Development of Multipurpose Digital Backend for ”Quasar” network radio telescopes

E. Nosov

Proceedings of the 22nd European VLBI Group for Geodesy and Astrometry Working Meeting, 25-29 (2015)

Аннотация

Multipurpose Digital Backend (MDBE) is a system intended to replace the currently used backend equipment of ”Quasar” network radio telescopes. MDBE has a compact size and can be easily located inside the focal cabin of the antenna. DBE digitizes up to 8 input signals with 512 MHz bandwidth or up to 4 signals with 1024 MHz bandwidth and processes the signals in FPGA. The system has several operating modes to perform all required types of observations. For VLBI observations, MDBE supports wide-band channel mode, digital downconverters (DDC) mode and polyphase filter bank mode. The output data stream is packed into 10G Ethernet frames and transferred through fiber optic lines. MDBE supports VDIF data format for all VLBI observation modes. For compatibility with existing data acquisition systems, the data in DDCs mode can also be packed in Mark5B data format. Besides VLBI observation modes, MDBE implements spectrometer and radiometric backend modes. The system implements a rich set of signal analysis features including PCAL extraction, 2-bits data statistics, input signals capture, power spectral density estimation and other. These features allow remote monitoring of the whole system condition and can greatly reducefault lookup time. MDBE replaces a lot of equipment with one compact device and significantly simplifies verall system complexity.