East Asian VLBI Network (EAVN)

Digital Signal Process

In NRO45 system, the baseband signal output is 512-1024 MHz and the A/D samplers perform 2-bit digitization with four quantization levels. A maximum recording rate of 2048 Mbps is possible with a total bandwidth of 512 MHz.

Since the total data recording rate is limited to 1024 Mbps (see the next section), only part of the sampled data can be recorded onto hard disks. The data rate reduction is done by digital filter system, with which one can flexibly choose number and width of recording frequency bands.

Observers can select modes of the digital filter listed in Table 6 of the KaVA Status Report [1]. For EAVN observations in 2018B semester, however, three digital filter modes are available, 'GEO1K' and 'GEO1S' (16 MHz X 16 IF channels for both setup), and 'VERA4S' (32 MHz X 8 IF channels).Refer to Section 3.3 for more details.




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EAVN ( East Asia VLBI Network)