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Discrete Fourier Transfom and Inverse Fourier Transform

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Discrete Fourier Analysis for Excel Files 

? Harald Kammerer, GERB Schwingungsisolierungen, Germany 

August 2008 

This application allows to import time history data from an Excel file. The first column of the file has to contain the time, the other columns have to contain the signal data. In this example the Excel files are stored in the directory c:\mapletemp. Please try some other places. Somtime you will get an error message because some input values are not valid at the beginning. If you change it everything should work fine. 


Complete path of the Excel Input Files 


The data must be in columns of the Excel file. The first column contains the time data in constant steps, the column of the corresponding signal values can be selected. 

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Input File 


 Here the file to edit to be selected from the list. 

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Number of Table Headers 


This is the number of the table headers or otherwise not to be considered top lines. 

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Column of the Signal Values 


Here is the column in which the observed signal values are. 

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Number of Time Steps taken into account ≤ Number of Actual Time Steps in the Data File 


The number of lines of the table which are considered may be limited. If the actual number available to be taken into account, you can enter 0, otherwise is a number less than or equal to the maximum indicated on the right to be given. 


 Note: If the time history in the Excel file starts from a complete number of cycles, including initial value and end value the number of time steps which taken into account has to be reduce by 1. 

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Time History 


 The representation of the time history is done automatically by change of the above requirements or when loading a new file by clicking on the button 'Time History'. 



 For the presentation of amplitude spectrum click the button 'Amplitude Spectrum', for the phase spectrum click the button 'Phase Spectrum'. 


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Time History 

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Amplitude SpectrumPhase Spectrum 

Limits for the Plot of the Amplitude Spectrum 


 Here, the frequency range of the representation is selected. Click on 'Amplitude Spectrum' effect again set to the extreme values. 

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Lower Cutoff Frequency 

Upper Cutoff Frequency 

Minimum Amplitude 

Maximum Peaks 

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After using the button 'Amplitude Spectrum' the result can be filtered according the setting of the four rotatory switches. 

Use Filter 

Save Frequency Spectrum into the Excel File 


 The filtered frequency spectrum is saved into the above given Excel file. 


 Note: The Excel file must consist at least three sheets. The amplitude is written to sheet 2, the phase to sheet 3. Existing data will be overwritten! 

Write Spectrum to the Excel File 

Save Filtered Time History into the Excel File 


 The filtered time history is saved into the above given Excel file. 


 Note: The Excel file must consist at least four sheets. The filtered time history is written to sheet 4. Existing data will be overwritten! 

Write Filtered Data to the Excel File 


Legal Notice: The copyright for this application is owned by the author(s). Neither Maplesoft nor the author are responsible for any errors contained within and are not liable for any damages resulting from the use of this material.. This application is intended for non-commercial, non-profit use only. Contact the author for permission if you wish to use this application in for-profit activities.