TELESCOPE TEAMS – STELLENBOSCH ENG. MTG.

P. Dewdney2016-10-03

Telescope Teams – relationships with System Design

OverallTelescopeSystemDesign

MaintainedbytheSKAO

• Requirements• Products• Interfaces• Functions• Model(s)• Errorbudgets• Otherbudgets

TelescopeTeams

• Issuesfocussed• Performancequestions• Specialistknowledgerequired• Problem-solving

• Calibrations• Analysiswork.• Allocations

ResolutionTeam

ManagedIssue1

Integrationofresults:ECPs,newrequirements,ICDcomponents,etc.

ResolutionTeam

ManagedIssue2

ResolutionTeam

ManagedIssueN

• Goals– Identify, define and supervise the resolution of major issues.

• Many issues will be referred from SKAO.• Technical issues only.

• Focus– Issues framed so that there are clear boundaries and deliverable

outcomes.• not too broad (e.g. ‘calibration’ is too broad).

• Management– Work on each RT should be no more than a few months long. – Assemble a prioritised, running list of issues.– Limit the number of highest priority issues to about 5 at one time. – Management Plan

• SKA-TEL-SKO 0000431_01_Management_Plan_for_the_Mid_and_Low_TT_Teams

Telescope Teams

Resolution Teams• Actually carry out the work to resolve issues.• Membership can be from anywhere – acknowledged experts.• Teams to include:

– A project manager,– A relevant SKAO staff member.

• Members of consortia to:– Ensure relevant consortia are represented.– Ensure relevant knowledge and experience is available.

• RT Management– Check that there is sufficient resource to complete the task by the agreed time.

• Note that the decision to allocate resources lies with the SKAO HoP in consultation with CLs and TT.

– Provide updates to the TT.– Maintain reporting on the relevant Confluence Page.

TT – LOW TT-MID

Chair* Mark Waterson Gie Han Tan

Requirements* Wallace Turner Wallace Turner

PM* Andre van Es Martin Austin

SE* Maria Grazia Labate Andrea Cremonini

PS* Jeff Wagg Tyler Bourke

Co-Chair* Jan Gerald Bij de Vaate Thomas Kusel

LFAA Andrew Faulkner Not applicable

DSH Not applicable Adriaan Peens-Hough

SDP Rosie Bolton Rosie Bolton

CSP Ben Stappers/Grant Hampson Ben Stappers/Michael Rupen

TM Alan Bridger Lize van den Heever

SaDT Richard Oberland Richard Oberland

INFRA AUS Shandip Abeywickrema Not applicable

INFRA SA Not applicable Steve Dennehy

AIV Michael Hayes/Adam MacLeod Donald Gammon

Operations Corrie Taljard Antonio Chrysotomou

Telescope Teams – membership

Footer text* Member of Exec. Ex-officio: Alistair McPherson, Peter Dewdney

SKA1-mid RT Topics• MID TT RT1 Construction Phasing

– Identify, prioritise and phase the commissioning/engineering requirements for AIV support.

• MID TT RT2 RFI Characterisation– Characterise the strongest external RFI sources with emphasis on Bands 1 & 2.

• MID TT RT3 Sampling Clock Offset– Identify benefits, investigate implementation requirements, assess impact, estimate resources.

• MID TT RT4 Telescope Calibration– First step towards defining calibration schemes by identifying error sources through an assessment

of their impact on science observations.

• MID TT RT5 Subarrays– Clarification of the precise definition and uses for sub-arrays, as well as a list of subsidiary

questions.

• MID TT RT6 Noise Injection– Considering implementation possibilities that minimise impact on pulsar timing, search, and

recommending solution(s).

• MID TT RT7 Delay Model– Delay system architecture, error analysis, and calibration.

• Blue is complete (final report); green is in progress.

SKA1-mid RT Topics (cont’d)• MID TT RT8 States & Modes

– Develop a common definition and a consolidated set of states and modes at telescope, sub-array and lower levels, including an inter-level mapping.

• MID TT RT9 RFI Characterization II– Characterise the strongest external RFI sources in Bands 5. Also high time-resolution RFI in Bands

1 & 2.

