# Why samples per symbols $\geq 2$ in the GNURadio Constellation Modulator block?

Let's say I want to emulate the design of a modulator I am building "in real life". I'd like the components, input data rate, and output bandwidth to be the same as in the real system. If I use the GNURadio Constellation Modulator block for this, it imposes a lower limit on samples/second. This results in a different bandwidth for the GNURadio graph, than the real system.

Why does this block impose this restriction? And, is there a canonical (or preferred) way around it, when emulating real systems?

• exactly, if you just want the symbol mapping, use xx_to_chunks; the Constellation modulator does include pulse shaping, and that makes little sense with 1sps – Marcus Müller Jan 17 at 21:15