This report is also available as an Acrobat file.
Contents
Glossary
Note: The Cray Communications Pocket Book Collection provided several of these
explanations and definitions.
ADPCM
Adaptive DPCM (where DCPM is differential
PCM, transmitting value differences, and
adaptive means dynamically adjusting
parameters to the data stream).
ATM
Asynchronous Transfer Mode networks (based
on packet switching). A mode of data transfer
in which units of data are not time-related to
each other.
B-ISDN
Broadband ISDN. A communication channel
having a bandwidth greater than a voice-grade
channel 1 and therefore capable of higher-
speed data transmission.
CBT
Computer-based training.
CCD camera
Charged Couple Device camera.
CCIR
International Radio Consultative Committee.
CCITT
International Telegraph and Telephone
Consultative Committee. A standards body
concentrating on definition of European
Communications Standards.
CELP
Code Excited Linear Prediction. The most
common vocoder technology in use today,
which uses "codebooks" to quantise the input
signal. The CELP algorithm provides excellent
speech quality and is well suited for tele-
conferencing.
CIF
Common source Intermediate Format.
CODEC
An item of equipment containing an encoder
and a decoder. A device which performs the
dual function of encoding two-way analogue
data and two-way digital data into analogue
data.
DARPA
Defense Advanced Research Project Agency.
DMA channels
Dynamic Memory Addressing.
DSP
Digital Signal Processor.
DVI
Digital Video Interactive (Trade Mark of the
Intel Corporation).
ETF
European Teleconferencing Federation.
Ethernet
A LAN transmission network utilising a bus
structure, first produced by Xerox in the USA,
later adopted by both DEC and Intel as well.
This was later adapted to create the IEEE 802.3
and ISO 8802-3 standards.
ETSI
European Telecommunications Standards
Institute. Membership is open and there are
currently 135 member organisations including
national administrations, public network
operators, manufacturers, users and research
bodies.
FDDI
Fibre Distributed Data Interface. A token
passing ring network specification developed
by ANSI, implementing dual optical fibre
rings. The network operates at 100Mbps and
can be up to 100 kilometres in length.
fps
Frames per second.
FTP
File Transfer Protocol. A protocol from the
Internet Protocol Suite which provides transfer
of files between two dissimilar machines.
H.320
A series of audio visual communications
recommendations which were ratified by the
CCITT in December 1990. The aim of the
series, which applies to audio visual
communications over 56/64 Kbps to 2.048
Mbps channels, is to ensure videoconferencing
systems and video terminals will interconnect
across any network. H.320 is an umbrella
standard encompassing a series of
recommendations, including:
- H.221 (frame structure for a 64-1920Kbps channel);
- H.230 (frame synchronous control and indication signals);
- H.242 (systems for establishing communications between audio visual terminals using digital channels up to 2 Mbps);
- H.261 (visual coding for transmission over 56/64-2048 Kbps digital channels);
- G.711 (3.5 kHz narrowband audio specification for 48-64 Kbps channels);
- G.722 (7 kHz wideband audio specification for 48-64 Kbps channels);
- G.728 (3.5 kHz audio specification for 16 Kbps channels).
HDTV
High definition TV (e.g. 1125 or 1250 lines).
HTTP
HyperText Transfer Protocol.
IEEE
Institute of Electrical and Electronic Engineers.
An American Institute responsible for
developing and publishing many
communications standards.
IETF
Internet Engineering Task Force. Part of the
organisation that develops Internet standards.
Internet
A vast community of computers, distributed
around the world, which share common
protocols (TCP/IP).
IP
Internet Protocol.
ISDN
Integrated Services Digital Network. Basically
the existing telephone network using existing
but upgraded switches and wiring, but all
digital, giving a bandwidth for a basic call of
64 kbps. This increased bandwidth allows the
transmission of high fidelity compressed audio,
as well as the potential for video
communication.
ISO
International Standards Organisation.
JANET
Joint Academic NETwork.
JBIG
Joint Broadcasting Information Group.
Generates standards for binary image
compression (e.g. faxes).
JISC
Joint Information Systems Committee (of the
Higher Education Funding Councils of
England, Scotland and Wales). Responsible for
funding SuperJANET.
JNT
Joint Network Team. Forerunner of UKERNA.
JPEG
Joint Photographic Experts Group. Generates
standards for still image compression.
LAN
Local Area Network. A system for
intercommunication between computer
terminals, PCs and related equipment operating
within the same general area.
LIVENET
London Interactive Video Network. A hybrid
network combining analogue and digital
communications, with gateways to ISDN,
SuperJANET, Internet and satellite.
