1. 上海天文台 Shanghai Astronomical Observatory VLBI correlators of Shanghai Astronomical Observatory ZHENG Weimin, Zhang Xiuzhong Shanghai Astronomical Observatory, Chinese Academy of Sciences 7th International eVLBI Workshop June 16, 2008, Shanghai

2. 上海天文台 Shanghai Astronomical Observatory Contents 1.Background 2.CVN hardware correlator 3.CVN software correlator 4.Applications in CE -1 project 5. R&D plan

3. 上海天文台 Shanghai Astronomical Observatory Background  1973~, VLBI technology introduced in Shanghai Astronomical Observatory (SHAO);  1987, S-2 VLBI processor constructed, copy of MK-2 correlator  2003, two-station hardware correlator completed, adapted from VLBA correlator of NRAO.  2003, Satellite Fringe Searcher (Matlab version of software correlator)  2004-2007, VLBI hardware & software correlator for Chang ’ E-1 project  1973~, VLBI technology introduced in Shanghai Astronomical Observatory (SHAO);  1987, S-2 VLBI processor constructed, copy of MK-2 correlator  2003, two-station hardware correlator completed, adapted from VLBA correlator of NRAO.  2003, Satellite Fringe Searcher (Matlab version of software correlator)  2004-2007, VLBI hardware & software correlator for Chang ’ E-1 project

4. 上海天文台 Shanghai Astronomical Observatory Chinese lunar exploration project Chang’E-1 and CVN  24, Oct, 2007, China lunched a lunar probe Chang ’ E-1 (CE-1) to the moon.  CE-1 Tracking through USB + VLBI 1. USB (Unified S-Band command) system for range & rate; 2. CVN (Chinese VLBI Network) for delay & rate and angular position. Tracking task contains 2 stages: 1. Critical flying mission 2. Long-term in-orbit operation  24, Oct, 2007, China lunched a lunar probe Chang ’ E-1 (CE-1) to the moon.  CE-1 Tracking through USB + VLBI 1. USB (Unified S-Band command) system for range & rate; 2. CVN (Chinese VLBI Network) for delay & rate and angular position. Tracking task contains 2 stages: 1. Critical flying mission 2. Long-term in-orbit operation

5. 上海天文台 Shanghai Astronomical Observatory 1st stage: Critical flying mission From 25,Oct- 18, Nov, 2007, ≈1 month Narrow band near-real time e-VLBI Data mode: 16Mbps/station, 4 station Transportation mode: By network Observation time: ≈15hous/day Data processing requirement: Data latency of VLBI center < 10 min ( 6min) From 25,Oct- 18, Nov, 2007, ≈1 month Narrow band near-real time e-VLBI Data mode: 16Mbps/station, 4 station Transportation mode: By network Observation time: ≈15hous/day Data processing requirement: Data latency of VLBI center < 10 min ( 6min)

6. 上海天文台 Shanghai Astronomical Observatory Two-stage Tracking task Tracking task contains 2 stages: 1. Critical flying mission Demonstration at CVN center, 12th floor. This afternoon coffee break time, 15:20~16:00. 2. Long-term in-orbit operation Tracking task contains 2 stages: 1. Critical flying mission Demonstration at CVN center, 12th floor. This afternoon coffee break time, 15:20~16:00. 2. Long-term in-orbit operation

7. 上海天文台 Shanghai Astronomical Observatory 2nd stage: Long-term in-orbit operation After 18, Dec,2007, ≈ one year Data mode: 64-128Mbps/station Recorded by Mark5 system Transportation mode: By express mail Observation time: ≈2days/week Data processing ability: Post process mode: Data latency of VLBI center < 2 weeks. After 18, Dec,2007, ≈ one year Data mode: 64-128Mbps/station Recorded by Mark5 system Transportation mode: By express mail Observation time: ≈2days/week Data processing ability: Post process mode: Data latency of VLBI center < 2 weeks.

8. 上海天文台 Shanghai Astronomical Observatory Data processing flow of CVN (CE-1)

9. 上海天文台 Shanghai Astronomical Observatory Haredware and software correlator

10. 上海天文台 Shanghai Astronomical Observatory Data processing Center

11. 上海天文台 Shanghai Astronomical Observatory 1. 5-Stations FX Correlator (8 IFs ) 2. Maxium date rate: 256Mbps/station, 1 or 2bit/sample 3. Integration Time: 1~59 second 4. Fixed FFT points/ IF: 1024 5. Input data format: MK5 6. Data source: Disk Array, Network 7. Output format ( special CVN format) 8. Fast fringe search and delay model reconstruction for satellite, Full PCAL detection ability (realized by software module on PC server and shared with software correlator). 2. CVN hardware Correlator

12. 上海天文台 Shanghai Astronomical Observatory Structure of Hardware Correlator Data Output MACMAC FFT 16bits Scaled Fixed Point FRINGEFRINGE DELAYDELAY 32bits LTA 7300A Board PBI_1 Model Input FSTCFSTC MCC DATA CLKPBI_1 PBI_5 32M 160M 8M 4M DATA CLKPBI_2 DATA CLKPBI_5 5 X c2v3000 Xc4vsx35 / ch

13. 上海天文台 Shanghai Astronomical Observatory i= 1, 2 …, linear Model period (160x1024 bits) Sine-Cosine Look-Up Table Sine Cosine 16bits PBI-1 14bits Unsigned PBI-2 PBI-5 16bits 1 (b) 2 (b) 5 (b) 1 (a) RAM 16x2 x1024 2 (a) RAM 16x2 x1024 5 (a) RAM 16x2 x1024 PING-PANG RAM Xilinx IP Core 5x2x16 bits ‘1’ = x“4000” ‘0’ = x”C000” Fringe Stopping Complex Multiply

