Digital Signal Processing Reference
In-Depth Information
Input and Output with the DSK
•
Input and output with the onboard AIC23 stereo codec
•
Programming examples using C code
2.1 INTRODUCTION
Typical applications using DSP techniques require at least the basic system shown
in Figure 2.1, consisting of analog input and output. Along the input path is an
antialiasing filter for eliminating frequencies above the
Nyquist frequency
, defined
as one-half of the sampling frequency
F
s
. Otherwise, aliasing occurs, in which case
a signal with a frequency higher than one-half
F
s
is disguised as a signal with a lower
frequency. The sampling theorem tells us that the sampling frequency must be at
least twice the highest-frequency component
f
in a signal, so that
Ff
s
>
2
which is also
(
)
1
T
>
2 1
T
s
where
T
s
is the sampling period, or
TT
s
<
2
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