A system, apparatuses, a method, and a computer program for producing signals for testing radio frequency communication devices are provided. The system comprises a non-real-time domain which includes a data generator for supplying a temporally discontinuous data stream which data stream includes signal waveform data and control data defining characteristics of a conversion from the signal waveform data into a radio frequency test signal. The temporally discontinuous data stream is fed into a transformer which transforms the temporally discontinuous data stream into a temporally continuous data stream, thus providing a transformation between the non-real-time domain and a real-time domain. The real-time domain includes a radio frequency unit which uses the temporally continuous signal data stream as input, and performs the conversion from the signal waveform data into the radio frequency test signal according to the control data.