Origin Of Digital Signal Processing; Section 1.2 Origin Of Digital Signal Processing - Motorola DSP56000 Manual

x(t)
INPUT
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SENSOR
FREQUENCY
The equivalent circuit using a DSP is shown in Figure 1-2. This application requires an
analog-to-digital (A/D) converter and digital-to-analog (D/A) converter in addition to the
DSP. Even with these additional parts, the component count can be lower using a DSP
due to the high integration available with current components.
Processing in this circuit begins by band-limiting the input with an anti-alias filter, eliminat-
ing 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
implement any filter that can also be implemented using analog techniques. Also, adap-
tive filters can be easily implemented using DSP, whereas these filters are extremely
difficult to implement using analog techniques.
The DSP output is processed by a D/A converter and is low-pass filtered to remove the
effects of digitizing. In summary, the advantages of using the DSP include the following:
1- 4

ORIGIN OF DIGITAL SIGNAL PROCESSING

ANALOG FILTER
x(t)
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R
i
+
t
y t ( )
R
--------- = – ----- -
x t ( )
R
FREQUENCY CHARACTERISTICS
IDEAL
FILTER
f
f
c
Figure 1-1 Analog Signal Processing
DSP56K FAMILY INTRODUCTION
R
f
C
f
y(t)
1
f
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1 + jwR C
i f f
y(t)
OUTPUT
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ACTUATOR
MOTOROLA