WP WBS 001. Signal Transport & Networks PrepSKA Work Breakdown Structure

Transcription

1 WP WBS 001 Signal Transport & Networks PrepSKA Work Breakdown Structure DOCUMENT NUMBER WP WBS-001-C REVISION C AUTHOR R. MCCOOL DATE Name Designation Affiliation Date Signature Submitted by: R. McCool Domain Specialist - Signal Transport & Networks SPDO D.DeBoer CSIRO Accepted by: S.Montebugnoli INAF J.G.b.d.Vaate ASTRON SIGNED SIGNED Agreed D.Barbosa IT C.Shenton UK R.Keller MPlfR SIGNED SIGNED SIGNED Project Plan P. E. Dedwney International Project Engineer Approved by: SPDO R. T. Schilizzi Director SPDO Page 1

2 WP WBS 001 DOCUMENT HISTORY Revision Date Of Issue Engineering Change Number Comments A First draft release for KO meeting B Updated following review by interested parties C Updated with deliverables specified by institution DOCUMENT SOFTWARE Package Version Filename Wordprocessor MsWord Word 2007 Document standards Rev B Block diagrams Other Name Physical/Postal Address COMPANY DETAILS SKA Program Development Office Jodrell Bank Centre for Astrophysics Alan Turing Building The University of Manchester Oxford Road Manchester, UK M13 9PL Fax. +44 (0) Website Page 2

3 WP WBS 001 Signal Transport and Networks - Work Breakdown Structure A plan of work is required, that will lead us to a dependable and affordable engineering solution for data transmission, control and timing distribution networks for the SKA. This document will address a number of areas related to the Signal Transport and Network (STaN), including, an adjustment of the PrepSKA WP2 STaN task descriptions and details of the scope, depth and quality of work required from those working in this area. This will be the first step for STaN in the formulation of a plan to deliver the PrepSKA WP2 goal; A detailed costed system design and an implementation plan for the SKA The SKA System Engineering Management Plan reference document, written by Kobus Kloete, describes how the prime PrepSKA objectives translate into more specific deliverables. It has been used in the preparation of this document to provide a basis of reference for interpreting requirements for STaN. Contents 1. Introduction Signal Transport & Networks Work Packages for the SKA Categories of solution Design & Analysis for SKA STaN subsystems Required inputs from other areas of the project Project Communications Description of the Work Dish Signal Cabling Design WP STaN for PAF systems WP STaN for WBSPF systems analogue WP STaN for WBSPF systems digital WP Central Processor internal fibre network. WP Digital Data Back Haul (DDBH) systems WP M&C Network. WP LO and timing systems WP APPENDIX 1 Adjusted PrepSKA WP2.7 workpackages Page 3

4 WP WBS Introduction In radio astronomy the signal transport networks are the backbone of the telescope. Signal transport networks connect to, and support many of the other telescope subsystems. The array configuration will dictate the network connectivity, but the choice of signal transport technologies will dictate the physical configuration and layout of cables between antennas and the correlator and the equipment required in between. These cable networks, once installed, may not be easy to upgrade. The cable routes are part of the fixed infrastructure of the telescope and as such need to be designed to support the instrument throughout its lifetime. At the antenna, the signal transport subsystems are an integral part of the antenna back-end. This means that they cannot be developed in isolation, as an abstract technology solution. They must be designed with an antenna subsystem in mind. Without this discipline essential questions, singular to the radio astronomy environment and a particular antenna implementation (e.g. RFI, cable wraps, interfaces & requirements on the signal quality), may not be answered. The nature of the work we intend to undertake and the inclusion of project plans in this document means that the WBS will, necessarily, be a living document and subject to change in the future, but this will only be on agreement with the relevant parties. 2. Signal Transport & Networks Work Packages for the SKA As described above, STaN subsystems are an integral part of an antenna and cannot be developed in isolation. We propose a framework that has the following aims: Energy is focused towards the tasks required to deliver the goals of PrepSKA WP2. Development programmes are on a trajectory towards implementing, not just SKA Phase I but also Phase 2 The PrepSKA work description (see Appendix 1) has been reviewed and adjusted to accommodate the development of subsystems for specific antenna designs. Signal Transport and Networks within both sparse and dense Aperture Arrays will be covered within the AA verification program and are not included in the work breakdown structure shown below. Monitor and Control is large enough to encompass many areas of expertise, including STaN, Software and Hardware. In order to reflect this fact, the M&C work has been moved into the systems area. The SPDO Systems engineer has overall responsibility for this work, but the M&C network will be costed, within STaN, for PrepSKA. Signal transport Design & Cost SigT Eng. Dish Signal Cabling Design STaN for PAF systems STaN for WBSPF analogue STaN for WBSPF digital Central Processor internal fibre network Digital Data Back Haul M&C network LO and timing Project code WP Signal transport Design & Cost SigT Eng. CSIRO CSIRO, ASTRON INAF, MPlfR, ASTRON UK, SPDO UK, ASTRON IT, (NRF), (CSIRO) UK, IT There are four new work packages that focus on the design of signal transport links for SKA dish systems; Page 4

