eVLBI Development

1
eVLBI Development

• Ralph Spencer, Richard Hughes-Jones, Matt Strong,
  Simon Casey, Paul Burgess
• April 2006 PMB

2
Achievements to date

• Line speed transmission using UDPJBO-JIVE
• Near line speed (900Mpbs) over days JBO-JIVE
• Global eVLBI demo at 512 Mbps (TCP) using UKLight
  links at iGRID2005 and SC2005
• Development of VLBI_udp
• Identification of MkV CPU power limitations
• Upgrade to JBO MkV machines
• eVLBI fringes obtained at up to 512 Mbps JBO-JIVE
• 1st open call eVLBI Science run 16 March 06
• eVLBI science run 20 April 06

3
Tests on the UKLight switched light-path
Manchester Dwingeloo

• Throughput as a function of inter-packet spacing
  (2.4 GHz dual Xeon machines)
• Packet loss for small packet size
• Maximum size packets can reach full line rates
  with no loss, and there was no re-ordering (plot
  not shown).

4
UKLight using Mk5 recording terminals
5
Continuous UDP flows
6
IGRID and SC 2005

• iGRID 2005 and SC 2005
• Global eVLBI demonstration
• Achieved 1.5 Gbps across Atlantic using UKLight
• 3 VC-3-13c 700 Mbps SDH links carrying data
  across the Atlantic from Onsala, JBO and
  Westerbork telescopes
• 512 Mps K4 Mk5data from Japan to USA
• 512 Mbs Mk5 real time interferometry between
  Onsala, Westford, Maryland Point antennas
  correlated at Haystack observatory
• Used VLSR technology from DRAGON project in US to
  set up light paths.

7
ltJBO Mk2 Westerbork arraygt
Onsala 20-m
Kashima 34-m gt
8
1st Successful Open Call eVLBI Science Run 20/21
April 2006Jb,Cm,Wb,On,Mc,Tr
9
The Future

• Regular eVLBI tests in EVN continue
• Test upgraded Mk5 recording devices
• Investigate alternatives to TCP/UDP DCCP,
  vlbiUDP, tsunami, etc.
• ESLEA comparing UKLight with production
• EUs EXPReS eVLBI project started March 2006
• Connection of 100-m Effelsberg telescope in 2006
• Protocols for distributed processing
• Onsala-JBO correlator test link at 4 Gbps in 2007
• eVLBI will become routine in 2006!