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Current plan for e-VLBI demonstrations at iGrid2005 and SC2005

This article discusses the current plans for e-VLBI demonstrations at iGrid2005 and SC2005, including the development of e-VLBI systems and the benefits of real-time correlation. It also highlights the applications of e-VLBI in geophysics, plate tectonics, radio astronomy, and reference frames.

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Current plan for e-VLBI demonstrations at iGrid2005 and SC2005

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  1. Current plan for e-VLBI demonstrations at iGrid2005 and SC2005 Yasuhiro Koyama*1, Tetsuro Kondo*1, Hiroshi Takeuchi*1, Moritaka Kimura, Masaki Hirabaru*1, Jason SooHoo*2, Kevin Dudevoir*2, Chet Ruszczyk*2, and Alan Whitney*2 *1 National Institute of Information and Communications Technology (NICT) *2 MIT Haystack Observatory

  2. Contents • Introduction • e-VLBI demonstrations in the past • SC2004 • JGNII Symposium 2004 in Osaka • Current e-VLBI demonstration plan for iGrid2005 and SC2005

  3. What is e-VLBI? VLBI=Very Long Baseline Interferometry Correlator Radio Telescope Network Correlator Radio Telescope e-VLBI Shipping Data Media (Tapes/Disks) Conventional VLBI

  4. VLBI Applications (1) • Geophysics and Plate Tectonics Kashima-Kauai Baseline Length -63.5  0.5 mm/year Fairbanks Fairbanks-Kauai Baseline Length -46.1 0.3 mm/year Kashima Kauai Kashima-Fairbanks Baseline Length 1.3 0.5 mm/year

  5. VLBI Applications (2) • Radio Astronomy : High Resolution Imaging, Astro-dynamics • Reference Frame : Celestial / Terrestrial Reference Frame • Earth Orientation Parameters, Dynamics of Earth’s Inner Core Halca（Muses-B） Radio Telescope Satellite ‘Halca’ and its images Earth Orientation Parameters NGC4261

  6. VLBI - Characteristics • Observing Bandwidth  Data rate  (Precision of Time Delay)-1  (SNR)1/2 • Wave Length / Baseline Length  Angular Resolution • Baseline Length  (EOP Precision)-1 Faster Data Rate = Higher Sensitivity Longer Distance = Better Results

  7. Why e-VLBI? • Currently it takes > 2 weeks to process (shipping + processing) • If it become 2 hours, it will improve accuracy of • satellite positioning and navigation • real-time orbit determination of satellites and spacecrafts • It potentially expands correlation/observation capacity • Currently ~16 stations with hardware correlator • Easy scalability with PC/distributed software correlator • No Recording Speed Limit with real-time correlation

  8. e-VLBI System Developments at NICT K5 system ADS1000 (1024Msample/sec 1ch 1bit or 2bits) PC-VSI Board (Supports VSI-H specifications) Correlator other DAS VSI VSI Internet IP-VLBI Board (~16Msample/ch·sec, ~4ch, ~8bits) ADS2000 (64Msample/ch·sec, 16ch, 1bit or 2bits) PC : Data Acquisition Correlation

  9. CPU array for Software Correlation Master Server VLBI@Home Server Correlation Master Table Linux/FreeBSD Clients VLBI@Home Client PCs

  10. Mark 5 VLBI Disk-Based Data System(MIT Haystack Observatory) • 1 Gbps continuous recording/playback to/from set of 8 inexpensive (ATA) disks • Developed at MIT Haystack Observatory with multi-institutional support • Mostly COTS components • Two removable ‘8-pack’ disk modules in single 5U chassis • With currently available 200GB disks – capacity of single ‘8-pack’ 1.6TB; expected to increase to 2.5TB by early 2003 at cost of ~$1/GB • GigE connection for real-time and quasi-real-time e-VLBI operations • Inexpensive: <$20K • ~20 Mark 5 systems now installed at stations and correlators

  11. e-VLBI demonstrations at SC20042004/11/7-12 @ Pittsburg, USA • Quasi real-time e-VLBI at 256Mbps (4 stations) • pre-recorded data were transferred to Haystack Observatory and processed by using Mark 4 correlator • Real-time e-VLBI at 512Mbps (Westford-GGAO) Kashima (Japan) Westford (MA, USA) GGAO (MD, USA) Onsala (Sweden)

  12. Real-time e-VLBI demo at SC2004 Haystack : Correlator 512 Mbps Bossnet Westford (Mark 5) Pittsburg Convention Center DRAGON Goddard 512 Mbps GGAO (Mark 5)

  13. JGN II Int’l (10G) Tokyo MITHaystack Abilene(10G) Osaka A JGN II (10G) 1G/2.5G 10G JGN II (1G/10G) NICTKashima B Venue LCD LCD SX SX T T GEN-B GEN-A Measure-B Measure-A T T T x4 T x4 LCD LCD #1 A B #2 NE ファイバー チャンネル #3 SX x2 Raid ファイバー チャンネル #4 SX x2 Raid NE (Network Emulator) JGNII Symposium 2005 in Osaka2005/1/17-18 @ Osaka, Japan • Run a program at Kashima and Haystack to generate fake data • Data were transferred to Osaka in real-time and the data were processed for cross correlation processing with distributed software correlator program

  14. Two Modes of Operation for e-VLBI (1) • Quasi real-time e-VLBI • Data buffering (hard disks) at observing sites • Data transfer after a series of observations • Correlation processing after data transfer • Easy enough • Operational in global sessions over shared IP networks (2003~) • Rapid turn-around UT1-UTC estimation (~4.5 hours, June 2004) • Huygens spacecraft tracking during decent to Titan (January 2005) • Better than tape-based VLBI with a standpoint of latency • Will not improve sensitivity over tape-based VLBI

  15. Two Modes of Operation for e-VLBI (2) • Real-time e-VLBI • No data buffering at observing sites • Correlation processing at the sane time with observations • Possibility to break sensitivity barrier • Operational with local/domestic ATM networks • Key Stone Project 1998-2001 • GALAXY Project 2000~ • Still challenging with shared IP networks over long distance • Standardization of the data transfer protocol required if heterogeneous systems are used  VSI-E VSI = VLBI Standard Interface (Versatile Scientific Interface) VSI-H : Hardware VSI-S : Software VSI-E : e-VLBI protocol

  16. VSI-E • Purpose: • To specify standardized e-VLBI data formats and transmission protocols that allow data exchange between heterogeneous VLBI data systems • Characteristics: • Based on standard RTP/RTCP high-level protocols • Allows choice of IP transport protocols (TCP-IP, UDP, FAST, etc.) • Scalable Implementation; supports up to 100Gbps • Ability to transport individual data-channel streams as individual packet streams; potentially useful for distributed correlators • Ability to make use of multicasting to transport data and/or control information in an efficient manner • Status • Draft VSI-E specification completed January 2004 • Prototype VSI-E prototype implementation Nov 2004 • Practical implementation for K5 and Mark 5 now is progress • Plan to use VSI-E in real-time demo at SC05, Nov 05

  17. VSI-E Architecture

  18. Plan for iGrid2005 and SC2005 • Target : real-time e-VLBI with K5 and Mark 5 systems • Telescopes : Kashima, Westford, Onsala • Data Rate : 256 Mbps or 512 Mbps Mark 5 Mark 5 Westford Correlator K5 vtp (sender) VSI-E vtp (receiver) Mark 5 Kashima Mark 5 Mark 5 GGAO Haystack Observatory

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