Issues with Time-frequency spectral analysis

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11.05.2011 à 21:51 #34315

Rien Polak
Participant

I`m using a [i]time-frequency spectral analysis [/i] (in Flexpro 9)on .txt files containing 20 columns (first 2 being date and time) of data. On several of these files the analysis works fine. However when I try to use the [i]time-frequency spectral analysis [/i]on several other files, the analysis object remains empty.

As far as I can discover all the source files are identical the way they contain the data and are all created by the same programme. Does anyone know of an issue with the sourcedata that could cause the analysis not to work?

Regards,

11.05.2011 à 21:51 #34321

Rien Polak
Participant

I`m using a [i]time-frequency spectral analysis [/i] (in Flexpro 9)on .txt files containing 20 columns (first 2 being date and time) of data. On several of these files the analysis works fine. However when I try to use the [i]time-frequency spectral analysis [/i]on several other files, the analysis object remains empty.

As far as I can discover all the source files are identical the way they contain the data and are all created by the same programme. Does anyone know of an issue with the sourcedata that could cause the analysis not to work?

Regards,

16.05.2011 à 15:06 #34316

Bernhard Kantz
Participant

Select the analysis object, click the right mouse button and choose the command [b]Open[/b] in the context menu. Run the FPScript formula (Ctrl+F5) and check the result / error message. Perhaps the input values are not equidistant.

support@weisang.com

16.05.2011 à 23:22 #34318

Rien Polak
Participant

The message states:
[i]The first argument of the function STFTSpectrum() does not meet the monotony requierements. The values of the x-component of signal must be equidistant with positive spacing.[/i]

However the x-component (time) is added manually in the project database. Or is this referring to the time component in the data signal?

16.05.2011 à 23:55 #34317

Rien Polak
Participant

Also on some datasets sometimes it will work sometimes it won`t. I`m not doing anything different at those times.

20.05.2011 à 13:40 #34319

Bernhard Kantz
Participant

At first you have to resample your x-values using the [b]Signal Sampling analyis object[/b] or the [b]Sample[/b] FPScript function. With equidistant x-values the STFT should work.

support@weisang.com

20.05.2011 à 14:13 #34320

Rien Polak
Participant

Everything is working now. Thank you.
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