Virtual Conferencing Glossary

P

Packets - A sequenced of digitised information that is sent and switched as a unit. Computer data is sent via packets. The traffic on the network is divided into small pieces called packets that are multiplexed onto high capacity intermachine connections. A packet, which usually contains only a few hundred bytes of data, carries identi-fication that enables computers on the network to know whether it is destined for them or how to send it on to its correct destination.

Packet Switching - A technique for transmitting data in which the message is subdivided into smaller units called packets.

PAL - Phase Alternate Line. .A colour television broadcasting system developed in West Germany and the U.K. that uses 625 picture lines and a 50Hz field frequency (frame rate is 25fps) NOTE: The number of pixels on a PAL or SECAM screen is almost 40 percent higher (20 percent greater vertically and horizontally) and im-ages look sharper. Also, since PAL and SECAM were developed after NTSC, they allow a greater bandwidth for color. This also helps to provide a sharper signal. NTSC standard was established for Black and White TV in the 1940s. The standard was expanded in the 1950s to include color, and it was constrained by having to be backward compatible with existing Black and White televisions.

Pan - To pivot a camera in a horizontal direction.

Pixel - Picture Element, is one of many small dots used to represent a picture.

Point-to-point - Videoconference between two sites.

POP (Point of Presence) - This is a point-of-presence of an Internet service provider, used to facilitate remote users' access to the range of applications and IP addresses in the internet.

POTS (Plain Old Telephone System) - Analog phone system that can carry frequencies from 300 Hz – 3.4 kHz.

PP (Point-to-Point Protocol) - Provides a standard means of encapsulating data packets sent over a single-channel WAN link. It is the standard WAN encapsulation protocol for the interoperability of bridges and routers. PPP is also supported in workstations, allowing direct dial-up access from a personal computer to a corporate LAN or Internet Service Provider. Using PPP ensures basic compatibility with non-Ascend devices. Both the dialing side and the answering side of the link must support PPP.

PRI (Primary Rate Interface) - An ISDN subscriber line, consisting of twenty-three 64 kbps B channels in North America (thirty 64 kbps channels elsewhere) and one 64 kbps D channel, used for signalling purposes.

Program sharing - A conferencing mechanism that allows more than one person, each on different computers, to use the same copy of the same program, working with the same document, and seeing the same displays on the screen.

Protocol - This is a standard procedure agreed upon by regulating agencies, companies, or standards-setting bodies to regulate transmission and therefore to achieve intercommunications between systems or networks.

Proxy server - In an enterprise that uses the Internet, a proxy server is a server that acts as an intermediary between a workstation user and the Internet so that the enterprise can ensure security, administrative control, and cach-ing service. A proxy server is associated with or part of a gateway server that separates the enterprise net-work from the outside network and a firewall server that protects the enterprise network from outside intru-sion.

PSTN - PSTN (public switched telephone network) is the world's collection of interconnected voice-oriented public telephone networks, both commercial and government-owned. It's also referred to as the Plain Old Tele-phone Service (POTS).

PTZ - PTZ (Pan-Tilt-Zoom). Camera functionality.