5 WP WBS Dish Signal Cabling Design [WP2.7.10] - This work will include responsibility for all those signal cables located on SKA antennas, up to and including an interconnection point between antenna riser cables and site networks at the base of the antenna. 2. STaN for PAF systems [WP2.7.20] This work covers the design, costing and deployment plan for signal transport and networks for antenna systems equipped with Phased Array Feeds. This will include links from the output of the receiver system to the input of the beam former. 3. STaN for WBSPF systems - analogue [WP2.7.30] This work covers the design, costing and deployment plan for all analogue signal transport and networks for Wide Band Single Pixel Feed systems. This will include links from the output of the receiver system to a digitising stage. 4. STaN for WBSPF systems digital [WP2.7.35] This work covers the design costing and deployment plan for digitising modules, including a signal transport function for Wide Band Single Pixel Feed systems. Four further work packages will address; 5. Central Processor Internal Fibre Network[WP2.7.40] - The internal fibre network at the central processor will need to be costed in PrepSKA, but no detailed design work will be undertaken until the post PrepSKA period. Estimated costs for PrepSKA will be provided by the STaN domain expert. 6. STaN for Digital Data Back Haul (DDBH) [WP2.7.50] - This work package will provide costed designs and deployment plans for the wide area networks that connect a digitising stage (e.g. beamformer) to the correlator. Resource from groups local to the candidate sites has been included here, to provide support for the investigation of long distance fibre links provided by national operators. 7. M&C Network[WP2.7.60] The systems group will define the requirements of the M&C network, but the STaN group will examine technical solutions to meet the requirements and cost those solutions for PrepSKA. 8. STaN for LO& Timing [WP2.7.70] This work will provide costed designs and deployment plans for the provision of a local oscillator reference signal, of the required precision, to antenna elements and digitising stages. 3. Categories of solution Subsystem designs in this area will be one of three flavours, with the important additional option of a turn-key solution. It will be important to ascertain in as objective a way as possible how these subsystems will operate in the final telescope. : 1. New design. If a design is brand new, then a prototype should be built and performance measurements taken to prove that it can meet all of the requirements. 2. An existing design that is being used in a non-standard way for the SKA. If a design exists, for instance in the field of telecommunications, but is being used in a non-standard way for the SKA, then designers will need to establish with confidence that aspects of its operation, such as interfaces and RFI levels are compatible with the environment in which it will be implemented. The assumption is often made that if a system works in one application it will automatically work in another. This is not a universal truth, and a design will need to be tested thoroughly to establish that it can meet all of the requirements. 3. A design that has been implemented in one of the path finder projects. This represents a design format that, in many ways provides us with more confidence, because we will have operational system designs. It will be important, in this instance, to establish that the design will scale as they may often have been hand-crafted with a smaller instrument in mind Page 5

