MDS 05-3627A01, Rev. D
LEDR Series Installation & Operation Guide
G-1
GLOSSARY
AIS—Alarm Indication Signal. Indicates all
ones are being sent or received.
AMI—Alternate Mark Inversion. A bipolar
format where consecutive marks (ones) have
the polarity inverted. Spaces (ones) are repre-
sented by zero volts. This technique prevents
long sequences of positive or negative volt-
ages.
Analog—Signals with a continuously varying
amplitude, such as the human voice.
BERT—Bit-error rate test. The results of a
BERT are normally expressed as a ratio (power
of 10) of the number of bits received in error
compared to the total number received.
BER—Bit-error rate. See also BERT.
Bit—Binary digit. The smallest unit of digital
data, often represented by a one or a zero. Eight
bits usually comprise a byte.
bps—Bits-per-second. A measure of the infor-
mation transfer rate of digital data across a
communication channel.
BSLIP—Bit Slip. Protocol that allows a bit to
be added or deleted without causing a reframe
sequence. Applies principally to Dutch PTT
National applications.
Byte—A digital “word” usually made up of
eight bits.
cas—Channel Associated Signalling.
dBi—Decibels of gain relative to an isotropic
radiator. (A hypothetical antenna which radi-
ates equally in all directions.) Used to express
antenna gain.
dBm—Decibels relative to one milliwatt. An
absolute unit used to measure signal power, as
in transmitter power output, or received signal
strength.
DTR—Data Terminal Ready. A control signal
sent from the radio indicating that it is ready to
transmit data.
CPE—Customer premise (provided) equip-
ment.
DCE— Data (circuit terminating) Communi-
cations Equipment. In data communications
terminology, this is the “modem” side of a
computer-to-modem connection. The trans-
ceiver is a DCE device which is designed to
connect to a DTE device.
Decibel (dB)—A measure of the ratio between
two signal levels. Frequently used to express
the gain or loss of a system.
DSP—Digital Signal Processing. A processing
technique that uses software algorithms to
filter, shape, or otherwise modify the character-
istics of a given signal. In the LEDR radio, DSP
is used primarily in modulation and demodula-
tion functions.
E1—An international telephony standard that
operates at 2.048 megabits-per-second (Mbps).
This transmission speed is commonly used
throughout the world except for North America
(which uses T1 1.544 Mbps). Framed E1 con-
sists of 30 digitized telephone channels and two
64 Kbps control channels.
EIRP—Effective Isotropic Radiated Power.
Commonly used to express the power radiated
from a gain antenna. It is equal to the power
transmitted (minus feedline loss) plus the
antenna gain.
