User Manual

9-7
E-CON Graph Window Operations
Analyzing a Graph Using Fourier Series Expansion
Fourier series expansion is effective for studying sounds by expressing them as functions.
The procedure below assumes that there is a graph of sampled sound data already on the
graph screen.
• Fourier series expansion is possible only with data sampled using the EA-200’s built-in
microphone. Attempting the following procedure with any other type of data causes an
error.
• The angle unit for a function obtained using Fourier series expansion is always radians,
regardless of the ClassPad’s angle unit setting.
u
To use Fourier series expansion to convert a waveform graph to a function
(1) On the E-CON Graph window [Analysis] menu, tap [Fourier].
• If there are multiple graphs on the screen, you can use
the up and down cursor keys to move between them.
When the graph you want is displayed, press the
E
key.
(2) Use the left and right cursor keys to move the vertical line to the start point of the range
for which you want to perform Fourier series expansion, and then press
E
.
• Alternatively, you could tap the start point of the range with the stylus.
(3) Use the left and right cursor keys to move the vertical line to the end point of the range for
which you want to perform Fourier series expansion.
• Alternatively, you could tap the end point of the range with the stylus.
• This displays a dialog box like the one shown to the
right.