6 WP WBS Turn-key solution A design and build contract given to an external provider based on a set of specific requirements. In this scenario much of the technical risk is transferred to the contractor. The risks in this approach lie in a few areas; (1) cost and cost accuracy, the price a company will charge for equipment and services will be subject to market forces and not predictably aligned with the cost of implementation, (2) interfaces, where particular attention must be paid when obtaining equipment that is not designed specifically for the SKA, (3) Specifications must be clear and stable, since they will define the contract. Designs provided by contributing institutions provide valuable insurance to the project in the event that a tender process reveals that commercial companies simply cannot provide the equipment desired, within budget. If designs developed for the SKA can, at a later date, be exploited for commercial gain then trading intellectual property rights (IP) for services may be of considerable advantage to both parties. Aspects of work that must be covered in PrepSKA in order to formulate and assess tenders for turn-key solutions, include; (1) preparation of interface related specifications, (2) detailed research into the operation of commercially available systems (3) Identification of those areas of technical performance or operation that are particular to the SKA. 4. Design & Analysis for SKA STaN subsystems The goal is to produce a costed design and deployment plan for the SKA. This plan must contain cohesive designs for SKA end to end systems that are capable of delivering science goals. Our design programme should aim to deliver comprehensive STaN solutions that are integral to the antenna subsystems and signal processing subsystems that they connect. Technology solutions that are included in this design must be selected by means of a fair comparison of performance metrics (from data tested in an objective manner) and an analysis of the relative advantages and disadvantages of proposed implementations. The development programmes will be punctuated by three design reviews that are described below. The information required for the reviews is an example of the coverage and depth of analysis expected for the SKA developments. However not all the required information needs to be in separate documents and not all information will be applicable in all cases. What is and is not applicable will be agreed between the domain specialist and the project groups before the design review. Concept Design Review (CoDR) A Concept Design Review (CoDR) will be conducted at the end of the concept phase. The aim of the CoDR is to confirm that the problem has been thoroughly explored and is well understood. This is important to be able to move forward to the next phases of the project where technology options will be investigated and selections being made. The review will also focus on whether the first order solutions that have been identified are indeed appropriate and will ensure that agreement is reached on the option(s) to be carried forward. Documents to be reviewed during the CoDR will include at least: Report outlining the findings of the investigations of the first phase including descriptions of competing technologies and statements and justifications of the candidate options to be carried forward First draft requirement specification, with supporting data such as calculated or estimated performance parameters First draft interface control documents (internal and external) First risk register and related mitigation strategies Page 6

7 WP WBS 001 First draft block diagram of the relevant system, element or subsystem First draft requirements traceability matrix/database Strategy and plans for proceeding to the next phase First draft cost, schedule, power and reliability estimates Identification of logistical activities to be conducted Identification of software and related software documentation activities that will be conducted (Sub)System Requirements Review (SRR) The SRR, conducted at the end of the definition phase, will review primarily the definition of the specific building item 1 as reflected in its relevant Requirement Specification. The review will typically be conducted after the conclusion of the requirement analysis and validation activities. Documents to be reviewed during the SRR will include: Report outlining the findings of the investigations of the candidate technology options and statements and justifications of the selected baseline option to be carried forward Finalised requirement specification (including the cross verification matrix indicating the kind of tests to be performed for each of the requirements). Updated interface control documents First draft of the architectural design description document First draft acceptance test plan/procedure Updated risk register and related mitigation strategies Updated block diagram of the relevant system, element or subsystem Updated requirements traceability matrix/database Strategy and plans for proceeding to the next phase Updated Cost, schedule, power and reliability estimates Logistical and software documents (To be defined) Health and safety The output of this review is a well defined item at the project level at which it is being performed. Preliminary Design Review (PDR) The PDR will be conducted at the end of the preliminary design phase and is aimed to review and confirm the final design of the item as reflected in its relevant Architectural Design Description Document. The review will be performed at the conclusion of the functional analysis, verification, synthesis and design verification activities at the end of the preliminary design phase. Documents to be reviewed during the PDR will include: Revised and final requirements specification Final architectural design description document Revised interface control documents Final block diagram Acceptance test plans and procedures First draft integration plan Updated requirements traceability matrix/database Consumables, spares and test equipment Updated risk register and relating mitigations strategies 1 The term item is used generically to represent any of the building blocks in the system hierarchy Page 7

8 WP WBS 001 Upgrade plans Roll out/build plans Logistical and software documents (To be defined) Audit of manufacturing datapacks for designs to be carried forward Health and safety Together, the above set of documents must reflect the fully costed design of the item. The output of the review will be a fully designed item. 5. Required inputs from other areas of the project. The STaN work will only be successful if the requirements for the system are defined as clearly and as early as possible. There are a number of inputs that are needed for this process to reach completion and they are defined in other areas of the project. Significant inputs are: Design Reference Mission System level technical specifications and requirements Configuration Studies EMC studies and related decision on number of bits required at digitisation. M&C system requirements & architecture Dish, mechanical designs Digital signal processing, protocol definitions 6. Project Communications The STaN work involves 7 different institutions across the globe, as well as the SPDO. Good communication is therefore required to ensure efficient direction of resource and produce a coherent and cohesive body of work for PrepSKA. The Domain Specialist, based at the SPDO will co-ordinate communication activities, these will include: Monthly teleconferences for various design groups: These teleconferences will be an opportunity to address project issues on a monthly basis. They are not singularly a vehicle for management of the project and should involve engineering staff engaged in development work. They will provide an opportunity to discuss technical matters related to STaN. Currently there is a monthly teleconference for groups involved in networks for the SKA and another for those involved with STaN for receptors. Further design groups of interested parties are likely to be formed as the project moves on, including an LO & timing design group and in all likelihood an M&C design group. Any group can request time in the teleconferences in order to direct technical discussions towards a specific topical subject. Monthly updates: It is not always possible to assemble all the groups at the monthly telecons. When a group misses a teleconference for some reason a quick update is requested. The project principle from the institutions should produce this update. This should include a statement about how the project is progressing against the project plan, details of any impediments to progress that need to be addressed and any significant progress to be highlighted Page 8

