microwave card 13 of the inlet sensor and the microwave card 13 u2032 of the outlet sensor 4 communicate with each other and can thus exchange results and possibly use them for their own evaluation this also applies to the processor card 14 of the inlet sensor 3 and the processor card 14 u2032 of the outlet sensor 4 these too communicate with each other and can if necessary use the quality data of the delivered fiber sliver 2 u2032 for the control signals with such an interconnection of the processor cards 14 14 u2032 it is also possible if necessary to make better use of their computing capacity with this type of construction a rapid exchange of data and in addition an economic structure can be achieved in most cases it suffices to provide a common power supply and data interface 15 u2033 fig4 shows another combination in form of the processing unit 12 u2032 u2033 with a correspondingly high capacity technology it suffices to use merely one microwave card 13 u2033 and one processor card 14 u2033 for the inlet sensor 3 and the outlet sensor 4 the corresponding signals of the sensors 3 and 4 can be processed in one single microwave card 13 u2033 and can be transmitted to the processor card 14 u2033 the processor card 14 u2033 can process simultaneously the signals of the microwave card 13 u2033 and convert then on the one hand into sliver thickness signals and then into control signals and on the other hand into quality monitoring signals therefore also into sliver thickness signals the evaluation of the signals of the inlet and outlet sensor 3 4 can be effected in this manner especially rapidly such a solution requires.