Download - Paul Alexander DS3 & DS3-T3 SKADS Review 2006 DS3 The Network and its Output Data Paul Alexander
SKADS Review 2006 Paul AlexanderDS3 & DS3-T3
DS3DS3The Network and its Output DataThe Network and its Output Data
Paul AlexanderPaul Alexander
SKADS Review 2006 Paul AlexanderDS3 & DS3-T3
OverviewOverview
Overall aim of this design study
Examine the System Design issues associated with producing the most cost-effective overall architectural design for the SKA “network”
SKADS Review 2006 Paul AlexanderDS3 & DS3-T3
processor
The physical network: Data flow, processing and analysis
& power
Telescope response
User network
signal and data transport
SKADS Review 2006 Paul AlexanderDS3 & DS3-T3
The Structure of DS3The Structure of DS3Six tasks
• T1 – Network infrastructure and data transmissionManchester
• T2 – Data handling; control and distributed computingASTRON
• T3 – Architecture and the functional simulatorCambridge
• T4 – Siting and related issuesOPAR
• T5 – SKA for the userCambridge
• T6 – Scaleable design and implementationASTRON
SKADS Review 2006 Paul AlexanderDS3 & DS3-T3
DS3 and the SKA DS3 and the SKA system designsystem design
Concerned with the overall SKA architecture not just the Aperture Array
Will consider compare and evolve:
• SKADS Benchmark specification
• ISPO reference design
• Other emerging system designs
SKADS Review 2006 Paul AlexanderDS3 & DS3-T3
Current StatusCurrent Status
• All tasks underway
• No DS deliverables or milestones in the first 12 month period
• Relatively slow start for some tasks:– Planned in the description of work
– Later than anticipated availability of UK funds
• At kickoff meetings identified:– the need for close inter task discussions and also with the need for close inter task discussions and also with
other DSother DS
SKADS Review 2006 Paul AlexanderDS3 & DS3-T3
Some of the interactionsSome of the interactions
DS2-T2Science
DS3-T3Simulator
DS3-T2Processing
DS3-T1Network
DS3-T6Scaleup
DS3-T4Siting
DS4-T2DSP
DS4-T6…2-PadDS5…
Embrace
SKADS Review 2006 Paul AlexanderDS3 & DS3-T3
Current StatusCurrent Status
• All tasks underway
• No DS deliverables or milestones in the first 12 month period
• Relatively slow start for some tasks:– Planned in the description of work
– Later than anticipated availability of UK funds
• At kickoff meetings identified: – the need for close inter task discussions and also with the need for close inter task discussions and also with
other DSother DS
– cost control and cost constraints central to system designcost control and cost constraints central to system design
SKADS Review 2006 Paul AlexanderDS3 & DS3-T3
Cost modelling in DS3Cost modelling in DS3
• In the original description of work there exist many work packages which are required to produce explicit cost models for particular aspects of SKADS technology
• Cost control central to work in DS3, DS4, DS5 and DS6
• Aim to coordinate this work and provide a good link to the wider project
Single identified point of contact to bring together the SKADScosting work
Provide an interface between SKADS costing work and the
ISPO development of a cost model
Communicate emerging cost output from SKADS to ISPO andcommunicate relevant aspects of ISPO cost model to SKADS
team
SKADS Review 2006 Paul AlexanderDS3 & DS3-T3
Highlights so farHighlights so far
DS3-T1 (more in a moment) Network infrastructure and data transmission
– A first good costing model for the physical network
DS3-T2 (more in a moment) Data handling, control and distributed computing
DS3-T3 (more in a moment) Overall architecture and network simulator
DS3-T5 (planned start end 06) SKA for the user
DS3-T6 – Need to adopt good practice for how we model and go about the
design process especially as we move into the Engineering Design phase
– Initial review of available methodologies
SKADS Review 2006 Paul AlexanderDS3 & DS3-T3
Highlights – DS3-T4 Highlights – DS3-T4
DS3-T4 Siting and related issues
Original view of the task
“The production of a full plan for siting and related issues for the SKA, encompassing environmental issues (including signal conditioning, impact and adopting the advanced technology to arid lands), radio
frequency monitoring/protection over a long term and potential maintenance regimes.”
SKADS Review 2006 Paul AlexanderDS3 & DS3-T3
Highlights – DS3-T4 Highlights – DS3-T4
DS3-T4 Siting and related issues
• Significant unforeseeable changes since SKADS planned in particular delay of site selection well beyond late 2006 as originally envisaged
• Some work originally planned in SKADS will now be done by International Project (specifically the Site Evaluation Working Group and its Task Group on Regulatory Issues, and the ISSC )
SKADS Review 2006 Paul AlexanderDS3 & DS3-T3
DS3-T4 Siting and related issues
• SKADS participants played central roles in helping to define regulatory requirements for radio quiet zones at each possible site
• ASTRON engineers have carried out the extensive and homogeneous Radio Frequency Interference (RFI) monitoring campaign of all four proposed SKA sites
• SKADS participants contributed towards ISPO Memo 73 on “Spectrum Protection Criteria for the SKA”
Highlights – DS3-T4 Highlights – DS3-T4
SKADS Review 2006 Paul AlexanderDS3 & DS3-T3
DS3-T3: Overall Architecture and DS3-T3: Overall Architecture and Network simulation Network simulation
SKADS Review 2006 Paul AlexanderDS3 & DS3-T3
DS3-T3: Refining the DS3-T3: Refining the Benchmark Specification Benchmark Specification
Aperture Array stations on long baselinesAperture Array stations on long baselines
• Benchmark specification has AA providing < 1GHz collector throughout. Can we define more precisely the requirements of an AA station?
