User's Manual

G-2 LEDR Series Installation & Operation Guide MDS 05-3627A01, Rev. D
Fade Margin—The maximum tolerable reduc-
tion in received signal strength which still pro-
vides an acceptable signal quality. This
compensates for reduced signal strength due to
multipath, slight antenna movement or
changing atmospheric losses. Expressed in
decibels.
fas—Frame Alignment Sequence.
FEC—Forward Error Correction. Extra data is
added to the transmitted signal to allow for
detection and correction of some transmission
errors.
Frame—A segment of data that adheres to a
specific data protocol and contains definite
start and end points. It provides a method of
synchronizing transmissions.
Fresnel Zone—A point of maximum width or
girth of the transmitted radio signal. Obstruc-
tions in this region (the “first Fresnel zone”)
can have a detrimental effect on reception
quality. As a general rule, 60 percent of the first
Fresnel zone should be free of obstructions in a
well designed system. (Additional consider-
ations are also required when planning a micro-
wave path.
G.703—The ITU standard defining the charac-
teristics of digital interfaces (pulse shape,
voltage levels, etc.). This applies to high-speed,
three-level data being sent over coaxial or
twisted pair lines.
G.821—The ITU standard by which data trans-
mission quality is measured. The analysis con-
siders available vs. unavailable time.
Half-Power Beamwidth—The customary
way of measuring the width of a directional
antenna’s radiation pattern. This beamwidth is
measured in degrees between the half-power
points (the point at which the power is reduced
3 dB with respect to the main beam).
HDB3—High density bipolar order of 3. A line
interface standard for E1 transmission that
employs coding to eliminate data streams with
four or more consecutive zeros.
Hitless Switching Operation—Refers to the
practice of switching between receive signal
paths without introducing bit errors or timing
slips. This feature is required for space or fre-
quency diversity applications.
Hot Standby—Refers to a state of the inactive
(standby) transceiver in a Protected or Redun-
dant configuration. In a Hot Standby configura-
tion, the standby transceiver is actively
transmitting.
ITU—International Telecommunications
Union.
kbps—Kilobits-per-second.
Linecode—Refers to the data coding format
used by the radio for the line interface. (It does
not pertain to the radio’s modulation coding.)
The available linecode selections are HDB3
and AMI.
Mbps—Megabits-per-second.
MIB—Management Information Base. The
MIB stores SNMP messages that are directed
to the management console. This can include
Server events, statistical data and system que-
ries.
Multipath Fading—Signals arriving at the
receiver out of phase which have a tendency to
cancel each other. It is caused by reflections of
the transmitted wave and results in distortion at
the receiver or weak received signal strength.
Multiplexer—A signal processing unit that
combines multiple streams of data into one for
transmission across a single data channel.
NMS—Network Management System. A soft-
ware application used to configure, diagnose
and monitor a communication network. The
LEDR radio’s SNMP program is an example of
an NMS.
Protected Radio—A radio configuration
where there are redundant modules that auto-
matically become active in the event of a
failure.