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Cable, Network Acronyms, Glossary and Term

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D

D-Subminiature: A common connector type that utilises multiple pins and a D shaped housing.

D: Delta or data channel, 16 kBit/s in BRI, 64 kBits in PRI, used for signalling and perhaps some packet data.

D3: Third generation channel blank, 24 channels on one T1

D4: Fourth generation digital bank, up to 48 voice channels on two T1's or one T1C.

D5: Fifth generation channel bank with ESF.

DA: Destination address, field in frame header, 802.

D/A: Digital to analogue decoding of voice signal

D/A: Drop and Add, similar to drop and insert.

DARPA: Defence ARPA, formerly just ARPA.

DAS: Dual Attach, Access Station, device on a main dual FO rings, 4 fibres FDDI

DASS: Digital Access Signalling, protocol for ISDN D channel in the UK.

dB: Decibel, 1/10th of a bel; 10 log (x/y) where x/y is a ratio or like quantities, i.e. power.

dBm: Decibel level referenced to 1mW at 1004 Hz into 600 ohms impedance.

dBm0: Power that would be at zero TLP reference level.

dBrn: Power level relative to noise, dBm + 90

dBrn: dBrn through a C weighted audio filter, matches the ear's response.

DB25: Code for 25 pin connector specific for RS232 interface.

D.C.: Direct current used for some signalling forms

DCC: Data Communications Channel, overhead connection in D bytes for SONENT management.

DCE: Digital circuit termination equipment

DCE: Data Communications equipment

DCS: Digital Cross Connected, DACS

DDCMP: Digital data Communications message protocol.

DDD: Direct distance dialling, refer to PSTN

DDS: Digital data system, network that supports DATAPHONE digital services

DDSD: Delay Dial Start Dial, a start stop protocol for dialling into a CO switch

DES: Data Encryption Standard, moderately difficult to break

D/I: Drop and Insert a mux function or type

Dielectric: The insulating material that separates the centre conductor and the shielding.

Digtal Camera cable finder

Digital Flat Panel connector:	was used in earlier digital LCD computer monitors. It was restricted by resolution and has been superseded by DVI. DVI-I graphics cards can be connected to DFP monitors by an adapter. The image shows a DFP socket.

DIP: Dual In-line Package, for silicon chips and switches

DIS: Draft International Standard, preliminary form of OSI standard

DISC: Disconnect, command frame sent between LLC entities, layer 2.

DLC: Data Link Connection, one logical bit stream in LAPD, layer 2.

DLC: Digtal Loop Carrier, mux system to gather analogue loops and carry them to CO.

DLCI: Data Link Connection Identifier, address in a frame, I.122

DLE: Data Link Escape, ESC.

DLL: Data Link Layer, Layer 2 OSI.

DM: Disconnected Mode, LLC frame to reject a connection request, layer 2.

DMC: Differential Manchester Code, pulse pattern that puts transition at centre of each bit time for clocking, transition at start of period for 0, 802.5

DMI: Digitally Multiplexed Interface, AT&T interface for 23 64 Kbits channel and a 24th for signalling.

Drawing: The mechanical process of making conductors smaller by forcing through dies.

DVI:

Digital Visual Interface (Digital only) connector:	is used in LCD computer monitors. A competitor to DFP, it allows higher resolutions and will connect to digital DVI and DFP graphics cards (with an adapter.). It is being superseded by DVI-I.

Digital Visual Interface (Integrated) Connector:	is the most versatile of connectors for monitors. A DVI-I connection on a monitor will connect to DVI-I graphics cards and to DVI-D, DFP and 15 pin VGA analogue cards with suitable adapters. Conversely, you can connect DVI-D and DFP monitors to DVI-I cards with suitable adapters.