Implementation of a useful signal into a square wave

The invention relates to a method for converting a useful signal (SN) oscillating around a predetermined signal level (U0) into a rectangular signal (SR), whereby the useful signal (SN) is compared with a reference signal (UR) in a first comparator (4). The invention is characterised in that each level conversion of the rectangular signal (SR) takes place the first time the useful signal (SN) passes positively or negatively through the signal level (U0). A circuit arrangement for converting a useful signal (SN) oscillating around a signal level (U0) into a rectangular signal (SR) has a first comparator (4), said first comparator having a plus-input (1) to which the useful signal (SN) can be connected and a minus-input (2) which is connected to the output (6) of a reference signal source (5), where a reference signal (UR) is emitted. The first comparator (4) has an output (3) where the rectangular signal (SR) is emitted. The reference signal source (5) can be switched over, with the result that the reference signal (UR) can be adjusted to the signal level (U0) and to at least two levels (U0+UH', U0-UH') which are different from the signal level (U0).