9 WP WBS 001 Quarterly report: This report should include details of how the project is progressing against the project plan and towards review dates, reports of results, details of plans and highlight any issues regarding impediments to progress. Project principles within the institutions are responsible for producing this report. Reviews: Each project has review points in the plan in order to take stock of the work undertaken. It is an opportunity to take into consideration views external to the project group and to place design solutions in the context of the SKA as a system. It is anticipated that reviews will be public within the project and will have an external, expert review panel to assess the work as it progresses and provide valuable inputs to the design teams. Annual WP2 meeting: This annual meeting is an opportunity for groups to meet with others working in the international SKA project in work package 2. The aim of this meeting is to provide a snapshot of the world-wide progess toward the design of the SKA and specifically within the PrepSKA Work Package 2 activities; to begin the process of confronting science goals, design choices, and technical risks within a system engineering approach; and to explore the impact of recent scientific and technical results for the SKA design. Annual SKA Science and Engineering meeting: The aim of this meeting is to bring together the astronomical and engineering SKA communities together. The latest astronomical results in SKA relevant areas will be discussed as well as the status of engineering studies for the SKA. Ad-hoc teleconferences, meetings and other communication: Lines of communication should not be restricted to the reports and meetings described above. If a particular issue requires additional attention then groups are encouraged to call meetings as they are needed. The domain specialist will support these activities from the SPDO. STaN wiki: The STaN wiki is a facility for sharing documentation with the design teams. This facility is available for all the groups involved in this area. Groups are encouraged to share information, work-in-progress and documentation. The wiki should be seen as a safe area for groups to share ideas (even if they are incomplete) and should not be seen only as a final publishing house for SKA material. The following pages describe the work breakdown structure for each project in the STaN domain. Each project has a description, a project plan and interface diagram and a list of deliverables Page 9

10 Dish Signal Cabling Design WP Description of the Work 7.1. Dish Signal Cabling Design WP This work will include responsibility for all those signal cables located on SKA antennas, up to and including an interconnection point between antenna riser cables and site networks at the base of the antenna. A cable system design will be produced, including specifications of cable and connectors and drawings describing interconnects on the antenna and routes through cable wraps. ICDs will be required o With the M&C group and the LO & timing group who will also require interconnects on the antenna. o with the site group who will provide the cable infrastructure required to connect the antennas to the rest of the array. o With the antenna group, who will provide designs for the cable wrap and dimensions of structures and routes on the dish. o With other STaN groups with transmission systems on the dish, who will provide specifications of the connectors, fibre types and requirements related to signal transmission. Examples of specific performance metrics related to cable systems are: Connector specifications (IL, Return Loss (RL)), Phase & amplitude stability through cable wraps and with temperature, linearity of the transmission medium. Operating and installation temperature ranges, allowed pulling force during installation will also be of interest. List of Deliverables Conceptual design review deliverables CoDR documentation (See section 4) Particularly a review of differences in WBSPF only dish cable wraps and PAF cable wraps. Sub-system requirements review deliverables Updated documentation from the CoDR (including an updated specification set & risk register) SRR documentation (See section 4) Particularly, measured performance metrics; including amplitude and phase stability vs temperature and movement. Particularly mechanical drawings of design. Preliminary design review deliverables Updated documentation from the SRR PDR documentation (See section 4) Page 10

