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Video & Web Conferencing Glossary

Asynchronous
Communication in which interaction between parties does not take place simultaneously.

Asynchronous Transfer Mode (ATM)
A method of sending data in irregular time intervals using a code such as ASCII. ATM allows most modern computers to communicate with one another. It is a high-speed network technology that is based on sending data in packets or cells of a consistent size. Because the cell is small and a fixed size, ATM equipment can transmit video, audio, and computer data over a single network.

Audio Bridge
A device used in audio conferencing that connects multiple telephone lines.

Audio Conferencing
Voice only connection of more than two sites using standard telephone lines.

Backbone
A primary communication path connecting multiple users.

Band
A range of frequencies between defined upper and lower limits.

Bandwidth
Information carrying capacity of a communication channel. This is the amount of data that can be transmitted at a given time over a channel. Video conferencing is very bandwidth intensive, the greater the bandwidth, the better the picture and sound.

Basic Rate Interface (BRI)
Three digital signals over a pair of copper wires, 2 voice (B) channels and 1 signal (D) channel. A Basic Rate Interface consists of two 64 Kbps B ("bearer") channels to carry voice, video and data and one 16 Kbps D-channel for control and signaling. For example, voice and fax on a single pair of wires.

Bit
Abbreviation for a single binary digit.

Bit rate
The speed of a digital transmission, measured in bits per second.

Broadband
The term applied to networks having bandwidths significantly greater than that found in telephony networks. Broadband systems are capable of carrying a large number of moving images or a vast quantity of data simultaneously. Broadband techniques usually depend on coaxial or optical cable.

Browser
Software that allows you to find and see information on the Internet.

Byte
A single computer word, generally eight bits.

Cable Modem
A device that connects your PC to your cable service, which allows the high-speed transmission of data.

Camera presets
Allows pre-defined camera angles to be programmed into a video conferencing system.

Channel
The smallest subdivision of a circuit, usually with a path in only one direction.

CODEC (COder/DECoder)
A CODEC takes an analog video signal and digitizes and compresses it so that it can be transmitted. The codec also needs to decompress the incoming transmission and convert it from digital to analog.

Compressed video
Compression of a broadband signal to a narrow band signal for the purpose of traveling along a smaller carrier. Only the changes in moving frames are captured and transmitted. The reconstructed image exhibits some motion, but depending on the available bandwidth, the motion may appear somewhat irregular.

Demarc (demarcation)
The location in a facility where the network service provider supplies the point of connectivity for internal writing and the end user equipment.

Desktop Videoconferencing
Videoconferencing on a personal computer.

Digital
Conversion of information into bits of data for transmission through wire, fiber optic cable, videoconference, or over air techniques. Method allows simultaneous transmission of voice, data, and video.

Distance Education
The process of providing instruction when students and instructors are separated by physical distance, and technology, often in tandem with face to face communication.

Distance Learning
The incorporation of video and audio technologies into the educational process so that students can attend classes and training sessions in a location distant from that where the course is being presented. Distance learning systems are usually interactive an becoming a highly valuable tool in the delivery of education to widely dispersed students.

Digital Subscriber Line (DSL)
A Digital Subscriber Line is a high-speed connection over a standard copper wire connection that becomes high-speed through special provisioning (programming). The distance from the telephone company office limits DSL because the digital signal quality degrades over distance.

Document Camera
The distance learning equivalent of an overhead projector. Images of two or three dimensional objects using either top or base lighting can be transmitted to remote sites when this video source is selected.

Echo Cancellation
The process of eliminating the acoustic echo in a videoconferencing room.

E1
A European format for a digital trunk that is similar to a T1. It transmits at a rate of 2 Mbps over 32 channels at 64 Kbps per channel.

Ethernet
One of the most widely used Local Area Network (LAN) standards and supports data transmissions of 10 Mbps. There is a newer version called 100 Base-T or Fast Ethernet that supports data transmission of 100 Mbps.

Facilitator
The individual at a remote location responsible for performing assigned tasks designated by the instructor.

Fiber Optic Cable
Glass fiber that is used for laser transmission of video, audio and/or data.

Fractional T1
Any data transmission rate between 56Kbps and 1.544 Mbps. It is typically provided by a carrier in lieu of a full T-1 connection to reduce costs for long distance videoconferencing.

Frame Rate
This is the Frequency that video frames are shown. They are usually described in frames-per-second (fps). The faster the frame rate, the better the video image.

Frequency
The space between waves in a signal. The amount of time between waves passing a stationary point.

Full Motion Video
Full motion video is television-like quality with a frame rate of 30 frames per second.

Gateway
The original Internet term for what is now called a router or, more precisely, IP router. Refers to systems that translate from one native format to another.

GUI
The abbreviation for Graphical User Interface, which uses pictures or icons on your screen to display to make it simpler and easier for a user than learning complicated commands.

H.320
A widely used standard for video and audio transmission to be used over ISDN lines.

H.323 Standard
Extends H.320 standard to Intranet, Extranet or Internet over packet-switched networks: Ethernet, Token-Ring, ATM and others. Also referred to as IP videoconferencing.

H.324
The standard for video and voice transmission over analog phone lines.

Instructional Television Fixed Service (ITFS)
Microwave-based, high frequency television used in educational program delivery.

Integrated Services Digital Network (ISDN)
A telecommunications standard allowing communications channels to carry voice, video, and data simultaneously. ISDN can come as BRI service that is commonly used for home and small offices, and PRI service that is used by larger organizations. Stands for Integrated Services Digital Network, ISDN is the most popular means of communicating between video conferencing systems. Both BRI and PRI use B-channels and a D-channel. Each B-channel carries voice video and data and the D-channel carries the control and signaling information.

