User Manual

AirLink Pro T1/E1 Rack Mount Installer’s Guide
Glossary
Rev. B - 1/97
D-3
BER Bit Error Rate. The measure of the frequency of errors in a
digital transmission, typically expressed in exponential
notation (e.g., 10
-6
BER).
Blue Alarm Signal An unframed all-ones bit pattern sent by equipment at the far
end to indicate that an alarm condition exists upstream in a
circuit leading to the downstream equipment. Also known as
an All Ones Keep-Alive or Alarm Indication Signal (AIS).
burst A sequence of signals counted as a unit in accordance with
some specific criterion or measure.
burst timing A form of timing in which the receiving device is
synchronized to the transmitting device by receiving bursts of
data.
cable loss The amount of signal attenuation (loss) for a particular type
of cable of a given length.
coaxial cable A type of transmission line, consisting of a center conductor
(wire) surrounded by a layer of insulation, which is in turn
surrounded by a conductive shield (wire braid and/or metal
foil) and another layer of insulation.
CRC Cyclic Redundancy Check. An error-checking control
technique using the remainder of a polynomial calculation
performed on the transmitted data to determine whether
that data was corrupted.
dB Decibels. The standard unit of measure for relative signal
power.
dBm Decibels referred to 1 milliwatt. The standard unit of
measure for absolute signal power (signal power relative to
1 mW).
DCE Data Circuit Equipment. A communication device that
establishes, maintains, and terminates a session on a network.
digital line rate The digital bit rate, as determined by the standard levels of
the digital hierarchy.
DS-0, 1, 2, 3 The first four levels of the North American Standard digital
hierarchy corresponding to the line rates of 64 Kbps (one
standard PCM voice channel), 1.544 Mbps, 6.312 Mbps, and
44.736 Mbps, respectively.
DSX-1, 2, 3 The Bell System interface specifications that define the line
rate, line code (bipolar), test load, pulse shape, and power