MAN
Metropolitan Area Network. A geographically
extended high-speed LAN designed to
interconnect users within a city or metropolitan
area.
MBONE
Multicast Backbone. A virtual network that has
been in existence since early 1992. Originated
from an effort to multicast audio and video
from meetings of the IETF. Shares the same
physical media as the Internet. MBONE today
is used by several hundred researchers for
developing protocols and applications for group
communication. It is a co-operative, volunteer
effort.
MCU
Multipoint Conferencing Unit.
MHEG
Multimedia and Hypermedia information
coding Experts Group. Generates standards for
multimedia data (such as integrating stills,
video, audio, text, etc.).
MICE
Multimedia Integrated Conferencing for
European Researchers. Co-ordinated by
University College London, this project aims to
provide a multi-way integrated conferencing
service between a number of European pilot
sites, and link them to the appropriate
communities in the US.
MPEG
Moving Picture coding Experts Group.
Generates standards for digital video and audio
compression.
NetBIOS
Network Basic Input/Output System. A
network communication system operating on
MS/DOS PC networks.
NTSC
(US) National Television System Committee -
TV standard.
ODA
Office Document Architecture. Defines the
structure of complex documents for interchange
between systems in an OSI environment. It also
provides for the creation, change, consolidation
and management of documents using screens or
printers as necessary for input and output (ISO
8613/CCITT T.411-T.418).
OSI
Open Systems Intercoynnection. The term
defined by the International Standards
Organisation as a basis for standards to enable
different vendor systems to interwork without
modification.
OSPF
Open Shortest Path First.
PAL
Phase Altering Line. The TV standard in much
of Europe which uses YUV colour space (i.e. Y
luminance, 1.3 MHz chrominance components
U, V).
PBX
Private Branch Exchange.
PCM
Pulse Code Modulation. An encoding
technique for digitising analogue voice signals
(used, for example, with CD audio).
PDH
Plesiochronous Digital Hierarchy.
PNO
Public Network Operator
POTS
Plain Old Telephone System.
PSTN
Public Switched Telephone Network.
QCIF
Quarter Common source Intermediate Format.
QuickTime
Produced by Apple, QuickTime is a set of
protocols that allow a Mac or a PC running
Windows to use a single interface to
create/display/manipulate movies that contain
digitised video, sound, text, etc.
RIFF
Resource Interchange File Format.
RIPE
Réseaux IP Européens. Co-ordinator of the
Internet community in Europe. Operational
since 1989. A RIPE Network Co-ordination
Centre in The Netherlands provides Internet
management functions, network software and
documentation.
RTP
Real Time Protocol. A transport protocol for
audio/video data that is being developed by the
Audio/Video Transport working group of the
Internet Engineering Task Force.
SDH
Synchronous Digital Hierarchy.
SGML
Standard Generalised Mark-up Language
(mark-up metalanguage - ISO 8879).
SMDS
Switched Multimegabit Data Service.
SuperJANET
A national high performance network
supporting UK education and research. It
currently provides three services: a high
performance IP service to all connected sites,
an ATM service to a sub-set of the connected
sites and a video network to the ATM sites.
Super VGA
High resolution VGA often 800X600 pixels
and 256 colours with faster scanning rate.
S-Video
Separate-video (also known as Y/C) in which
the luminance and chrominance information of
a video signal are carried on separate wires.
T1
A digital communications path operating at
1.544 Mbit/sec.
TCP/IP
Transmission Control Protocol/Internet
Protocol. Two main network communication
protocols, part of the Internet Protocol Suite.
TLTP
Technology in Learning and Teaching
Programme (run through UCOSDA).
Token Ring
A LAN transmission network utilising a ring
structure. The most common form is IBM
Token Ring. This network type is detailed by
the IEEE 802.5 and ISO 8802-5 standards.
TUA
Telecommunications Users Association.
UDP
User Datagram Protocol.
UKERNA
UK Education and Research Networking
Association. A company that has been set up to
manage the networking programme for the UK
higher education and research community.
VADPCM
Variable rate ADPCM compression.
VESA
Video Electronics Standards Association.
VGA
Virtual Graphics Adapter. Standard 640X480
resolution PC monitor configuration.
WAN
Wide Area Network. A network which uses
public or private circuits to link terminals, PCs
and computers over long distances that also
often allows some user choice in destination.
Following the implementation of routers,
bridges and gateways, many LANs are
becoming WANs, but more typically networks
such as X.25 are classed as WANs.
WWW
World Wide Web.
Contents
Graphics Multimedia
Virtual Environments Visualisation
Contents