for Antenna Support Structure Cable Support Poles Velcro Cable TiesFoundations: building polesCivil EngineeringCoolingPower SuppliesRacking TrenchesInfrastructure Build – 3 man yearsBunkers

Analogue Data Transport:Connection to PCBs = no. of cablesPreparation of cablesCable - total length reqd per stationMale plugsPCB Outlet plugs (i.e. PCB inputs to first processor)Install cables in field

~€1.5M each array, NPV

10%

27%

18%9%

22%

9%6%

Element Cost

Dual Pol Antenna element (aluminium)LNADiff driver+filter+regPassivesSmall feed boardAssemblyGround plane

~€11 each element, 2011


Summary

A great SKA

can be built.........with lots of work

Documents

Designing an Optimal SKA