CIS 105 -- Survey of Computer Information Systems

Essential Concepts and Terminology -- Study Unit 9.

The process of sending information of any kind over telephone lines.
Public Switched Telephone Network (PSTN).
The technology enabling direct and almost instantaneous connections between any of nearly one-half billion telephones world-wide.
Local Exchange Carriers (LEC).
Telephone services which provide direct, wired connections between subscribers without accessing long-distance carriers. Also known as local access and transport areas (LATA).
Analog Telephone.
A device that transmits a continuously varying signal matching the acoustics of the human voice.
Subscriber Loop Carrier (SLC).
A telephone system installation that connects as many as 96 subscribers (a local loop) to a local exchange. The SLC may transform local analog signals to digital signals before transmission to the local exchange.
Interexchange Carrier (IXC).
A long-distance telephone company.
The data transmission capacity of a communications channel. The bandwidth of a digital signal is measured in bits per second (bps); of an analog signal in Hertz.
T1 Carrier.
Specially conditioned copper wires capable of transmitting 24 voice calls or 1.544 Mbps of data simultaneously.
Fiber-Optic Cable.
A bundle of thin strands of glass used to transmit data by means of pulses of light.
T3 Carrier.
A fiber-optic cable capable of transmitting 672 voice calls or 43 Mbps of data simultaneously.
An electromagnetic wave with a frequency of at least 1 gigahertz. High-frequency radio waves requiring line-of-sight transmission.
Wireless Networks.
Networks that use radio or infrared signals (instead of cables) to transmit data from one network device to another.
Cell Sites.
A network of automatic repeating transmitters which broadcast a signal throughout a limited geographic are (a cell).
Mobile Telephone Switching Office (MTSO).
The technology connecting cell sites and connected to the standard PSTN telephone system.
A device that transforms digital signals into analog form and vice-versa. Modems send and receive data to and from computers over telephone lines.
The process of changing the characteristics of a signal (for example, when a modem changes a digital pulse into an analog signal).
Modulation Protocols.
Rules set by international standards organizations to ensure that modem made by different manufacturers can communicate correctly.
Integrated Services Digital Network (ISDN).
A telephone company service that transports data digitally over dial-up or dedicated lines.
Basic Rate ISDN (BRI).
Service offering one or two 64 Kbps channels. Two channel ISDN allows a 128 Kbps data transfer rate, and one channel of data transfer during voice calls.
Primary Rate ISDN (PRI).
Service with 23 channels at 64 Kbps each and one signaliong channel, requiring a T1 carrier (1.544 Mbps).
ISDN Adapter.
The digital connection between a computer and an ISDN line, also called a digital modem (a misnomer).
Asymmetric Digital Subscriber Line (ADSL).
A type of DSL service for Internet access that enables download speeds of up to 1.5 Mbps.
Coaxial Cable.
A type of high-bandwidth connecting cable with an insulated center wire surrounded by a grounded shield of braided wire.
Cable Modem.
A communications device that delivers 0.5 to 1.0 Mbps or more of data, used to connect a computer to the cable TV infrastructure.
The transformation of media into digital data.
A term used to refer to communication channels that provide high bandwidth using multiplexing.


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