Patent ID: 7397753

Claim:
A method for measuring a signal deviation, applied to an optical recording/reproducing apparatus, the optical recording/reproducing apparatus comprising an optical pickup head for receiving a Differential Push Pull (DPP) signal reflected from an optical recording medium to trace tracks on a surface of the optical recording medium, the DPP signal comprising a Main beam Push Pull (MPP) signal and a Sub-beam Push Pull (SPP) signal, the method comprising the following steps: receiving the MPP signal and the SPP signal; according to the MPP signal and the SPP signal, generating a MPP waveform and a SPP waveform, respectively, by a data acquisition card; combining the MPP waveform and the SPP waveform to generate an amplitude waveform function A(t); and according to the amplitude waveform function, estimating a phase difference between the MPP signal and the SPP signal.