Digital signal processing

CHAPTER

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The Breadth and Depth of DSP

Digital Signal Processing is one of the most powerful technologies that will shape science and engineering in the twenty-first century. Revolutionary changes have already been made in a broad range of fields: communications, medical imaging, radar & sonar, high fidelity music reproduction, and oil prospecting, to name just a few. Each of these areashas developed a deep DSP technology, with its own algorithms, mathematics, and specialized techniques. This combination of breath and depth makes it impossible for any one individual to master all of the DSP technology that has been developed. DSP education involves two tasks: learning general concepts that apply to the field as a whole, and learning specialized techniques for your particulararea of interest. This chapter starts our journey into the world of Digital Signal Processing by describing the dramatic effect that DSP has made in several diverse fields. The revolution has begun.

The Roots of DSP
Digital Signal Processing is distinguished from other areas in computer science by the unique type of data it uses: signals. In most cases, these signals originate as sensory datafrom the real world: seismic vibrations, visual images, sound waves, etc. DSP is the mathematics, the algorithms, and the techniques used to manipulate these signals after they have been converted into a digital form. This includes a wide variety of goals, such as: enhancement of visual images, recognition and generation of speech, compression of data for storage and transmission, etc. Suppose weattach an analog-to-digital converter to a computer and use it to acquire a chunk of real world data. DSP answers the question: What next? The roots of DSP are in the 1960s and 1970s when digital computers first became available. Computers were expensive during this era, and DSP was limited to only a few critical applications. Pioneering efforts were made in four key areas: radar & sonar, wherenational security was at risk; oil exploration, where large amounts of money could be made; space exploration, where the

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The Scientist and Engineer's Guide to Digital Signal Processing

data are irreplaceable; and medical imaging, where lives could be saved. The personal computer revolution of the 1980s and 1990s caused DSP to explode with new applications. Rather than being motivatedby military and government needs, DSP was suddenly driven by the commercial marketplace. Anyone who thought they could make money in the rapidly expanding field was suddenly a DSP vendor. DSP reached the public in such products as: mobile telephones, compact disc players, and electronic voice mail. Figure 1-1 illustrates a few of these varied applications. This technological revolution occurredfrom the top-down. In the early 1980s, DSP was taught as a graduate level course in electrical engineering. A decade later, DSP had become a standard part of the undergraduate curriculum. Today, DSP is a basic skill needed by scientists and engineers

Space

-Space photograph enhancement -Data compression -Intelligent sensory analysis by remote space probes -Diagnostic imaging (CT, MRI,ultrasound, and others) -Electrocardiogram analysis -Medical image storage/retrieval -Image and sound compression for multimedia presentation -Movie special effects -Video conference calling -Voice and data compression -Echo reduction -Signal multiplexing -Filtering -Radar -Sonar -Ordnance guidance -Secure communication -Oil and mineral prospecting -Process monitoring & control -Nondestructive testing -CADand design tools -Earthquake recording & analysis -Data acquisition -Spectral analysis -Simulation and modeling

Medical

Commercial

DSP

Telephone

Military

Industrial

Scientific

FIGURE 1-1 DSP has revolutionized many areas in science and engineering. A few of these diverse applications are shown here.

Chapter 1- The Breadth and Depth of DSP

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in many fields. As...