Controls
  1. Get x[n] | h[n]
  2. Flip x[n] | h[n]
  3. Index Label:  n = #
  4. Plot Box:  Input
  5. Plot Box:  Impulse Response
  6. Plot Box:  Signal / Flipped Signal
  7. Plot Box:  Multiplication
  8. Plot Box:  Output
  9. Close
  10. Help
  Get x[n] | h[n]

These buttons bring up a new window which allow you to pick x[n] and h[n].  A list box at the top provides a limited choice of signals.  If one wishes, the signal's parameters (e.g., length, amplitude, etc...) can be changed with the controls along the right edge of the window.  When satisfied clicking the OK button imports the chosen signal into the main window.

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

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  Flip x[n] | h[n]

These radio buttons allow you to change which signal is being flipped.  Flipping a signal means reflecting the signal to the other side of the origin.

Note:  The current n index indicates the sliding location of the flipped signal.  For example, the default starting position is to plot the signal with the index n =  -5.  Thus, whatever sample was at the origin in the flipped signal is shifted to k = -5.

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  Index Label:  n = #

There are two labels for the current n index.  Dragging these with the mouse will change the value of the current index.  The current index can also be changed by using the numeric 4 and 6 keys.

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  Plot Box:  Input

This plot displays the Input signal imported with the Get x[n] button dialog box.

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  Plot Box:  Impulse Response

This plot displays the Impulse Response imported with the Get h[n] button dialog box.

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  Plot Box:  Signal / Flipped Signal

This is a plot of two signals.  The first signal labeled Signal is either the Input signal or the Impulse Response depending on the settings of the Flip x[n] | h[n] radio buttons.   Accordingly, the signal being flipped is labeled Flipped Signal.  Changing the current n index will change the location of Flipped Signal.

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  Plot Box:  Multiplication

This plot shows the result of the point by point multiplication between the two signals displayed in the Signal / Flipped Signal plot box.  The plot changes depending on the relative overlap between the two signals.

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  Plot Box:  Output

This plot shows the output of the linear convolution between the Input signal and the Impulse Response.

Note that the sample at the current n index is highlighted in the Output plot.  The numeric value (i.e., the value on the y axis) of this sample is determined by adding together all the values of the samples within the multiplication plot.

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  Close

Pressing this button will allow you to exit the MATLAB convolution tool.

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  Help

Pressing this button will launch the host computer's internet browser and to load the index.html page found in the help directory.  If an error occurs you can manually load the page into your browser or navigate to http://www.ece.gatech.edu/users/jr/convolution/help/index.html where another copy of the help pages are found.  (Of course, you probably know this or else you could not be reading this!)

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