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Issues with Time-frequency spectral analysis

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Viewing 7 posts - 1 through 7 (of 7 total)
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  • May 11, 2011 at 9:51 pm #12721
    Rien PolakRien Polak
    Member

    I`m using a time-frequency spectral analysis (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 time-frequency spectral analysis 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,

    May 11, 2011 at 9:51 pm #8384
    Rien PolakRien Polak
    Member

    I`m using a time-frequency spectral analysis (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 time-frequency spectral analysis 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,

    May 16, 2011 at 3:06 pm #9174
    Bernhard KantzBernhard Kantz
    Participant

    Select the analysis object, click the right mouse button and choose the command Open 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

    May 16, 2011 at 11:22 pm #9176
    Rien PolakRien Polak
    Member

    The message states:
    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.

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

    May 16, 2011 at 11:55 pm #9175
    Rien PolakRien Polak
    Member

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

    May 20, 2011 at 1:40 pm #9177
    Bernhard KantzBernhard Kantz
    Participant

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

    support@weisang.com

    May 20, 2011 at 2:13 pm #9178
    Rien PolakRien Polak
    Member

    Everything is working now. Thank you.

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