Terms used as applied to Data (and some Voice) Transmission over Copper Wire

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10BaseT- The Institute of Electrical and Electronic Engineers (IEEE) 802.3 specification for Ethernet over thin coax cable.

2B1Q (2 Binary, 1 Quaternary) -- A one-dimensional modulation for transmitting 2 bits per symbol. 2B1Q is a 4-level PAM (pulse amplitude modulation) system used for HDSL, SDSL and ISDN BRI.



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Adjacent Binder
ALARM Circuits
Ayschronous Interface




























AAL - ATM Adaptation Layer - Standard of protocols that adapt user traffic into ATM cell format. AAL is sub-divided into Convergence Sublayer (CS) and the Segmentation and Reassembly (SAR) Sublayer. 4 types of these layers support the various AAL service classes.
  • AAL1 - AAL type 1 - Protocol standard for the transport of time-dependent Constant Bit Rate (CBR) traffic (i.e. audio and video) and the emulation of TDM-based circuits (i.e. DS1, E1). Timing information exchanged between the source and the destination. AAL1 supports QoS Class A.
  • AAL2 - AAL type 2 - Protocol standard for supporting time-dependent slow or Variable Bit Rate (VBR-RT) connection-oriented traffic (e.g. packetized and compressed audio and video). Timing information is required to be exchanged between the source and the destination. AAL2 supports QoS Class B.
  • AAL 3/4 - AAL type 3 and 4 - Protocol standard for supporting both connectionless and connection-oriented Variable Bit Rate (VBR-NRT) traffic. AAL3 supports QoS class C while AAL4 supports QoS class D. They are currently combined into one type. AAL3/4 also performs resequencing and cell identification operations. AAL3/4 services are suitable for supporting interworking with Frame Relay, SMDS and X.25.
  • AAL5 - AAL type 5 - Protocol standard for supporting connection-oriented Variable Bit Rate (VBR-NRT) data traffic and signaling messages. AAL5 supports QoS Class X. AAL5 services are suitable for supporting interworking with most data networking protocols, such as Frame Relay, SMDS, Ethernet and IP.

Adjacent Binder -- Refers to the groups of twisted pairs of copper wires within a protected coating. A binder could contain several sub-'binders' of wires. An adjacent binder refers to the 'binder' that is physically next to another 'binder'. See: unbundling

ADSL(Asymmetric Digital Subscriber Line) -- A method for moving data from client (home or business) to the Telco's CO over regular copper phone lines. An ADSL circuit must be configured to connect two specific locations (point to point). In that regard, ADSL is similar to leased line modems. It is important to note that ADSL and normal "POTS" are allowed to CO-exist simultaneously over the same copper pair in most instances. Speeds vary significantly by distance, cable noise, modulation type (DMT or CAP) and manufacturer. Downstream speeds vary from 128Kbps to 8Mbps. There are some discussion of 50Meg via VDSL (Loosely related) Some supporters of ADSL and RADSL have a claimed (not necessarily founded) range of downstream speeds depending on distance:

Up to: 18,000 feet 1.544 Mbps
16,000 feet 2.048 Mbps
12,000 feet 6.312 Mbps
9,000 feet 8.448 Mbps


ASCII (American Standard Code for Information Interchange) -- Worldwide standard for the code numbers used by computers to represent all the upper and lower-case Latin letters, numbers, punctuation, etc. There are 128 standard ASCII codes, each of which can be represented by a 7 digit binary number: 0000000 through 1111111.

Asynchronous Interface -In serial data transmission interfaces, refers to the data that does not require an associate clock on another pin to indicate the voltage levels on the send and received data pins. Asynchronous data requires a start and stop bit to frame each data character. Asynchronous interfaces are the popular method of data in and out of Personal Computers. RS232 and V.24 / V.28 are a popular Asynchronous serial Interface but also can be a Synchronous Interface by adding the clocking pins.

ATM (Asynchronous Transfer Mode) -- A method of communication which can be used for both LAN and WAN technologies. Today, in many instances, separate networks are used to carry voice, data and video information-mostly because these traffic types have different characteristics. For instance, data traffic tends to be in random block lengths at intermittent periods - not needing to communicate for an extended period of time and then needing to communicate large quantities of information as fast as possible. Voice and video, on the other hand, require more consistency in the amount of information required-but are very sensitive to when, and the order the information arrives. Theoretically with ATM, separate networks will not be required. .ATM uses fixed length packets or cells. ATM is the only standards based technology, which has been designed to accommodate the simultaneous transmission of data, voice and video. ATM is the emerging standard for communications. This is possible because ATM is available at various speeds from Megabits to Gigabit speeds. ( See: Frame Relay

ATU-C (ADSL Transceiver Unit - Central office)

ATU-R (ADSL Transceiver Unit - Remote) - Originally conceived by the ADSL Forum as the designation for "ADSL-CO" equipment and "ADSL-Remote" equipment. The CO is the chassis mount side and the R is the customer premsis(CPE) side. More recently, with the invent of several forms of xDSL equipment, the ATU-C/R designation is a generally accepted term for other types of DSL services including RADSL, SDSL, HDSL, HDSL2 and even IDSL.



Copyright 1997-2008 Floyd Kling 
- All Rights Reserved -