Quick Start

Hopefully, a person could start using the MATLAB convolution tool without any need to read these help files.  Features were designed to be intuitive and familiar to those with basic computer experience. If not send me mail by clicking on my name in the Overview section!!

For those who like to read the manual (don't be ashamed, I am one of these people), 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 convolution tool.

To begin, pick an input signal and an impulse response:

  1. Press the Get x(t) button in the main window.  A second window should open with a pulse signal displayed.  If you wish, alter the signal type using the list box at the top of the window, and alter the signal parameters with the controls along the right side.  Note that time parameters for the sine and cosine (length, period, delay) must be specified in seconds.  When satisfied click the OK button.  The signal you picked is now displayed within the Input plot box.

    Note:  The signal may not be fully displayed when changing the signal parameters.  To replot the signal, click inside the plot box.

  2. Make sure the Flip h(t) radio button is checked and then pick an impulse response by pressing the Get h(t) button.  After choosing an impulse response and closing the window, the three large axes will now contain the following information:

    - The top axis displays the Input signal in blue and flipped version of the Impulse Response in red.

    - The middle axis shows the multiplication of the Input signal and Impulse Response at that particular instance of time.  (This may initially be empty.)

    - The bottom axis shows the output of the linear convolution between the Input signal and the Impulse Response signal.

  3. There are two labels with arrows pointing to the current time.  One is below the Signal / Flipped Signal plot box.  The other is above the Output plot box.  Move the mouse over either of these.  The mouse pointer should become a hand symbol indicating that the current time can be changed by dragging the t time label.

    Go ahead and drag the time label around to change the value of the current index location.  Quite a few things happen: The Flipped Impulse Response follows the location of the time location, and the multiplication plot changes depending on the relative overlap between the Input signal and the Flipped Impulse Response.

  4. Change the time so that the two signals overlap in the Signal / Flipped Signal window. There will now be a nonzero plot within the multiplication axis.

    Note that the current time is highlighted in the Output plot.  The numeric value (i.e., the value on the y axis) of this time is determined by integrating the area within the multiplication plot.

    Ex.  If the signals overlapped so that the multiplication plot integrated to a value of 6, the highlighted value in the output plot would have a value of 6.

That's it!  You now understand the basics of how to use the MATLAB convolution tool.  For a more in depth description of convolution theory and how a convolution is calculated see the Theory section.  The Controls and Menus sections provide a description of all the elements in the user interface.