Figure 1-5 Digital Signal Processing - Motorola DSP56800 Manual

Low-Pass
Anti-Aliasing Analog-to-Digital
Filter
x(t)
Analog In
Processing in this circuit begins by band limiting the input signal with an anti-alias filter, eliminating
out-of-band signals that can be aliased back into the pass band due to the sampling process. The signal is
then sampled, digitized with an A/D converter, and sent to the DSP.
The filter implemented by the DSP is strictly a matter of software. The DSP can directly employ any filter
that can also be implemented using analog techniques. Also, adaptive filters can be easily put into practice
using DSP, whereas these filters are extremely difficult to implement using analog techniques. (Similarly,
compression can also be implemented on a DSP.)
Sampler and DSP Operation
Converter
FIR Filter
N
∑
c k ( )
A/D
k = 0
x(n)
Finite Impulse
Response
A
Ideal
Filter
Frequency
A
Analog
Filter
Frequency
A
Digital
Filter
Frequency
Figure 1-5. Digital Signal Processing
Introduction
Introduction to Digital Signal Processing
Digital-to-Analog
Converter
× ( )
n k –
D/A
y(n)
f
c
f
c
f
c
Reconstruction
Low-Pass
y(t)
Analog Out
f
f
f
AA0004
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