11 Dish Cable System Design WP Project Plan Page 11

12 Dish Cable System Design WP Page 12

13 Dish Cable System Design WP Interface Diagram Page 13

14 STaN for PAF systems WP STaN for PAF systems WP This work covers the design, costing and deployment plan for signal transport and networks for antenna systems equipped with Phased Array Feeds. This will include links from the output of the receiver system to the input of the beam former. It is likely that this work package will provide new designs, showing PAF signal transmission solutions for an instantaneous bandwidth defined by the Reference Science Mission (currently defined in Memo 100 as 750 MHz), and as such it is expected that pre-production prototype systems will be built, tested and engineered for installation on dishes used in the Dish Verification Programme. Pathfinder telescopes that include PAFs are the APERTIF telescope at ASTRON and the ASKAP telescope at CSIRO. Examples of telescopes transporting wideband data from antenna are; the ATA, ALMA, EVLA & e-merlin. Specific tasks related to signal transmission for PAF Dish systems are: Both APERTIF and ASKAP have a bandwidth of 300 MHz, however the SKA Phase2 specification requires a larger instantaneous bandwidth (currently defined as 750 MHz in Memo 100). Precursor solutions will have to show they can reliably transmit at wider bandwidths. Study of the available multiplexing techniques for the efficient use of fibre infrastructure. Formulation of an ICD in conjunction with the receiver group that addresses the interface between the signal transport system and the antenna receivers. This ICD will provide details of the required specifications for link lengths and signal bandwidths. In particular the location of the downconversion stage is of interest here. The available bandwidth of signal transport designs could enable downconversion to occur at a hub, shared by groups of antennas. Alternatively, downconversion at the antenna could reduce bandwidth transmission requirements and therefore costs in the signal transport subsystems. The PAF signal transport infrastructure and the WBSPF signal transport infrastructure will have to co-exist on the dish. (Neither APERTIF nor ASKAP has an integrated WBSPF on the dish.) Solutions for the SKA will require antenna cable system designs that accommodate both the PAF & the WBSPF signal transport infrastructure. An ICD will be required between the antenna group, the signal cable on dish design group, the STaN PAF group and the STaN WBSPF group in order to ensure mechanical assemblies provide room & protection for equipment and that cable wraps perform to a required specification. An ICD will be required with the Dish Signal Cable design group defining the requirements of cable systems on the dishes. Example specifications are: Connector specifications (IL, Return Loss (RL)), Phase & amplitude stability through cable wraps and with temperature, linearity of the transmission medium Page 14

15 STaN for PAF systems WP Where transmission designs specify that beamforming occurs at some distance from the dish, and an additional fibre link is required between the dish network and the digital data backhaul network, then this link will be specified in this work package and an ICD written in conjunction with the site group for its provision. Examples of specific performance metrics related to analogue systems for these dishes will be calculated and measured. These performance metrics are: Phase and Amplitude linearity across the frequency band, Spurious free dynamic range (SFDR), Third Order Intercept Point (IP3), 1dB compression point, Power Budget (Gain (G), Insertion Loss (IL)), dispersion (chromatic & modal) and wavelength stability. Examples of specific performance metrics related to digital systems for these dishes will be calculated and measured. These performance metrics are: Bandwidth, RFI levels and mitigation strategies, Bit Error Rate (BER), Power Budget (Gain (G), Insertion Loss (IL)), dispersion (chromatic & modal) and wavelength stability. List of Deliverables Conceptual design review deliverables CoDR documentation (See section 4) Preliminary review of configurations for technology solutions Sub-system requirements review deliverables Updated documentation from the CoDR (including an updated specification set & risk register) SRR documentation (See section 4) Prototype transmission system for PAFs Measured performance metrics including, reliable transmission at required instantaneous bandwidth, RFI levels. Design of local link configuration, if required Specification of local link cable network, if required Preliminary design review deliverables Updated documentation from the SRR PDR documentation (See section 4) List of candidate suppliers and reference customers, where available Page 15

