File:Comparison of periodogram and Welch methods of spectral density estimation.png

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Summary

Description
English: The power spectral density of a segment of music is estimated by two different methods, for comparison.
Category:Accuracy disputes
Date
Source Own work
Author Bob K
Permission
(Reusing this file)
I, the copyright holder of this work, hereby publish it under the following license:
Creative Commons CC-Zero This file is made available under the Creative Commons CC0 1.0 Universal Public Domain Dedication.
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Category:CC-Zero#Comparison%20of%20periodogram%20and%20Welch%20methods%20of%20spectral%20density%20estimation.png
Category:Self-published work
PNG development
InfoField
Octave/gnuplot source
InfoField
click to expand

This graphic was created with the help of the following Octave script:

graphics_toolkit gnuplot
pkg load signal

load 'music.mat'    % adds variables wavedata and samplerate to the workspace
whos                % displays the workspace
%{music.mat was created by these steps in program Audacity:
  • Open a stereo mp3 file.
  • Right-click on the filename, and choose Split Stereo to Mono in the drop-down menu.
  • Delete one channel.
  • Highlight a section to be exported.
  • Choose Export Selected Audio.
  • Choose Save As Type:  Other Uncompressed Files.
  • Under Options, set Header=MAT5 and Encoding=Signed 16-bit PCM
%}
periodogram (wavedata, [], 512, samplerate, 'twosided')
grid on
xlim([0 samplerate])
title("Periodogram",'FontSize', 14)
xlabel('Frequency (Hz)','FontSize', 14)
ylabel('Amplitude (dB)','FontSize', 14)

figure
pwelch(wavedata, hann(512), 0.25, 512, samplerate, 'twosided', 'dB')
grid on
xlim([0 samplerate])
ylim([-60 60])
title("Welch's method",'FontSize', 14)
xlabel('Frequency (Hz)','FontSize', 14)
ylabel('Amplitude (dB)','FontSize', 14)
Category:Created with GNU Octave Category:Digital signal processing Category:Images with Gnuplot source code Category:Images with Octave source code Category:Spectral power distribution
Category:Accuracy disputes Category:CC-Zero Category:Created with GNU Octave Category:Digital signal processing Category:Graph images that should use vector graphics Category:Images with Gnuplot source code Category:Images with Octave source code Category:PNG created with LibreOffice Category:PNG that should use vector graphics Category:Pages using deprecated source tags Category:Self-published work Category:Spectral power distribution