1. General Information
The correlation process is carried out by the Daejeon correlator located at KASI Daejoen headquarter. The maximum number of antenna stations that can be correlated at the same time is 16 for the Mark5B and VERA2000(DIR-2000) system. Thus, the correlator can process at once the data recorded by Mark5B with the three KVN stations and DIR-2000 with four VERA stations. In the correlator output, the maximum number of spectral point per antenna is 8192 points across all channels for Mark5B and DIR-2000. The time resolution of the correlator output is usually set to be 1.6384 second, but the high time resolution (down to 409.6 milliseconds for C5 mode(16 MHz bandwidth, 16stream)) is also available upon requests (though the total amount of output data becomes larger). Detail information about correlation mode, Integration time, and Channel integration are listed in below. Table 1 shows the detail specification of Deajeon Correlator.
Table 1. Specification of Daejeon Correlator.
| # of antennas
|# of inputs/antenna
||4 bands(4Fx1P, 2Fx2P, 1Fx2P+2Fx1P)
|Max. # of corr./input
||120 cross + 16 auto
||2 case(12+4, 8+8)
||1 Gsps by 2bit/sample
|Maximum data rate/antenna
||2 Gbps VSI-H(32parallels, 64 MHz clock
|Maximum delay compensation
|Maximum fringe tracking
||FX-type with FPGA
|FFT word length
||16+16 bits fixed point for real, imaginary
||25.6 msec~10.24 sec
|Data output channels
|Data output rate
||Maximum 1.4GB/sec at 25.6msec integration time
2. Correlation Processing
2.1 Correlation mode and Integration time
KJCC can currently support the following correlation mode.
-C5 (16 MHz BW, 16stream), Integration time : 1.6384sec @ correlation
Min. Integ. time : 409.6msec @ correlation
KJCC plans to support the following correlation mode until 2013.
-C2 (128 MHz BW, 2stream), Integration time : 1.6384sec @ correlation
-C1 (256 MHz BW, 1stream)
-W1 (512 MHz BW, 1port)
KJCC will basically support the following number of frequency channels in the prepared FITS file.
-Basic output channel of correlator : 8192 frequency channel
-Continuum : 128 frequency channel(64 channels integrated in post-correlation)
-Spectral line : 512 frequency channel(16 channels integrated in post-correlation)
2.3 FITS delivery
KJCC will deliver the FITS file to the PI via FTP server or USB memory or mobile disk.
2.4 Archiving policy
KJCC will organize the archiving policy for observation data, CODA and FITS file as below.
-Observation data : basically 2 months, and then it will be released.
-CODA : if correlated data will be used for astrometry or geodesy, it will be permanently stored at CODA server. Otherwise, the correlated raw data and CODA file system will be deleted after receiving the response from PI.
-FITS : it will be permanently archived at Archiving server.
2.5 Correlation expected time
Correlation processing will be about 1 week for preparing 1st version of FITS. However, KJCC will do their best to make correlation as fast as possible to deliver FITS file to PI.