NoodleTrip Video Conferencing Resources

• What is Video Conferencing?
• Video Conferencing Glossary
• Troubleshooting
• Video Conferencing Tips

ATM - Asynchronous Transfer Mode. An emerging networking method that can be used for carrying voice, video and data simultaneously over low speed (T1 — 1.5 Mbps) or very high speed (622 Mbps) networks.

Asynchronous Transfer Mode (ATM) - (1) A standard for cell relay wherein information for multiple types of services (voice, video, data) is conveyed in small, fixed-size cells. ATM is a connection-oriented technology used in both LAN and WAN environments. (2) A fast-packet switching technology allowing free allocation of capacity to each channel. The SONET-synchronous payload envelope is a variation of ATM. (3) ATM is an international ISDN high-speed, high-volume, packet switching transmission protocol standard. ATM currently accommodates transmission speeds from 64 Kbps to 622 Mbps.

bandwidth - Information-carrying capacity of a communication channel. Analog bandwidth is the range of signal frequencies that can be transmitted by a communication channel or network. Digital bandwidth is the rate at which bits can be transmitted.

bit - One binary digit; a pulse of data.

bits per second (bps) - The number of bits passing a point per second. The transmission rate for digital information.

bps - Bits Per Second

bridge - Device that connects and passes packets between two network segments that use the same communications protocol.

Codec (COder/DECoder) - A device that encodes an incoming analog signal into a digital signal for transmission to another codec. The digital signal is decoded into analog format. In videoconferencing, codec typically code an decode video and audio.

Continuous Presence Video - A type of videoconference that provides simultaneous and continuous pictures of all participants. The images are usually close-range shots of the group and may be viewed on a large screen or on one or more monitors. People images are usually "stacked" on one another.

dedicated line - A communications circuit or channel provided for the exclusive use of a particular subscriber. Dedicated lines are used for computers when large amounts of data need to be moved between points.

Document Camera - Allows you to share overheads, charts, slides, and other "hard-copy" presentation materials with conferees at the other site.

frame - A group of bits organized in fields of information. A field that has been filled with data and is ready to transmit onto the network is a packet.

frame relay - A packet switched networking technology used for low speed (T1 - 1.5Mbps and lower) WAN connections. Primarily used to connect a companyÕs routers on their data network.

frames per second (fps) - Frequency with which video frames appear on a monitor. Broadcast-quality video generally consists of 30 frames per second. Full-motion videoconferencing typically offers video in the range of 10 — 15 frames per second. At very low bandwidths, such as 56 or 112 Kbps, the frame rate may be lower.

full duplex - Method to transmit and receive in both directions simultaneously as in normal human conversation.

full-duplex audio - Audio that lets local and remote conference participants speak simultaneously without losing audio contact.

H.221 - The ITU-T standard relating to communications protocol for videoconferencing.

H.230 - The ITU-T standard that defines call control and indication.

H.231 - Multipoint for linking three or more H.320 codecs.

H.233 - Encryption.

H.242 - Call set-up and disconnect of two point videoconferencing.

H.243 - Defines call control procedures between H.231 MCU and H.320 codecs.

H.261 - The ITU-T Px64 standard relating to the video compression algorithm.

H.320 - Umbrella standard for videoconferencing.

H.323 - A standard approved by the International Telecommunication Union (ITU) that defines how audiovisual conferencing data is transmitted across networks. In theory, H.323 should enable users to participate in the same conference even though they are using different videoconferencing applications. Although most videoconferencing vendors have announced that their products will conform to H.323, it is too early to say whether such adherence will actually result in interoperability.

H.324 - Video over POTS.

Hertz (Hz) - Cycles per second.

Hz - Hertz

half duplex - Method to either transmit or receive without the ability to do both simultaneously.

half-duplex audio - Audio that permits only one site to speak at a time.

