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The history of digital filters essentially began in the mid - 1970s, concurrent with the
advent of the fi eld of study called digital signal processing (DSP). Over the ensuing
30 something years, digital filters have become both a facilitating and enabling
technology. They serve as analog replacements as well as serving in unique DSP
roles in a host of application domains including communications, control, defense,
audio, biomedicine, geophysics, radar, entertainment, and others. I have been blessed
to be able to witness and participate in all of these phases of digital fi lter
evolution.
A digital filter is a device that can modify the attributes of a signal using digital
means. Required filter attributes can be assumed or defined in terms of published
standards that specify amplitude and phase behavior as a function of frequency.
Besides altering a signal’ s attributes, digital fi lters must often meet a host of other
constraints such as speed, complexity, power consumption, cost, and other factors.
In the pantheon of digital filters, the majority are identifi ed as being finite impulse
response (FIR), infi nite impulse response (IIR), or multirate systems. The book’ s
primary goal is to provide the needed understanding of both design and analysis
strategies as they apply to mainstream digital filters.
In the normal course of an engineer’ s career, regardless of their disciplinary
training, they will be called upon to design or analyze a mainstream fi lter.
Unfortunately, many engineers and technologists have little to no formal digital fi lter
experience. Fortunately, today’ s workplace is abundant with fi lter design software
packages with various levels of sophistication. One of the leaders in this fi eld is
Mathwork’ s MATLAB ™ . Today, both practicing engineers and students of engineering
exhibit a growing reliance on these tools with MATLAB being a de facto standard.
However, after observing how these tools are being used in the workplace and
classroom, concerns arise in that users are often overwhelmed with a plethora of
fi lter design options, often developing a fi lter solution that may not be best for the
target application. In addition, users often have insufficient experience or understanding
of fi lter theory to be able to make even minor enhancements to a MATLAB -
produced fi lter outcome. This too is a motivation for developing this book, which
elevates the reader’ s understanding of how to characterize a digital fi lter, to make
proper design choices, and to enhance a computer - generated design into a well -
crafted outcome. |