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

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

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

 Geophysics and Plate Tectonics VLBI Applications (1)  0.5 mm/year  0.3 mm/year 1.3  0.5 mm/year Kauai Fairbanks Kashima Kashima-Kauai Baseline Length Fairbanks-Kauai Baseline Length Kashima-Fairbanks Baseline Length

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

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

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

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

CPU array for Software Correlation Correlation Master Table Client PCs Linux/FreeBSD Clients Server Master Server

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

e-VLBI demonstrations at SC2004 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)

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

JGNII Symposium 2005 in Osaka 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 MIT Haystack NICT Kashima Abilene (10G) JGN II Int’l (10G) Tokyo JGN II (1G/10G) 1G/2.5G JGN II (10G) Osaka Venue 10G #1 #2 #3 #4 GEN-AGEN-B A B AB TT SX T x4 Raid ファイバー チャンネル LCD NE (Network Emulator) NE T x4 SX x2 ファイバー チャンネル TT LCD Measure-BMeasure-A

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

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 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

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

VSI-E Architecture

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 vtp (sender) vtp (receiver) K5Mark 5 GGAO Kashima Westford Correlator Haystack Observatory VSI-E