August 08 - 12, 2011

1. 2011 AOGS @Taipei Design & Implementation of the Korean IPS Array Cheol-Oh Jeong 1, Jung-Hoon Kim 2 , Jae-Woo Park 1, Seok-Hee Bae 3, Jin-Wook Han 3, Yong-Sun Park 4 1 Electronics and Telecommunications Research Institute 2 SET system, Inc. 3 Radio Research Agency 4 Dept. of Physics and Astronomy, Seoul National University August 08 - 12, 2011

2. Overview About KSWC of RRA 1. Requirement & Design 2. Prototype Test 3. Conclusion 4.

3. 1. AboutKSWC of RRA

4. Overview of RRA & KSWC

5. Progress of KSWC Dec 29, 2010

6. Status of observation systems @ KSWC

7. 2. Requirement & Design

8. Background • Radio Research Agency (RRA) has interested in the study of solar wind, as one of the space weather indicators in radio range. • RRA wanted to develop & operate solar wind monitoring system • ETRI was requested to make concept design and design spec. for solar wind monitoring system from RRA • ETRI with SET & SNU had performed this job and made prototype of solar wind monitoring system for checking the its function and performance which will be met with RRA’s requirement

9. Req. from RRA • Requirement • Propose new system with digital phased array & interferometer • Stable, inexpensive • No moving parts, electronic beam steering • Not transit type, but still limited field of view • Can be used at night for astronomical purpose (Option) • Have functions & can be measured as follows • Solar wind monitoring • Solar imaging at radio Frequency • Observation of time-varying radio sources • Wide field imaging of radio sky

10. System Design & Spec.

11. Block Diagram 32 nodes

12. Considerations for Technical Issues • During design phase, following considerations were issued. • Radio frequency interference (RFI) • Phase control and electronic beam steering • Data rates and storage • Correlation/combining • Clock synchronization and trigger

13. Technical Issues - RFI • Radio frequency interference (RFI) measurement was performed at Jeju island • Date : 3rd ~ 5th June, 2010 (3 days) • Measured frequency : • 300MHz ~ 470MHz (IPS frequency area) • 1GHz ~ 18GHz (Radio Interference Measured System frequency area) • Found out that 327MHz ±5 MHz was quiet as IPS frequency area • 327+/-5 MHz will be blocked for IPS frequency area by RRA Measured result of 300MHZ ~ 470MHz

14. Technical issues – Phase control • Phase control and beam steering in two stages • Beam former • controls delays of signals from 24 antennas for electronic beam steering and combines the signals • allows 2π wrapping since bandwidth is narrow • S/W • controls delays of signals from tiles

15. Technical Issues – Data rates • Datarates • For IPS mode • Less than 1 Mbytes/source/day x 128 tiles = < 128 Mbytes • For Solar Imaging or other application • Min. 20 MBytes/sec ⅹ 128 tiles = 2.56 Gbytes/sec • Max. ~ 4 ⅹ Min. • Storage • For IPS mode • < 128Mbytes x 365 days = about 46 Gbytes / year • For Solar imaging or other application • If we save 1 hour raw observation data, we may need temporary disk space of min. 7 Tbytes for off-line data processing.

16. Technical Issues – Correlation/Combining • Correlation/combining • In case of phased array mode, we simply align and add the data from tiles, which needs far less processing time. • In case of solar imaging, we are planning to try S/W correlation using multi-core CPU or GPU in future. (Optional)

17. Technical Issues – Clock synchronization & trigger • Clock synchronization and trigger • To synchronize the clock, we use GPS receivers at each node, i.e. one GPS signal control 4 tiles

18. 3. Prototype Test

19. Overview • Purpose • To prove the proposed technology and to realize the functions • Beam forming function using interferometer theory • Beam steering function without mechanical motion • Detection of astronomical signal using multiplication method • Prototype Test • Data : 15th October 2010 • Place : KSWC @ Jeju • Test item : • Beam size • Beam forming function • Time series and spectrum display function of data taking program • Cross correlation display and auto-save function • Astronomical signal detection function • Locationof lag where cross correlation peak appears • GUI for astronomical source selectionand delay calculation function

20. Test setup • Tiles : 3 ea • 1 tile : 4x4 dipole antennas • Components • Tile & Antenna • LNA and filter • Beam former • Heterodyne receiver • Digitizer • Control PC • SW : • Control program for tile, beam former & source trace • Data acquisition & handling program • GUI program • Data reduction • Use LabView • Simply look for fringe N Tile 1 4x4 antennas with LNA Beam Former Beam Former Receiver Tile 3 4x4 antennas with LNA Tile 2 4x4 antennas with LNA Beam Former Beam Former Beam Former Beam Former Receiver Receiver Digitizer PC Control GUI

21. Components LNA Receiver Antenna Tile Beam Former

22. Test Result

23. Beam Pattern

24. GUI for control and data acquisition

25. Picture of Prototype test at Jeju Island

26. 4. Conclusion

27. Conclusion • Prototype test of Korean IPS array was successfully conducted • Confirmed that proposed technology was met with RRA’s requirement • Confirmed that all functions were realized • Beam forming function • Beam steering function • Detection of astronomical signal • Construction schedule of Korean IPS array • KSWC has a plan to install Korean IPS array gradually up to 128 tiles • KSWC’s plan is 32 or 64 tiles will be installed every year • 32 tiles will be installed at KSWC in Jeju by the end of thisyear

28. Thank you.