Patent ID: 7457713

Claim:
A determination method for correcting errors in a position signal, comprising: scanning a measuring scale having a plurality of equally-spaced scale divisions by at least two sensors which are moveable relative to the measuring scale; supplying measuring signals based upon the scanning, wherein the measuring signals: are periodic for a uniform relative movement of the measuring scale, have essentially the same amplitude, are essentially sinusoidal, have a phase offset relative to one another which is essentially 90°, and have a basic frequency which corresponds with the relative movement of the measuring scale, and during the course of one period of the measuring signals, the measuring scale executes a relative movement of one scale division; determining corrected signals from the measuring signals based upon correction values; determining a position signal of the measuring scale relative to the sensors based upon the corrected signals; determining Fourier coefficients for a supplementary signal based upon the basic frequency, wherein the supplementary signal is equal to a sum of squares of the corrected signals or a value derived from this sum; and adjusting the correction values based upon the Fourier coefficients; wherein the correction values are based upon a value selected from the group consisting of: at least two offset correction values, at least one amplitude correction value, at least one phase correction value for the measuring signals and combinations thereof, together with at least one correction value for at least one higher-frequency wave in the measuring signals.