| |
::
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W X Y Z :
Home :
Guide TOC
:: |
| |
Satellite: Properly, a celestial body orbiting another of larger size. Commonly used to describe communications transceivers that are in geostationary orbit around the earth.
Satellite microphones: Additional microphones attached to quality speakerphones. Often distributed around a conference room table as “satellites” around the speakerphone.
Satellite time: Often referred to as space segment, referring to the amount of time booked on a communications satellite. In most cases satellite time is sold in one-hour increments.
Scan converter: A term formerly used in the place of “transceiver” for still video systems.
Scene adaptive coding: An intraframe coding scheme used in compressing video images. The algorithm was used by Compression Labs, Inc.
Scrambling: An analog procedure used to secure a signal sent in a data channel. Used for both voice and video.
SECAM: See Sequential Couleur A’Menoir (below).
Sequential Couleur A’Menoir (SECAM): Broadcast television standard used in France and the Soviet bloc, calling for 625 lines per frame.
Session Initiation Protocol: A protocol recommended by the Internet Engineering Task Force (IEFT) for the compression and transmission of spoken voice over packet networks. The protocol is getting wide support from the telephone companies and is expected to replace H.323 (G.723.1) for VoIP and IP telephones.
Set-top systems: These systems are designed for small conference rooms. They tend to be affordable in price, easy to use and offer quality performance. [Source: York Telecom] The “set” referred to is a monitor or television set.
Sha-Mail: A mobile telephone service offered by J-Phone of Japan that makes possible the transmission of video snapshots. The service relies on a mobile telephone that has a built-in digital camera. Sha-Mail has become very popular among teenagers who send photos back and forth, often before they decide if they are going to date one another. The service’s popularity is growing quickly. More than two million teens signed up to use it during the first year it was offered (2001). The word Sha in Japanese is an abbreviation for “taking pictures.” (See TeleSpan, December 3, 2001 and February 18, 2002.)
Short Message Service (SMS): A service that allows the sending of limited text messages over mobile telephones, using the telephone key pad. The service was made popular in Japan by NTT’s DoCoMo through its iMode phone system.
Signal to noise ratio: A measure in decibels of the ability to differentiate the signal being sent from interference or noise in the transmission channel. In amplified systems, such as long distance terrestrial circuits or satellite circuits, the noise is amplified along with the signal.
Simultaneous interaction: A feature that allows all participants and all sites participating in an audio teleconference or a point-to-point videoconference to speak and be heard simultaneously. Also called full duplex or open audio.
Single-talker bridge: A teleconferencing bridge that only allows one participant or participating site to speak at one time. All other sites are locked out through the action of a voice switch embedded in the bridge.
SIP: See Session Initiation Protocol (above).
SMS: See Short Message Service (above).
Software-based: A generic term used to describe a device that relies more on software than hardware for the management and delivery of communications signals such as voice, video, and other rich media. Generally software-based devices are computer servers, and can take advantage of lower costs of manufacturing, as they use parts commonly used in personal computers and PC-based servers.
Speakerphone: A loudspeaking telephone device that allows hands-free use. Usually equipped with an amplifier, loudspeaker, and microphone.
Special assembly room sound systems: Systems used when a speakerphone is not enough to handle the special sound needs in a conference room or an auditorium. Such systems use specialized audio equipment, speakers, microphones, and amplifiers that are assembled by audio engineers for the room. Special assembly room sound systems are many times installed in boardrooms or in distance education facilities and large auditoriums.
Spontaneous mobile conferencing: A term used to describe how people might use mobile telephones in the future to join conference calls, ad hoc, or with little notice.
SS7 (Signaling System 7) call routing: On the public switched telephone network, Signaling System 7 (SS7) is a system that puts the information required to set up and manage telephone calls in a separate network rather than within the same network that the telephone call is made on. Signaling information is in the form of digital packet. Currently used with Global Crossing’s Ready-Access system. [Source: Global Crossing]
Station lines: Telephone lines around an office and connected by a private branch exchange (PBX).
Streaming: The real-time or on-demand distribution of audio, video (VoD) and multimedia on the Internet. It’s the simultaneous transfer of digital media (video, voice, and data) so that it is received as a continuous, real-time stream. These applications can start displaying video or playing back audio as soon as enough data has been received and stored in the receiving station’s buffer. A streamed file is simultaneously downloaded and viewed, but leaves behind no physical file on the viewer's machine. [Source: York Telecom]
Switched network: A network that allows any site connected to it to communicate with any other site connected to the same network. The toll telephone network is referred to as the “public switched network.”
