Rotation and Precession Periods Estimation of Unstable Satellite via Variational Mode Decomposition

Attitude motion periods of the unstable satellites are important parameters for space target surveillance. Traditional period estimation methods can only be used for single period. Aiming at rotation and precession of unstable satellite, a double-period estimation method based on variational mode decomposition (VMD) and mutual information is proposed. First, the radar cross section (RCS) of unstable satellite is processed by VMD to obtain intrinsic mode functions (IMFs) and corresponding center-frequencies. Then, through calculating and comparing the mutual information of IMFs and RCS sequence, the rotation period and precession period of satellite are obtained. The experimental results indicate that both rotation period and precession period can be estimated correctly. Compared with spectrum analysis, autocorrelation function and empirical mode decomposition (EMD), the phenomenon of frequency multiplication and mode mixing can be restrained effectively, and the accuracy of period estimation is improved.