• MID TT RT10 Fast Noise Injection Implementation– Follow-up to RT6 to consider implementation aspects of pseudo-random noise injection.

• SKA1-low RTs have been allocated to 5 Themes– Recommendation of the survey/review held earlier this year.– This allows the RTs to be focused on very specific questions.

• Themes (currently)– Configuration– Calibration– Planning– Technical Clarification– System Budgets– Costing

SKA1-low - themes

SKA1-low RT Topics• Low TT RT1: Calibration & Configuration

– Establish a baseline configuration for SKA1-low.

• Low TT RT2: CSP Relocation– Investigate the relocation of CSP to a coastal location to save on-site power.

• Low TT RT3: Synchronised Telescope Network Time– Clarify what is required for synchronous telescope network time embedded in telescope products.

• Low TT RT4: Station Lay-Out (added to issue 1)– Define limits to the station size, based on science and calibration requirements.

• Low TT RT5: Array Lay-Out (added to issue 1)– Define distribution of stations taking into account array-beam, ratio inner/outer, costs.

• Low TT RT6: Sub-Arraying– Review science objectives for which sub-arrays would be beneficial. Coordinating with TT-mid.

• Low TT RT7: LOW Construction Phasing– Alignment of Construction with AIV. Milestones needed for an achievable AIV plan.

• Low TT RT9: Performance Budgets– Define and tabulate sources of error, calibration methods and allocation of error budgets.

• Low TT RT10: Low Network Architecture– Verify existing requirements for the LOW network (between LFAA and CSP) and to identify gaps.

• Low TT RT11: Collecting data for RAMS on AAVS1– Review FMECA for SKA1-low and isolate aspects that can be tested using AAVS1.

SKA1-low RT Topics• Low TT RT12: Cost Reduction Work Group

– Collect, filter and summarise cost-reduction information/ideas pertaining to Low.

• Low TT RT13: Calculation of Pulsar Beamforming Weights– Define method (delay model), and implementation, including update rates, for beam-forming weights

used for pulsar search and timing.

• Low TT RT14: Identify the handover point from SDP to EoR KSP team(s)– Given that it is acknowledged that SDP will not be able to carry out the specialised EoR processing,

identify the most appropriate handover point from the SDP to the KSP team(s).

• Low TT RT15: Implementation of Transient Buffers– Define how transient buffers will be implemented, trigger mechanisms, etc.

• Low TT RT17: Low Configuration Update– Develop cost-limited proposals to improve the baselined array configuration.

• Low TT RT18: Ionospheric calibration model– Develop a well-substantiated position on the ionospheric calibratability of SKA1-low based on the

baseline configuration.

• Low TT RT19: Calibration requirements across the array– Consider whether the calibration requirements for the core and the longer baselines can be treated

significantly differently.

• Low TT RT20: Operational Aspects of Calibration– Outline calibration methods, based on the conclusions.

SKA1_Low & Mid TT sessions

Footer text

• Individual TT sessions at 2016 Engineering Meeting

• SKA1_Low TT Workshop Tues. Oct 4.– Mark Waterson / André van Es– 09:00 – 13:00 (by invitation only) Simonsberg Room

• SKA1_Mid TT Wed. Oct 5.– Gie Han Tan / Martin Austin– 09:00 – 12:30 (by invitation only) Simonsberg Room

• https://confluence.skatelescope.org/pages/viewpage.action?spaceKey=MTT&title=MID+Telescope+Team+Home

• https://confluence.skatelescope.org/display/LTT/LOW+Telescope+Team+Home

End12

Mid-RT4 - SKA1-mid calibration• Physical survey antennas after installation• Calibrate locations and delays (initially on installation and then monthly?)• Calibrate antenna pointing model (initially weekly)• Calibrate antenna polarization (P Jones) (initially weekly and then as needed

weekly)• Calibrate absolute flux scale (weekly)• Calibrate bandpass (Jones B) as often as possible (6 hours?). Bandpass

calibration will depend on having either a strong calibrator or the field itself. SDP will have to support both.

• Calibrate/monitor antenna gains (G Jones) (0.5 - 1 hour?) This is really just a health check since the gains should be very stable.

