EXPReS Network Progress and Upgrades: An Overview of the Latest Developments

1. EXPReS progress, Mark5 and e-VLBI Arpad Szomoru, JIVE

2. Correlator upgrades • New data output platform • Solaris AMD server with large raid array • Fully interchangeable with control computers • Needs endian-safe re-work of correlator code • First fringes 2/10/07! • Re-circulation • Has been demonstrated to work • Will be implemented on new platform • Network upgrade • All internal JIVE and e-VLBI traffic now through own router • Has removed dependencies on ASTRON network

3. JIVE upgrade Mk5A+ and Mk5B • Mark5A • Upgrade of hardware (motherboards, memory, power supplies) nearly completed (12 out of 16) • Mark5A+ • Upgrade of Mark5A, enables play-back of Mark5B data on Mark5A units • Used at JIVE with geodetic data sets • And on converted Australian LBADR data • Being used to help debug Westerbork TADUmax • e-VLBI still an issue..

4. JIVE upgrade to Mk5B • Two JIVE Mark5As converted to Mark5B • One integrated in correlator • One to Wb for TADUmax • New control code: • Dimino (at stations): • Needs additional work to enable e-VLBI • Let alone UDP transfer • Domino (at correlator): • Re-write of correlator control code progressing well • Haystack engineers helping with modifications of Mark5B code • First autocorrelations, though still no fringes

5. EXPReS network upgrade

6. New modes, feedback and streamlining • Currently under development: • Adaptive observing (to be tested soon) • On-the-fly fringe fitting • Real-time station-log processing, display of Tsys, status information • Use of Westerbork synthesis data to improve e-VLBI calibration and target selection • Recently completed: • General speedup of correlator control code • Real-time Mark5 debug info feedback to stations • Re-connecting of individual stations without job re-start • Space-craft tracking mode

7. Pilot for e-shipping • We have the infrastructure, let’s use it! • In principle data can be shipped electronically • This is NOT e-VLBI, mostly driven by economic arguments • Use the “free” bandwidth available now • Concerns: • Requires extra work at correlator and stations • May require additional disk packs at first • Does not fit well with intensive sessions and 1 Mk5/station • Needs good logistic procedures • Pilot project • Benchmark the burden on staff, work out safe logistics • Develop procedures and software using infrastructure available from EXPReS • But this is not an EXPReS deliverable, formally no resources • For stations with high connectivity at first • because of smaller impact on operations • Maybe do some of the last NME’s in a session

8. e-VLBI science • 17 e-VLBI science projects accepted since 2006: • 2 failed (in early 2006) • 8 active binary systems • Algol-type, X-ray or gamma-ray binaries); • 4 of these were ToO projects • 3 part of multi-wavelength campaign • 1 adaptive observation of 16 X-ray binaries • 4 after compactness of calibrator or target • 1 spectral line run • 1 supernova ToO

10. e-VLBI: data rate improvements

11. EXPReS: connectivity progress • Connectivity in Europe • Dedicated 1-Gbps lightpaths to 5/6 stations • Upgraded Mark5 hardware at 5/6 tels. • 512 Mbps from all stations possible • but not reliably with TCP • Move to UDP works great • green leds at ~1024 Mbps from Torun... • And beyond... • Shanghai, Australian telescopes at 512 Mbps • Arecibo, TIGO at 64 Mbps • Thanks to large development effort • Arecibo to higher bandwidth soon • Still waiting for big dishes • Progress at Effelsberg

12. EXPReS: connectivity progress • Long-haul high-bandwidth data transport • TCP on old linux kernels clearly inadequate • Circuit TCP perfoms well (TCP with UDP-like behaviour, without congestion control) • UDP better, but needs modification of Mark5A control code • And can be hostile to other users on open network • Stability of original code a serious issue • Has led to complete re-write of subset of Mark5 control code

13. Trans-siberian demo at Xi’An

14. The APAN demo: Opened up Siberia connection Excellent PR Longest (e) baseline ever e-VLBI results

15. e-VLBI results • The Australia-JIVE EXPReS demo: • Three Australian telescopes (Mopra, ATCA, Parkes) • 12 hours at 512 Mbps without a hitch • Beautiful detection of SN1987a

16. SCARIe FABRIC • Software correlator developments • First level of parallelization completed • multiple subbands and time slices on multiple CPUs/cluster nodes • New version was used to process recent FTP fringe tests. • Web services to interface with workflow manager • VLBI grid broker will be tested soon (with PSNC). • Start doing benchmarking soon • Spacecraft tracking mode versus performance • Next step is to deliver AIPS compatible output data

17. Software correlation (2)

18. UDP development • Initial work by Harro Verkouter, (re-)enable UDP on Mark5A • Collaboration with Richard Hughes-Jones and Simon Casey, integrate vlbi-udp in Mark5A code (some serious hacking) • Packet dropping, re-ordering, spacing • Quick-and-dirty solution by Harro, used for APAN and EXPReS-Oz demos • Simon version improved, green leds at 1024 Mbps from Tr • Harro despairs of stability and racing conditions in original Mark5A code, completely re-writes sub-set of code (in2net2out, disk2net2disk) • Casey features incorporated, rigorous thread management, very stable • Will be used in next e-VLBI run

19. Dim and dom, to A or not to B • Mark5A+: works fine with MarkB e-VLBI data • Demonstrated in EXPReS-OZ demo • On-the-fly conversion from LBADR to Mark5B format • Playback on A+ at JIVE • Mark5B: • Dimino: was thought to do e-VLBI, but... • Domino: no e-VLBI at all • Effort ongoing at Haystack to enable e-VLBI • First tests end of November • Need to ensure reliable high data-rate transfer • Message to stations: do NOT change over to B just yet