Virtual Conferencing Glossary

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FCIF - Standards-based formats for communicating between videoconferencing systems from different vendors.

FDDI - Fiber Distributed Digital Interface. A high bandwidth networking scheme that uses fiber optic cable. The to-pology relies on two rings for redundant 100Mbps transmissions. FDDI uses a token passing access method similar to token ring which results in a more deterministic performance than the contention-based Ethernet.

FDX - Full-duplex. Two-way, simultaneous transmission of data; a communication protocol in which the communi-cations channel can send and receive data at the same time.

FECC (Far-End Camera Control) - This can be selected if you need to control the camera at the far end. This option does not work with all systems.

Filtering - The removal of undesired frequencies. Most commonly, filtering is used to remove high-frequency audio and video signals to avoid aliasing in sampling.

Firewall - A firewall is a system designed to regulate access between networks and enforce an organisation’s security policy. It is usually a combination of hardware and software. It can exist within a router, a personal computer, a host computer, or a collection of host computers. A firewall simplifies the management of network security by providing a single point of access to the network. All traffic entering or leaving the network must pass through the firewall. The firewall examines all data and blocks data that does not meet specified security cri-teria.

Focal length - The distance from the optical center of a lens to the point where light rays converge (are in focus). Shorter focal lengths correspond to a wider field of view and vice versa.

FPS - Frames per second. The number of frames contained in a single second of a moving series of video images. 30 fps is considered to be "full-motion" video in Japan and the US, while 25 fps is considered to be "full-motion" video in Europe.

Fractional T-1 - FT or fraction T-1 refers to any data transmission rate between 56 kbps and 1.544 mbps. It is typically pro-vided by a carrier in lieu of a full T-1 connection and is a point-to-point arrangement. A specialised multi-plexer is used by the customer to channelise the carrier's signals.

Frame - A segment of an analogue or digital signal that has a repetitive characteristic, in that corresponding elements of successive frames represent the same things.

Frame rate - Frequency in which video frames are displayed on a monitor, typically described in frames-per-second (fps). Higher frame rates improve the appearance of video motion. Broadcast TV (full motion video) is 30 frames-per-second.

Frame relay - Industry-standard, switched data link layer protocol that handles multiple virtual circuits using HDLC encap-sulation between connected devices. Frame Relay is more efficient than X.25, the protocol for which it is generally considered a replacement. See also X.25.

Frequency - The number of cycles per unit of time (of a sound or radio wave, for example).

Frequency division multiplexing (FDM) - Division of a transmission facility into two or more channels by splitting the frequency band transmitted by the facility into narrower bands, each of which is used to constitute a distinct channel.

FTP - FTP (File Transfer Protocol) is a standard Internet protocol. It is the most common way to exchange files be-tween computers on the Internet. It is also commonly used to transfer Web page files from the creator to the computer that is acting as the server.

Full-CIF - Full Common Intermediate Format: A 352-by-288 video format that is described by the ITU's H.261 specifica-tion. FCIF is sometimes called CIF.

Full-duplex - Two-way, simultaneous transmission of data; a communication protocol in which the communications chan-nel can send and receive data at the same time. Compare to half-duplex, where information can only be sent in one direction at a time.

Full duplex audio - 2-way audio simultaneously transmitted and received without any interference or "clipping." A common fea-ture of room-based videoconferencing systems.

Full motion video - Video reproduction at 30 frames per second (fps) for NTSC signals or 25 fps for PAL signals. Also know as continuos-motion video. Videoconferencing systems today run 10 to 15 frames per second at 128 Kbps, at higher speed such as 384 Kbps a 30 fps is achievable.