to-printer outputs in which the data must Glossary of Terms be transferred very rapidly but over a short distance. The opposite method of transmission is serial in which information travels over a single channel a bit at a time. passband A range of frequencies transmitted by a network or captured by a device. Pay-Per-View PPV. A type of CATV or DBS service whereby a subscriber notifies a provider that he or she is interested in receiving a program and is billed for the specific service on a one-time basis. A self-contained desktop or notebook computer that can be operated as a standalone machine or connected to other PCs or mainframes via telephone lines or a LAN. Pulse Code Modulation. A method of converting an analog signal to a digital signal that involves sampling at a specified rate (typically 8,000 per second), converting the amplitude of the sample to a number and expressing the number digitally. Picture element. Generally synonymous with pixel, the term pel is used in the analog world of television broadcasting. As television moves toward the digital world of HDTV the term pixel is being embraced by the broadcasting industry. peripheral equipment Accessories such as document cameras, scanners, disks, optical storage devices that work with a system but are not integral to it. persistence 1) The time taken for an image to die away. 2) Ability to maintain a session despite inactivity or interruption. phase The relationship between the zero-crossing points of signals. A full cycle describes a 360-degree arc; a sine wave that crosses the zero-point when another has attained its highest point can be said to be 90 degrees out of phase with the other. phase modulation The process of shifting the phase of a sine wave in order to modulate it onto a carrier. Phoneme An element of speech such as, "ch," "k," or "sh," that is used in synthetic speech systems to assemble words for audio output. Video Communication: the Whole Picture phosphor Substance that emits visible light of specific wavelengths when irradiated, as,