Development of Distributed e-vlbi Data Correlation Technologies in Ventspils International Radio Astronomy Center

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Development of Distributed e-vlbi Data Correlation Technologies in Ventspils International Radio Astronomy Center Normunds Jekabsons 1, Karina Krinkele 1,

1 Development of Distributed e-vlbi Data Correlation Technologies in Ventspils International Radio Astronomy Center Normunds Jekabsons 1, Karina Krinkele 1, Ivars Shmeld 1, Dominik Stoklosa Ventspils University College(VUC), Ventspils, Latvia; 2. Poznan Supercomputing and Networking Center (PSNC), Poland.

2 Where we are from? a

3 Outline 1. VIRAC site/radio telescopes; 2. VLBI networks of interest; 3. Near Earth object radar VLBI data processing; 4. SFXC adaption and e-vlbi; 5. Conclusions.

4 1.RT-32 Radio telescope

5 1.The new registration system: Mark5B with DBBC as video converter and formatter

for reconstruction technologies; In year 2012 (or till dish replacement) will be used for radar VLBI;

6 1.RT-16 Radio telescope Diameter: 16m; Recently pointing capability is restored; Large scale corrosion damage of mirror supporting structure, to be replaced with a new one in a next 5 years; Used as test bead for reconstruction technologies; In year 2012 (or till dish replacement) will be used for radar VLBI; Installation of GHz receiver is planned till year 2012; Older Russian made video converter will be moved to RT-16.

1.VIRAC HPC computer cluster Recently rack-mounted unit with 30

00GHz, Linux reports 5600 bogomips; 4GB ram per diskless node

Debian Linux, shared NFS, rsh infrastructure, gigabit Ethernet;

7 1.VIRAC HPC computer cluster Recently rack-mounted unit with 30 nodes: 2 CPU x 2Cores Intel(R) Xeon(R) CPU 3.00GHz, Linux reports 5600 bogomips; 4GB ram per diskless node (can be activated internal SCA disk of 80Gb on each node); Debian Linux, shared NFS, rsh infrastructure, gigabit Ethernet; Update to mixed system - Power 7 / i86_64 is considered in a few upcoming years.

1.Telescope control adapted NASA field system software The software was adapted for RT-32 mirror pointing control system of old Soviet design (still has vacuum valves in it).

8 1.Telescope control adapted NASA field system software The software was adapted for RT-32 mirror pointing control system of old Soviet design (still has vacuum valves in it). Renovation of the system is on it's way. The Field System provides a suite of programs to assist with pointing calibration and sensitivity measurements for antennas. There are automated programs for measuring pointing offsets and antenna performance. There are also programs for fitting pointing data to a model (from FS authors). At the moment tested ssh remote control capability is reached.

2.VLBI networks and observation sessions The European VLBI Network (EVN) is an interferometric array of radio telescopes spread throughout Europe (and beyond) that conducts unique, high resolution,

9 2.VLBI networks and observation sessions The European VLBI Network (EVN) is an interferometric array of radio telescopes spread throughout Europe (and beyond) that conducts unique, high resolution, radio astronomical observations of radio sources. It is one of most sensitive VLBI array in the world, thanks to the collection of extremely large telescopes that contribute to the network. Successful fringe test may allow VIRAC to participate in EVN sessions.

10 2. Fringe test, summer 2011 with EVN network Unsuccessful, likely due to uncontrolled time drift of maser clock

11 2. Single dish maser W3(OH) observation - successful Session date: November 10, 2011 Object: Maser W3(OH) Result: observation was successful

12 2.VLBI networks and observation sessions Observation modes: Beam parking; Tracking. Radar-VLBI observations of nearearth objects Low Frequency VLBI network : Russia, Ukraine, Italy, Latvia and China. Transmitter is located in Evpatoria, Ukraine. Transmitted signals: Monochromatic; Frequency modulated.

13 3. Data processing Recently we are dealing with two software correlators: In-house developed code, engineered to process radar VLBI data from space debris and near-earth objects, pre-alpha stage (some functionality still missing); JIVE's (Joint Institute for VLBI in Europe) SFXC for EVN related VLBI data processing.

14 Software correlator; 3. Radar VLBI data processing, VIRAC correlator ANSI C programming language and POSIX compatibility; JSON (JavaScript Object Notation) for control parameters; MPI (Message Passing Interface) for parallel processing; Automated procedures (like reflected signal detection), batch processing; Real-time data streaming + processing for e-vlbi sessions (work in progress); Frontends for NRFI, MARK5a,b (planned - VDIFF) data formats.

