"Exploring the Universe with the
world's largest radio telescope"
AAVP Workshop
SKA System Design
Kobus Cloete
9 December 2010
The System in Context
SPDO
Level 7
User System
User
system
Level 6
System
(See full hierarchy presented as part of R. Schilizzi’s talk yesterday)
Trenching
Buildings
Infrastructure
Station
Processor
Receptor
AA-low
PAF
WBSPF
Dish
Level 4
Receiver
Dish Array
Data links
Level 5
Subsystem
Roads
System
SKA High Level Conceptual SKA1 System
Block Diagram
SKA Conceptual
SPDO
Remote
cluster
SKA Conceptual
High Level
Block
Block Diagram
Diagram
Remote
cluster
Remote
cluster
Remote clusters
on spiral arm
(only one arm is
shown)
Remote
cluster
On Site
SKA HQ
(Off Site)
Remote
cluster
Operations
and
Maintenance
Centre
AIP
AIP
Dish
Array
Single pixel
feeds (SPF)
Phased
array
feeds
(PAF)
AIP
Wide
band
SPF
(WBSPF)
Mid Frequency
Aperture Array
(AA-Mid)
Low Frequency
Aperture Array
(AA-Low)
Central
Signal
Processing
Facility
Central Beamforming
Correlation
Non-visibility Processing
Global
Regional
Science
Centre(s)
Science
Computing
Facility
High Performance Computing
Data Storage
Regional
Engineering
Centre(s)
Drawing number : TBD
Date : 2010-09-29
Revision : F
SKA Memo 125
SPDO
Memo 125 – Summary (1)
SPDO
•
Definition of Baseline
–
–
–
–
–
–
–
–
–
Low frequency sparse aperture array
Dish array
Signal transport and networks
Correlator and Non visibility processor
Central Data Processing, Science Processing and
System Software.
Central timing and synchronisation subsystem,
including time and frequency reference distribution,
Infrastructure (buildings, roads, facilities, labs etc.),
Power delivery and distribution,
Support and maintenance equipment and facilities
Memo 125 – Summary (2)
SPDO
•
Advanced Instrumentation Program
– Dense Aperture Arrays
– Phased Array Feeds
– Ultra Wide band Single Pixel Feeds
•
Decision points for AIP identified
– 2016, or
– As modular sub-systems of the SKA1 dishes
•
How do we continue with the SKA definition and
design and at the same time take all of these
aspects into consideration?
1. How do we get to this?
2. How do we move from this …..
SPDO
To this!
Challenges
•
Challenges include:
SPDO
– Maintaining a focus on full SKA
– Definition of potential Phase 2 envelopes to ensure Phase 1
extensibility for example:
 Scope of the infrastructure to be developed for Phase 1 balancing cost
and Phase 2 view/extension
– Selection of receptor technologies for Phase 2 in 2016 implies
that the full scope, definition and design of Phase 2 will only be
finalised after selection
– Potentially higher costs because of wrong choices and resulting
rework
– Degree of integration of the AIP receptors with the Phase 1
instrument
– Guard against discontinuity in buildout
– Carry risks for longer
Route to SKA
SPDO
•
•
•
How do we continue with the SKA definition and
design and at the same time take all of these
aspects into consideration?
Recently a conceptual Route to SKA was
developed attempting to maintain the structure
of the project but at the same time maintain
flexibility to accommodate all the identified
future enhancements.
Always maintain focus on the full SKA.
Costed system
design
approval
Construction
2026
7
2025
2024
Risk
Observing
2023 SKA2 Shared-
6
2022
2021
Start of SKA2
Construction
Detailed Des
& Test Sub-
5
2020
2019
AIP
4
2018
2017 & AIP Decision
SKA2
3
2016 Start of SKA1
2015
2014
SKA1
2
2013 SKA1 const’n
2012
Site decision
SKA1
Baseline
Design
1
2011
2010
2009
Graphical Representation (from PEP)
Build
8
9
TR Levels
Part B
SPDO
Start
SKA2
Define initial science
requirements for SKA1.
