The assembly includes a first sub-assembly with, on a transmitter side, a modem having a plurality of inputs, an output for a total data stream, and signal paths connected in parallel. Each signal path includes a modulation stage, a stage for sampling modulated signals and a mixer stage Outputs of mixer stages are connected to inputs of a summation stage, and output of the summation stage is connected to output of the modem. A second sub-assembly has an input for initialization data connected to an assembly for controlling a test operation. The sub-assembly is connected to a downstream carrier management assembly having a plurality of outputs. Each output is connected to a test sequence generating unit. Outputs of all test sequence generating units are connected to a parallel/serial converter assembly connected downstream of a filter assembly. Output of the filter assembly is connected to output of the second sub-assembly.