How can I change the time axis unit in a spectrogram from minutes to seconds?

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Deborah Müller
Deborah Müller on 4 Aug 2017
Using spectrogram everything works fine, but the x-axis is displayed in minutes. Is there a way to change this generally? I changed the x-tick labels but this is very uncomfortable.

Answers (2)

Adam
Adam on 4 Aug 2017
Edited: Adam on 4 Aug 2017
How are you creating the spectogram? Its axes will be whatever come from your input data, by default, but if you just create the spectogram outputs and plot them yourself you can set them to whatever you want.
Or if you let spectogram do the plot for you make sure you keep its handle:
h = spectogram(...)
then you can set
h.XData = ...
to be whatever you want.
  2 Comments
Adam
Adam on 4 Aug 2017
Ah yes, I was giving that off the top of my head. The single output argument syntax for spectrogram just returns the STFT matrix.
Generally I always plot it myself from the outputs of spectrogram, then I have control over what is actually being plotted and can interpret the result more sensibly.
e.g.
[S, F, T, P] = spectrogram( ... );
figure; imagesc( hAxes, F1, T1, P1 );
The frequency and time axes can be altered as you wish though, e.g.
figure; imagesc( hAxes, F1, T1 * 60, P1 );
Alternatively you can query the 'Children' property of the axes onto which the spectrogram plotted and retrieve the image and then change the XData that way.

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