(Subset of DRM)
Define SKA1
technical requirements
Site Decision
Adjust
SKA1
scope
Definition
Preliminary Design
SKA1
Preliminary system
design
AIP
Carry out first order
SKA2 system designs,
based on 4 technology
combinations.
Extract SKA2 Extensibility
Requirements for SKA1
Element/subsystem
design, based on SKA2
requirements.
Detailed verification
programme design.
Develop, build, deploy
prototype(s).
Continue to track and
refine SKA2
requirements.
Evaluate SKA1 system:
·
Cost/performance tradeoff
·
Extensibility from SKA1 to
SKA2
SPDO
Analyse SKA2
requirements to develop
AIP technical
requirements
Define initial science
requirements for SKA2,
extracted from DRM
AIP
Concept, Definition &
Early Preliminary Design
Concept, Definition
SKA1
Note: options are:
[1] Baseline Design (BD)
[2] BD + Phased Array Feeds
[3] BD + Dense Aperture Arrays
[4] BD + Ultra-Wideband Single-Pixel Feeds
Carry out verification,
using a small set of
converging prototypes.
OK to finalise
SKA1 design?
Detailed Design
Sufficient maturity
demonstrated to consider
in SKA2 design?
Detailed design for
SKA1
Pre-Construction
Drop immature
technology
Yr 2016
Yr 2016
SKA2
Preliminary system
design
Construct & continuously
evaluate SKA1
Operate SKA1 to
generate science results
Preliminary Design,
Cost/Performance Trade-offs for SKA2,
considering AIP technology.
Build,
Test, Integrate
No
Yes
Adjust
SKA2
scope
SKA2 Decision
Evaluate SKA2 system. Optimise
SKA2 system for selected
technologies.
·
PAF technology
·
DAA technology
·
BL technology
·
WBSPF technology
Consider:
·
AIP outcomes
·
Cost/performance tradeoff
·
Risk
·
Total System Cost
·
Schedule
·
SKA1 ops experience
·
Requirements
·
Functional
·
Non-functional
Yes
Detailed Design, Build,
Test, Integrate
Detailed design for
SKA2
OK to finalize
SKA2 design?
Construct & continuously
evaluate SKA2 in
parallel with operating
SKA1
Yes
Operate the
Final SKA
SKA1 Construct
SKA2 Design
Start
SKA2
Site Decision
Preliminary Design
SKA1
Preliminary system
design
Adjust
SKA1
scope
Evaluate SKA1 system:
·
Cost/performance tradeoff
·
Extensibility from SKA1 to
SKA2
AIP
Carry out first order
SKA2 system designs,
based on 4 technology
combinations.
Extract SKA2 Extensibility
Requirements for SKA1
Continue to track and
refine SKA2
requirements.
SPDO
Analyse SKA2
requirements to develop
AIP technical
requirements
Define initial science
requirements for SKA2,
extracted from DRM
Element/subsystem
design, based on SKA2
requirements.
AIP
Define SKA1
technical requirements
Definition
Define initial science
requirements for SKA1.
(Subset of DRM)
Concept, Definition &
Early Preliminary Design
Concept, Definition
SKA1
Note: options are:
[1] Baseline Design (BD)
[2] BD + Phased Array Feeds
[3] BD + Dense Aperture Arrays
[4] BD + Ultra-Wideband Single-Pixel Feeds
Detailed verification
programme design.
Develop, build, deploy
prototype(s).
Carry out verification,
using a small set of
converging prototypes.
OK to finalise
SKA1 design?
Detailed Design
Sufficient maturity
demonstrated to consider
in SKA2 design?
Yr 2016
Yes
Detailed design for
SKA1
No
Drop immature
technology
Yr 2016
Pre-Construction
SKA1
SPDO
•
From the SKA1 science requirements (Memo 125)
– Derive the SKA1 technical requirements
– Develop initial SKA2 system technical requirements based on
the science requirements contained in the Design Reference
Mission (DRM).
•
•
Derive all other requirements
Perform preliminary system design for SKA1
– To be informed by early preliminary designs for the SKA2
options, so as to ensure extendibility to SKA2.