Systems integrators: Engineering firms who will install video equipment, as well as sophisticated audio systems, for customers. Such video equipment is often installed in specialized cabinets to match the decor or physical requirements of the room. (For audio, see Special assembly room sound systems.)
|
| |
::
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W X Y Z :
Home :
Guide TOC
:: |
| |
T.120: A standard recommended by the International Telecommunications Union (ITU) in 1994 for the transmission and sharing of graphics and text over packet networks for use in teleconferencing. The standard was widely accepted in the middle and late 1990s due to the support of backers such as Robert Gill of ConferTech (now Global Crossing), Neal Starkey of DataBeam (now IBM-Lotus), Brian Hinman of Polycom (who later founded TwoWire), and many others at Microsoft. T.120 is available through Microsoft’s NetMeeting product and Lotus’s SameTime. Today, though, with streaming and other Web conferencing packages widely available, T.120 is not as popular as it was in the late 1990s.
T channels: A series of standardized data channels, originally devised to carry digital voice. Includes the T1, T2 and T3 channels.
T1 channel: In North America, a channel that communicates at a data rate of 1.544 Mbps. In Europe, a channel that communicates at 2.048 Mbps.
T1 codec: A picture processor that compresses a digital video image to a data rate of 1.544 Mbps, or a T1 channel. See Codec.
T2 channel: In North America, a digital channel that communicates at 6.312 Mbps.
T3 channel: In North America, a digital channel that communicates at 46.304 Mbps.
Talker list: A logical device within some bridges that allows for more than one talker to speak at the same time. Generally employed in multi-talker bridges.
TCP/IP: Transmission Control Protocol/Internet Protocol. Transmission Control Protocol provides reliable transmission of data. Internet Protocol is the network layer product that offers a connectionless inter-network service. [Source: York Telecom] TCP specifies how packets addressed using IP travel to their destination, by creating a virtual connection between the sending and receiving sites. Think of it as your two hands, holding the two ends of the communication path. Whether the path goes directly across your arms or makes a detour through both legs along the way, TCP makes sure that the two ends don’t lose each other.
TDM: See Time Division Multiplexing.
TDMA: See Time Division Multiple Access.
Telecommunications: Communications over distance using electronic means; types of telecommunications channels include twisted pair telephone lines, coaxial cable, microwave, satellite and fiber optic cable. [Source: University of Wisconsin-Extension]
Telecommunications-travel tradeoff: A paradigm or theoretical framework formerly used in an examination of the potential for teleconferencing and other telecommunications services to substitute for travel.
Telecommuting: Commuting to work electronically rather than physically. The employee connects to the network when necessary via remote accesses and may attend meetings via videoconference. [Source: York Telecom]
Teleconferencing: 1. The use of telecommunication systems by groups of three or more people, at two or more locations, for the purpose of conferring with one another. [Source: Dr. Martin Elton, NYU] 2. Two-way communication between two or more groups, or three or more individuals, remote from each other using a telecommunications medium. [Source: University of Wisconsin-Extension] 3. Interactive group communication through an electronic medium. [Source: Dr. Robert Johansen, Institute for the Future]
Telemedicine: 1. A telecommunications system, sometimes employing teleconferencing, for the delivery of medical information and/or assistance. 2. Using videoconferencing technologies to diagnose illness and provide medical treatment over a distance. It is often used in rural areas where health care is not readily available as well as to provide medical services to prisoners, among other applications. [Source: York Telecom]
Telephone conferencing: See Audio conferencing.
Telephone conferencing service: See Audio conferencing.
Teletext: One-way broadcast of videotex-type information capable of being viewed on an ordinary TV set.
Television standards: See NTSC, Phase Alternating Line (PAL), Sequential Couleur A’Menoir (SECAM).
Telewriter: 1. As a general term, refers to an electronic device that produces hand-drawn information that can be transmitted over a telecommunications channel; 2. May specifically refer to a device that has an electro-mechanical pen to originate and/or reproduce hand-drawn information sent/received over a narrowband telecommunications channel. [Source: University of Wisconsin-Extension]
Test call: A video or audio call that takes place prior to the scheduled conference call to ensure that all locations/equipment are operating properly. [Source: Global Crossing]
Time division multiple access (TDMA): An accessing technique that allows separate communications sources to share the same telecommunications channel. Each user site has a time slot allocated during which data for that site may be transmitted or received.
