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Introduction to Real-Time
Digital Signal Processing
Signals can be divided into three categories ± continuous-time (analog) signals,
discrete-time signals, and digital signals. The signals that we encounter daily are mostly
analog signals. These signals are defined continuously in time, have an infinite range
of amplitude values, and can be processed using electrical devices containing both
active and passive circuit elements. Discrete-time signals are defined only at a particular
set of time instances. Therefore they can be represented as a sequence of numbers that
have a continuous range of values. On the other hand, digital signals have discrete
values in both time and amplitude. In this book, we design and implement digital
systems for processing digital signals using digital hardware. However, the analysis
of such signals and systems usually uses discrete-time signals and systems for math-
ematical convenience. Therefore we use the term `discrete-time' and `digital' inter-
changeably.
Digital signal processing (DSP) is concerned with the digital representation of signals
and the use of digital hardware to analyze, modify, or extract information from these
signals. The rapid advancement in digital technology in recent years has created the
implementation of sophisticated DSP algorithms that make real-time tasks feasible. A
great deal of research has been conducted to develop DSP algorithms and applications.
DSP is now used not only in areas where analog methods were used previously, but also
in areas where applying analog techniques is difficult or impossible.
There are many advantages in using digital techniques for signal processing rather
than traditional analog devices (such as amplifiers, modulators, and filters). Some of the
advantages of a DSP system over analog circuitry are summarized as follows:
1. Flexibility. Functions of a DSP system can be easily modified and upgraded with
software that has implemented the specific algorithm for using the same hardware.
One can design a DSP system that can be programmed to perform a wide variety of
tasks by executing different software modules. For example, a digital camera may
be easily updated (reprogrammed) from using JPEG ( joint photographic experts
group) image processing to a higher quality JPEG2000 image without actually
changing the hardware. In an analog system, however, the whole circuit design
would need to be changed.
Real-Time Digital Signal Processing. Sen M Kuo, Bob H Lee
Copyright # 2001 John Wiley & Sons Ltd
ISBNs: 0-470-84137-0 (Hardback); 0-470-84534-1 (Electronic)