• Calibrate atmospheric phases (T Jones) (3 minute?)• Derive Faraday Rotation from GPS and apply as needed.• Self-calibrate everything again (P, B, G, T).• Reference pointing may be required, with the timescale depending on well-

behaved the antennas actually are. At low frequencies, fields can be complex with many sources. For this reason, reference pointing should take advantage of the full processing power of the SDP to return pointing offsets expeditiously.

Mid-RT5 - Sub-arrays• We define SKA1 subarrays and describe how they might be used. We propose a

distinction between scientific and engineering subarrays, and introduce the concepts of resource pools and subarray templates. After reviewing the various scientific and operational drivers, we conclude that 16 subarrays is a reasonable design requirement for those consortia which require an exact number, while suggesting that this be made a parameter rather than a hard-coded limit where possible. The relation between subarrays and Scheduling Blocks, and the thorny issue of trading information and resources between subarrays, is discussed in some detail.

Mid-RT6 - Noise Injection• Imaging experiments require noise diode for achieving high

dynamic range and beating 1/f noise.• Pulsar timing needs noise diodes (between observations) for

flux and polarisation calibration.• Pulsar search abhors noise diodes.• How do we preserve commensality?

• Investigations– CBF noise diode handling– Fast periodic firing– Slow periodic firing– Fast pseudo-random firing– Firing between NIP observations

Mid-RT7 - Delay models

• A- How accurate must the applied delay models be?• B- What does this imply for the polynomial orders and update

rates for those• delay models?• C- What are the implications for:

– Operations – SDP– TM – CSP – SaDT– DSH

• D- Review the functional requirements related to delay models to the various Elements

Mid-RT8 - States and Modes• There are currently many different definitions of States & Modes floating around

in the project at different levels. These definitions need to be consolidated and agreed so that the project can go ahead with:

• - A common definition of States & Modes at a defined set of levels• - A defined mapping between the States & Modes at the different levels

• It is proposed that States & Modes be defined for the project at the following levels:

• Telescope system level states & modes: Whether it is observing, idle, not able to observe etc. This is of interest to the observatory management in terms of understanding the availability and operational efficiency of the telescope.

• Sub-array level states & modes: The functional mode of each sub-array, depending on how the signal processing machine is set up in terms of channelisation modes, data products, etc. In radio telescopes, this is often closely related to the Correlator states and modes that are set up for each sub-array.

• Element and sub-element states & modes: For redundant systems (e.g. Dishes or processing units) their states and modes are mostly of interest for defining resource availability for sub-array resource allocations. For single point of failure items (e.g. TM), this may have a direct impact on the Telescope system level modes.

Mid-RT9 - RFI Characterization II• Despite all efforts that are being made to reduce external RFI at the SKA1_Mid

site, the telescope will be exposed to interference from transmitters either ground based, aeronautical or from space. The elements in the SKA1_Mid signal chain should be able to cope with this external RFI in a predictable and controlled manner. To achieve the latter goal it has been identified at the SKA Signal Chain RFI workshop (refer to reference documents above, workshop documents available on https://www.dropbox.com/home/SKA%20RFI%20Signal%20Chain%20Workshop%20Sep%202015) that additional information about this external RFI is needed as input for the detailed design process of the involved elements.

• After SKA1-Mid RT1, RFI Characterization, addressed the strongest external RFI sources in SKA1_Mid Bands 1 and 2, this RT will focus on:

• 1. External RFI in Band 5 (4.6 - 13.8 GHz);• 2. High time resolution, down to 1 μs, RFI.

Mid-RT10 -• Most radio telescopes insert a broadband noise source (switching noise diode)

in the signal chain to monitor rapid variations in gain and sensiviity (Tsys). Typically these are switched in and out (or ON and OFF) with periods of a few to a few hundred hertz. Such periodic signals may pose problems for pulsar detection and timing, and various refinements have recently been suggested to minimize these effects.

• SKA1-Mid RT6, Noise Injection, has investigated the above issue and suggested a novel noise injection scheme based on fast, pseudo-random noise calibration among different antennas. This scheme overcomes the issues with traditional periodic, noise injection and allows for parallel multi-mode observations. RT6 did not address the implementation of this new noise injection scheme. This folow-up Resolution Team is tasked with considering the implementation aspects of the new noise injection scheme.