ISDN - Integrated Services Digital Networks

ISDN (Integrated Services Digital Networks) - A switched network service providing end-to-end digital connectivity for transmitting voice, data, and video simultaneously over a single line verses multiple. Uses high-speed, out-of-band signaling. There are two major forms of ISDN BRI and PRI.

ISDN BRI - A digital access line that is divided into three channels. Two of the channels, called B channels, operate at 64 Kbps and are always used for data or voice. The third D channel is used for signaling at 16 Kbps.

ISDN PRI- Based physically and electrically on an E1 circuit, but channelized so that two channels are used for signaling and 30 channels are allocated for user traffic. ISDN PRI is available in E1 and T1 frame formats, depending on country.

Internet - The largest Internet in the world consisting of a large national backbone and a myriad of regional and local campus networks all over the world. The Internet uses the Internet protocol suite. To be on the Internet you must have IP connectivity, i.e., be able to Telnet to or ping other systems. Networks with only e-mail connectivity are not actually classified as being on the Internet.

Internet Protocol (IP) - A Layer 3 (network layer) protocol that contains addressing information and some control information that allows packets to be routed. Documented in RFC 791.

Internet Service Provider (ISP) - (1) Any of a number of companies that sell Internet access to individuals or organizations at speeds ranging from 300 bps to OC-3. (2) A business that enables individuals and companies to connect to the Internet by providing the interface to the Internet backbone.

intranet - A private network inside a company or organization that uses the same kinds of software that you would find on the public Internet, but that is only for internal use. As the Internet has become more popular, many of the tools used on the Internet are being used in private networks for example, many companies have Web servers that are available only to employees.

Kilobits per Second (Kbps) - Measure of rate of digital transmission, often abbreviated Kbps. Equal to 1,000 bits per second.

kbps - Kilobits per second

kilobit - One thousand bits.

Multipoint Control Unit (MCU) - Bridging equipment that facilitates a single conference between multiple locations.

Mbps - Megabits per second

megabit - One million bits.

modem - Device that converts digital signals to analog signals for transmission on analog lines.

multiplexer - A device that permits subdivision of a given bandwidth to combine several channels to be carried by one line or fiber. For example, a T1 Multiplexer may divide a T1 line (1,544Kbps) into two capacities of 768Kbps each.

multiplexing - Method of combining several channels to be carried by one line or fiber.

Multipoint Conferences - A videoconference involving three or more locations. Multipont conferences are usually voice activated, meaning that the "speaking site" is the one that is seen by the rest of the conference participants.

out of band - Transmission taking place external to allocated bandwidth. A video call with out-of-band audio requires a separate phone line for the audio.

out-of-band signaling - Using a separate signaling channel for controlling a call

packet - (1) A logical grouping of information that includes a header and (usually) user data. (2) Continuous sequence of binary digits of information is switched through the network and an integral unit. Consists of up to 1,024 bits (128 octets) of customer data plus additional transmission and error control information.

packet loss rate - The measure loss, over time, of data packets as a percentage of the total traffic transmitted.

Quality of Service (QoS) - Measure of performance for a transmission system that reflects its transmission quality and service availability.

TCP/IP - The international standard protocol used on the Internet and company data networks. It provides worldwide connectivity and includes serves such as the World Wide Web, e-mail, file transfer and remote terminal login

Transmission Control Protocol/Internet Protocol (TCP/IP)- (1) The common name for the suite of protocols developed by the U.S. Department of Defense in the 1970s to support the construction of worldwide internetworks. TCP and IP are the two best-known protocols in the suite. TCP corresponds to Layer 4 (the transport layer) of the OSI reference model. It provides reliable transmission of data. IP corresponds to Layer 3 (the network layer) of the OSI reference model and provides connectionless datagram service. (2) The collection of transport and application protocols used to communicate on the Internet and other networks.

videoconferencing - Communication across long distances with video and audio contact.

voice activated switching - In multiway videoconferencing, used so that all participating sites automatically see the site which is currently speaking.

voice over internet protocol - The transmission of voice signals over the IP based Internet.