Data processor for a position measuring device comprising a magnetic dimensional scale consisting of consecutive poles with alternating polarity and a magnetic field sensor generating trace signals with period cycles when passing the poles , wherein the data processor is configured to - retrieve measurement data representing at least two period cycles of first and second trace signals from the magnetic field sensor , wherein the sensor moves at a pole frequency relative to the poles , - calculate, using the measurement data for each of the minimum two period cycles , at least one phase angle ( φ ) of the first and second trace signals and at least one characteristic parameter ( r ) that characterizes the behavior of these trace signals 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 , - determine a correction signal ( K ) from at least one period comparison value ( u ), wherein the correction signal ( K ) is a periodic function ( F ) or a superposition of periodic functions ( F ), 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 (I) using the measurement data , and - calculate a corrected position signal ( P ) from the uncorrected position signal ( U ) and the correction signal ( K ). - retrieve measurement data representing at least two period cycles of first and second trace signals from the magnetic field sensor , wherein the sensor moves at a pole frequency relative to the poles , - calculate, using the measurement data for each of the minimum two period cycles , at least one phase angle ( φ ) of the first and second trace signals and at least one characteristic parameter ( r ) that characterizes the behavior of these trace signals 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 , - determine a correction signal ( K ) from at least one period comparison value ( u ), wherein the correction signal ( K ) is a periodic function ( F ) or a superposition of periodic functions ( F ), 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 (I) using the measurement data , and - calculate a corrected position signal ( P ) from the uncorrected position signal ( U ) and the correction signal ( K ). <EOS>