Glossary-3
Glossary
DTMF Dual Tone Multi-Frequency. A signaling method used for push-button telephones that
combines two output signals to create a unique tone for each of the 12 keys.
EBCDIC Extended Binary Coded Decimal Interchange Code . A method of coding digital signals
using eight bits to generate 256 different characters.
Echo Reflection back to the sender of a transmitted signal (as heard on telephone circuits
involving long distances, or poor transmission facilities).
EIA Electronic Industries Association. The American electronics standards group.
EIA/TIA 232-D The most commonly used computer/modem interface. An electrical standard for
interconnecting data communications equipment (DCE) and data terminal equipment (DTE)
established by EIA. (The pinout is the same as for EIA 232-C and is nearly equivalent to
ITU V.24.)
EOT End-of-transmission control character in character-oriented protocols (applied to BISYNC).
Tells the receiver that all user data (text) has been sent.
ETX End-of-text control character. Tells the receiver that the end of a message has been reached.
Exclusion key
telephone
Allows calls to be answered manually and transferred to the modem using an integral
exclusion key.
Fallback Switching the data system to a lower transmission speed either for reduced traffic during
off-peak hours or because of distortion in the telephone system.
Fall forward Switching from a lower to a higher data rate.
Flow control Controls data transfer between endpoints in a data network; line signals or flow control
characters stop and start the flow of data.
Four-wire A circuit cont aining two pairs of wires, on e pair for each transmission direction.
Full-duplex A signaling circuit that a llows simultaneous 2-way transmission and reception.
Frame A group of bits transmitted serially over a communications channel. The basic data
transmission unit used with bit-oriented protocols.
Gain The amount by which an amplifier (or power) increases the amplitude of a signal passing
through it; often represented in dB.
Half-duplex A circ uit tha t allows a lternat ing tra nsmit an d receive s ignals , but not both simultaneously.
HDLC High-level data link control. ITU-specified, bit-oriented, data-link control protocol; any
related control of data links by specified series of bits rather than by control characters.
Hexadecimal Base 16 number system with digits ranging from 0 to F.
ITU. See CCITT International Telecommunications Union. Formerly CCITT.
ITU -T Telecommunication Standardization Sector of ITU.
ITU V.13 V.13 signaling allows your modem to communicate with non-Telenetics modems. This
signaling operates when the modem is configured for synchronous mode.
ITU V.22 bis 2400 bps modem standard for use with dial and leased-line circuits.