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Additional Terms
Analog: The traditional means of sending traffic over copper wires.
Analog signals are continuously variable, like a flowing line orwave, as opposed
to 1/0 digital signals. Analog signals must be converted into digital signals in
order for computers to be able to understand them.
AVI: Audio Video Interleaved. Microsoft format for digital audio and
video playback from Windows Has been replaced by the ASF format, but still used
by some multimedia developers.
Backbone: A pathway or cable that joins multiple computers across small
distances (within the same building) or multiple LANs across long distances.
Bandwidth: The capacity or speed of a telecommunications transmission
medium (e.g., 64 Kbps).
bps (bits per second): Defining the speed of a network connection in
number of bits transmitted every second.
Coaxial cable: A coaxial cable can carry great quantities of information
compared to
twisted pair copper wire and is typically used by cable providers to carry
television signals into houses and schools.
Chrominance: The portion of a video signal that specifies color of the
picture.
Composite video: A method of carrying video information, which combines
chrominance and luminance on a single wire, resulting in lower video quality
than S-Video or component.
CPE: Customer Premises Equipment. Network interface equipment not
provided by the network provider.
Digital: An electronic signal coded in binary format as opposed to
analog’s continuously variable flow. All digital information is ultimately
stored in 1/0 signals that computers process.
Ethernet: Ethernet refers to the family of local-area network (LAN)
products covered by the IEEE 802.3 standard that defines what is commonly known
as the CSMA/CD protocol. Ethernet is a bus-based topology that is connected to a
single cable with terminators at each end. Three data rates are currently
defined for operation over optical fiber and twisted-pair cables:
10 Mbps—10Base-T Ethernet
100 Mbps—Fast Ethernet
1000 Mbps—Gigabit Ethernet
Fiber-optic cable: A cable technology that carries light signals over
thin glass fiber at unlimited speeds.
Hub: A device used to concentrate incoming data from multiple nodes (see
definition) onto a common network medium. Also commonly referred to as a
concentrator or repeater.
Internet 2: a U.S.-led effort to build cyberspace all over again,
designed for the next generation of applications. The Internet 2 backbone in the
United States moves billions of bits of data per second, 300,000 times faster
than the connection we have at home. Moving with such speed, Internet 2 will be
able to provide remote diagnosis for doctors, send detailed medical files in a
flash, would really change how we do teaching, learning and education, stage
high-resolution videoconferences and download virtual reality applications.
Kbps (kilobits per second): A measurement for the speed of data
transmission. One kilobit equals 1,000 bits.
Latency: The length of time it takes a packet to move from source to
destination; delay.
Luminance: The portion of a video signal that specifies how bright each
portion of the picture is to be.
Mbps (megabits per second): A measurement for the speed of data
transmission. One megabit equals approximately 1,000,000 bits.
MPEG (Moving Picture Experts Group): is a series of ISO standards for
digital video and audio, designed for different uses and data rates.
MPEG-1: The initial MPEG standard, designed to encode full motion video
so it could be played back off of a CD (150 kb/s). The bit rate of a standard
MPEG1 is 1.5Mbps. MPEG-1 has a frame size of 352x240 pixels, which gives a
picture quality slightly better than VHS videotape. MPEG-1 included three audio
standards, most video systems use MPEG-1 layer 1 or layer 2 audio. MPEG-1 layer
3 audio (commonly known as MP3), is being used widely for audio on the Internet.
MPEG-2: the follow-on standard supporting higher data rates, and thus
higher quality. MPEG-2 is the standard used in DVD video players, most digital
satellite systems in North America, and in the new North American Digital TV
system.
MPEG-4: MPEG-4 is designed to deliver DVD (MPEG-2) quality video at lower
data rates and smaller file sizes. And the same folks who created the popular
.mp3 file format — a.k.a. MPEG-1 layer III — developed the new Advanced Audio
Coding (AAC) codec, providing much more efficient compression than MP3 with a
quality rivaling that of uncompressed CD audio. MPEG-4 promises to create
interoperability for video delivered over the Internet and other distribution
channels. MPEG-4 will play back on many different devices, from satellite
television to wireless devices.
NIC: Network Interface Card.
nodes: A point of interconnection to a network, such as computers,
printers, routers, faxes, or bridges.
point-of-presence (POP): The IXC equivalent of a local phone company’s
central office. The POP is your long-distance carrier’s office inside your
community. It is the place where the long distance carrier terminates its
long-distance lines and connects to the local phone company’s lines.
Protocol: A procedure for adding order to the exchange of data. A
protocol is a specific set of rules, procedures, or conventions relating to the
format and timing of data transmission between two devices.
Proxy server: A server that sits between a client application, such as a
Web browser, and a real server. It intercepts all requests to the real server to
see if it can fulfill the requests itself. If not, it forwards the request to
the real server. Proxy servers have two main purposes.
Improve Performance: Proxy servers can dramatically improve performance for
groups of users. This is because it saves the results of all requests for a
certain amount of time.
Filter Requests: Proxy servers can also be used to filter requests. For example,
a company might use a proxy server to prevent its employees from accessing a
specific set of Web sites.
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 Telephone Service (
POTS ).
QuickTime: file-format and architecture developed by Apple Computer for
use with digital audio and video. MPEG 4 is now incorporated into QuickTime.
Available on most computing platforms.
RealAudio: A proprietary system for streaming audio and video over the
Internet.
Router: a router is a device or, in some cases, software in a computer,
that determines the next network point to which a packet should be forwarded
toward its destination. The router is connected to at least two networks and
decides which way to send each information packet based on its current
understanding of the state of the networks it is connected to.
Streaming Video: Streaming video is a sequence of "moving images" that
are sent in compressed form over the Internet and displayed by the viewer as
they arrive. Streaming media is streaming video with sound. With streaming video
or streaming media, a Web user does not have to wait to download a large file
before seeing the video or hearing the sound. Instead, the media is sent in a
continuous stream and is played as it arrives.
S-Video: A method of carrying video information on a cable (s-cable) that
separates luminance and chrominance on separate wires, thereby providing higher
video quality than composite video. Also called Y/C.
Switch: In a telecommunications network, a switch is a device that
channels incoming data from any of multiple input ports to the specific output
port that will take the data toward its intended destination.
Twisted pair: Traditional copper wiring well suited for short distance
transmission of information. It consists of two insulated copper conductors
twisted around each other and surrounded by a plastic coating.
Webcast: The term "Webcasting" is used to describe the ability to use the
Web to deliver live or delayed versions of sound or video broadcasts.
VoIP (voice over IP): voice delivered using the Internet Protocol) is a
term used in IP telephony for a set of facilities for managing the delivery of
voice information using the Internet Protocol ( IP ). In general, this means
sending voice information in digital form in discrete packets rather than in the
traditional circuit-committed protocols of the public switched telephone network
(PSTN).
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