standards and guidelines for communication sites - Radio And ...

GLOSSARY CHAPTER 1: INTRODUCTION
RFP: Request For Proposal.
RF Distribution System: A system that combines RF signals so that multiple transmitters and
receivers tuned to different frequencies can use a single antenna.
RGB: Rack Ground Bus Bar.
RH: Relative Humidity.
RMS: Root-Mean-Square.
R-Value: A standardized rating system of thermal insulation effectiveness. Higher values denote
greater insulating effectiveness.
SAD: Silicon Avalanche Diode.
Safety climb: Equipment that is attached to a tower to safely enable tower climbing.
Sag: A root mean square (RMS) reduction in the AC voltage, at the power frequency, for durations
from a half cycle to a few seconds (IEEE STD 1100-1999). (see also Swell). It is a multi-cycle, undervoltage
condition that can be caused by ground faults, undersized power systems, lightning, or a sudden
start-up of a large electrical load. The IEC terminology for sag is “dip.”
SBCCI: Southern Building Code Congress International, Inc.
Seismic rating: Any of several standardized systems of rating an area's probability and intensity of
seismic activity based on geological and empirical data. This publication references the Moment
Magnitude (MM) rating standard recognized by the Uniform Building Code. Ratings of “0” (least
probability with the least intensity) through “4” (greatest probability with the greatest intensity) are
accordingly assigned to various regions.
Separately Derived System: A premises wiring system in which power is derived from a
transformer or converter winding. It has no direct electrical connection, including a solidly connected
grounded circuit conductor, to the supply conductors originating in another system.
Service Entrance: The point at which the utility enters a facility and the utility ground rod is
attached.
Shelter: A Permanent structure built on a foundation that contains communications equipment and
related ancillary support systems, and may contain other unrelated equipment and/or facilities. A
Shelter shall be suitable for temporary human occupancy during equipment installation, maintenance,
and use.
Silicon Avalanche Diode: A two-terminal voltage protection device in which resistance across the
device markedly decreases when the voltage across the device reaches a specified threshold.
Simulcast: A system configuration using simultaneous transmissions of information on the same
frequencies. This configuration extends communications over a large coverage area. Each repeater on
the same frequency has identical transmit parameters to ensure the intended transmission format.
SPD: Surge Protection Device
Swell: An increase in RMS voltage or current at the power frequency for durations from 0.5 cycles to
1.0 minute (IEEE STD 1100-1999 and IEEE STD 1159-R2001).
TETRA Terrestrial Trunked Radio
Total Harmonic Distortion (THD): The ratio of the root square value of the harmonic content to the
root square value of the fundamental quantity, expressed as a percent of the fundamental (IEEE STD
1100-1999).
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