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KVNRecent Progress of Daejeon Correlator
Se-Jin OhDuk-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
2nd IVTW, ICC Jeju, Korea. 10-12, Oct. 2013
Contents
BackgroundSystem Introduction
Playback System RVDB System VLBI Correlation Subsystem Correlated VLBI Data Buffer(CVDB) Post Processing SW
Recent StatusKJCC OperationExperimental ResultFuture 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 (2005. 7. 7.) Development of Korea-Japan Joint VLBI Correlator, Common facility of correlation & data center
Joint Development Project was initiated respectively.Japan : 5 years from April 2005Korea : 5 years from Jan. 2006
Korea-Japan Joint VLBI Correlator(KJJVC) Development ProjectBackgrounds
Items Specifications
Number of Antennas 16
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- 512 MHz- Logically Associated Sub-streams
Maximum Delay Compensation (Largest Baseline Length) ±36,000 km
Maximum Fringe Tracking (Fastest Phase Drift Cancella-tion)
1,075 kHz
Architecture FX type, with FPGA and DSP chips
Specification (1) of KJJVC
KASI + NAOJ 2006~2010
Items Specifications
FFT Processing- Freq. Resolution- Size of FFT points- Word length in FFT- Scaling- Re-quantization
- 0.05km/sec @ 22GHz- 256k/128k/64k/32k/16k/8k Adjustable- 20+20 bits fixed point for real & imagi-nary- Yes- 16+16 bits fixed point for real & imagi-nary
△W Correction Yes
Correlations- Number of Correlation Outputs/Input- Total Number of Correlation Out-puts- Polarization Mode - Data compression(Binning)- Word length- min. max Integration Time
- Max. 120 Cross- and 16 Auto-correla-tions- Max. 480 Cross- and 64 Auto-correla-tions- RR or LL ; Full Operation for 16 anten-nas RR and LL ; Full Operation for 16 anten-nas RR, RL, LR and LL : Full Op. for 8 anten-nas- Yes, 8,192 channels / correlation output- 32+32 bits Fixed Point for R & I- 25.6msec ~ 10.24sec
Data Output to Archive (Max.) 1.4 GBytes/sec
Subarray Operation 2 cases (12 + 4, 8 + 8)
Specification (2) of KJJVC
KJJVC Framework
Mark5B
VERA2000
OCTADISK
Optical Fiber
RawVLBIDataBuffer(RVDB)
VLBICorrelationSubsystem(VCS)
CorrelatedVLBIDataBuffer(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 OpticalAdapter(OCTAVIA)
From Playing Back Units
1Gbps, nominal
10GbE
Sw
itch
2Gbps, nominal OCTADDB
OCTADDB
OCTADDB
OCTADDB
4 D-ports
4 C-ports To CorrelatorInput Ports
OCTADISK
Control PC
VDIF
VLBI Correlation Subsystem (VCS)(2007.8-2009.7)
• 16 Stations, 8Gbps /sta-tion
• Serialized data sub-streams in time domain, and Parallel processing in frequency channels after FFT.
• Full polarization correla-tion is supported (up to 8 stations)
• Two sub-array modes are prepared (12+4 and 8+8).
• Max. data output rate is 1.4GB/sec @ 25.6ms in-tegration
Antenna UnitAntenna Unit Corr & Acu.Unit
CVDB(Correlated VLBI Data Buffer)
Max. data rate : 1.4GB/sec @25.6ms 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 deletion @ band start Phase concentration deletion @ band
start FFT operation : 16bit20bitExperiments 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.
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
now future
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 : 1.6384sec
Correlation(backlog) StatusExp. Object Correlation Status
R11027BKVN+VERA
Evaluation for KJCCFinished In Analyzing
K12098CKVN 4channel simulta-
neous obsFinished In Analyzing
R11025AKVN+VERA
22GHzFinished In Analyzing
R11026AKVN+VERA
43GHzFinished In Analyzing
R12280AKVN+VERA
43GHz surveyFinished In Analyzing
R11088BR11089BR11090BR11091BR11093BR11095B
KVN+VERASgrA* campaign
Finished In Analyzing
R11094A,B
22/43 GHz KVN+VERA Finished In Analyzing
R13082BR13083BR13084BR13085BR13086BR13102A
KVN+VERASgrA* campaign
In progress for corre-lation
Undergoing correla-tion
From 2013,Daejeon correlatoris normally operatingfor C5 mode(16MHz-16channel)
Future plansupporting for other mode(wideband etc)
EAVN evaluation observation 24th Sept. 2013 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.