eVLBI progress in the South

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e-VLBI progress in the South
Towards e-VLBI ? e-VLBI

• Tasso Tzioumis
• ATNF, CSIRO
• September 2006

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Outline

• Overview - details in other presentations/posters
• Current LBA systems/developments
• Tapes - phasing out
• DAS - digital filters
• Disks - LBADR
• Software Correlators
• Network developments
• Real e-VLBI tests
• Plans the Future

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LBA
x NTD
x New Norcia
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Long baseline Array (LBA)

• Telescopes in Australia
• ATNF, U.Tasmania, NASA - core Oz VLBI network
• South Africa
• Telescopes in Asia Pacific region
• Japan, China, Hawaii, VLBA,
• Asia Pacific Telescope (APT) (VSOP support)
• Open network (EVN model of operations)
• http//www.atnf.csiro.au/vlbi
• ( Tests with NZ - fringes ok - no large antenna)

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LBA -S2 tape system

• Canadian S2 VCR-based recorder
• 8 VCR recorders ? 128 Mbps max data rates
• S2 maintenance issues (no external support)
• 7-station S2 LBA correlator at ATNF Sydney
• XF architecture (ATCA correlator design)
• Difficult to upgrade correlator
• The main production-VLBI system for 12 years
• 2005 workshop Phase-out S2 within 3-4 years?
• 2006 workshop Decommission S2 in 2006-7!!
• Move to disk-systems software correlation
• Correlation contracted to Swinburne - 1 October
  2006

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LBA - DAS

• DAS Based on Digital Filters ( 10 years old!)
• 2 input IFs _at_ 64 MHz BW (2 pols or 2 frequencies)
• Sampling (10 bits) Digital filters (ideal
  passbands)
• Bands 64MHz ? 125 KHz
• S2 mode 2 x 16 MHz (? 128 Mbps to match S2)
• Huygens mode 4 x 16 MHz (256 Mbps)
• Maximum 2 x 64 MHz (512 Mbps) - tested in 2006
• Multibit mode 2 x 16 MHz x 8(10) bits ? 1 Gbps
• Interference excision?
• ATNF stations 2 DAS units
• 512 Mbps for Huygens (8 x 16 MHz)
• 1 Gbps by 4 x 64 MHz channels - developed
  tested in 2006
• Remains the main DAS for LBA system(s)
• BUT no more units available!!
• Move to new VLBI dBBC units? (Haystack) -
  timescales?

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LBADR - Disk recorders

• (See C. Phillips poster for details)
• PCEVN-Metsahovi VSI interface system
• VSIC (ECL-LVDS) VSIB(computer)
• Connects to LBA DAS
• All LBA antennas equipped
• COTS computers
• New Tyan Thunder K8WE motherboards (2005)
• Multiple PCI bus systems
• Internal disks IDE removable disks X-RAID on
  fibre channel
• (Replaced test systems on Dell 1600SC servers)
• Apple Xserve hardware RAID systems (7 TB)

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Software correlators

• See poster by S. Tingay A. Deller
• FX software correlator(s)
• Swinburne Supercomputer
• 300 Dell computers in cluster
• Real time correlation (normal modes) - 30-50
  nodes
• Smaller clusters at telescopes
• (Parkes 32 nodes ATCA 16 nodes)
• Cray XD-1 supercomputer in WA FPGAs
• Under development
• Very versatile robust (can run on most systems)
• Only correlators in Australia for disk systems!

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Real-time fringe testing

• Disk-systems
• Can run parallel to S2 VCRs (S2 C2 output port)
• Short segment (0.1s) data or use full recorded
  data
• Transfer to Swinburne - (slow) ftp or fast links
• Correlate and post on web
• Start correlating immediately (not all data
  needed)
• Fringe in a few secs web post within minutes
• Semi-automatic operation
• Routine for all LBA observations
• Setup fringe tests for all observations
• http//pentane.ssi.swin.edu.au/cphillip/
• ?Increased LBA reliability and robustness

