CHAPTER 12
COMMUNICATIONS, LIFE SAFETY, AND SECURITY SYSTEMS
OVERVIEW
This chapter covers the engineering of low-voltage auxiliary systems in buildings.
Covering basic wiring for all forms and functions of information systems, security
systems, closed-circuit television, and fiber optics, this chapter establishes rules of thumb
for the design and wiring of distributed systems. Special emphasis is placed on the
importance of signal quality matching the impedance of transmission wiring to the
frequencies called for by the terminal equipment.
Included in this chapter is a review of the fundamentals of systems electronics including a
discussion of the properties of digital and analog systems and the commonly used wiring
that support them. Each of the commonly used media is reviewed from the standpoint of
their infrastructure requirements with special emphasis on those related to compliance
with building codes.
Of critical importance is the understanding of efficient and flexible distribution of
auxiliary systems across the building infrastructure. The Selection of Wiring Systems
section details the wire-speed and transmission capacities of traditional twisted-pair
cabling groups, coaxial cable, and fiber optic systems. Electronic Industry Association
(EIA) standards for the category specifications for shielded and unshielded twisted pair
(STP and UTP) are covered in detail, as are the standards for coaxial and RGB cable. A
describes and discusses network topologies and their impact on the availability of
bandwidth and signal quality. Wide Area Networks, Virtual Private Networks, and the
Internet are discussed in light of network segmentation strategies that deploy an array of
systems options, such as traditional leased lines and today’s packetized and switched
modes of high-speed transmission. Also covered are the fundamentals of wireless
96
CHAPTER 12
COMMUNICATIONS, LIFE SAFETY, AND SECURITY SYSTEMS
QUESTIONS AND ANSWERS
12.1 What are the forms and functions of information systems?
12.2 What is the difference between analog and digital signals? Can they be
converted from one to the other?
12.3 What are the forms and functions that can be provided by radio, TV, and
computer systems?
12.4 Human hearing frequency extends over 10,000 Hz. What is the highest
frequency that can normally be transmitted by a conventional telephone
system?
12.5 What are commonly used wires for telecommunications systems?
12.6 What is fiber optics? What is an optic fiber?
12.7 Name several advantages of an optic fiber when comparing with twisted pair
or coax cables.
12.8 What is meant by critical angle in an optic fiber?
12.9 The index of refraction of glass is 1.5 (n1 = 1.5) and the index of refraction of
air is 1.0 (n2 = 1.0). What is the critical angle when light passes from glass to
air?
12.10 What are the metal compounds commonly used to generate laser in fiber
optic systems? What is the range of wavelengths in nanometers (nm)?
12.11 What is the applicable transmission speed range in Mbps for a coax cable?
A single mode optic fiber?
12.12 What are the frequency bands assigned for FM radio in the U.S.? VHF/TV
channels (2 to 6)? Cellular telephones? Satellite UHF?
12.13 What is meant by geostationary type telecommunication satellite? What is
its orbit (miles above the earth)?
12.14 What is a LAN? A WAN?
12.15 What are the disadvantages of wireless LAN?
12.16 What are the common techniques used in access control?
12.17 What are the commonly employed principles in intrusion detection?
12.18 What are the detection devices commonly used within a building?
12.19 What are the two types of telephone dialing systems?
12.20 What is PBX, DOD, and DID in a telephone system?
PBX stands for Private Branch Exchange. It is a private telephone system
12.21 What are a coded, a supervised, a zoned, and an addressable fire alarm
system?
12.22 Why are flashing or strobe lights required in fire alarm systems?
12.23 What is a public address (PA) system? What are the basic components?
12.24 What size ceiling or wall-mounted speakers are normally used in buildings
and what is the approximate area of coverage?
12.25 What wire types are normally used for sound systems? Can optic fiber be
used?
12.26 What is a time and program system? Where is it mostly installed?
12.27 How are clocks synchronized in the time-clock system?
12.28 Name as many as you can of the telecommunication systems which should be
considered for a large residence, a hospital, a hotel, and a department store.
12.29 Low voltage cabling typically does not require traditional EMT conduit.
What methods are commonly used to support low-voltage cable?
12.30 When would conduit (EMT) be necessary when installing low-voltage cable?
12.31 RGB cable is typically used for high-resolution video signals. What are the
individual video components carried by the RGB cable?
12.32 What are the two most common types of data projectors used to display
computer graphics?
12.33 The card installed in a PC workstation to connect it to a LAN or WAN is
known as?
12.34 What is the most common type of topography used for a LAN?