East Asian VLBI Network (EAVN)

Correlators

The correlation process is carried out by KJCC (Korea-Japan Correlation Center) at Daejeon, Korea. Hereafter it is tentatively called "Daejeon correlator", and its basic specifications are summarized in Table 5. The Daejeon correlator can process the data stream of up to 8192 Mbps from maximum 16 stations at once. Currently, available data formats are 16 IFs X 16 MHz ("C5 mode" in the Daejeon correlator terminology) at K- band, and 8 IFs X 32 MHz ("C4 mode") at both K- and Q-bands, and 2 IFs X 128 MHz ("C2 mode"). Minimum integration time (time resolution) of Daejeon correlator is 0.2048, 0.8192, and 1.6384 seconds for both C4 and C5 modes, and the number of frequency channels within each IF is 8192 for both modes (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 spectral 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 provided as FITS-IDI file.

Table 5: Specification of the Daejeon Hardware Correlatora.
Max. number of antennas 16
correlation mode C2b(128 MHz Bandwidth, 2 stream)
C4(32 MHz Bandwidth, 8 stream)
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 ± 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 ~ 10.24 sec
Data output channels 8192 channels
Data output rate Max. 1.4GB/sec at 25.6msec integration time
aFor more details, see the following website: http://kvn.kasi.re.kr/status report/correlator_status.html
bThis mode is not available for observations using NRO45 and Tianma65.



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EAVN ( East Asia VLBI Network)