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Network connectivity -1

• See talk by Shaun Amy
• AARNet3 Regional Network
• Fibre tails to ATNF antennas in 2005-6
• 2M project, funded by CSIRO corporate
• Fibre tails owned by CSIRO
• e-vlbi tests in March 2006 - Official start
  June 2006!
• Legal contract problems!!
• 2 x 1 Gbps connectivity
• 1 operating now 2nd circuit to be connected
• 10 Gbps (x multiple wavelengths) backbone
• Good international connectivity

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AARNet3 Regional Network
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Network connectivity -2

• Swinburne 1 Gbps link(s) constructed
• Operation delayed by legal problems!! (again)
• (10 Gbps link from Parkes?)
• Enables software correlator connectivity
• Hobart Fibre links funded and in construction
  (2006)
• 1 Gbps - telescope --- University
• 10 Gbps to AARNet
• (BUT Bass-link limited to 0.5 Gbps?)
• WA Connectivity (Cray _at_ UWA)
• CeNTIE 3 x 1 Gbps BUT closes in 2006!
• AARNet3 links planned
• Impact on x-NTD?
• (Tidbinbilla - NASA 2 Mbps commercial links
• Future links? )

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First Oz real e-VLBI

• Date 24 August 2006
• Antenna Parkes, Mopra, ATCA
• Data rate 128 Mbps (per station)
• Bandwidth 2x16 MHz (per station)
• Processor Dual AMD server (ie only 2 CPUs)
• No disk buffering -- e-VLBI
• Time 10minutes
• 1-bas test Parkes-ATCA at 256 Mbps/station

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Plans - Near term

• Transition production VLBI to disk systems
  software correlation (2006-7)
• Investigate remote-disk recording
• Acquire 0.5M of disks
• Extensive real e-VLBI tests
• To Swinburne cluster correlator (in 2006)
• To JIVE correlator under EXPReS (2006-7)
• Data disk formatting issues (LBA - Mk5a) -
  VSI-E??
• Tests to Haystack/Japan/Global - VSI-E??
• DAS replacement?

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Special e-VLBI Instrument?

• Parkes-Mopra- Narrabri
• 1 Gbps links installed
• 1 Gbps data from 2 x DAS systems
• Software correlation (Parkes or ATCA cluster)
• ? Real-time VLBI instrument at 1 Gbps
• Cf PTI instrument (Parkes -Tid _at_ 10 MHz BW)
• Very popular with non-VLBI specialists
• Fast detection observations/surveys
• May operate in parallel with disk recording
• E.g. correlate 2nd 512 Mbps stream from ATNF
  antennas

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Plans - Longer term

• CABB - Broadband upgrade of ATCA
• 4 Gsamples x (8) bits ?? 32 Gbps streams
• 4 IFs per antenna 8 antennas
• Digital Polyphase filters -- CABB Correlator
• ATCA operation in 2007-8
• VLBI capability designed-in (2008?)
• Need for VLBI operation
• n x 10 Gbps connections to ATCA (Narrabri)
• Broadbanding of Rx systems (Mopra, Parkes)
• Narrabri polyphase filters?
• Broadband and Fast links from non-ATNF antennas
• ? Multiple 10 Gbps inputs e-VLBI

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A Wideband Upgrade for the Australia Telescope
Compact Array
Luneburg Lens Phased Array
Luneburg Lens Phased Array
6 22m antenna AT Compact Array
FPGA hardware may be completely reprogrammed to
produce many different filterbank configurations,
as different observations may require.
A 2GHz bandwidth polyphase digital filterbank
with 4096 channels ... ... will fit into
four XC2V6000 FPGAs
Filterbank Architecture
RF, IF and Baseband Signal Path
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Summary

• S2 tape LBA system to be decommissioned 2006-7
• LBADR - disk recorder developed
• Software correlation - real time speeds
• Very versatile, robust and portable
• LBA transition disk recording software
  correlation
• Digital DAS - need to augment/replace
• 1 Gbps links to ATNF antennas operating
• Links to correlator and other telescopes in
  construction
• First real e-VLBI tests successful
• Plans for eVLBI instrument (Pks-Mop-Nar)
• Future 10 Gbps links CABB correlator