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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