16 STaN for PAF systems WP Project Plan Page 16

17 STaN for PAF systems WP Page 17

18 STaN for PAF systems WP Page 18

19 STaN for PAF systems WP Interface Diagram Page 19

20 STaN for WBSPF systems analogue WP STaN for WBSPF systems analogue WP This work covers the design, costing and deployment plan for all signal transport and networks for Wide Band Single Pixel Feed systems. This will include links from the output of the receiver system to a digitising stage. Adapting existing designs from the pathfinder telescopes may provide the best design choice for WBSPF systems within the time allowed in PrepSKA. If this is the case much of the work will be concentrated on the choice between analogue or digital designs and the optimisation studies required in order to make that choice (which should also include antenna cabling configuration studies). Once a design choice has been made then the focus will be on the adaptation of an existing system for SKA specific; dishes and subsystems, operating environment and cost drivers. It will be important to establish that the design will scale to an SKA implementation, as they may have been hand-crafted with a much smaller instrument in mind. Alternatively a new design specific to the requirements of SKA Phase 2 may be pursued and pre-production prototypes developed. Pathfinder telescopes that relate to this solution are the ATA, EVLA, e-merlin and ALMA. Specific questions related to signal transmission for WBSPF dish only systems are: Analogue or digital transmission for dishes? Is the ATA RF over fibre solution or the EVLA digital transmission solution optimum for the SKA? Can the DDBH system start at the base of the dish? What is the optimum combination of technology solution and antenna configuration? Are there points of aggregation that provide opportunities to share infrastructure and services? Formulation of an ICD in conjunction with the receiver group that addresses the interface between the signal transport system and the antenna receivers. This ICD will provide details of the required specifications for link lengths and signal bandwidths. In particular the location of the downconversion stage is of interest here. The available bandwidth of signal transport designs could enable downconversion to occur at a hub, shared by groups of antennas. Alternatively, downconversion at the antenna could reduce bandwidth transmission requirements and therefore costs in the signal transport subsystems. This ICD will also address the RFI reduction requirements related to digital systems on dishes. The PAF signal transport infrastructure and the WBSPF signal transport infrastructure will have to co-exist on the dish. (Neither APERTIF nor ASKAP has an integrated WBSPF on the dish.) Solutions for the SKA will require antenna cable system designs that accommodate both the PAF & the WBSPF signal transport infrastructure. An ICD will be required between the antenna group, the STaN PAF group and the STaN WBSPF group in order to ensure mechanical assemblies provide room & protection for equipment and that cable wraps perform to a required specification Page 20

21 STaN for WBSPF systems analogue WP An ICD will be required with the Dish Signal Cable design group defining the requirements of cable systems on the dishes. Example specifications are: Connector specifications (IL, Return Loss (RL)), Phase & amplitude stability through cable wraps and with temperature, linearity of the transmission medium. Where transmission designs specify that digitisation occurs at some distance from the dish, and an additional fibre link is required between the dish network and the digital data backhaul network, then this link will be specified in this work package and an ICD written in conjunction with the site group for its provision. Examples of specific performance metrics related to analogue systems for these dishes are: : Phase and Amplitude stability and linearity across the radio frequency band - Spurious free dynamic range (SFDR), Third Order Intercept Point (IP3), 1dB compression point, Power Budget (Gain (G), Insertion Loss (IL)), dispersion (chromatic & modal) and wavelength stability. Examples of specific performance metrics related to digital systems for these dishes are: Bandwidth, RFI levels and mitigation strategies, Bit Error Rate (BER), Power Budget (Insertion Loss (IL)), dispersion (chromatic & modal) and wavelength stability. List of Deliverables Conceptual design review deliverables CoDR documentation (See section 4) Preliminary review of configurations for technology solutions Sub-system requirements review deliverables Updated documentation from the CoDR (including an updated specification set & risk register) SRR documentation (See section 4) Prototype transmission system for WBSPFs Measured performance metrics including, reliable transmission at required instantaneous bandwidth, RFI levels. Design of local link configuration, if required Specification of local link cable network, if required Preliminary design review deliverables Updated documentation from the SRR PDR documentation (See section 4) List of candidate suppliers and reference customers, where available Page 21

