Telecom Dictionary Navigation

Telecom Dictionary - D

DAMA - Stands for Demand-Assigned Multiple Access. This is a way to instantaneously assign telephony channels in a transponder according to the immediate traffic demands.

Dash - This is the the character "-".

Data - This term typically refers to anything that is not a voice, and it is, according to AT&T, "a representation of facts, concepts or instructions in a formalized manner, suitable for communication, interpretation or processing."

Database - This term refers to a collection of data that is catalogued in a logical way to ensure quick and reliable access.

Data Carrier Detect (DCD) - This is a hardware signal that indicates when a modem is online and capable of transmission.

Data Communications Equipment (DCE) - This is a device that translates a digital signal from data terminal equipment (DTE) into a form acceptable to the receiving device.

Data Compression - This is when data file size is reduced by elimination unnecessary information.

Data Grade Circuit - This is a circuit, such as a phone line, that is capable and suitable for transmitting data.

Data Link - This term describes communications paths that are used for data transmissions.

Data Set - (1) According to AT&T a data set is modem, but (2) according to IBM, a data set is a collection of data.

Data Set Ready (DSR) - This is a control signal that says that says a modem is ready to begin initial stages of transmission (i.e., configuration).

Data Terminal Equipment (DTE) - This is equipment that only receives information (i.e., no transmission), such as a printer.

Data Terminal Ready (DTR) - This is another control signal that says that modems have completed their initial configuration session and are ready for transmission.

DBS - This stands for Direct Broadcast Satellite, and refers to service that uses satellites to broadcast multiple channels of television programming to home mounted small-dish antennas, such as those provided by DirecTV or Dish Network.

dBi - The dB power relative to an isotropic source.

dBW - The ratio of the power to one Watt; it is expressed in decibels.

DCD - see Data Carrier Detect.

DCE - see Data Communications Equipment.

Decibel (dB) - The standard unit used to express the ratio of two power levels. In the communications field, It is used to express either a gain or loss in power after the signal has traveled between the input and output devices.

Declination - The offset angle of an antenna from the axis of its polar mount.

Decoder - Also called a receiver, this is a television-top device that converts an electronically scrambled television picture into a signal viewable on the TV.

Deemphasis - Reinstatement of a uniform baseband frequency response following demodulation.

Default - This is the factory setting or configuration of software or hardware.

Delay - This is the wait time between to specific events, and regarding satellite communications, it is the time it takes for a signal to go from the transmission station up to orbit and through the satellite and back down to the receiving earth station (about 1/4 of a second).

Delete - This terms means to discard (i.e., destroy) information.

Delivery on-orbit - A contractual term describing a service to deliver the satellite at its intended orbital location in space.

Demodulation - This is the process of extracting the electrical signal (i.e., the data) from the carrier signal.

Demodulator - A satellite receiver circuit which extracts or "demodulates" the desired data from from the received carrier signal.

Deviation - The modulation level of an FM signal determined by the amount of frequency the signal is from the frequency of the main carrier signal.

Dial - This refers to the sending out of either pulses or tones with the intent of establishing a connection (i.e., a circuit) with another phone or modem.

Dialup Modem - This is a modem that is used over normal telephone lines (i.e., not DSL or cable)

Dial String - This is the string of characters used to contact another device over telephone lines.

Dial Tone - This sound signifies that a telephone is ready to receive instruction (i.e., make a call).

Dibit - This is group of two bits.

Digital - Referring to communications techniques whereby information and data are encoded as discrete elements in a binary language, as opposed to analog representation of information in variable, but continuous, wave forms.

DIP - This is the act of extracting particular information from a database.

Diplexer - This is a device which combines two transmitters onto one single transmission line.

Dipole - This is an antenna that is fed from the center (such as rabbit ears).

Disconnect - To break a connection (i.e., a circuit) so communication is no longer possible.

Domain - On the internet, a domain is a place to visit with your internet browser.

Door - This is a software program that allows BBS users to run a program while a user is simultaneously using the BBS.

Down - This is a general term that means that something is not currently working.

Downlink - The segment of a satellite circuit that extends from the satellite to the user terminal (such as, but not limited to, a television).

Download - This term means to receive data from another source.

Driver - This is a software program that provides instructions to a computer on how to communicate with peripheral devices, such as printers or modems.

DTE - see Data Terminal Equipment.

DTMF - see Dual Tone Multi-Frequency.

DTR - see Data Terminal Ready.

DTV - Stands for Digital Television.

Duplex Transmission - This is the capability for simultaneous data transmission between a sending and receiving station.

Dual Tone Multi-Frequency (DTMF) - This is when two tones are used to represent each digit dialed on a telephone.

Dumb Switch - This is a switch that contains only basic switching equipment and need to be instructed by an outside source.

Dumb Terminal - This is a terminal with no programming or processing capabilities, and it is used primarily for information entering.

Duplex - (1) This term refers to the condition where two-way, simultaneous transmission is possible. (2) It is also the technical term for a common, electrical wall outlet.

DVB - This stands for Digital Video Broadcasting and is the European-backed project to standardize elements of digital video.