SA Bursary ConferenceDecember 2009 SKA Design
Designing an Optimal SKA
Andrew Faulkner
SA Bursary ConferenceDecember 2009 SKA Design
Designing an optimal SKA around AAs at low
frequencies plus dishes at higher frequencies –
maximising the science output for a fixed cost
SA Bursary ConferenceDecember 2009 SKA Design
..
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
SA Bursary ConferenceDecember 2009 SKA Design
..
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
SA Bursary ConferenceDecember 2009 SKA Design
..
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
SA Bursary ConferenceDecember 2009 SKA Design
..
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
SA Bursary ConferenceDecember 2009 SKA Design
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
SA Bursary ConferenceDecember 2009 SKA Design
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.
SA Bursary ConferenceDecember 2009 SKA Design
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
SA Bursary ConferenceDecember 2009 SKA Design
Science Requirements....
The Design Reference mission
http://www.skatelescope.org/PDF/091001_DRM_v0.4.pdf
SA Bursary ConferenceDecember 2009 SKA Design
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
SA Bursary ConferenceDecember 2009 SKA Design
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
SA Bursary ConferenceDecember 2009 SKA Design
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
3. Protoplanetary disks
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
SA Bursary ConferenceDecember 2009 SKA Design
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
5. Wide Field Polarimetry
11. Galaxy Evolution via HI Absorption
12. HI BAO
3. Protoplanetary disks
6. Continuum deep field
7. Deep HI Field
9. Galactic centre pulsars
10a, 13a. Pulsar search
10b, 13b. Pulsar timing
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
SA Bursary ConferenceDecember 2009 SKA Design
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
SA Bursary ConferenceDecember 2009 SKA Design
Some design trade-offs......
SA Bursary ConferenceDecember 2009 SKA Design
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
SA Bursary ConferenceDecember 2009 SKA Design
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
SA Bursary ConferenceDecember 2009 SKA Design
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
SA Bursary ConferenceDecember 2009 SKA Design
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
SA Bursary ConferenceDecember 2009 SKA Design
Central Processing Facility
SA Bursary ConferenceDecember 2009 SKA Design
Central Processing Facility
... AA slice
... AA slice
... AA slice
... D
ish & A
A+D
ish Correlation
......
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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
SA Bursary ConferenceDecember 2009 SKA Design
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
SA Bursary ConferenceDecember 2009 SKA Design
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
SA Bursary ConferenceDecember 2009 SKA Design
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
SA Bursary ConferenceDecember 2009 SKA Design
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
SA Bursary ConferenceDecember 2009 SKA Design
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
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......
UV Processors
UV data
Gb/s
SA Bursary ConferenceDecember 2009 SKA Design
From Bruce Elmegreen, IBM
Processing
Technology Roadmapping
SA Bursary ConferenceDecember 2009 SKA Design
Modelling: Design and Costing Tool
Also tracks Power & data rate
SA Bursary ConferenceDecember 2009 SKA Design
Hierarchical designs..
SA Bursary ConferenceDecember 2009 SKA Design
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)
SA Bursary ConferenceDecember 2009 SKA Design
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
SA Bursary ConferenceDecember 2009 SKA Design
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
SA Bursary ConferenceDecember 2009 SKA Design
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.
SA Bursary ConferenceDecember 2009 SKA Design
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
AA-lo
AA-hi
Dish
Can this reqt.be 5000 m2K-1?
This reqt. is ~16 Km2 AA!!
SA Bursary ConferenceDecember 2009 SKA Design
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
3. Protoplanetary disks
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
AA-lo
AA-hi
Dish
Does the science require this?
SA Bursary ConferenceDecember 2009 SKA Design
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
5. Wide Field Polarimetry
11. Galaxy Evolution via HI Absorption
12. HI BAO
3. Protoplanetary disks
6. Continuum deep field
7. Deep HI Field
9. Galactic centre pulsars
10a, 13a. Pulsar search
10b, 13b. Pulsar timing
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?
SA Bursary ConferenceDecember 2009 SKA Design
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
SA Bursary ConferenceDecember 2009 SKA Design
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
SA Bursary ConferenceDecember 2009 SKA Design
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
SA Bursary ConferenceDecember 2009 SKA Design
Summary
A great SKA
can be built.........with lots of work