Internet
An international network of networks primarily used to connect education and research networks begun in the United States government.

Internet Protocol (IP)
the international standard for addressing and sending data via the Internet.

Intellectual Property
As it applies to distance learning, it is a question of ownership of a creative piece of work: the instructor, artist or institution.

Interaction
The active engagement of students in their own learning.

Inverse Multiplexer (IMUX)
Hardware that aggregates available ISDN lines together to achieve a required transmission rate. (Two channels – 128kbps, four channels – 256kbps, six channels – 384kbps).

Kbps
Kilobits per second (thousands of bits per second)-a measurement of bandwidth.

Listserv
An e-mail program that allows multiple computer users to connect onto a single system, creating an on-line discussion.

Local Access and Transport Areas (LATA)
The areas within which the Bell Operating and independent telephone companies can provide transport services. Inter-LATA connections must be provided by Interexchange or long-distance carriers.

Local Area Network (LAN)
Two or more local computers that are physically connected. A computer network in a defined area such as an office, building or group of buildings.

Mbps
Megabits per second or millions of bits per second-a measurement of bandwidth.

Microwave
Electromagnetic waves that travel in a straight line and are used to and from satellites and for short distances (i.e., up to 30-40 miles).

Modem (MOdulator/DEModulator)
A piece of equipment to allow computers to interact with each other via telephone lines by converting digital signals to analog for transmission over analog lines.

Multimedia
Any document which uses multiple forms of communication, such as text, audio, and/or video.

Multipoint
Multipoint Video conferencing is conferencing more than two points. This requires a system that is capable of multipoint conferencing or using a conferencing bridge (an external service that connects multiple systems together.

Multi-Point Control Unit (MCU)
Computerized switching system that allows video conferencing between more than two points, and may support fifteen or more points in a simultaneous video conference.

Network
A series of pints connected by communication channels in different locations.

NTSC
The television format used in the United States and Japan NTSC transmits at 525 lines of resolution 60 half-frames per second. Abbreviation for the National Television Standards Committee.

On-Line
Active and prepared for operation. Also suggests access to a computer network.

Origination Site
The location from which a teleconference originates.

PAL
Stands for Phase Alternating Line. The television format used in Europe. PAL transmits 625 lines at 50 half-frames per second.

Point of Presence (POP)
Point of connection between an interexchange carrier and a local carrier to pass communications into the network.

Point-to-Point
Transmission between two locations.

Point-to-Multipoint
Transmission between multiple locations using a bridge.

POTS
Stands for Plain Old Telephone Service. The common analog phone service.

Primary Rate Interface (PRI)
A PRI is the ISDN equivalent of a T-1 circuit and used in medium to large organizations. It provides 23 B-channels for data, voice, and other services and a D-channel for the control and signaling information. The channels can be used flexibly and allocated to video conferencing applications when needed.

Protocol
A formal set of standards, rules, or formats for exchanging data that assures uniformity between computers and applications.

PTZ Camera
Stands for Pan, tilt and zoom camera

Public Network
A telecommunications network designed for open, public access.

Real Time
The processing of information that returns a result so rapidly that the interaction appears to be instantaneous. Telephone calls and videoconferencing are examples of real-time applications.

RS-232
The standard interface for serial devices that is used for nearly all modems. It stands for Recommended Standard-232. Most PC's contain an RS-232 port to support connecting a modem or other devices.

RS-449
The RS-449 is a functional and mechanical description of the DB37 (37-pin) connector used on data terminal equipment.

Satellite TV
Video and audio signals are relayed via a communication device that orbits around the earth.

SXGA
Stands for Super Extended Graphics Array. A specification for a high-resolution video display of 1280 x 1024.

Synchronous
Communication in which interaction is simultaneous.

T-1 (DS1)
High-speed digital data channel that is a high volume carrier of voice and/or data. Often used for compressed video teleconferencing. A high capacity, digital line that transmits at 1.544 million Mbps over 24 channels, at 64 Kbps per channel.

T-3 (DS3)
A digital channel that communicates at a significantly faster rate than T-1.

TCP/IP
Transmission Control Protocol/Internet Protocol is a protocol that can be used on the Internet and other packet based networks.

Telecommunication
The science of information transport using wire, radio, optical, or electromagnetic channels to transmit/receive signals for voice or data communications using electrical means.

Teleconferencing
Two way electronic communications between two or more groups in separate locations via audio, video, and/or computer systems.

Transmission Control Protocol (TCP)
A protocol that makes sure that packets of data are shipped and received in the intended order.

Transponder
Satellite transmitter and receiver that receive and amplify a signal prior to re-transmission to an earth station.

Uniform Resource Locator (URL)
The address of a homepage on the WWW.

Uplink
The communication link from the transmitting earth station to the satellite.

V.35
A protocol that support data communications equipment to support T1/E1, PRI and satellite modems for customer on public or private networks.

Video Teleconferencing
A teleconference including two way video.

Virtual Private Network (VPN)
This is a network that uses the public network to connect the nodes as if it were a private network.

Wide Area Network (WAN)
A communications network that services a geographic area larger than that served by a local area network or metropolitan area network.

World Wide Web (WWW)
A graphical hypertext-based component of the Internet that provides access to web pages created by individuals, businesses, and other organizations.

XGA
Stands for eXtended Graphics Array. A standard for high-resolution graphics.