Empirical Wavelet Transform Method for GNSS Coordinate Series Denoising

Random noise inevitability affects positioning accuracy for Global Navigation Satellite System (GNSS) measurements. For effectual elimination of the noise mixed in the coordinate series, this paper proposes applying the empirical wavelet transform (EWT) method, which has the multi-scale decomposition capability identical to the empirical mode decomposition (EMD) method. EWT adaptively constructs the wavelet basis functions, divides the different signal modes by designing appropriate wavelet filters, and provides a complete mathematical theory. Compared to EMD, EWT exhibits higher calculation efficiency, sufficient theory, and an excellent adaptation capability. Thus, this paper analyzes and compares EWT with EMD and its improved version. The experimental results demonstrate that the EWT method has no frequency liaising phenomenon that characterizes EMD, and the signal after EWT noise reduction is quite close to the original. The measured data reveals that the noise reduction effect of EWT is superior to EMD and its improved version.