Normalized spectrogram of a seismic acceleration
Normalized spectrogram to seismic acceleration written in Matlab. The algorithm used is the following:
1. Baseline correction 2. Tuckey window is applied with r=5%. 3. FFT on window signal. 4. Spectrum is smoothed by 5 points halfwidth moving average. 5. Each element of spectrum is normalized by maximum spectral amplitude.
The normalized spectrogram function is defined by:
[matrix, matrix_t, matrix_f] = norm_spectrogram(t, acc)
|t||Time of the seismic accelerogram|
|acc||Acceleration (g) of the seismic accelerogram|
This function returns a matrix in where columns refer to mean window time (matrix_t), rows are the frequency of the spectrogram (matrix_f) and the value of the matrix are the amplitude of the spectrogram from each time-window on each frequency.
To print matrix you should use:
plot_norm_matrix(m, mt, mf, t, acc, regname)
|mt||Time array from matrix|
|mf||Frequency array from matrix|
|t||Time of the seismic data|
|acc||Acceleration of seismic data|
|regname||Name of the seismic data (plot title)|
Lets suppose that a seismic registry is stored on data/CNV_APED_201604162359_N_100.txt, the file structure is like:
0.000000 -6.329500 0.010000 2.539600 0.020000 12.822900 0.030000 9.435300 0.040000 -5.397100 0.050000 -14.233900 ...
% Load the data data = load('data/CNV_APED_201604162359_N_100.txt'); % Set time and acceleration array t = data(:, 1); acc = data(:, 2) ./ 980; % Convert from cm/s2 to g
After that we will use
[m, mt, mf] = norm_spectrogram(t, acc);
plot_norm_matrix(m, mt, mf, t, acc, 'APED 2016/04/16 23:59 N-S');
This project is licensed under GPLv2 [https://www.gnu.org/licenses/gpl-2.0.html]
Pablo Pizarro R. | 2017 - 2019
Pablo P (2023). normalized-spectrogram (https://github.com/ppizarror/normalized-spectrogram/releases/tag/1.2), GitHub. Retrieved .
MATLAB Release Compatibility
Platform CompatibilityWindows macOS Linux
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!Start Hunting!
See release notes for this release on GitHub: https://github.com/ppizarror/normalized-spectrogram/releases/tag/1.1
See release notes for this release on GitHub: https://github.com/ppizarror/normalized-spectrogram/releases/tag/1.0