Based on the theory of cyclostationarity and two orders cyclic statistic for the spectrum correlation (SC) or spectrum correlation density (SCD)

a time-frequency analysis method

namely improved spectrum correlation (ISC)

was proposed and used in fault feature extraction of rolling bearing compound fault. Results show that the proposed method can extract the modulated frequency only and has more intuitive advantage than the traditional envelope demodulation spectrum method because the latter extracts the modulated frequency and carrier frequency simultaneously. The feasibility and effectiveness of proposed method are verified through simulation and experiment.