MDS 05-3627A01, Rev. D
LEDR Series Installation & Operation Guide
G-3
Protected Operation—Refers to the practice
of providing redundant transmit and receive
signal paths through the radio (antenna to cus-
tomer payload interface) so that no single point
of failure in a single radio will interrupt the
link. This feature is also referred to as 1+1
Operation and is usually provided by operating
the system using Hot Standby.
PSC—Protected Switch Chassis. Chassis
holding data and RF control/switch circuitry in
a redundant/protected configuration.
QAM—Quadrature Amplitude Modulation.
Uses phase shifts and amplitude changes to
send high-speed data in a comparatively
narrow RF channel. See also QPSK.
QPSK—Quadrature Phase Shift Keying. Uses
four levels of phase shift to send high-speed
data with a higher system gain than QAM mod-
ulation. See also QAM.
Redundant Switching—Refers to the practice
of switching between transmit signal paths
when a fault condition occurs on the currently
active radio.
rai—Remote Alarm Indication. Sometimes
referred to as “yellow” alarm.
RSSI—Received signal strength indication.
Expressed in dBm.
SNMP—Simple Network Management Pro-
tocol. A common network management system
(NMS) protocol used to monitor and control a
communications network
SNR—Signal-to-noise ratio. Expressed in
decibels (dB).
SWR—Standing Wave Ratio. A parameter
related to the ratio between forward transmitter
power and the reflected power from the antenna
system. As a general guideline, reflected power
should not exceed 10% of the forward power
(2:1 SWR).
TFTP—Trivial File Transfer Protocol. A stan-
dard network protocol used to send and receive
files between two devices.
Warm Standby—Refers to a state of the inac-
tive (standby) transceiver in a Protected or
Redundant configuration. In a Warm Standby
configuration, the standby transceiver is not
transmitting and must be keyed after switching.
