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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).