Shaw, L. “Section VII – Communications”
The Electrical Engineering Handbook
Ed. Richard C. Dorf
Boca Raton: CRC Press LLC, 2000
The IRIDIUM system is a satellite-based, wireless personal communications network designed to permit any
type of telephone transmission—voice, data, fax, or paging—to reach its destination anywhere on earth. The
IRIDIUM constellation will consist of 66 interconnected satellites like the one shown above.
Each IRIDIUM satellite, weighing approximately 689 kg (1,500 lb), will orbit above the earth at an altitude
of 420 nautical miles and communicate directly with subscriber equipment. Each of the satellites will function
like extremely tall cellular towers and will project tightly focused beams over the ground. The low-earth orbit
of IRIDIUM satellites as well as recent advances in microelectronics make it possible to communicate with a
handheld phone.
The IRIDIUM system was conceived in 1987 by engineers at Motorola’s Satellite Communications Division.
It is being financed by a private international consortium of telecommunications and industrial companies and
is expected to begin operation in 1998. (Photo courtesy of Motorola.)
? 2000 by CRC Press LLC
? 2000 by CRC Press LLC
VII
Communications
69 Broadcasting
R.C. Dorf, Z. Wan, J.F. Lindsey III, D.F. Doelitzsch, J. Whitaker,
M.S. Roden, S. Salek, A.H. Clegg
Modulation and Demodulation ? Radio ? Television Systems ? High-Definition
Television ? Digital Audio Broadcasting
70 Digital Communication
R.C. Dorf, Z. Wan, L.B. Millstein, M.K. Simon
Error Control Coding ? Equalization ? Spread Spectrum Communications
71 Optical Communication
T.E. Darcie, J.C. Palais, I.P. Kaminow
Lightwave Technology for Video Transmission ? Long Distance Fiber Optic
Communications ? Photonic Networks
72 Networks
M.N. Huber, J.N. Daigle, J. Bannister, M. Gerla, R.B. Robrock II
B-ISDN ? Computer Communication Networks ? Local-Area Networks ? The Intelligent
Network
73 Information Theory
H.V. Poor, C.G. Looney, R.J. Marks II, S. Verdú, J.A. Thomas,
T.M. Cover
Signal Detection ? Noise ? Stochastic Processes ? The Sampling Theorem ? Channel
Capacity ? Data Compression
74 Satellites and Aerospace
D.F. DiFonzo
Satellite Applications ? Satellite Functions ? Satellite Orbits and Pointing Angles ?
Communications Link ? System Noise Temperature and
G/T
? Digital Links ? Interference ?
Some Particular Orbits ? Access and Modulation ? Frequency Allocations ? Satellite
Subsystems ? Trends
75 Personal and Office
W.C.Y. Lee, R.E. Ziemer, M. Ovan, G.D. Mandyam
Mobile Radio and Cellular Communications ? Facsimile ? Wireless Local-Area Networks for the
1990s ? Wireless PCS
76 Phase-Locked Loop
S.L. Maddy
Loop Filter ? Noise ? PLL Design Procedures ? Components ? Applications
77 Telemetry
C.H. Hoeppner
Introduction to Telemetry ? Measuring and Transmitting ? Applications of Telemetry ?
Limitations of Telemetry ? Transmitters and Batteries ? Receivers and Discriminators ? Antennas
and Total System Operation ? Calibration ? Telemetry Frequency Allocations ? Telemetry
Antennas ? Measuring and Transmitting ? Modulating and Multiplexing ? Passive Telemeters ?
The Receiving Station
78 Computer-Aided Design and Analysis of Communication Systems
W.H. Tranter,
K.L. Kosbar
The Role of Simulation ? Motivation for the Use of Simulation ? Limitations of Simulation ?
