Feature Extraction of a Non-Stationary Seismic-Acoustic Signal Using a High-Resolution Dyadic Spectrogram

• Published in: Sensors (Basel, Switzerland) Vol. 23; no. 13; p. 6051
• Main Authors: Seuret-Jiménez, Diego, Trutié-Carrero, Eduardo, Nieto-Jalil, José Manuel, García-Aquino, Erick Daniel, Díaz-González, Lorena, Carballo-Sigler, Laura, Quintana-Fuentes, Daily, Gaggero-Sager, Luis Manuel
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 30.06.2023; MDPI
• Subjects: <named-content content-type="inline-formula"> <mml:math id="mm666"> <mml:mi mathvariant="script">T</mml:mi> e </mml:math> </named-content>-gram; <named-content content-type="inline-formula"> <mml:math id="mm667"> <mml:mi mathvariant="script">T</mml:mi> e </mml:math> </named-content> transform; Acoustics; Analysis; Dictionaries; dyadic frequency spectrum; Earthquakes; Energy; Environment; Fourier transforms; Frequencies; Frequency domain analysis; Mexico; Noise; Researchers; scale–frequency; Seismic activity; seismic–acoustic signal; Sensitivity; Stochastic processes; Time-frequency analysis; Mexico; T e -gram; scale–frequency; dyadic frequency spectrum; T e transform; seismic–acoustic signal
• ISSN: 1424-8220; 1424-8220
• DOI: 10.3390/s23136051

Using a novel mathematical tool called the Te-gram, researchers analyzed the energy distribution of frequency components in the scale-frequency plane. Through this analysis, a frequency band of approximately 12 Hz is identified, which can be isolated without distorting its constituent frequencies. This band, along with others, remained inseparable through conventional time-frequency analysis methods. The Te-gram successfully addresses this knowledge gap, providing multi-sensitivity in the frequency domain and effectively attenuating cross-term energy. The Daubechies 45 wavelet function was employed due to its exceptional 150 dB attenuation in the rejection band. The validation process encompassed three stages: pre-, during-, and post-seismic activity. The utilized signal corresponds to the 19 September 2017 earthquake, occurring between the states of Morelos and Puebla, Mexico. The results showcased the impressive ability of the Te-gram to surpass expectations in terms of sensitivity and energy distribution within the frequency domain. The Te-gram outperformed the procedures documented in the existing literature. On the other hand, the results show a frequency band between 0.7 Hz and 1.75 Hz, which is named the planet Earth noise.