Broadband Cable Association of Pennsylvania

Glossary - S

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Satellite - Device located in geostationary orbit above the earth which receives transmissions from separate points and retransmits them to cable systems, DBS and others over a wide area.

Satellite Dish Antenna - A system for concentrating the weak signals sent from a satellite.

Satellite Downlink - A data service that broadcasts data from an orbital satellite to terrestrial receivers. Used by some satellite TV vendors to provide a high-speed feed for receiving data from the Internet. Data sent to the Internet (Web page requests, outbound email, etc.) must be sent by more conventional means, such as a dial-up modem connections to a local ISP.

Satellite Master Antenna Television System (SMATV) - Systems that serve a concentration of TV sets such as an apartment building, hotel, etc., utilizing one central antenna to pick up broadcast and/or satellite signals.

Scanning Line - A single continuous narrow strip of the picture area containing highlights, shadows, and halftones, determined by the process of scanning.

Scramble - A signal security technique for rendering a TV picture unviewable, while permitting full restoration with a properly authorized decoder or descrambler.

Selective Reception - A characteristic of spatial processing that monitors incoming signals and distinguishes between desirable information and interference; by filtering out interfering signals and appropriately combining the reception from all the antennas in the array, this approach provides significant improvement in signal quality.

Server - A computer and/or software that provides and controls resources for clients on a network. These resources can include hardware devices such as printers and storage systems, or files as in the case of a web server.

Set-Top Box - Any of several different electronic devices that may be used in a customer's home to enable services to be on that customer's TV. If the "set top" device is used only for extending the channels available, it is called a converter. If it restores scrambled or otherwise protected signals, it is a descrambler.

Share - The percent of television households tuned to a particular program or category of programming.

Shared Wired Network - A topology where multiple households connect to a common piece of wire.

Shop-At-Home - Programs allowing customers to view products and/or order them by cable TV, including catalogues, shopping shows, etc.

Signal Leakage - Undesired emission of signals out of a cable television system.

Signal to Noise Ratio (SNR) - The sensitivity of a communications receiver is generally specified in terms of the audio signal-to-noise ratio that results from an input signal of a certain number of microvolts.

Signaling - The process by which an end system notifies a network that it wants service.

Skin Effect - The behavior whereby electricity migrates to the outside wall of a wire.

Slope - Difference in amplifier gain, or change in cable attenuation, between lowest and highest frequency present.

Slope-compensation - The action of a slope-compensated gain control, whereby slope of amplifier equalization is simultaneously changed with the gain so as to provide the correct cable equalization for different lengths of cable; normally specified by range and tolerance.

Smear - A term used to describe a picture condition in which objects appear to be extended horizontally beyond their normal boundaries in a blurred or "smeared" manner.

Snow - Heavy random noise.

Software - Programming and programming materials such as films, videotapes, and slides.

Solid State - A term taken from physics, used interchangeably with the work transistorized; also includes other semiconductor elements, such as diodes. Generally refers to tubeless equipment.

Spacing - Length of cable between amplifiers expressed as dB loss at the highest TV channel provided for in a system, equal to amplifier gain in main trunks.

Span - Distance between line extenders or distribution amplifiers; also, distance between taps.

Spatial Diversity - An antenna configuration of two or more elements that are physically spaced (spatially diverse) to combat signal fading and improve signal quality; the desired spacing depends on the degree of multipath angle spread.

Spectrum Management System (SMS) - A system for managing the radio frequency (RF) cable spectrum.

Splitters - A passive device (one with no active electronic components) which distributes a television signal carried on a cable in two or more paths and sends it to a number of receivers simultaneously.

Sports Blackout - Federal law requires cable systems and television stations to delete coverage of local sports events to protect gate receipts.

Spot Revenue - Revenue gained from advertising that is placed on a cable system by a local or national advertiser.

Spread Spectrum - Enables the successful transmission to hostile transmission environments.

Staggercast - This term is used to designate the interval of time, in NVOD; that is, the time between the beginning of a movie or program, on one channel and the beginning of the same program on another channel. (Ex: A movie starts at 7:00 on channel 50, at 7:15 on channel 51, at 7:30 on channel 52-the movie is staggercast 15 minutes.)

Start Bits - A sequence of bits sent by a device transmitting data so that the device receiving the data can synchronize its clock, which dictates the intervals at which individual bits are expected to be sent and received.

Stop Bits - A sequence of bits sent by a device transmitting data so that the device receiving the data can synchronize its clock, which dictates the intervals at which individual bits are expected to be sent and received.

Store and Forward - Technique for examining incoming packets on an Ethernet switch or bridge whereby the whole packet is read before forwarding or filtering takes place. Store and forward is a slightly slower process than cut-through, but it does insure that all bad or misaligned packets are eliminated from the network by the switching device.

Streaking - A term used to describe a picture condition in which objects appear to be extended horizontally beyond their normal boundaries.

Streaming Media - Digital Video, Audio, and Data Services that are selectively delivered to individual users, either in response to a user request or based upon a user profile. These services are delivered over a data transport stream, either via real-time transmission to the user, or via off-peak data-carousel transmission to a storage device at or near the user's location for subsequent retrieval.

Sub Band - The frequency band from 6 MHz to 54 MHz, which may be used for two-way data transmission.

Subscriber - A household or business that legally receives and pays for cable and/or pay television service for its own use.

Subscriber Unit - The fixed, typically wall-mounted equipment used by the subscriber in a wireless local-loop system to send and receive messages; a standard telephone is attached to it by wire to complete the connection to the user.

Subsystem - An element in a hierarchical division of an open system that interacts directly with elements in the next higher division or the next lower division of that open system.

Superband - The band of cable television channels J through W lying between 216 and 300 MHz.

Superstation - Originally referred to television station WTBS in Atlanta; now generally used to describe any broadcast TV station that has its signal distributed nationally by satellite.

Switch - A mechanical or electric device that is used to deliberately interrupt or alter the path of the current through the circuit.

Switched Network - Any network in which switching is present and is used to direct messages form the sender to the ultimate recipient. Usually switching is accomplished by deconnecting and reconnecting lines in different configurations in order to set up a continuous pathway between the sender and the recipient.

Switched Service - A cable communications service in which each subscriber has a terminal and may communicate with any other subscriber.

Switcher - A control which permits the selection of one image from any of several cameras to be fed into the television display or recording system.

Switcher/Fader - A device permitting gradual, overlapping transition from the image of one camera to another. Sometimes incorporated as part of a special effects generator.

Sync - An abbreviation for the words "synchronization", "synchronizing", etc. Applies to the synchronization signals, or timing pulses, which lock the electron beam of the picture monitors in step, both horizontally and vertically, with the electronic beam of the pickup tube. The color sync signal (NTSC) is know as the color burst.

System Level - The level of signal in a cable television system at the output of each amplifier. Must be carefully chosen and maintained for least distortion and noise.

System Loss - Cable TV distribution systems are designed to compensate the cable and device losses. The spacing between cable amplifiers can increase as system losses are minimized through the proper choice of connectors, cable and related hardware. System losses are referred to as a "dB of cable" without reference to specific cable size or device losses. Generally these losses are understood to be at the highest operating frequency of the system.

System Noise - Refers to the random energy generated by thermal and shot effects in the system. It is specified in terms of its rms level as measured in a 4 MHz bandwidth centered within a 6 MHz cable television channel.

System Operator - The individual, organization, company or other entity that operates a cable TV system.

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