KVN Recent Progress of Daejeon Correlator Se-Jin Oh Duk-Gyoo Roh, Jae-Hwam Yeom, ChungSik Oh, Jinseung Jung, Dong-Kyu Jung, Youngjoo Yun, A. Miyazaki, T. Oyama, N. Kawaguchi, H. Kobayashi, K. Shibata, and staff of Correlator team of KASI/NAOJ 2 nd IVTW, ICC Jeju, Korea , Oct. 2013

Contents  Background  System Introduction  Playback System  RVDB System  VLBI Correlation Subsystem  Correlated VLBI Data Buffer(CVDB)  Post Processing SW  Recent Status  KJCC Operation  Experimental Result  Future Work

Target Array : EAVN  For KVN, KVN+VERA/JVN, and EAVN.  And also for Chinese Space-VLBI Antenna(s) in the Space

 To establish the bigger, more powerful correlator and get the best performance in East Asian VLBI Network, we concluded that KASI & NAOJ join together to develop new Correlator.  MOU between KASI & NAOJ ( )  Development of Korea-Japan Joint VLBI Correlator,  Common facility of correlation & data center  Joint Development Project was initiated respectively. Japan : 5 years from April 2005 Korea : 5 years from Jan Korea-Japan Joint VLBI Correlator(KJJVC) Development Project Backgrounds

ItemsSpecifications Number of Antennas16 Number of Inputs / Antenna - Input Interface - Maximum Data Rates 4 - 2Gbps VSI-H (32parallels, 64 MHz clk) - Total of 8,192 Mbps Digitization for Each Inputs - Number of Bits - Quantization Levels - Sampling Rates - Input Bandwidth - Sub-stream Specification - 2 bits/sample - 4 levels - 1,024 Msamples/sec MHz - Logically Associated Sub-streams Maximum Delay Compensation (Largest Baseline Length) ±36,000 km Maximum Fringe Tracking (Fastest Phase Drift Cancellation) 1,075 kHz ArchitectureFX type, with FPGA and DSP chips Specification (1) of KJJVC KASI + NAOJ  2006~2010

ItemsSpecifications FFT Processing - Freq. Resolution - Size of FFT points - Word length in FFT - Scaling - Re-quantization - 22GHz - 256k/128k/64k/32k/16k/8k Adjustable bits fixed point for real & imaginary - Yes bits fixed point for real & imaginary △ W Correction Yes Correlations - Number of Correlation Outputs/Input - Total Number of Correlation Outputs - Polarization Mode - Data compression(Binning) - Word length - min. max Integration Time - Max. 120 Cross- and 16 Auto-correlations - Max. 480 Cross- and 64 Auto-correlations - RR or LL ; Full Operation for 16 antennas RR and LL ; Full Operation for 16 antennas RR, RL, LR and LL : Full Op. for 8 antennas - Yes, 8,192 channels / correlation output bits Fixed Point for R & I msec ~ 10.24sec Data Output to Archive (Max.)1.4 GBytes/sec Subarray Operation2 cases (12 + 4, 8 + 8) Specification (2) of KJJVC

KJJVC Framework Mark5B VERA2000 OCTADISK Optical Fiber Raw VLBI Data Buffer (RVDB) VLBI Correlation Subsystem (VCS) Correlated VLBI Data Buffer (CVDB) Correlator Control & Operation S/W  Yellow : NAOJ, Green : KASI

Playback Systems  Mark5B playback  VSI compatible : KVN  DIR2000 is in use extensively at VERA.  VERA 2000, which is modified by NAOJ according to DIR1000, used for Playing back DIR2000 tape media for VERA.  OCTADISK : modified using RVDB with 4Gbps recorder/playback developed by NAOJ.  Optical Fiber : Capable of dealing with the full data rate of 8 Gbps. OCTADISK(VDIF) VERA2000Mark5B

Raw VLBI Data Buffer (RVDB)  Purpose :  Adjust data format as like # of bits per sample, and so on  Easily synchronize the data while playback (heterogeneous recorder models)  Maintain the buffering between recorder speed(1 Gbps) and correlation speed(8 Gbps) (N. Kawaguchi / NAOJ)

Raw VLBI Data Buffer (RVDB) basic configuration VSI Optical Adapter(OCTAVIA) From Playing Back Units 1Gbps, nominal 10GbE Switch 2Gbps, nominal OCTADDB 4 D-ports 4 C-ports To Correlator Input Ports OCTADISK Control PC VDIF