22 STaN for WBSPF systems analogue WP Project Plan Page 22

23 STaN for WBSPF systems analogue WP Page 23

24 STaN for WBSPF systems analogue WP Interface Diagram Page 24

25 STaN for WBSPF systems digital WP STaN for WBSPF systems digital WP Central Processor internal fibre network. WP The internal fibre network at the central processor will need to be costed in PrepSKA, but no detailed design work will be undertaken until the post PrepSKA period. The project plan will be developed in conjunction with plans in the DSP & Computing domains. Estimated costs for PrepSKA will be provided by the STaN domain expert and derived from the costs of fibre management for other telescopes, such as e-merlin and EVLA Digital Data Back Haul (DDBH) systems WP This work package will provide costed designs and deployment plans for the wide area networks that connect a digitising stage (e.g. beamformer) to the correlator. Resource from groups local to the candidate sites has been included here, to provide support for the investigation of very long distance fibre links provided by national operators. Pathfinder telescopes that are distributing high speed signals over wide area networks include e-merlin, LOFAR, evlbi and ASKAP. It is possible that the DDBH may be provided under a turn-key solution contract with a commercial supplier. However the SKA must have an alternative design, one that is fully costed and addresses SKA specific requirements. Specific questions relating to this work package are: What are the data rates from the different antenna subsystems and what are the cost/science tradeoffs related to a reduction in bandwidth? Is 10 GE proposed, universally, as the data link layer for digital data back haul? On first inspection 10 GE seems to be proposed by all groups working in this area. This should be established as an uncontroversial standard for the SKA? What are the SKA functional requirements for Digital Data Back Haul? The point to point data streaming nature of our applications means these are not always the same as one might expect from traditional switched networks. ICDs will be required between the DDBH group and digital systems groups to establish how the data will be transported between digitisers & beamformers and the correlator. Any requirements for switching should be fully documented as this will change the nature of the DDBH problem. The digital system protocols, operation and connection interfaces to the digital equipment (which may be at the board level) will impact upon the requirements of the DDBH system and should be included in the ICD. The other end of the DDBH system will be at the correlator and an ICD will be required between the DDBH and the Correlator groups to define the interface at the connection between the two systems. Optimised solutions for external cable system configurations for the SKA and infrastructure sharing will be part of this work package. LO & Timing groups and M&C groups will also use fibre in the data cables and ICDs will be required between these groups. This work will be supported by; (1) Cambridge University who are modelling cabling infrastructure layouts for costing Page 25

26 STaN for Digital Data Back Haul WP purposes, (2) Groups from the candidate sites that can provide local knowledge about site specific features and services, (3) SPDO site engineer who will have responsibility for implementing infrastructure at the SKA site. The DDBH group will need to provide an ICD with recommendations about cables, connectors, joints, cable layouts etc. to the SKA Site Engineer. It is expected that this will take a similar form to work prepared for ALMA by Corning Cable Systems [Refs: ALMA External Optical Cabling Design project; BEND A-BOM- Bill of Materials and Installation Cost analysis & BEND A-DSN Network Design] The use of optical techniques, such as DWDM and optical amplification will enable the efficient use of fibre optic infrastructure. However they come with their own system impairments and a design is required that uses them to their full effect without compromising signal quality. Specific performance metrics related to digital systems for DDBH are: Bit rates, RFI levels and mitigation strategies, Bit Error Rate (BER), Power Budget (Insertion Loss (IL)), dispersion (chromatic & modal), optical nonlinearities in amplified systems and wavelength stability of component lasers. List of Deliverables Conceptual design review deliverables CoDR documentation (See section 4) Preliminary review of configurations for technology solutions Sub-system requirements review deliverables Updated documentation from the CoDR (including an updated specification set & risk register) SRR documentation (See section 4) Prototype transmission system for short links Measured performance metrics including; reliable transmission, RFI levels. Design of transmission systems for all required distances in the SKA Cable network design for the SKA for both candidate sites. Preliminary design review deliverables Updated documentation from the SRR PDR documentation (See section 4) List of candidate suppliers and reference customers, where available. Plan for simultaneous operations during build phases Where applicable, an upgrade plan Page 26

27 STaN for Digital Data Back Haul WP Project Plan Page 27

28 STaN for Digital Data Back Haul WP Page 28

29 STaN for Digital Data Back Haul WP Page 29

30 STaN for Digital Data Back Haul WP Interface Diagram Page 30

31 STaN for M&C Networks WP M&C Network. WP The systems group will define the requirements of the M&C network, but the STaN group will examine technical solutions to meet the requirements and cost those solutions for PrepSKA. The nature of the M&C network means that it is likely the technical solution will be an Ethernet solution. Versions of M&C Ethernet networks are commercially available and there are many implementations in industry that may be used as exemplars of this kind of network. This work package is a subset of the Systems M&C work package. It will cost technical solutions that meet requirements set by the Systems M&C group. Close communication and co-operation will be required by these two groups. The demands of data and timing signal transport in a radio astronomy environment far exceed those of M&C. It is therefore assumed that the networks designed to meet the needs of these functions will meet the needs of M&C. This assumption needs to be tested by matching the technical capabilities of products available in the marketplace to the network design provided by other areas of STaN work packages. The M&C network needs to be capable of addressing individual network points in a two way fashion. This means that the network will need to address questions such as traffic capacity requirements and switching. ICDs will be required with many functional blocks within the SKA. The systems group will define the relevant interface points as part of the Systems M&C work package Page 31

