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Selection

The Tab named Selection is divided into four sections: "Window general data"; "Automatic selection"; "Manual selection"; "Filter".

In this Tab the windows that are used in the analysis process are identified, starting from the traces imported in the previous phase. The charts section within the application window takes on two configurations that are explained further on in this page of the manual.

Window general data

Window size

In this box the time size of the windows into which the recording traces are divided is entered, according to the procedure reported in the section that describes the analysis process in this guide. According to the indications of the SESAME project, its value must be at least equal to 20 seconds.

Overlap

In this box the percentage value of the overlap allowed between the time windows into which the recording traces are divided is entered, according to the procedure reported in the section that describes the analysis process in this guide.

Automatic selection

The selection of the windows can be carried out automatically by Easy HVSR through the indications contained in this section.

In practice, two values are set: one for the initial instant and the other for the final instant. These two values identify an interval within the duration of the entire recording. This interval is then automatically divided into windows consistent with the settings present in the previous section.

The two fields in this section are therefore useful to set the values of the initial and final instant of that interval, expressed in seconds. The button placed right next to the field relating to the final instant serves exclusively to set the value of the final instant equal to the duration of the entire recording, which represents the maximum value that can be entered in this field.

Once the two values are set, the button named Select starts the automatic selection procedure.

When the procedure is completed, the identified windows are reported in the table of the following section for further considerations.

Manual selection

In this section there are the tools useful to manually identify the windows to be included in the analysis. The table collects the information regarding the single identified window, that is, it indicates the time order of the window, its initial instant and its final instant.

When a row of this table is selected, the related window is highlighted in the charts present in the right-hand part of the application window. The buttons just above the table have the following usefulness:

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On the chart

By clicking on the button named On the chart, the procedure for inserting a window into the list of those possibly already identified is started. After clicking on this button, you move onto one of the three trace charts. By clicking and holding the click on one of these charts, a window appears, of a size consistent with the indications in the window general data section, whose initial instant moves together with the position of the mouse pointer. In this way it is possible to position the window at a precise point of the trace chart (you can notice that regardless of the chart in which you clicked, the window that moves with the mouse appears in the charts of all three traces). When the mouse button is released the window is positioned, and consistently with the previously entered data it is possible to receive a message from the application asking for confirmation of the insertion in case a previously imposed condition is violated (for example an overlap greater than the one chosen in the window general data section). As soon as the window is inserted, it is also inserted into the table and can therefore be inspected and selected.

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Add

By clicking on the button named Add, a dialog window is opened in which you are asked to enter the value of the initial instant of the window to be added. Once this information is entered, by clicking on the button named Insert of this dialog window, or by pressing the "Enter" key on the keyboard, the new window is inserted consistently with the data entered in the section regarding the window general data. If some previously imposed condition is not respected, a dialog window appears asking for confirmation of the insertion of the window.

As soon as the window is inserted into the list of identified windows, it is shown on the trace chart and inserted into the table to be inspected and selected.

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Remove

By clicking on the button named Remove, it is possible to remove the window currently selected within the table below from the list of identified windows.

Filter

In this section there are the fields for entering the parameters useful to the window selection technique for excluding those in which there are transients that disturbed the recording. The specifications of the technique are reported in the section of the techniques used by Easy HVSR in this guide. The fields in this section are:

Control window size

In this field the value of the time size of the windows into which the windows identified with the techniques of the previous sections are further subdivided is entered

Upper and lower admissibility limit

In these two fields the dimensionless values that identify the validity interval of the filtering technique are set.

Consider residual windows

If activated, this option allows you to also consider, in the window filtering, those that have sizes smaller than the ones set. For further details see the relevant section of the Easy HVSR techniques in this guide.

The filtering procedure is started by pressing the button named Filter.

General buttons

The button named Remove selection allows you to delete all the windows identified up to that moment in a single block.

The button named Apply makes effective the changes made up to that moment.

Chart configuration

If no windows have been identified yet, or if the selection has been removed, the charts present are only those of the traces as in the previous phase. In this configuration it is in any case possible to proceed with a graphical selection of the first window to be inserted into the list of identified windows, as better specified in the description of the button named On the chart of this help page.

If instead at least one window has been identified, in addition to the three trace charts in the three directions there are also: a chart for the average spectra; a map for the stationarity of the spectra; a map for the directionality of the spectra. For the meaning of each chart, refer to the Charts section of this manual.

In this configuration, unlike that of the previous phase, if windows have been identified, on the trace chart there are rectangles that represent the identified time windows, within which fall the recording samples that belong to them.

In case the user selects a row within the manual selection table, the rectangle corresponding to the window relating to the table row is highlighted with a rectangle of a different color and a greater thickness.

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