• Changeability; it is easy to reprogram digital systems for other applications, or to fine
tune existing applications. A DSP allows for easy changes and updates to the
application.
• Repeatability; analog components have characteristics that may change slightly over time
or temperature variances. A programmable digital solution is much more repeatable due to
the programmable nature of the system. Multiple DSPs in a system, for example, can also
run the exact same program and be very repeatable. With analog signal processing, each
DSP in the system would have to be individually tuned.
• Size, weight, and power; a DSP solution that requires mostly programming means the
DSP device itself consumes less overall power than a solution using all hardware
components.
• Reliability; analog systems are reliable to the extent to which the hardware devices
function properly. If any of these devices fail due to physical condition, the entire system
degrades or fails. A DSP solution implemented in software will function properly as long
as the software is implemented correctly.
• Expandability; to add more functionality to an analog system, the engineer must add more
hardware. This may not be possible. Adding the same functionality to a DSP involves
adding software, which is much easier.
DSP systems
The signals that a DSP processor uses come from the real world. Because a DSP must respond
to signals in the real world, it must be capable of changing based on the changes it sees in the
real world. We live in an analog world in which the information around us changes,
sometimes very quickly. A DSP system must be able to process these analog signals and
respond back to the real world in a timely manner. A typical DSP system (Figure 1-1) consists
of the following:
• Signal source; something that is producing the signal such as a microphone, a radar sensor,
or
a flow gauge.
• Analog signal processing (ASP); circuitry to perform some initial signal amplification or
filtering.
• Analog-to-digital conversion (ADC); an electronic process in which a continuously
variable signal is changed, without altering its essential content, into a multi-level (digital)
signal. The output of the ADC has defined levels or states. The number of states is almost
always a power of two e that is, 2, 4, 8, 16, etc. The simplest digital signals have only two
states, and are called binary.
• Digital signal processing (DSP); the various techniques used to improve the accuracy
and reliability of modern digital communications. DSP works by clarifying, or
standardizing, the levels or states of a digital signal. A DSP system is able to
Introduction to Digital Signal Processing 3
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