Normalization and STFT-WVD (short-time Fourier transform and Wigner-Ville distribution) time-frequency analysis method for ENPEMF (earth's natural pulse electromagnetic field) signals

Abstract

The invention provides a normalization and STFT-WVD (short-time Fourier transform and Wigner-Ville distribution) time-frequency analysis method for ENPEMF (earth's natural pulse electromagnetic field) signals. The ENPEMF signals are subjected to STFT and WVD to obtain an STFT array and a WVD array; maximums in the STFT array are normalized to obtain an array STFT_1; the position of 1 and minimums are recorded; numbers 0 valued are replaced with the minimums; numbers, at the same positions, in the WVD array are normalized to obtain a temporary array A; the temporary array A is point-divided by the array STFT_1 to obtain a temporary array B; numbers, greater than x valued positions, in the temporary array B, and those, at the corresponding positions, in the WVD array are all set to 0; the temporary array B and the WVD array are output. The method has the advantages that cross-term interference is better eliminated, high time-frequency resolution of the WVD is carried on, the defect that changes in input signals require re-adjustment of threshold and power adjustment coefficients is overcome, results are ideal, and the method is flexible to use.

Description

technical field [0001] The invention relates to an ENPEMF signal normalized STFT-WVD time-frequency analysis method, which belongs to the field of earthquake electromagnetic precursor research and earthquake prediction. Background technique [0002] Earthquakes have brought huge disasters to human life. According to statistics, among the natural disasters in the world, the death toll caused by earthquakes accounts for 54% of all natural disasters, which is the highest among natural disasters. How to predict earthquakes has always been a hot and sensitive topic. However, due to the three major difficulties in earthquake prediction, the "impenetrability" of the earth's interior, the "infrequent occurrence" of major earthquakes, and the "complexity of the physical process of earthquakes", earthquake prediction has become a recognized worldwide problem. Prediction is of great significance to the safety of human life and social property. [0003] In the existing research proces...

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Problems solved by technology

The method shown in Equation (1) has poor flexibility, and the input signal amplitude or energy directly affects the selection of the c value. At present, no one can propose an effective adaptive threshold selection method, and the useful component amplitude in the actual signal The value and energy are often different or even quite different, so it is easy to eliminate the information item by setting the threshold value to eliminate the cross item; the method shown in formula (2) is slightly improved, but there is no theoretical basis for the determination of the power adjustment coefficient. How to determine the power adjustment coefficient according to the characteristics of the signal to be analyzed needs to be further studied, which will cause inconvenience to use, and at the same time, there will be unavoidable cross-item interference. It is often necessary to further process the obtained signal by filtering and other methods in order to obtain a time that is easy to interpret. Spectrograms and spectrograms

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