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

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RADSL (Rate Adaptive DSL) -- An extension of ADSL to include a wide variety of data rates depending on the line's transmission capability. While generally used for CAP/ADSL, a DMT/ADSL also can vary speed depending upon line conditions, therefore RADSL may be either symmetric or asymmetric, CAP or DMT based.

Rate/Reach -- Rate vs Reach - The relationship between the data speed, (Rate) and the distance (Reach) that a particular data speed can be obtained. The two components are inversely proportional. i.e. the further this data must travel, means the lower the throughput. The longer distances insert the outside impairments that degrade the transmitted carrier signal and therefore lower data throughput. Noise, copper diameter and length of the copper are the main factors that must be considered when calculating this relationship.

RBOC (Regional Bell Operating Company) -- One of the seven US holding companies (also called Baby Bells) that were formed to own the Local Exchange Carriers (LECs) created by the divestiture of AT&T (also called the breakup of Ma Bell), which occurred in 1984. Each RBOC own the previously AT&T-owned telephone companies in a specific geographic region. Since the break up, slowly these RBOCS have been merging.

RJ-11 -- A six position telephone plug and mating jack (receptacle) usually holding 4, but capable of hold up to 6 wires. RJ-11's are the well-known telephone jacks you find in your house. They could be found with 2, 4, or 6 wires that corresponds to 1, 2 or 3 telephone lines in a single jack

RJ-27 -- Connector holding 100pins. Normally used in high-density chassis applications to manage 50 pairs of telco wires.

RJ-45 -- An eight position telephone plug and mating receptacle holding up to 8 wires. Similar to RJ-11 but slightly larger. In Telco applications, the extra pins were originally (and still) used for 'exclusion switch' detection and 'programmable transmit levels' for older analogue leased line modems. The RJ45 one type of connector used in many Ethernet connections.

Router -- A special-purpose computer (or software package) that handles the connection between 2 or more networks. Routers spend all their time looking at the destination addresses of the packets passing through them and deciding which route to send them on. See: Packet Switching, Server

RS-232 -- The Electronic Industries Association (EIA) standards for serial data communications for various computer, terminal and modem interfaces. RS-232 is the most common asynchronous and synchronous serial line standard especially for personal computers for lower data speeds (Usually under 230Kbps). RS-232 is the EIA equivalent of ITU-T V.24 and V.28. RS-232 specifies the gender and pin use of connectors. 25-way D-type connectors are most common but DB9s are also common, especially in laptops. By definition, maximum speed is 20Kbps but higher speeds (115Kbps to 230Kbps) are commonly used. See: V.24, V.28, USB, IEEE-1394

RS-422A-The Electronic Industries Association (EIA) standard for the electrical characteristics of balanced-voltage digital interface circuits.

RS-423A -- The Electronic Industries Association (EIA) standard for the electrical characteristics of unbalanced-voltage digital interface circuits.

RS-449 -- The Electronic Industries Association (EIA) standard that is compatible with RS-232C, but supports higher data rates at greater distances. The RS-449 interface is a 37-pin connector that supports transmission at data rates up to 2 Mbps at distances up to 200 feet between data communications equipment (DCE) and data terminal equipment (DTE). The additional connections implement more control functions.

RS530 -- The RS530 interface is a generic connector specification not an actual interface. The connector pinning can be used to support RS422, RS423, V.35 X.21 and other connections. It is a 25pin DB25 which signaling is almost identical to RS232.

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