Authors: John D. Bunton CSIRO Telecommunications and Industrial Physics Carole A. Jackson RSAA, Australian National University Elaine M. Sadler School of Physics, University of Sydney Submitted to the SKA Engineering and Management Team by The Executive Secretary Australian SKA Consortium Committee PO Box 76, Epping, NSW 1710, Australia June 2002 Updated 11 July 2002 17 Jul 02 Release 1 CSIRO Table of contents Table of contents ................................................................................................................. 2 Executive summary............................................................................................................. 5 1 Introduction..................................................................................................................6 1.1 Relative Costs: the best of both worlds................................................................. 7 1.2 Instrument Overview............................................................................................. 7 2 Science Drivers .......................................................................................................... 10 2.1 Milky Way and local galaxies............................................................................. 10 2.2 Transient phenomena .......................................................................................... 10 2.3 Early Universe and large-scale structure ............................................................ 11 2.4 Galaxy formation ................................................................................................ 11 2.5 Active Galactic Nuclei and supermassive black holes........................................ 12 2.6 Life cycles of stars .............................................................................................. 12 2.7 Solar system and planetary science..................................................................... 12 2.8 Intergalactic medium........................................................................................... 12 2.9 Spacecraft tracking.............................................................................................. 12 2.10 Multibeaming...................................................................................................... 13 3 Preferred Array Configuration ................................................................................... 13 4 Antenna solution........................................................................................................ 16 4.1 Offset versus centre feed..................................................................................... 17 4.2 Antenna station design........................................................................................ 19 5 RF systems .................................................................................................................19 6 Signal encoding/transport and beamforming ............................................................. 20 7 Signal processing ....................................................................................................... 21 8 Data Management ...................................................................................................... 22 9 Array Control, Diagnostics and Monitoring .............................................................. 22 10 Pivotal technologies ................................................................................................... 22 11 Proposed SKA location.............................................................................................. 23 12 Representative system performance and cost estimates............................................. 23 12.1 Cost ..................................................................................................................... 24 13 SKA Molonglo Prototype (SKAMP) Concept demonstrator..................................... 26 14 Synergies with other SKA concepts........................................................................... 27 15 Upgrade paths for the SKA........................................................................................ 27 16 Acknowledgments...................................................................................................... 27 17 Update History ........................................................................................................... 28 18 References.................................................................................................................. 28 17 Jul 02 Release 2 CSIRO Appendix A ....................................................................................................................... 30 Costing of Existing Telescopes.................................................................................. 30 Appendix B ....................................................................................................................... 34 Historical Perspective................................................................................................. 34 B.1 SKA Perspective.................................................................................................. 35 B.2 Conclusion........................................................................................................... 36 Appendix C ....................................................................................................................... 38 Cost of an Imaging Correlator for the SKA............................................................... 38 C.1 Introduction ......................................................................................................... 38 C.2 Reference correlator ............................................................................................ 38 C.3 Filled aperture antenna stations........................................................................... 38 C.3 Antenna station arrays ......................................................................................... 39 C.4 Conclusion...........................................................................................................40 C.5 Beam width and average beam area of an array................................................. 40 Appendix D ....................................................................................................................... 42 Horizontal Axis Cylindrical Reflector ....................................................................... 42 D.1 Mechanical construction ..................................................................................... 42 D.1.1 Molonglo Maintenance Issues – Multiple separate units ............................ 43 D.1.2 Drive options ............................................................................................. 44 D.2 Surface................................................................................................................ 44 D.3 Fan beam rotation with longitude........................................................................ 45 Appendix E........................................................................................................................ 46 Vertical Axis Cylindrical Reflector ........................................................................... 46 E.1 Selecting the Basic Antenna Topology ............................................................... 47 E.2 Construction......................................................................................................... 48 E.2.1 Foundation, track and bogies ....................................................................... 48 E.2.2 Supporting structure..................................................................................... 48 E.2.3 Reflecting surface and line feed................................................................... 49 Appendix F........................................................................................................................ 50 Fixed Cylindrical Reflector........................................................................................ 50 Appendix G ....................................................................................................................... 53 Surface construction................................................................................................... 53 G.1 Purlin spacing...................................................................................................... 53 G.2 Surface material options...................................................................................... 54 G.3 Surface alignment................................................................................................ 54 Appendix H ....................................................................................................................... 55 Line feed..................................................................................................................... 55 H.1 Feed elements...................................................................................................... 55 H.2 LNAs ................................................................................................................... 55 H.3 System Temperature............................................................................................ 56 H.4 RF Beamformer................................................................................................... 56 H.5 Digital beamformer