Digital Signal Processing Reference
In-Depth Information
(
a
)
(
b
)
FIGURE 2.11.
CCS graphs with the
loop_store
program: (
a
) time-domain plot of stored
input data representing a 1-kHz sine wave; (
b
) FFT magnitude of stored data representing a
1-kHz sine wave.
Build this project as
loop_store
. Input a sinusoidal signal with amplitude of
approximately 1/2 V p-p and a frequency of 1 kHz. Run and verify your output
results.
Use CCS to plot the stored input data in both the time and frequency domains
(see also Example 1.2). Select View
Time/Frequency. For the time-
domain plot, specify a starting address “buffer,” 512 points for the acquisition buffer
size, 64 points for the data size display (for a clearer plot), a 16-bit signed integer
for the data type, and 8000 for the sampling rate. Verify the 1-kHz time-domain sine-
wave plot within CCS, as shown in Figure 2.11
a
.
Select View
Æ
Graph
Æ
Time/Frequency again and FFT magnitude for display
to obtain a frequency-domain plot of the stored input data. Specify a display data
size of 512 with an FFT order of
M
Æ
Graph
Æ
512. The spike at 1 kHz in Figure
2.11
b
represents the 1-kHz sine wave plot within CCS.
=
9, where 2
M
=
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