Data processor for a position measuring device comprising a magnetic dimensional scale consisting of consecutive poles (10, 10a, 10b) with alternating polarity (12a, 12b) and a magnetic field sensor generating trace signals (16a, 16b) with period cycles (18, 18a, 18b) when passing the poles (10, 10a, 10b), wherein the data processor is configured to - retrieve measurement data representing at least two period cycles (18a, 18b) of first and second trace signals (16a, 16b) from the magnetic field sensor, wherein the sensor moves at a pole frequency relative to the poles (10, 10a, 10b), - calculate, using the measurement data for each of the minimum two period cycles (18a, 18b), at least one phase angle ( φ) of the first and second trace signals (16a, 16b) and at least one characteristic parameter ( r) that characterizes the behavior of these trace signals (16a, 16b) at this phase angle ( φ), - identify, by comparing a section of the calculated characteristic parameters ( r), at least one period comparison value ( u) that represents a cross-period difference in the behavior of the first and second trace signals (16a, 16b), - determine a correction signal from at least one period comparison value ( u), wherein the correction signal is a periodic function or a superposition of periodic functions, each with an amplitude factor (a), a frequency factor ( f), and a phase shift constant ( p), wherein the amplitude factor ( a) and the phase shift constant ( p) are dependent on at least one period comparison value ( u), while the frequency factor ( f) remains constant and independent of at least one period comparison value ( u), - calculate an uncorrected position signal using the measurement data, and - calculate a corrected position signal from the uncorrected position signal and the correction signal. - retrieve measurement data representing at least two period cycles (18a, 18b) of first and second trace signals (16a, 16b) from the magnetic field sensor, wherein the sensor moves at a pole frequency relative to the poles (10, 10a, 10b), - calculate, using the measurement data for each of the minimum two period cycles (18a, 18b), at least one phase angle ( φ) of the first and second trace signals (16a, 16b) and at least one characteristic parameter ( r) that characterizes the behavior of these trace signals (16a, 16b) at this phase angle ( φ), - identify, by comparing a section of the calculated characteristic parameters ( r), at least one period comparison value ( u) that represents a cross-period difference in the behavior of the first and second trace signals (16a, 16b), - determine a correction signal from at least one period comparison value ( u), wherein the correction signal is a periodic function or a superposition of periodic functions, each with an amplitude factor (a), a frequency factor ( f), and a phase shift constant ( p), wherein the amplitude factor ( a) and the phase shift constant ( p) are dependent on at least one period comparison value ( u), while the frequency factor ( f) remains constant and independent of at least one period comparison value ( u), - calculate an uncorrected position signal using the measurement data, and - calculate a corrected position signal from the uncorrected position signal and the correction signal.