4: Errors

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Page ID: 50169

Paul Penfield, Jr.
Massachusetts Institute of Technology via MIT OpenCourseWare

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In Chapter 2 we saw examples of how symbols could be represented by arrays of bits. In Chapter 3 we looked at some techniques of compressing the bit representations of such symbols, or a series of such symbols, so fewer bits would be required to represent them. If this is done while preserving all the original information, the compressions are said to be lossless, or reversible, but if done while losing (presumably unimportant) information, the compression is called lossy, or irreversible. Frequently source coding and compression are combined into one operation.

Because of compression, there are fewer bits carrying the same information, so each bit is more important, and the consequence of an error in a single bit is more serious. All practical systems introduce errors to information that they process (some systems more than others, of course). In this chapter we examine techniques for insuring that such inevitable errors cause no harm.