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

ContentsContents 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?What is e-VLBI?

VLBI=Very Long Baseline Interferometry

Radio Telescope

Radio Telescope

Correlator

Correlator

Network

Conventional VLBIConventional VLBI

e-VLBIe-VLBIShipping Data Media (Tapes/Disks)

Geophysics and Plate Tectonics

VLBI Applications (1)VLBI Applications (1)

鹿島

ハワイ

アラスカ

5700km5700km

5400km5400km

4700km4700km

鹿島－ハワイの基線長変化

- 400

- 200

0

200

400

1984 1986 1988 1990 1992 1994

年

基線

長（ｍ

ｍ）

アラスカ－ハワイの基線長変化

- 400

- 200

0

200

400

1984 1986 1988 1990 1992 1994

年基

線長

（ｍｍ

）

鹿島－アラスカの基線長変化

- 400

- 200

0

200

400

1984 1986 1988 1990 1992 1994

年

基線

長（ｍ

ｍ）

-63.5 0.5 mm/year

-46.1 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)VLBI Applications (2)

Halca （ Muses-B ）

NGC4261

Radio Telescope Satellite Radio Telescope Satellite ‘Halca’ and its images‘Halca’ and its images

Earth Orientation ParametersEarth 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 - CharacteristicsVLBI - Characteristics

Faster Data Rate = Higher Sensitivity

Longer Distance = Better Results

Why e-VLBI?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 NICTe-VLBI System Developments at NICTK5 systemK5 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 AcquisitionCorrelation

VSI

Correlatorother DAS

Internet

PC-VSI Board(Supports VSI-H specifications)VSI

CPU array for Software CorrelationCPU array for Software Correlation

Correlation Master Table

VLBI@Home Client PCs

Linux/FreeBSD Clients

VLBI@Home Server

Master Server

Mark 5 VLBI Disk-Based Data SystemMark 5 VLBI Disk-Based Data System(MIT Haystack Observatory)(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 SC2004e-VLBI demonstrations at SC20042004/11/7-12 @ Pittsburg, USA2004/11/7-12 @ Pittsburg, USA

Quasi real-time e-VLBI at 256Mbps (4 stations)– pre-recorded data were transferred to Haystack Observatory and processe

d 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

512 Mbps

JGNII Symposium 2005 in OsakaJGNII Symposium 2005 in Osaka2005/1/17-18 @ Osaka, Japan2005/1/17-18 @ 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

MITHaystack

NICTKashima

Abilene(10G)

JGN II Int’l(10G) Tokyo

JGN II(1G/10G)

1G/2.5GJGN II(10G)

Osaka

Venue

10G

#1

#2

#3

#4

GEN-AGEN-B

AA

BB

AA BB

TT

SX SX

T x4

Raid

Raidファイバーチャンネル

LCDLCD

NE (Network Emulator)

NE

T x4

SX x2

SX x2

ファイバーチャンネル

TT

LCDLCD

Measure-B Measure-A

Two Modes of Operation for e-VLBI (1)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)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 hetero

geneous systems are used VSI-E

VSI = VLBI Standard Interface (Versatile Scientific Interface)VSI-H : Hardware VSI-S : Software VSI-E : e-VLBI protocol

VSI-EVSI-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 VSI-E Architecture

Plan for iGrid2005 and SC2005Plan 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)

K5 Mark 5

Mark 5 Mark 5

Mark 5 Mark 5

GGAO

Kashima

Westford

Cor

rela

tor

Haystack Observatory

VSI-E