Now that you are comfortable with creating plots in KST, we can explore some of the plot manipulation features
available through the KST graphical user interface.
Start KST from the command-line with the
mykstsession.kst
file you saved earlier:
kst mykstsession.kst
All the plots you created earlier should now be loaded in KST.
Examine the plot with the y axis label of PSD of Column 2 (V/Hz^{1/2})
.
To take a closer look at the plot, right click on it and select the
menu item, as shown below:
The plot is now maximized within the current window.
Note that anything beyond about 4 Hz does not look interesting in this plot, so it would be
useful to view only the area of the plot that looks interesting. To do so,
make sure you are in XY Mouse Zoom mode (select
toolbar button). Then, simply drag
a rectangle from approximately (4, 0.025) to (0,0), as shown below.
Note that the coordinates of the mouse cursor
are displayed in the lower right corner of the KST window (if they are not, ensure that
is checked in the
menu).
The plot axes will change to “zoom in” on the selected area of the plot. You may notice that there is a peak at the left end of the power spectrum that extends beyond the new upper y axis limit. Suppose that you wish to view the top of this peak. Right-click on the plot and select from the submenu. The plot should scroll upwards. Of course, it is most likely easier to use the shortcut key associated with the menu item this is true for most of the zooming and scrolling functions. In this case, the shortcut key is Up Arrow, so the quickest way to scroll upwards would be to hold down the Up Arrow key. To return to maximum zoom at any time, right-click on the plot and select from the submenu (or type M, the shortcut key associated with ).
Restore the size of the power spectrum plot by right-clicking the plot and unchecking
.
Now look at the plots with y axes labelled Column 2
and Column 3
.
These are plots of the pitch gyro and roll gyro, respectively, from the 1998 BOOMERANG flight.
Since these two plots are related, it can be useful to zoom and scroll them simultaneously. Click on the
squares located at the top right corners of the two plots. They should turn dark in colour to indicate that
the two plots are now tied together:
Before we try zooming in, we should delete all plots other than the two we are working with. Select
toolbar button. For each plot other than
the two we want to keep, right-click on the plot and select . Then,
right-click anywhere inside the current window and select .
Now the two plots should share maximal space inside the window. Return to XY Mouse Zoom mode when you
are done.
Now try zooming in on any portion of the upper plot. You will find that the lower plot will become blank.
This is because the lower plot axes have changed to match the upper plot axes, and there is no data in that particular
region of the lower plot. Type M while the mouse cursor is over either plot
to return to maximum zoom on both plots. Now hold down Ctrl (this is equivalent to
selecting from the menu or clicking the
toolbar button). The mouse cursor
will change shape as visual feedback. While keeping Ctrl held down, drag a rectangle in the upper
plot. Note that the height of the dotted rectangle is restricted so that only the x axis will be zoomed.
Now both plots will display data when zoomed in, as the y axis for either plot was not changed.
You can quickly tie or untie all the plots in the window by selecting
toolbar button.
When you are finished experimenting with the zooming features, you can close KST. There is no need to save the plots this time (unless you wish to).