Time division multiplexing (TDM): The complement of time division multiple access. The technique by which data from several sources can be sent via the same telecommunications channel by allocating a time slot for each sending source.
Transcoding: Converting a data stream from one format to another, such as MPEG 1 to H.263, or an H.320 videoconferencing session to H.323. [Source: York Telecom]
Transcription: A written record of a conference call. [Source: Global Crossing]
Transformation coding: The process of using mathematical transforms in compressing a signal for transmission at a lower data rate than normally required. Used in codecs.
Transforms: Mathematical functions that are used by picture processors in certain coding schemes for compressing video signals. See Codec, Cosine transform coding.
Transponder: That portion of a communications satellite that acts as a receiver, amplifier, and retransmitter for all signals communicated up to and down from the satellite.
Travel substitution: A description for the assumption that teleconferencing is a replacement for travel. See Telecommunications-travel tradeoff.
Trunk lines: Telephone lines outside of a customer’s premises used for local toll or long distance toll calls.
|
| |
::
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W X Y Z :
Home :
Guide TOC
:: |
| |
Uniform Resource Locator (URL): An addressing scheme for the Internet. The first part of the URL gives the protocol to use (for example, http is hypertext transfer protocol; ftp is file transfer protocol), and the rest of the URL gives the address of the resource (usually the domain name, but may include folders and subfolders, file names, and locations within files, as well as arguments—for a password or search, for example).
Uplink: A satellite earth station capable of transmitting and receiving information.
|
| |
::
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W X Y Z :
Home :
Guide TOC
:: |
| |
Video on Demand (VoD): Being able to view stored streamed video when you want to. [Source: York Telecom]
Videoconferencing: Communication between two or more groups, or three or more individuals, who are remote from one another, using telecommunications channels for fully interactive video and audio or one-way video and two-way audio; includes full-motion video and limited motion video, and, in some definitions, freeze-frame video images. [Source: University of Wisconsin-Extension]
Video teleconferencing: See Full motion video, videoconferencing.
Virtual-Private Network: A special switched network service that carriers typically offer to high-volume customers. The service commits the customer to a long-term agreement in return for a substantial discount on basic services. [Source: York Telecom]
Visual communications: Term used to describe the industry segment encompassing videoconferencing, streaming video, web-conferencing and the multimedia networks that support these applications. [Source: York Telecom]
VoD: See Video on Demand (above).
Voice activated switching: Automatically switching the video feed [camera] to whoever is speaking in a multipoint videoconference. Usually a function of the MCU (multipoint conferencing unit). [Source: York Telecom]
Voice grade line: A communications circuit that generally delivers 3 kHz of analog bandwidth. Typically used for telephone conversations or graphic or data communications devices requiring narrowband circuits.
Voice-switched: A teleconferencing device or system that switches control of certain functions based on which individual talker is speaking. Some audio teleconferencing bridges use voice switches to select the single talker whose voice will be heard by all other sites. See Single-talker bridge.
VoIP: Voice over IP. See Internet Protocol voice telephones.
|
| |
::
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W X Y Z :
Home :
Guide TOC
:: |
| |
WAN: See Wide Area Network (below).
Web-based conferencing: See Web conferencing (below).
Web-based collaboration: See Web conferencing (below).
Web conferencing: Also known as data conferencing, it describes conferencing that allows participants to share data, diagrams, and even video and audio (then called “rich media”). The data shared comes either from a PC a person brings into the meeting, or is pre-stored and available on the Web, hence the name Web conferencing.
Webcasting: A live broadcast format over the World Wide Web (WWW). See Streaming. [Source: York Telecom]
Wide area network (WAN): A set of widely separated computers connected together. Video networking requires a broad range of WAN connections that can be directed to multiple locations at different bandwidths on a call-by-call basis. [Source: York Telecom]
Wideband: See also Broadband. Typically to describe an analog signal that has a bandwidth of 20 kHz or greater. When used in describing switches, typically implies a system capable of switching circuits at 4 kHz or higher.
|
| |
::
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W X Y Z :
Home :
Guide TOC
:: |