15 3 modes of data processing MODE 1 auto-correlation of received signal for each VLBI station MODE 2 correlation between transmitted and received signals MODE 3 correlation between received signals of two VLBI stations 3. Radar VLBI data processing,virac correlator

16 Observation data file storage or Data flow Station 1 Data flow Station 2... Data flow Station N Coordination of data flow on cluster nodes... Output data Auto-correlation (video frequency,... etc.) (MODE 1) Processor 1 Processor n Auto-correlation (MODE 1) Output data (video frequency, etc.) At least N processors for N data flow Is signal detected?... Is signal detected? Yes Yes Processor 1 Data correction (frequency correction, time delay correction, etc.)... Processor n Data correction (frequency correction, time delay correction, etc.) At least N processors for N data flow......

17 Processor 1 Data correction (frequency correction, time delay correction, etc.)... Processor n Data correction (frequency correction, time delay correction, etc.) At least N processors for N data flow Output data (Doppler frequency, time lags) Correlation between transmitted signal and received signal (MODE 2) Procesors 1 Procesors 1 Correlation between two station pair received signals (MODE 3) Output data (Doppler frequency, time lags) Output data (Doppler frequency, time lags) Correlation between transmitted signal and received signal (MODE 2) Procesors n Procesors n Correlation between two station pair received signals (MODE 3) Output data (Doppler frequency, time lags) At least N processors for N data flow At least N(N-1)/2 processors for N data flow

3. Example Object: 35303 (shiver from IRIDIUM 33 and COSMOS 2251 collision); Observation: VLBR 10.

18 3. Example Object: (shiver from IRIDIUM 33 and COSMOS 2251 collision); Observation: VLBR 10.1 Correlation between transmitted signal and received signal in RT-32. Peak in spectra represents the Doppler shift in signal path transmitter object receiver.

19 4. Software FX correlator for radioastronomical VLBI data processing SFXC - Software FX correlator; Developed by JIVE (Joint Institute for VLBI in Europe), mainly C++ code; Known to work with far-field objects; Two controls files needed to start correlation VEX file and JSON based correlation file; SFXC is adapted to work on Ventspils University College (VUC) HPC cluster.

20 4. Automatic e-vlbi SFXC sessions Deployed automatic e-vlbi system consisting of 6 main modules: Field System positioning module (NASA/Goddard Space Flight Center, Space Geodesy Project); DBBC+mark5B registration system; Translation Node module for data splitting in chunks(developed in JIVE); Correlation Node module for data processing tool or correlator(developed in JIVE); VLBI broker central element of the e-vlbi system(developed in PSNC); Workflow manager the main interface between user and the system(developed in PSNC).

21 4. Translation Node (TN) Developed by JIVE; TN service processes transfers the data to required Correlation Node; Can connect to Mark5 data system and download requested data; Copy the files over grid ftp.

22 4. Correlation Node Developed by PSNC; Responsible for managing and executing correlation jobs on the cluster; The implemation with VLBI Broker is required.

23 4. VLBI Broker (VB) Developed by PSNC; Central element of the e-vlbi System providing the centralized control of the entire experiment; The VB module processes experiment definition submitted from Workflow Manger application; VB is also responsible for coordination and submission of computational jobs with the distributed correlation of chunked data. Slide 2

24 Java windowbased application; Create observation workflow; Developed by PSNC. 4.WorkFlow Manager

25 4. New WorkFlow Manager, ongoing effort, NEXPReS project Workflow Manager = KIWI Portal (CLIENT) + Workflow Manager Service(WfMS, SERVER) Web-based interface; Server-side components; INFRASTRUCTURE Liferay/Websphere; Flex; Role-oriented access. Proxy between client and infrastructure; Central component containing all logic and persistence;

26 5. Conclusions During the last 1.5 years VIRAC has gained rudimentary VLBI data correlation capabilities; JIVE's SFXC, e-vlbi facilities and Field System are adapted technologies, now we can start to contribute to NEXPReS; Home-brewn near field radar VLBI correlator - first functionality is gained, development continues; E-VLBI cabaility is considered as goal for both correlators; Our goal is to be distributed e-vlbi ready, NEXPReS...

27 Thank you for your attention! The participation of the authors at this conference is supported by ERDF project «SATTEH, No.2010/0189/2DP/ /10/APIA/VIAA/019» being implemented in Engineering Research Institute «Ventspils International Radio Astronomy Centre» of Ventspils University College (VIRAC). Investing in Your future!

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