Abstract: Correlators in radioastronomyG Comoretto PoS(MCCT-SKADS)016Correlators in radioastronomy G Comoretto in mathematical form using a general purpose language like MatLab, and this is translated by a specific software to the required instrument.A smaller example is the Digital BBC system, developed by the European VLBI Network and initially conceived as a all-digital replacement for a VLBI terminal.The system, including a fast sampler and individual modules containing a single FPGA, can be used as a general-purpose, modular back-end.