14. 上海天文台 Shanghai Astronomical Observatory 1 (b) 3 (b) 5 (b) 1 (a) RAM 16x2 x1024 3 (a) RAM 16x2 x1024 5 (a) RAM 16x2 x1024 PING-PANG RAM FFT 16 bits 1024 Fixed Point Xilinx IP Core DATA_R DATA_I (16 bits) 1 3 5 Address 10 bits Index 9 bits FFT_R 16 bits Done FSTCFSTC FFT_I FFT (Fast Fourier Transform)

15. 上海天文台 Shanghai Astronomical Observatory τ = d + e(f-1) f= 1, 2 …,FFT num per linear Model period (160) FSTC = i* τ/ N i=1, 2 …, N/2 N is FFT point Sine-Cosine Look-Up Table Sine Cosine 16bits Sign FFT_R 14bits Unsigned FFT_I 16 bits 1 (b) 3 (b) 5 (b) 1 (a) RAM 16x2x512 3 (a) RAM 16x2x512 5 (a) RAM 16x2x512 PING-PANG RAM Xilinx IP Core 1 DATA_R DATA_I (16 bits) 3 5 DATA_R = FFT_R * Cosine - FFT_ I * Sine DATA_ I = FFT_ I * Cosine + FFT_R * Sine FSTC (Fractional Sample Time Correction)

16. 上海天文台 Shanghai Astronomical Observatory X_R 16 bits X_I Y_RY_I 16 bits Dout_R Dout_I R RAM 44x512 I RAM 44x512 R RAM 44x512 I RAM 44x512 1~1023 次 1024 次 Output RAM Acc RAM 44x2 bits DOUT_R = X_R * Y_R + X_I * Y_I DOUT_ I = X_I * Y_R - X_R * Y_I MAC (multiply-accumulate )

17. 上海天文台 Shanghai Astronomical Observatory LTA Monitor (real time fringe display) PBD CCC LTA MOXA Card PBI (xc2v3000) FFT & MAC (xc4vsx35)

18. 上海天文台 Shanghai Astronomical Observatory ML402 Evaluation Platform (V4-SX35) FFT & MAC Board

19. 上海天文台 Shanghai Astronomical Observatory  Near Real-time software correlator (NRSC)  Wideband software correlator 3. CVN Software correlator

20. 上海天文台 Shanghai Astronomical Observatory  4-station FX type correlator  Near real time correlation ability (< 3 min)  Fast fringe search and delay model reconstruction for satellite  Full PCAL detection ability  Hardware platform: SMP (Symmetric Multiple Processor) PC server ， 4 dual core X86 CPU,2.2GHz  Software platform: Linux enterprise OS (Operation System)  Correlation speed: ≈45Mbps/station actual data speed: 16Mbps/station (near real- time mode) Near Real-time Software correlator

21. 上海天文台 Shanghai Astronomical Observatory Specifications of the NRSC for CE-1 ArchitectureFX Correlation station number1~4 IF number1~16 FFT points/ IF32 ~16484/IF Integration period0.1~60 second Input data format Mark5 (1bit sample ） Output data formatCVN Fringe search2-4 stations Correlation speed45Mbps/station (4 stations, 1024/IF) Data latency< 3 minutes PCAL detectionYes

22. 上海天文台 Shanghai Astronomical Observatory Block diagram NFS: Network File System

23. 上海天文台 Shanghai Astronomical Observatory  Deal with the high speed data of long-term in- orbit operation.  PC cluster with Two-level parallelisms:  Intra-node shared-memory programming mode (pthreads)  Inter-node Message-Passing Programming mode (MPI) Wide band software correlator

24. 上海天文台 Shanghai Astronomical Observatory Correlator architecture of SMP cluster 3 Nodes = 24 CPU cores 3 Nodes = 24 CPU cores

25. 上海天文台 Shanghai Astronomical Observatory 4. Applications in CE -1 project First fringe of CE-1 probe In one-month critical mission, Earth phase orbit->earth-moon transfer orbit- >lunar capture orbit-> lunar circum orbit In Long-term in-orbit operation period First fringe of CE-1 probe In one-month critical mission, Earth phase orbit->earth-moon transfer orbit- >lunar capture orbit-> lunar circum orbit In Long-term in-orbit operation period 2007 ， 10 ， 25

26. 上海天文台 Shanghai Astronomical Observatory Fringe searching function in CE-1 satellite tracking

27. 上海天文台 Shanghai Astronomical Observatory Meet CVN astronomy, geodesy and Deep space exploration requirement, Characteristics of new correlator: 10 stations ， High speed: >1Gbps/station Scan-based correlation Output format :FITS Real-time ability 5. R&D plan

28. 上海天文台 Shanghai Astronomical Observatory 8-station observation data processing  Observation time:2006,12,20  8-station, sino-japan Geotail satellite experiment, correlating time: 2007,5

29. 上海天文台 Shanghai Astronomical Observatory Cluster platform: 4 nodes (4 dual core SMP PC server) Cluster platform: 4 nodes (4 dual core SMP PC server) 10-station SMP cluster prototype correlator Correlator speed vs. station number

30. 上海天文台 Shanghai Astronomical Observatory Thanks for your attention