• Consider basic parameters: station size, filling factor and data rate
• Constraint: ability to calibrate the station
SKADS Review 2006 Paul AlexanderDS3 & DS3-T3
DS3-T3: Refining the DS3-T3: Refining the Benchmark Specification Benchmark Specification
Consider the ionosphere:
• typical size of isoplanatic patch at 300MHz is ~ 2 degrees
• Calibration is relativelystraightforward if each stationbeam subtends an anglesmaller than the isoplanaticpatch
SKADS Review 2006 Paul AlexanderDS3 & DS3-T3
DS3-T3: Refining the DS3-T3: Refining the Benchmark Specification Benchmark Specification
• For a larger beam we need a more complex ionospheric model which can be solved for if reltively short baselines available as in compact core
• On long baselines however, sparse station coverage
• d ~ 70 m
1d
SKADS Review 2006 Paul AlexanderDS3 & DS3-T3
DS3-T3: Refining the DS3-T3: Refining the Benchmark Specification Benchmark Specification
• Need 1 source on average per beam/isoplanatic patch to calibrate; Poisson statistics to give P(1) for 99% of time needs N = 10 sq deg
• At 1.4GHz, use FIRST counts(unresolved or model)
• Require S ~ 15 mJy; for 70m AA,70% efficiency
• f > 20%
mJy1010150
4.32/12/11
MHzs
f
K
TS s
log(S / Jy)
log(
N o
r dN
/dS
/ sq
deg
ree)
Integrated FIRST source count
SKADS Review 2006 Paul AlexanderDS3 & DS3-T3
• Long baseline AA station– Diameter 70 m
– Filling factor > 20%
– Data rate:• assume 8-bit digitisation for 300 – 1000 MHz
• Per square degree full bandwidth 24 Gbs
• 250 beams ( 250 sq degrees or ~ 60 uniform sensitivity) gives 6 1012 bs
• Compare to LNSD station giving 1 sq degree at 1.4 GHz
• f = 10% and 25 13m antennae
• Beam form in central processor
• Data rate 6.4 1012 bs
DS3-T3: Refining the DS3-T3: Refining the Benchmark Specification Benchmark Specification
SKADS Review 2006 Paul AlexanderDS3 & DS3-T3
DS3: Dynamic range DS3: Dynamic range
• Sensitivity from large collecting area is only sensible if the telescope can also achieve the necessary dynamic range given is FOV, beam shape, side lobes etc.
• e.g. Tim Cornwell as investigated in detail the effects of the telescope quadrupod on the producing asymmetries in the beam and hence limiting the dynamic range:
This is a big issue which needs to be carefully This is a big issue which needs to be carefully considered for any antenna used in a given bandconsidered for any antenna used in a given band
SKADS Review 2006 Paul AlexanderDS3 & DS3-T3
DS3: The Next 18 Months DS3: The Next 18 Months
SKADS Review 2006 Paul AlexanderDS3 & DS3-T3
DS3: Next 18 months DS3: Next 18 months
• People now in post for DS3-T1 and T3 in UK and very significant ramp-up of these tasks is underway confidently expect to meet SKADS milestones and deliverables on time
• DS3-T2 is now ramping up as planned
• DS3-T4 effectively complete; report will be written after ISSC complete site selection
• First “SKA for the user” workshop planned in next 4 months (DS3-T5)
• Scaleup and design issues: work on track as planned
SKADS Review 2006 Paul AlexanderDS3 & DS3-T3
SKADS Review 2006 Paul AlexanderDS3 & DS3-T3
OverviewOverview
Overall aim of this design study
Examine the System Design issues associated with producing the most cost-effective overall architectural design for the SKA “network”
By Network we mean
• The physical network: signal and data transport & power
• The data network: data flow, processing and analysis
• The output network: telescope response warts and all
• The user network: how the telescope appears to the end-user astronomer
SKADS Review 2006 Paul AlexanderDS3 & DS3-T3
The next 18 monthsThe next 18 months
On track to meet milestones and deliverablesOn track to meet milestones and deliverables
• Phase transfer links (T1)
• Frame work for the network simulation / analysis (T3)
• Overview report on site selection (T4)
• Report MDA constructs, interfaces and platforms (T6)