Appendix A - Glossary - Polycom 1500 Getting Started Manual

Glossary
This appendix lists the terms and abbreviations that are related to the RealPresence Collaboration Server
(RMX) 1500/1800/2000/4000, and are commonly used in the Collaboration Server documentation.
Abbreviation/Term
AGC
Bandwidth
Bonding
Bps, Kbps
BRI
Carrier
CIF, 4CIF, QCIF
Codec
Polycom®, Inc.
Explanation
Auto Gain Control. A mechanism that regulates noise and audio volume by keeping the
received signal of all participants balanced.
Defines the information carrying capacity of a channel. In analog systems, it is the
difference between the highest frequency that a channel can carry and the lowest,
measured in hertz. In digital systems, bandwidth is measured in bits per second. The
larger a connection's bandwidth, the more data can be transmitted in a given amount of
time, allowing for greater video resolution and more sites in a conference. For more
information, see Line Rate.
Bandwidth ON Demand INterpolarity Group. A transmission protocol that aggregates two
64 Kbps B channels to function as one 128 Kbps channel. When using several BRI
channels, Bonding means that only one D-channel serves all BRI channels, while the
remaining D-channels are used for data transfer.
See also: BRI.
Bits and kilobits per second; a unit of bandwidth, which is the amount of data that can flow
during one second over a communications line (using a transmission medium).
1 Kbps = 1000 Bps
Basic Rate Interface. A type of ISDN connection for transiting data, consisting of 3
channels: two B-channels (each of 64 Kbps) and one D-channel (16 Kbps).
A telephone or other company that provides telecommunication transmission services.
Common Intermediate Format, an optional part of the ITU-T's H.261 and H.263 standards.
CIF specifies 288 non-interlaced luminance lines, that contain 176 pixels. CIF can be sent
at frame rates of 7.5, 10, 15, or 30 per second. When operating with CIF, the amount of
data to transmit cannot exceed 256 K bits (where K equals 1024).The CIF video format has
the capacity to transmit video images of 352x288 pixels at 36.45 Mbps and 30 frames per
second. A 4CIF format has four times the capacity of CIF; QCIF has quarter the capacity of
CIF.
Coder-decoder. A device that converts voice and video into digital code, and vice versa.
Refers to the endpoint video camera and video board that are used for video conferencing.
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