KVN and VERA Array

Correlators

The correlation process is carried out by a VLBI correlator at KJCC (Korea-Japan Correlation Center) of KASI, which has been developed by the Korea-Japan joint correlator development project, and named as "Daejeon correlator". The Daejeon correlator can process the data stream of up to 8192 Mbps from maximum 16 antenna stations at once. Currently the raw observed data of KVN stations are recorded and playbacked with Mark5B, and those of VERA stations are recorded and playbacked with DIR-2000(VERA-2000) at the data rate of 1024 Mbps. The only data format available in the next observing season is 16 IFs16 MHz ("C5 mode" in The Daejeon correlator terminology). Minimum integration time (time resolution) is 1.6384 seconds at this mode, and the number of frequency channels within each IF is 8192 (i.e. maximum frequency resolution is about 1.95 kHz). By default, the number of frequency channels is reduced to 128 (for continuum) or 512 (for line) via channel integration after correlation. One may put a special request of number of frequency channels to take better frequency resolution. The number of frequency channels can be selected among 512, 1024, 2048, 4096 or 8192. Final correlated data is served as FITS-IDI file.

Specification of The Daejeon correlator is summarized in Table 7.

Table 7:Specification of Daejeon correlator.
Max. number of antennas 16
correlation mode C5(16 MHz Bandwidth, 16 stream)
Max. number of corr./input 120 cross + 16 auto
Sub-array 2 case(12+4, 8+8)
Bandwidth 512 MHz
Max. data rate/antenna 2048 Mbps VSI-H(32 parallels, 64MHz clock)
Max. delay compensation $\pm$ 36,000 km
Max. fringe tracking 1.075 kHz
FFT work length 16+16 bits fixed point for real, imaginary
Integration time 25.6 msec $\sim$ 10.24 sec
Data output channels 8192 channels
Data output rate Max. 1.4GB/sec at 25.6msec integration time
For more details, see http://kjcc.kasi.re.kr/doc/kjcc-spec.html

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KaVA ( KVN and VERA Array )