X-ray pulsar signal denoising based on EMD with adaptive thresholding

X-ray pulsar is an effective tool for navigation in deep space exploration. However, the noise contained in X-ray pulsar signal may severely decrease the accuracy of navigation system. This paper presents a signal denoising method based Empirical Mode Decomposition (EMD) method with thresholding method. For thresholding method, we propose a new adaptive thresholding method which can overcome the shortcomings of fixed thresholding method. In this method, the X-ray pulsar signal is decomposed into several Intrinsic Mode Functions (IMFs). By analyzing the decomposition procedure, these IMFs are divided to three parts: the noisy part, the useful structure, the IMFs which contain noise and useful structure simultaneously. Then, an adaptive threshold is set to remove the noise from the third part mentioned above. Finally, the signal is reconstructed. In order to demonstrate the validity of the proposed method, this improved method is compared with the conventional EMD based method. Simulation results show the proposed method can achieve better performance than the conventional EMD based denoising method.