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SASLab Manual

Spectrogram window : Tools > Cursors >

The spectrogram window provides two different types of measurement cursors:
  • Marker mode: Markers are used for marking time (and frequency) sections and measuring durations. Markers can be positioned by clicking and dragging.
  • Reticule cursor mode: The mouse cursor changes into a single reticule while moving through the area of the spectrogram image. Reticule cursors are being used to measure time and frequency stamps.

Marker mode

A subsection of the spectrogram can be marked by clicking on the desired start point and dragging the cursor to the end point.

Once a section has been marked this marker can be resized by dragging the margins of the section. The whole marker can be shifted by clicking inside the marked section and dragging it away. The marker can be removed by executing the command Tools > Cursors > Remove Marker. The parameters of the marker (t1: begin, t2: end, dt: duration) are displayed in the unit seconds on the right of the window. This allows easy measuring of signal durations.

For precise determination of signal frequencies there are three types of frequency cursors available:

Frequency cursor

Up to four free moveable cursors can be activated by clicking inside the area between the bottom of the status line and the top of the spectrogram.

Then you can drag the cursor into the spectrogram. The cursor can be removed by dragging it back to the top of the spectrogram.

Harmonic frequency cursor

In order to support the determination of the fundamental frequency a special harmonic cursor can be activated in the standard marker mode.

This is done by clicking inside the area between the bottom of the upper status line and the top of the spectrogram while the Shift key is pressed. That cursor marks all harmonics of the fundamental cursor frequency. The harmonic cursor can be shifted by dragging any of its harmonics.

Bound frequency cursor

Up to two bound cursors can be activated by clicking inside the area between the left margin of the window and the left margin of the spectrogram.

Then you can drag the cursor into the spectrogram. This cursor can be moved only along the frequencies with the maximal intensities. The cursor can be removed by dragging it back to the left of the spectrogram. Bound cursors allow very easy determination of signal frequencies. When two bound cursors have been activated, the slope between the two points on the spectrogram is displayed on the top right-hand side of the spectrogram. The slope is expressed on Hz/ms or kHz/ms if the sample rate of the sound file is higher than 100 kHz.

Reticule Cursor mode

Alternatively a single Reticule Cursor can be activated. This cursor replaces the normal mouse cursor when it is inside the area of the spectrogram.

Cursor type selection

The standard cursor mode of the spectrogram window allows activating some cursors that are not linked with the mouse cursor. It is possible to display several of these cursors (markers) at the same time.

Standard marker cursor : Activates the standard marker mode.

Alternatively a single reticule cursor can be activated. In this mode, the normal mouse cursor changes into a reticule if it is inside the area of the spectrogram. There are several different reticule cursors available:

Free reticule cursor : Activates a free reticule cursor.

Bound reticule cursor : Activates a cursor, bound to the frequency with maximum intensity.

Magic reticule cursor : Activates a special cursor that can automatically locate peaks or entire elements. It can be setup from the Magic Cursor Setup... command at the bottom of the menu.

There are two special cursors for erasing portions of the spectrogram image:

Large rectangular eraser cursor : in this mode, left clicking and dragging can mark a rectangular section of the spectrogram image. That section can then be erased by the command "Tools"/"Erase marked section" or by pressing the right mouse button. The whole track can be erased by pressing the left and right mouse button while moving the cursor. Use this eraser mode for deleting larger rectangular regions.

Standard eraser cursor : The mouse cursor will change into an eraser. The shape of the eraser can be selected from the appearing tool set ( ). The area under the cursor will be deleted once the left mouse button is pressed. The undo button will undo the most recent erasing action. Use this eraser mode for deleting small or filigree regions.

The following three commands add specific frequency cursors in the standard marker mode:

Insert bound frequency cursor: Inserts a bound frequency cursors that moves along the peak frequency.

Insert frequency cursor: Inserts a free-moveable frequency cursor.

Insert harmonic frequency cursor: Inserts a harmonic frequency cursor.

Remove Marker: The current marker in the spectrogram window is removed.

Remove Cursors: Removes all cursors from the spectrogram window.

Erase marked section: Erases the currently marked section of the spectrogram. Use this command to remove unwanted sounds from the spectrogram image.

(Move reticule cursor by one pixel) > left, right, up, down: These commands are accessible through keyboard shortcuts (e.g. arrow keys) only, which have been defined from Tools/Keyboard Shortcuts and Popup Menu...

Copy cursor value: Copies the current cursor measurement values into the clipboard (or transfers them by DDE).

Copy the marker to the main window: Copies the current marker of the spectrogram window to the main window

Cursor linkage between Instances...

Display amplitude at reticule cursor cross: If this option is activated, the amplitude [dB] at the cursor position is displayed on the spectrogram image close to the cursor cross (for reticule cursors only).

Magic Cursor Setup...

Avisoft Bioacoustics last modified on 27 May 2019