Chapter 9 - Data Storage and Compression Techniques

Abstract

Acquired data must be permanently stored by a PC to allow retrieval for display and analysis. The conventional storage devices of PCs are magnetic or optical media. A file is physically located on a magnetic disk or other permanent storage medium such as a CD-ROM. The physical structure of a magnetic disk consists of concentric rings known as cylinders and angular segments known as sectors. Hard drives consist of multiple platters. The cylinder on a single surface of a disk is referred to as a track. The read/write sensor used in a disk drive is the head. This chapter further discusses several data compression techniques. Sometimes, there are very obvious ways to reduce the size of a data file. If a set of numerical data is stored in an ASCII format, encoding it directly as binary numbers could produce large space savings. Another popular technique for compressing strictly numerical data is delta encoding. This approach is especially useful when the data represents a continuous waveform with relatively low instantaneous slopes. Delta encoding consists of keeping the first value of the data set at its full bit resolution.