Hopefully, a person could start using the MATLAB Strobe Demo
tool without any need to read these help files. Features were designed to be
intuitive and familiar to those with basic computer experience.
For those who like to read the manual, this section will give you the minimum
you need to get started and be comfortable with the use of the GUI.
First, if you have not already done so, follow the information given in the
Installation section to install and start the
MATLAB Strobe Demo tool.
- To begin with, set the motor's frequency, this will determine the angular frequency of the arrow.
You can set the frequency in Hz by using the Motor Frequency (Hz) edit-box.
Another way to set the motor's frequency is, you can use the Motor rotations/min
slider/edit-box to set the motor frequency in revolutions per minute. You should be able to see
change in Samples plot and the corresponding Spectrums.
- You can also set the strobe's flashing rate at which the disk's arrow is sampled. This can be done
using the Flash Frequency (Hz) edit-box at bottom-right of the GUI, which sets the
sampling frequency in Hz. The flashing rate can be alternatively specified in flashes per minute
by using the Flashes/min slider/edit-box.
- Once the motor frequency and the strobe's flashing frequency has been set, you can use keyboard
keys k and l to change the flashing rate and observe changes made to
Samples and Spectrums plots. If the flashing frequency selected is
less than the Nyquist rate (2*Motor Frequency), then you will see the text ALIASING! displayed in the Discrete Time Spectrum plot,
indicating aliasing.
- You can also toggle the Fine radio button to change the step-size when advancing
the sliders.
- Another useful feature of the Demo is its color-coded plots.
- If the frequency of the motor lies within the range indicated by
the 'yellow' strip, then the arrow is not aliased.
- Un-aliased frequency components are marked in 'blue' and the aliased
components are marked in 'red', in the spectrum plots.
- When Aliasing occurs, such that the rotation of the arrow appears to reverse its
direction, then the text ALIASING! is displayed
in the Discrete Time Spectrum plot axis.
That's it! You now understand the basics of how to use the
MATLAB Strobe Demo tool; For a more in depth description of the theory behind
Strobe Demonstration see the Theory section. The Controls and Menus sections provide a description of the various
elements in the user interface.