LAUSR

The earth’s natural pulse electromagnetic field (ENPEMF) signal, which is released by the instantaneous disturbance of the earth’s natural changing magnetic field, contains a large amount of information about the changing geological structures and their kinetic principles. The analysis based on the time-frequency (TF) representation can provide significant interpretations for the ENPEMF signal. Wigner–Ville distribution (WVD) is one of the typical TF representations and has a high degree of TF concentration but is accompanied by severe cross-term interference. Hence, we propose a new TF representation called matching pursuit-based double WVD (MP-DWVD) to suppress cross-term interference, and synthetic signals are used to demonstrate the high TF concentration of the proposed TF analysis method. Furthermore, we apply MP-DWVD to explore the TF characteristics of the ENPEMF signal collected during the Lushan Ms7.0 earthquake. The results show that MP-DWVD can reveal accurate TF distributions of the ENPEMF signal before and after the earthquake and extract anomaly TF components, which have the potential to reveal electromagnetic anomaly information contained in the ENPEMF signal.