User's Manual
Trailblazer Installation and User Manual version 1.02 51
6.8 Glossary
ANSI
Acronym for American National Standards Institute. Devises and proposes recommendations for
international communications standards.
asynchronous
A method of data transmission which allows characters, that are preceded by a start bit and are
followed by a stop bit, to be sent at irregular intervals.
bandwidth
A range within a band of frequencies or an amount of data that can be transmitted in a preset
amount of time. The bandwidth determines the rate at which information can be sent.
bridge
A connectivity advice that operates at the OSI Data Link Layer and filters and forwards packets
by physical addresses. See also router.
CD
Acronym for Carrier Detect. It is a signal generated by a modem or DSU/CSU and indicates the
presence of a carrier signal on a communications link.
CSU
Acronym for Channel Service Unit. A device used to connect a digital phone line from the phone
company to a multiplexer, channel bank, or directly to another device producing a digital signal. A
CSU performs line-conditioning and equalization functions, responds to loop-back commands
sent from the central office, regenerates digital signals and monitors them for problems, and
provides a way of testing a digital circuit.
CLASS features
Acronym for Custom Local Area Signaling Services. Consists of number-translation services, such
as call-forwarding and caller identification.
clock
Is an oscillator-generated signal that provides a timing reference and generates periodic signals
for the timing of certain functions in a transmission link.
CPE
Acronym for Customer Premise Equipment. It includes all telecommunications terminal
equipment located on the customer premises, including telephone sets, PBXs, data terminals,
and customer-owned coin-operated telephones.
CTS
Acronym for Clear To Send. A signal on the DTE interface indicating that the DCE is clear to
send data.
dB
Is an abbreviation for decibel, a logarithmic unit used to measure sound level or signal strength.
DCE
Acronym for Data Communications Equipment. A device that provides all the functions required
for connection to telephone company lines and for converting signals between telephone lines
and DTE. Also see DTE.
DSR
Acronym for Data Set Ready. It is a signal on the EIA-232 interface that indicates a connection
and readiness to start handshaking control signals for communication to begin.
DSU
Acronym for Data Service Unit. A hardware component needed to transmit digital data over a
hardware channel. It converts signals from bridges, routers, and multiplexers into the bipolar
digital signals used on the telephone company digital lines and ensures that voltage levels are
correct.
DSU loop back
Is a Telco initiated test which loops the DSU back to the Telco and is used to test the DDS circuit
as well as the DSU/CSU.
DTE