– Tradeoffs of performance against cost.
•
Full detailed design for SKA1.
SKA2
SPDO
•
To inform the SKA1 design process
– Draft initial technical requirements for the four
system options for SKA2 (Baseline Technology alone
+ the three AIP options in combination with the
Baseline Technology),
– Carry out early preliminary system designs for each
of the options.
•
Continue to track Phase 2 requirements to
prepare for a decision on technology selection in
2016.
AIP
SPDO
•
•
The AIP will build up the level of maturity in anticipation
of their utilisation in SKA1 and SKA2.
General steps:
– Analyse the SKA requirements to maximise potential to
enhance system performance, achieve more of the initial
system requirements and/or reduce cost, as compared with
the baseline.
– Develop a preliminary design assuming the particular AIP
technology will be used at the element or subsystem level of
the system.
– Carry out a verification program to test the level of
achievement of requirements, to develop performance/cost
models for the AIP technology, and to ascertain remaining
risk.
Requirements emanate from various sources
SPDO
Local communities
and environment
(cultures)
Security
Regulatory
Health
and
Safety
Existing
Infrastructure
Technology
Science
Operations
Natural
Environment
Sources
of interest
External RFI
Environment
System
Science
Academic and
Science institutions
(Local and global)
Other Constraints
(Virtual Observatory,
VLBI, TOO interface, web
delivery interface)
Performing science
operations while
construction is
proceeding
Human
factors
Maintenance
and support
Transitioning
between
phases
Obsolescence
Standardisation
Skill level of maintainers
Test equipment
Simulators
….
Users,
Operators,
Scientists
Flow of requirements
SPDO
Science and others
Requirements
Top - down
System
Requirements
Element
Requirements
Sub-system
Comply to?
Existing Solution 1
Existing Solution 2
New Solution
Bottom - up
Process in more detail
SPDO
Science and other
requirements
Science and other
requirements
System
Element 1
Element 2
System
System
Element 1
Element 2
Element 3
Element 3
Subsystem 1
Subsystem 1
CoDRs
SRRs
(More comprehensive view)
SKA Science Case
How does it all fit together?
DRM
SYSTEM
Tradeoffs
Concept Phase
System Definition Phase
DRM Analysis
Memo
125
Concepts
System Prelim Design Phase
Requirements
Development
Analysis
Validation
High level
requirements
Memo 100
SPDO
C
O
D
R
Design
Functional analysis, verification and synthesis
Design verification
S
R
R
P
D
R
Technologies
Risk
Management
Plan
Selections for reference design
Risks
ELEMENTS
Concept Phase
Concepts
Tradeoffs
Definition Phase
C
O
D
R
Prelim Design Phase
S
R
R
Requirements (Development, Analysis , Validation)
P
D
R
Design (Functional analysis, verification and synthesis, Design verification)
Risk mitigation strategies and projects
Verification programmes (DVP, AAVP, other domains), Design studies, Precursors, Pathfinders
Risks
Time
RISK MANAGEMENT
Verification Programs
SPDO
•
Example considerations:
– What is the aim of the verification program?
– Which requirements will be verified and how?
– If not all, will a next development model be built and
tested to verify these requirements?
– Other considerations?
Where are we?
SPDO
•
System CoDR was held in February 2010
– Provided guidance an all these aspects
– Documents available at WP2 wiki:
 http://www.skatelescope.org/public/2010‐02_System_CoDR_Documents/
 WP2 wiki
•
•
•
•
Memo 125
System documents being reworked for delta CoDR in
February 2011
Will be followed by element level CoDRs during 2011
System Requirements Review in 2012.
Other presentations for reference
SPDO
•
Annual WP2 meeting (October in Oxford)
– Presentations available of SKA Indico Site
– Turner
 Systems Methodology for the SKA
– Dewdney
 Refining the DRM & Deriving Technical Requirements
– Cloete
 System Design Plan
 System Engineering Tools and Strategies
 WP2 planning and Beyond PrepSKA
– McCool, Hall, Bolton
 Costing Strategy
Thank you
SPDO