| 摘要 |
A detection apparatus detecting an error component contained in two signals (A, B) approximated by a cosine and sine functions representing an object position, the detection apparatus including an arithmetic portion (3, 4) which reduces an error contained in the signals (A, B) based on an error prediction value to output two error correction signals (A*, B*), a phase arithmetic portion (5) which calculates a phase (theta) based on the error correction signals (A*, B*), an arithmetic storage unit (9, 10) which stores the error correction signals (A*, B*) and a plurality of sampling values of the phase (theta), and a Fourier transform portion (11, 12) which obtains coefficients alphak, betak, gammak, and deltak in the following two expressions: A*=alpha0+alpha1 cos theta+beta1 sin theta+ . . . +alphak cos ktheta+betak sin ktheta B*=gamma0+gamma1 cos theta+delta1 sin theta+ . . . +gammak cos ktheta+deltak sin ktheta (k>=2) wherein the arithmetic portion (3, 4) updates the error prediction value using the coefficients.
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