When we developed analog systems, interconnecting the circuit
elements provided a natural starting place for constructing
useful devices. In discrete-time signal processing, we are not
limited by hardware considerations but by what can be
constructed in software.
Problem 1
One of the first analog systems we described was the
amplifier. We found that
implementing an amplifier was difficult in analog systems,
requiring an op-amp at least. What is the discrete-time
implementation of an amplifier? Is this especially hard or
easy?
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Solution 1
In discrete-time signal processing, an amplifier amounts to
a multiplication, a very easy operation to perform.
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In fact, we will discover that frequency-domain implementation
of systems, wherein we multiply the input signal's Fourier
transform by a frequency response, is not only a viable
alternative, but also a computationally efficient one. We begin
with discussing the underlying mathematical structure of linear,
shift-invariant systems, and devise how software filters can be
constructed.
"Electrical Engineering Digital Processing Systems in Braille."