32 LO & Timing Systems WP LO and timing systems WP This work will provide costed designs and deployment plans for the provision of clocks, of the required precision, to antenna elements and digitising stages. This work package is likely to concentrate on two specific problems: 1. Identification of frequency standards available that meet SKA requirements Hydrogen Masers, Rubidium & GPS governed clocks are all commercially available systems that provide frequency standards of varying degrees of stability. Alternatively optical LO systems may be used as in ALMA. 2. Distribution of those frequency standards to elements in the SKA array by time transfer. Time transfer is a recognised technique in aperture synthesis telescopes and most observatories around the world undertake some form of time transfer. This may be over radio (MERLIN), fibre (ATNF, EVLA & e-merlin) or GPS (LOFAR). Alternatively the use of clock recovery circuits from high speed digital transmission equipment may be used. This work package will need to establish the requirements of the various technical solutions proposed for the SKA. These requirements will not be uniform and a number of designs may emerge. It is very likely that some prototype designs will need to be built and tested, as well as commercial solutions examined for their applicability to the SKA. In the event that the e-merlin time transfer solution is chosen as a method of delivery for LO & timing signals, a programme of development will be required to replace the legacy terminal equipment designs with cost-effective solutions for the SKA. In addition to a view of how individual receptor systems drive designs in this area it will be important to take a system view of the provision of a station clock. It may be that a single, station-wide, reference frequency provides a cost effective solution to timing signal provision when compared to several designs that meet the specific needs of only one receptor type. This will need to be investigated. An optimised cable network configuration design will be required. Particularly for designs where one or more masers are required to provide frequency standards. Cable system specifications and required performance of links will be defined in this design. The optimisation will need to focus on both performance and cost. ICDs will be required between the LO and Timing group and; o The dish signal cabling design group. Specifications related to phase stability may be of particular importance here. o The DDBH group, who will manage provision of the fibre network connecting into the central processor Page 32

33 LO & Timing Systems WP o The site group who will provision a specified local cable network. o Receiver groups who will specify the requirements of the station clock with regard to LO signals. o The digital system groups who will specify the requirements of the station clock for digitisation of incoming signals. Performance metrics in this area include Allan deviation of frequency (or phase) with time. List of Deliverables Conceptual design review deliverables CoDR documentation (See section 4) Preliminary review of configurations for technology solutions Sub-system requirements review deliverables Updated documentation from the CoDR (including an updated specification set & risk register) SRR documentation (See section 4) Prototype transmission systems for clocks and timing distribution Measured performance metrics including; Allen deviation FoM. Design of cabling networks for timing distribution systems Preliminary design review deliverables Updated documentation from the SRR PDR documentation (See section 4) List of candidate suppliers and reference customers, where available. Plan for simultaneous operations during build phases Where applicable, an upgrade plan Page 33

34 LO & Timing Systems WP Project Plan Page 34

35 LO & Timing Systems WP Page 35

36 LO & Timing Systems WP Page 36

37 LO & Timing Systems WP Interface Diagram Page 37

38 Appendix 1 APPENDIX 1 Adjusted PrepSKA WP2.7 workpackages. The PrepSKA documentation describes several work packages for the SKA. This work programme has been translated into work matrices and those tasks related to WP2.7 are shown below. P7 P7 Signal transport prototyping SigT Eng. Signal transport prototyping Intra-antenna data links S13F24/36 CSIRO UCAM, INAF, MPIfR, NRF Intra-station data links S13F24/36 INAF UMAN, IT,MPIfR, TDP Station-core data links S13F24/36 UMAN INAF, NRF,ASTRON LO and timing S13F36 UMAN, TDP,IT, ASTRON Monitor and control S13F36 UCAM TDP, NRF The PrepSKA work description has been reviewed and adjusted to accommodate the development of subsystems for specific antenna designs. These are shown below. Signal Transport and Networks within Aperture Arrays will be covered within the AA verification program and are not included in this work breakdown structure; Signal transport Design & Cost SigT Eng. Dish Signal Cabling Design STaN for PAF systems STaN for WBSPF analogue STaN for WBSPF digital Central Processor internal fibre network Digital Data Back Haul M&C network LO and timing Project code WP XX 20.XX 30.XX 35.XX 40.XX 50.XX 60.XX 70.XX Signal transport Design & Cost SigT Eng. CSIRO CSIRO, ASTRON INAF, MPlfR, ASTRON UK, SPDO UK, ASTRON IT, (NRF), (CSIRO) UK, IT Page 38