VLBI Correlation Subsystem (VCS) ( ) 16 Stations, 8Gbps /station Serialized data sub-streams in time domain, and Parallel processing in frequency channels after FFT. Full polarization correlation is supported (up to 8 stations) Two sub-array modes are prepared (12+4 and 8+8). Max. data output rate is 25.6ms integration Antenna Unit Corr & Acu.Unit

CVDB(Correlated VLBI Data Buffer)  Max. data rate : integ. (~10% at average operation)  need to implement massive storage to save the correlation results with four 10GbE of VCS  CVDB (specification)  Architecture Infiniband  Max. Capacity 1~3 PB for 1 year (EAVN, Space VLBI) 500 TB at initial phase (KVN, KJJVN) ~119 TB

Post-Processing SW configuration Developing with Japanese colleagues, NAOJ(CODA) and Kagoshima Univ.(GFS) CODA file system (CCcoda ver2.1), FITSgen  to reduce the developing efforts & cost, and to have compatibility with MTK FX

Recent Status : Hardware(RVDB)  By NAOJ  In RVDB system, 3 OCTADDB system changed to OCTADISK so as to support VERA(JVN) wideband observation, these are now testing in Mitaka.  After completion of test, these will be delivered to KJCC until end of October this year.  2set OCTADISK2 systems were already ordered to manufacturer for supporting VERA wideband data with high speed(over 8 Gbps) recording  Please refer to Kono-san’s presentation in detail on Saturday

Recent Status: Hardware(VCS)  New firmware was installed  DC-like component band start  Phase concentration band start  FFT operation : 16bit  20bit  Experiments of scaling factor/requantization for FFT were performed, so new reasonable factors were determined.  Correlation is currently conducted using modified firmware as indicated above.

Recent Status: Software  CODAgen/FITSgen  By Kan-ya san’s great effort of Leonid/NAOJ, creating time for CODA F/S was reduced within 3~4 hours for 8hours observation with 16MHz-16stream.  Also creating time for FITS was reduced within 1 hour for 8 hours observation with 16MHz-16stream.  Creating time depends on the observational(correlation) mode.

New Building East Asia VLBI Research Center ( ) KASI

Daejeon Correlator ~ current

KJCC(Korea-Japan Correlation Center) Operation room

MoA for KJCC joint operation(’ )

KJCC - Operation Structure Executive Board KVN + VERA(+ EAVN) Oper. Support Group KVN VERA / JVN EAVN Mitaka Correlator Korea-Japan Correlation Center Project manager 1, 1 Operation manager 1, 1 System Engineer 3, 3 Operator 2, 6 Data quality analyzer 2, 4 nowfuture KASI operates KJCC with supporting operational budget and know-how of NAOJ.

Experimental Results  To adjust the scaling factor, requantization bit position and verify the performance of Daejeon Correlator  Observation Code : r11027b  Array : KVN+VERA combined 7stations  Observation frequency : 22 GHz  Observation time : 9.2hours  Correlation mode : C5(16MHz BW, 16stream)  Integration time : sec

FFT scale factor, Re-quantization

SgrB2M

By S.S. Lee et al (22GHz)

Correlation(backlog) Status Exp.ObjectCorrelationStatus R11027B KVN+VERA Evaluation for KJCC FinishedIn Analyzing K12098C KVN 4channel simultaneous obs FinishedIn Analyzing R11025A KVN+VERA 22GHz FinishedIn Analyzing R11026A KVN+VERA 43GHz FinishedIn Analyzing R12280A KVN+VERA 43GHz survey FinishedIn Analyzing R11088B R11089B R11090B R11091B R11093B R11095B KVN+VERA SgrA* campaign FinishedIn Analyzing R11094A, B 22/43 GHz KVN+VERAFinishedIn Analyzing R13082B R13083B R13084B R13085B R13086B R13102A KVN+VERA SgrA* campaign In progress for correlation Undergoing correlation From 2013, Daejeon correlator is normally operating for C5 mode(16MHz -16channel)

Future plan supporting for other mode(wideband etc)  EAVN evaluation observation  24 th Sept  KVN, VERA, CVN(Shanghai, Kunming, Urumuqi), JVN ~ 13 stations had been joined  These observed data will be correlated by Daejeon correlator  Until the end of 2013  C2 (128MHz BW, 2streams)  C1 (256MHz BW, 1stream)  W1 (512MHz BW)  Polarization correlation Test correlation will be also performed soon or within this year.

Change Tape to KJCC/VERA (Planned) 1Gbps 80 min. 4Gpbs 6 Hours or longer In VERA, parallel operation of tape and disk are now going on. VERA2000 OCTADISK