The Digital Base Band Converter project developed in the last decade produced a general architecture and a
class of boards, firmware and software, giving the possibility to build a general purpose back-end system for
VLBI or single-dish observational activities. Such approach suggests the realization of a digital radio system,
i.e. a receiver with conversion not realized with analogue techniques, maintaining only amplification stages in
the analogue domain. This solution can be applied until a maximum around 16 GHz, the present limit for the
instantaneous input band in the latest version of the DBBC project, while in the millimeter frequency range this
maximum limit of 0.5-2 GHz of the previous versions allows the intermediate frequency to be processed in the
A description of the elements developed in the DBBC project is presented, with their use in different environments.
The architecture is composed of a PC controlled mainframe, and of different modules that can be
combined in a very flexible way in order to realize different instruments. The instrument can be expanded or
retrofitted to meet increasing observational demands. Available modules include ADC converters, processing
boards, physical interfaces (VSI and 10G Ethernet).
Several applications have already been implemented and used in radioastronomic observations: a DDC (Direct
Digital Conversion) for VLBI observations, a Polyphase Digital Filter Bank, and a Multiband Scansion
Spectrometer. Other applications are currently studied for additional functionalities like a spectropolarimeter,
a linear-to-circular polarization converter, a RFI-mitigation tool, and a phase-reference holographic tool-kit.