DAB
Digital audio broadcasting.
A technology for broadcasting of audio using digital radio transmission.

Dark fibre
Fibre optic cable that is not being used at the time.

DECT
Digital enhanced cordless standard.

Digital
Representation of voice or other information using digits 0 and 1. The digits are transmitted as a series of pulses. Digital networks allow for higher capacity, greater functionality and improved quality.

Digital network
A telecommunication network in which information is converted into a series of distinct electronic pulses and then transmitted as a digital bitstream (see also Analogue network).

DMB
Digital multimedia broadcasting.
A technology for broadcasting of multimedia (audio, TV, data) using digital radio transmission, mainly used in Republic of Korea.

DOCSIS
Data over cable systems interface specifications (ITU-T J.112).
An ITU Recommendation for cable modems. It specifies modulation schemes and the protocol for exchanging bidirectional signals over cable.

DOCSIS2
Data over cable systems interface specifications 2 (ITU-T J.122).
The newest, revised version of DOCSIS, approved at the end of 2002.

Domain name
The registered name of an individual or organization eligible to use the Internet. Domain names have at least two parts and each part is separated by a dot (point). The name to the left of the dot is unique for each top-level domain name, which is the name that appears to the right of the dot. For instance, the International Telecommunication Union’s domain name is itu.int. “ITU” is a unique name within the gTLD “int”.

DSA
Dynamic spectrum access.
This approach to spectrum management involves unitizing spectrum in terms of time slots or geographical location. It is closely related to flexible spectrum management and spectrum trading.

DSA
Dynamic spectrum allocation.

DSL
Digital subscriber line.
See also ADSL, ADSL2, ADSL2+, SHDSL, SDSL, VDSL and xDSL.

DSLAM
Digital subscriber line access multiplexer.
A device, located at the central office of a DSL provider, that separates and routes the voicefrequency signals and data traffic on a DSL line.

DSP
Digital signal processing.
The study of signals in a digital representation and the processing methods of these signals.

DTH
Digital-to-home.
A satellite television system that allows end users to receive signals directly from geostationary satellites. The term DBS (Direct broadcast satellite) is also used.

DTT or DTTV
Digital terrestrial television.

DTV
Digital television.
A system for broadcasting and receiving video and sound through digital signals rather than through traditional analogue signals.

Duct
A tube or passage that confines and conducts cables (copper or fibre optic) of a physical network.

DVB
Digital video broadcasting.
An open standard for digital television maintained by the DVB Project, an industry consortium with more than 270 members, and published by a Joint Technical Committee (JTC) of the European Telecommunications Standards Institute (ETSI), the European Committee for Electrotechnical Standardization (CENELEC) and the European Broadcasting Union (EBU). A number of DVB standards exist including DVB-C (Cable), DVB-H (Handheld), DVB-T (Terrestrial television) and RCS (Return channel via satellite).

DVB-H
DVB-handheld.

DVB-T
DVB-terrestrial.