KVNKJCC system andCorrelation status
Se-Jin Ohand staff of Correlator team of KASI/NAOJ

VERA User’s Meeting, 24~25 Sept. 2015, @ Mizusawa, Japan

Contents
KJCC system status
 Problem(known, like~) and others
 MaintenanceCorrelation Status
Recent Activities
Future Work

2-layer Problem in VCS

Incorrect Read pointer in Memorymap
In incorrect case, first stream1
is correctly read, but the otherstreams read stream1 datafrom memory.
 Coding miss in FPGATest Result(Before, After)
BeforeAfter

CORR or Sampler Spurious ?

16MHzBy Imai-san’s report
Unfortunately, raw data wasAlready deleted.

16MHz

Sometimes 2-layer (old HDD error)
 HDD used in RVDB OCTADDB had speed access error
due to old or its performanceRVDB dummy data
 In SNPLT task, you can see strange feature for this reason.
This feature is dummy(previous obs data) data in RVDB.

VCS maintenanceWith Elecs Industry Co. Ltd. Including RVDBPeriod : 2015. 9/13~9/19
Check list
 AU, CAU checking• Cleaning, Fan unit, Power unit, Optical output level checkfor each AU/CAU• VCS inside interface check, CAU#10 check• AU#10 – by changing optical module, it is repaired.
• AU#3, #12 - QDR Memory Error ( needs to be sent toFactory)• FG + Surge protector
 RVDB (DIO,DDB) : firmware update Test run

Correlation Status in KJCC web
http://kjcc.kasi.re.kr

Correlation StatusSeason

Observation

Corr
Finished

Remain Corr

FITS
release

2015B

8171

2015A

4242042

2014B3030030

2014A

56

56056

The correlation is now conducted normally.

Average Correlation Time Media delivery time KJCC to each VERA site, it took 4 or 5 days
 Each VERA site to KJCC, it took almost 2 weeks or16 days due to Korean Customs
 Media staying time in KJCC
 OCTADISK pack is staying in KJCC average 40days
or longer. VERA AOC often requested to us morefast returning due to lack of media. Sometimes
VERA used their own diskpack for KaVA obs.
 Average correlation time 1 correlation per day is general. Sometimes 2correlations are conducted.

2Gbps test correlation
 512MHz BW x 1 IF KVN only test observation
 2Gbps test observation will be regularly performed
DiFX

KJCC
312128ch output
3214096ch output

C4 mode32MHz BW x 8IFs
2014 vs. 2015
Digital Filter setting is fixedExpected normal operation in 2016A
2014

2015

Request from KJCC
 Short description
 Some observations are quite complicated to understand.
 If you want to receive FITS file correctly as you expected,
please let us know your short description of correlation
scheme.
 Data keeping request
 We would like to keep all observation data over 2months, butdiskpacks are sometimes released due to lack of media.
 If you want to keep observation data, please ask us yourrequest within 2weeks after FITS distribution.
 We will discuss purchase of media in Director’s Meeting.
 Diskpack for KaVA Each KVN/VERA should consider for buying disk-pack in orderto operate steadily.
 If possible, each PI have interest for buying disks.

Episode @ KJCC
 Re-correlation is requested including data copy againand again
 PIs firstly suspected that Correlation have wrong orproblem. But sometimes correlation processing iswrong due to set of wrong parameter or data copyproblem. But many of observation were also
conducted with error or not. In AOC report, NOPROBLEM is written, but it is not always correct.
 Correlator team is encouraged with your shortmessage in presentation for this obs correlated by
KJCC efforts.

Future Work
4/8Gbps test correlation
CODA/FITS generation SW modification for
Fast switching (already started)New Data Archive for Correlator outputsaving in 2016
Support fully Geodesy correlation andAstrometry correlation with in close
cooperation with VERA team

2/4/8Gbps playback support
 Support playback of Mark6(KVN)/OCTADISK2(VERA) toDaejeon Corr at KJCCMark6OCTADISK2 VDIF data transfer SW developed(Big Storage
Server(Mark6 or others) to RVDB)