Noise analysis method for frequency transfer systems by using ADEV combined with EMD-WT

In precision frequency transfer systems, stringent requirements are imposed on the phase stability of transmitted signals. Throughout the transmission process, the inherent challenges of long-haul signal propagation inevitably introduce multiple noise components, including, but not limited to, thermal noise, phase fluctuations, and environmental interference. The system is inclined to use the conventional evaluation index - Allan deviation (ADEV) to reflect the system stability in order to evaluate the noise level. Whereas, ADEV can only provide numerical expression and lacks the time-frequency details, a complete evaluation system is therefore required by the system. In this paper, we present a groundbreaking integration of ADEV and wavelet-transformed empirical mode decomposition (EMD-WT), establishing a novel analytical framework that enables simultaneous characterization of noise types and time-frequency domain properties. This synergistic approach achieves unprecedented dual-domain resolution in noise discrimination in frequency transfer systems.