电信专业英英词典D-1（在线收听）

　　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.