An imaging device outputs imaging data captured with a predetermined exposure time, and a brightness determination unit determines whether the brightness of the imaging data is within a predetermined range. The apparatus adaptively estimating a position error contained in position information of a rotor of a motor, which is digitalized by a resolver-digital converter, and subtracting the estimated position error from the measured position information of the rotor, thereby calculating compensated position information. A plurality of binary multi-frequency signals are generated based on these input parameters and the frequency spectra of these BMF signals are calculated.