asis for calculations." In general usage, however, data usually means characters (letters, numbers, and graphics) that can be stored or transmitted over various types of telecommunications networks. Until recently, voice and video signals were not considered data but now that they are being converted to a digital format they are being referred to as data. data compression Reducing the size of a data file by reducing unnecessary information, such as blanks and repeating or redundant characters or patterns. Data Over Cable Service A standard interface for cable modems, the devices Interface Specifications that manipulate signals between cable TV operators and customer computers or TVs. DOCSIS specifies modulation schemes and the protocol for exchanging bi-directional signals over cable. Now known as CableLabs Certified Cable Modems, the ITU ratified DOCSIS 1.0 in March 1998. Decibel. One-tenth of a Bell and a logarithmic Glossary of Terms measure of electric energy. A decibel expresses the ratios between voltages, sound intensities, currents, the power (amplitude) of sound waves, and SO on. Direct broadcast satellite, a transmission scheme used for program delivery, most generally entertainment. There are several DBS providers; none of the systems that they use are, however, compatible. These systems provide downstream speeds of 400 Kbps to 30 Mbps or higher and upstream speeds of 28 Kbps or higher. Direct Current. Data communications equipment. The network side of an equipment to network connection with DTE, data terminal equipment that plugs into DCE, which provides a means of network connection. See Discrete Cosine Transform. DCT coefficient An expression of a pixel block's average luminance, as used in DCT. The value for which the frequency is zero in both the horizontal and vertical directions. decode A process that converts an incoming bitstream, that consists of digitized images and sounds, into a viewable and audible state. decryption Decryption reverses an encryption process to return an encrypted transmis