1.1 General Introduction of Use via Field Line Resonances

Since this is the first example of use, the very basics of the handling of the IMF - Toolbox are described here also.

Before starting the IMF - Toolbox for the first time, please read the instructions in the file Readme.html.

To start the graphical user interface, type ‘IMF_tool’ in the MATLAB Command Window (see Figure 1.1). A window containing the main settings will then appear (see Figure 1.2).

·   Work - Path: Path where the ws*.MAT-files are stored

·   Maximum size for splitting a flat file in bytes: If a flat file bigger than this specified value is read, it will be stored in more than one ws*.MAT-files. This value should be chosen according to the main memory of the computer.

·   Your name: The IMF - Toolbox stores this name together with the data in the ws*.MAT - files. This name is displayed in the Log - Window which is on the right side or below every subplot. If users exchange ws*.MAT - files, the original name of the person who created the ws*.MAT - file is displayed.

The initial values of those three variables described above can be permanently stored if they are written in the file IMF_ini.M.

By clicking the OK-button, the main window of the IMF - Toolbox appears (see Figure 1.3). It displays the current main settings and a picture of the Data Management System. Choose IMF_read_flat from the Data Management - menu to read a flat file (see Figure 1.4). Select a flat file as shown in Figure 1.5. After the flat file is read, the data are stored in a new ws*.MAT-file. This ws*.MAT-file is loaded automatically into the main memory if the option ‘Automatically load last created ws*.MAT-file’ (menu item in: Options, General Options) is turned on. If this option is turned off, the command IMF_load_wsp from the Data Management - menu must be performed additionally.

Figure 1.1: MATLAB Command Window

Figure 1.2: Main Settings Dialogue

Figure 1.3: Main Window

Figure 1.4: Data Management Menu

Figure 1.5: Selection of a Flat file

After a flat file is loaded, the ‘Select Data Series’-window appears (see Figure 1.6). The window shows the data series of two flat files. For this example a second flat file was read in, which is not shown here because the same procedure is used for every file. In the ‘Select Data Series’-window the two horizontal components are chosen using the mouse and CRTL-key. After pressing the ‘Plot and Analyze’-button, the ‘Select Plot’-window (see Figure 1.7) appears where the settings for generating plots can be defined. We select the two data series and press the ‘>> Plot 1’-button. The data IDs appear in the highest input line. Algorithms and methods can be applied to this data series by choosing from the ‘Select Calculations’-listbox and pressing the proper ‘>>’-button. After pressing ‘Select Plot’ the ‘Draw Selected Plot’-window appears, showing the two horizontal components (see Figure 1.8).

Figure 1.9 shows the AC-filtered (high pass with a cut-off-frequency of 0.002 Hz) signals which were generated by selecting ‘Filter: AC’ from the ‘Select Calculations’-listbox and by pressing the ‘>>’-key and ‘Select Plot’.

The Dynamic Cross Power Spectrum can be calculated with the selections shown in Figure 1.10. Figure 1.11 shows the Dynamic Cross Power Spectrum in the unmodified state. To do modifications click with the right mouse button at the spectrum and a context menu appears (see Figure 1.11). A dialogue window containing all the settings for the Dynamic Cross Power Spectrum appears (see Figure 1.12). Figure 1.13 shows the plot with the selections shown in Figure 1.12.

Figure 1.6: ‘Select Data Series’-window

Figure 1.7: ‘Select Plot’-window

Figure 1.8: ‘Draw Selected Plot’-window

Figure 1.9: AC-filtered Signals

Figure 1.10: ‘Select Plot’-window

Figure 1.11: Dynamic Cross Power Spectrum in the unmodified state

Figure 1.12: Settings-dialogue for the Dynamic Cross Power Spectrum

Figure 1.13: Dynamic Cross Power Spectrum with the proper settings

Figure 1.14 additionally shows the settings for plotting the Dynamic Cross Phase Spectrum.

Remark:

The ‘Keep Display - Settings for Plot 1’-checkbox is selected. This stores the settings that were created earlier for the first subplot. If this checkbox is not selected the standard settings are chosen again. If the user forgets to set this checkbox, the previous state can always be reached again by choosing History and Back in the ‘Draw Selected Plot’-window.

After pressing ‘Selected Plot’ the Dynamic Cross Power Spectrum and the Dynamic Cross Phase Spectrum are displayed (see Figure 1.15). After using the right mouse button and the settings shown in Figure 1.16, the Dynamic Cross Phase Spectrum is displayed in Figure 1.17.

It is also possible to hide the regions having low coherence because the values for the Dynamic Cross Power Spectrum and the Dynamic Cross Phase Spectrum in such regions contain random values. Figure 1.18 shows how to hide the low coherence regions. Additionally, a linear scale for the frequency axis is chosen and the frequency range is set from 0 Hz to 0.06 Hz. The ‘Apply to All’-checkboxes apply the settings to all subplots. The result after pressing ‘Selected Plot’ is shown in Figure 1.19.

Figure 1.14: ‘Select Plot’-window

Figure 1.15: Dynamic Cross Power Spectrum and Dynamic Cross Phase Spectrum in the unmodified state

Figure 1.16: Settings-dialogue for the Dynamic Cross Phase Spectrum

Figure 1.17: Dynamic Cross Power Spectrum and Dynamic Cross Phase Spectrum with the proper settings

Figure 1.18: Settings dialogue for the Dynamic Cross Phase Spectrum

Figure 1.19: Dynamic Cross Power Spectrum and Dynamic Cross Phase Spectrum with hidden low coherence areas

Figure 1.20 shows the settings for additional Cross Power and Cross Phase spectra which are displayed using lines instead of dynamic spectra. This method allows a more accurate estimation of the resonant frequency in most cases.

The ‘Enable Plot’-checkboxes for subplot 1 and subplot 2 are disabled, so just the Cross Power and the Cross Phase spectra are displayed in Figure 1.21. By clicking with the right mouse button on the background of one of the two subplots the settings dialogue appears as shown in Figure 1.22. After choosing a linear frequency scale, a frequency range from 0.01 Hz to 0.06 Hz and a longer window for both subplots (‘Apply to all’-checkboxes), the spectra are displayed in Figure 1.23.

Figure 1.20: ‘Select Plot’-window

Figure 1.21: Cross Power Spectrum and Cross Phase Spectrum displayed using lines

Figure 1.22: Settings-dialogue for Cross Power Spectrum and Cross Phase Spectrum

Figure 1.23: Cross Power Spectrum and Cross Phase Spectrum with the proper settings

Remark:

All selections that were made can be reset in the ‘Select Plot’-window using ‘Reset’ and one of the following:

·   Display: Resets the selections that were made in the ‘Select Plot’-window.

·   History: This deletes the plot history.

·   Selections: Resets the current time selections. This is useful if, for example, the selection of the time range was made smaller several times, and the full time range must be displayed again.

·   Display, History and Selections: Resets all three items that are described above.

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