File:STFT colored spectrogram 25ms.png
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STFT_colored_spectrogram_25ms.png (560 × 420 pixels, file size: 9 KB, MIME type: image/png)
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[edit]DescriptionSTFT colored spectrogram 25ms.png |
This picture is one of the four spectrograms I have created of the following signal: sampled at 400 Hz. I have created this picture and all the other three spectrograms with the following Matlab code, that is based on my stft script that you can find at User:Alejo2083/Stft script: clear all;
%sampling frequency
fc=400;
%duration of the signal
T=20;
%zero padding factor
my_zero=10;
%generate the signal
t=linspace(0,T,fc*T);
x=zeros(1,length(t));
%thresholds
th1=0.25*T*fc;
th2=0.5*T*fc;
th3=0.75*T*fc;
th4=T*fc;
x(1:th1)=cos(2*pi*10*t(1:th1));
x((th1+1):th2)=cos(2*pi*25*t((th1+1):th2));
x((th2+1):th3)=cos(2*pi*50*t((th2+1):th3));
x((th3+1):th4)=cos(2*pi*100*t((th3+1):th4));
%calculate and show the spectrograms
[spectrogram, axisf, axist]=stft(x,10,1,fc,'blackman',my_zero);
spectrogram=spectrogram/max(spectrogram(:));
figure,imagesc(axist,axisf,spectrogram),
title('Spectrogram with T = 25 ms'),
ylabel('frequency [Hz]'),
xlabel('time [s]'),
colorbar;
[spectrogram, axisf, axist]=stft(x,50,1,fc,'blackman',my_zero);
spectrogram=spectrogram/max(spectrogram(:));
figure,imagesc(axist,axisf,spectrogram),
title('Spectrogram with T = 125 ms'),
ylabel('frequency [Hz]'),
xlabel('time [s]'),
colorbar;
[spectrogram, axisf, axist]=stft(x,150,1,fc,'blackman',my_zero);
spectrogram=spectrogram/max(spectrogram(:));
figure,imagesc(axist,axisf,spectrogram),
title('Spectrogram with T = 375 ms'),
ylabel('frequency [Hz]'),
xlabel('time [s]'),
colorbar;
[spectrogram, axisf, axist]=stft(x,400,1,fc,'blackman',my_zero);
spectrogram=spectrogram/max(spectrogram(:));
figure,imagesc(axist,axisf,spectrogram),
title('Spectrogram with T = 1000 ms'),
ylabel('frequency [Hz]'),
xlabel('time [s]'),
colorbar;
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Date | |
Source | Own work |
Author | Alessio Damato |
Other versions | see below |
The four spectrograms | |
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[edit]I, the copyright holder of this work, hereby publish it under the following licenses:
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Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled GNU Free Documentation License.http://www.gnu.org/copyleft/fdl.htmlGFDLGNU Free Documentation Licensetruetrue |
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Date/Time | Thumbnail | Dimensions | User | Comment | |
---|---|---|---|---|---|
current | 08:11, 18 September 2007 | ![]() | 560 × 420 (9 KB) | Alejo2083 (talk | contribs) | {{Information |Description=working... |Source=self-made |Date=September 2007 |Author= ~~~ |other_versions= }} |
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