Apparatus for reducing an interference portion in a time-discrete signal further including a useful portion, including a first provider for providing the time-discrete signal including the interference portion and the useful portion a second provider for providing a first time-discrete reference signal including a first interference portion, and a second time-discrete reference signal including a second interference portion, the second interference portion being shifted in phase relative to the first interference portion. The apparatus further includes a subtractor for generating a differential signal from the two reference signals, the differential signal including a frequency component caused by the first and second interference portions and a manipulator for manipulating the time-discrete signal on the basis of the differential signal such that in a manipulated time-discrete signal the frequency component is reduced.
