Telecom Dictionary Navigation

Telecom Dictionary - S

Sampling - When continuous signals are converted into discrete values.

Satellite - (1) This is any body of matter orbiting another body (like our Moon). (2) Regarding the telecommunications industry, it is a device with the purpose of receiving and relaying electronic communications. Satellites in geosynchronous orbit (also known as the Clarke orbit) are 22,237 miles above the equator, and orbiting at this height allows them to move at the same speed and in the same direction as the Earth's rotation.

S-band - The portion of the electromagnetic spectrum between 2 and 2.4 GHz.

Scalable - This term describes something that can easily be enlarged or reduced in size.

Scanner - (1) A device used to input graphics into a computer system, or (2) a radio receiver that skips across frequencies so you can listen for conversations.'

Scintillation - Regarding electromagnetic wave propagation, this is a random deviation (usually small) of the received field strength about its average value.

Scrambler - This is a device that is used to alter a signal electronically so that a receiver must decode the signal before it can be heard or viewed.

Script - This is a programming term that refers to a set of instructions (a program) that is executed by another program rather than the computer's processor.

Script Language - A programming language that uses commands in the form of English-statements.

SDTV - see Standard Definition Television.

Search Engine - An internet term that means a website that uses a program to return a listing of websites that are relevant to user-entered search keywords.

Secam - A color television system developed by the French but used in Russia. See the PAL or NTSC system.

Sector - This is a portion of a hard disk.

Secure Channel - This is a point-to-point communications link that has been protected against unauthorized access.

Semiconductor - This is a material, such as Silicon, possessing resistive properties somewhere in between a conductor and insulator, used to effectively control current flow.

Sequencing - Dividing information into smaller, numbered pieces, transmitting it, and reassembling it once it has been received.

Serial - Meaning in a row, or one after the other (as opposed to parallel).

Serial Port - A port that transmits data one bit at a time.

Server - (1) A computer containing files available on a network, or (2) a program that provides a service to other programs.

Servlet - If it runs on a server, and it's an applet, then it's a servlet.

Session - An active connection, from beginning to end.

Set - In the telecom business, a set is a telephone.

Shareware - Software that is in the public domain, meaning that it is free to be distributed, used, or altered.

Shielded Pair - A pair of insulated wires that is shielded from interference by a metallic foil.

Shielding - Wrapping conductors with a metallic foil (a shield) to insulate them from interference. Shielding improves the quality of transmission.

SIG - Special Interest Group.

Signal - This is an electric quantity (i.e., voltage, current or field strength) sent from a source to a receiver whose modulation represents a data transmission.

Signal to Noise Ratio (S/N) - This is simply ratio of the signal power and noise power, expressed in decibels (dB).

Sign-Off - To end a working session.

Sign-On - To begin a working session.

Silicon - A crystalline, gray element used in semiconductor devices.

Simplex Transmission - Like half duplex, this is the capability for transmission in only one direction at a time between the sending and receiving stations.

Simulcast - When two different channels broadcast the same thing.

Slant Range - This is the length of the path between a satellite and a particular earth station.

Slot - This is the particular longitudinal position (typically 2 to 3 degrees apart for above the US) in the geosynchronous orbit into which a satellite is permanently located. See orbital slot.

Smart Terminal - see Intelligent Terminal.

Snail Mail - Regular postal service mail (as opposed to electronic mail).

Snow - Video interference in the form of white specs.

Software - Written instructions for a computer.

Solar Outage - Solar outages can be accurately predicted and occur when the sun passes within the field of view of an antenna. See Rain Outage.

Solid State - A term describing electric circuits made of solid components (i.e., no moving parts).

Sound - These are audible vibrations transmitted by a medium (such as air).

Space Parity - Setting the parity bit so it is 0 in data transmissions.

Spam - Internet junk, in many forms. Junk email, keyword stuffed websites, and unsolicited self-promotion are all forms of spam. Keeping spam out of the search engine rankings is an ongoing struggle for search engines.

Spectrum - A continuous range of frequencies.

Spider - A program that crawls around the internet gathering information.

Spillover - This is the portion of the satellite signal that falls outside a particular beam pattern's determined edge of coverage.

Splitter - This is a passive device (that is, it has no active electronic components and thus requires no power) which allows one signal to be sent over multiple paths.

Spooler - A program that stores files in a queue for outputting (such as to a printer).

Spot Beam - This is a tightly focused antenna pattern that is sent to a limited geographical area, such as Hawaii or other easily definable area.

Standard Definition Television (SDTV) - This is the current NTSC standard for television broadcast transmissions.

Static - Signal interference caused by electrical disturbances (usually natural).

Stationary Orbit - see Geostationary Orbit.

Stop Bit - This is the bit, always a 1, which terminates the character group in asynchronous transmissions.

Streaming - A method of transmitting information on the web continuously.

String - A sequence of related elements.

Subcarrier - This is a second signal that "rides" on the main signal with the purpose of carrying additional information. In satellite TV transmissions, for example, the video is transmitted by the main carrier signal, and the audio information is relayed by an FM subcarrier.

Subscriber - A telephone or telecommunications company's paying customer.

Subscriber Line - The telephone line that a customer (subscriber) is paying for. It goes from your desired location (like your home) to the telephone company's closest central office.

Superconductors - Materials that don't have any resistance to electrical current flow. Zero resistance can be achieved only at very, VERY cold temperatures.

Surf - To jump around from page to page on the internet via hyperlinks, skimming the information, possibly without any particular page destination.

Surge Protector - A device for protecting electrical equipment from power surges or spikes.

S-Video - "Separate" Video is a physical video interface that carries the luminance and color information separately, thus avoiding the color encoding process and loss of picture quality.

Switch - A device that has the purpose of opening and closing circuits.

Syntax - A language's grammatical rules.

System - A coherently-organized assembly of elements.

System Disk - A disk containing instructions that can be used to start up your computer from an initial state.