Simulation Structure ? The Interdisciplinary Nature of Simulation ? Model Design ? Low-Pass
Models ? Pseudorandom Signal and Noise Generators ? Transmitter, Channel, and Receiver
Modeling ? Symbol Error Rate Estimation ? Validation of Simulation Results ? A Simple Example
Illustrating Simulation Products
? 2000 by CRC Press LLC
Leonard Shaw
Polytechnic University, New York
LECTRICAL TECHNOLOGY has been involved in aiding communication between a sender and a
receiver of information since the advent of the electrical telegraph. The evolution of electrical commu-
nications technology has been influenced by both advances in devices for processing and transmitting
electrical signals, as well as the growth and variety of communications applications that have become essential
to modern society. A large fraction of electrical engineers are involved with some aspect of communications,
as evidenced by the size of the IEEE Communications Society, which is second only to the Computer Society.
In fact, communication between computers makes up a large part of communication system traffic, and
communication technology is playing an increasing role
within
computers as they employ multiple processors
and processors that are geographically distributed.
This section presents an overview of a variety of communication systems that have been developed to
overcome the constraints of physical communication channels by exploiting the capabilities of the electronic
and optoelectronic devices that are described elsewhere in this handbook. As a reflection of the dual influences
of electrotechnology and user applications, some of the following chapters have application themes (broad-
casting, satellite and aerospace, personal and office, and telemetry), while the rest have themes related to systems
techniques (digital, optical, network, information theory, phase-locked loop, and computer-aided design).
The conventional radio station is a prototype of a broadcasting system in which a single transmitter sends
the same message to multiple receivers. Chapter 69 reviews the basic notions of modulation needed to match
the transmitted signal to the propagation and noise characteristics of the transmission medium and outlines
recent developments in systems for high-definition television (HDTV) and digital audio broadcasting (DAB).
The chapter on digital techniques emphasizes the coding techniques used to detect and correct transmission
errors (which are inevitable even if systems can be designed to reduce their frequency of occurrence). Since the
rate of pulse transmission over a channel can be maximized by having an accurate model for the channel, such
systems are improved by continually readjusting the channel model as the characteristics change with time.
This chapter also discusses adaptive equalizers that match electrical pulse shapes to changing channels.
The development of fiber-optic cables and efficient solid-state lasers has revolutionized telephone commu-
nications. Chapter 71 describes some of the related developments in signal design and transmission for optical
systems that carry voice, video, and computer data messages.
Traditional telephone switching has evolved into a huge field of telecommunication networks, with the advent
of new media such as fiber-optic cables and satellites and the rapidly growing digital traffic such as that between
computers, and supporting e-mail and the World Wide Web. Chapter 72 describes switching and transmission
protocols and other standards that are being developed to coordinate the design of equipment that sends and
receives messages over the networks.
The chapter on information theory uses that term in a broad sense to describe mathematical models and
techniques for describing and simplifying both deterministic and random signals. These techniques can be used
for efficient communication by removing inessential information and by showing how a receiver can distinguish
useful information from noise disturbances.
Satellite and aerospace applications, described in Chapter 74, provide dramatic examples of challenging
communication environments where, due to equipment weight limitations and great distances, signals are weak
compared to the associated noise, and propagation characteristics are nonlinear.
Personal and office innovations related to communication systems are as dramatic to the ordinary citizen as
those in entertainment applications such as HDTV and digital audio. Chapter 75 describes how facsimile
systems, which are especially useful for rapid transmission of graphical information, exploit standardized
techniques for compressing black-and-white images. Also presented are new developments in modulation
techniques and propagation modeling that have been stimulated by mobile telephone and wireless network
applications.
Phase-locked loops are presented in Chapter 76 as good examples of electronic systems that are able to detect
weak signals whose characteristics change with time in environments where there is strong interference from
noise and from competing transmitters.
E
? 2000 by CRC Press LLC
Telemetry systems are dedicated to collection and transmission of data from many sensors, often in hostile
or distant environments. Chapter 77 describes how constraints on equipment size, weight and power often lead
to novel methods for data multiplexing and transmission.
This section concludes with a chapter on computer-aided design methods that are being exploited to design
communication systems more rapidly and effectively. Many of the problems, such as best location of a large
number of nodes in a network where the construction costs and performance measures are a complex function
of design parameters, are best solved by a designer who works interactively with computer algorithms.
Nomenclature
Symbol Quantity Unit
A
eff
effective area of antenna m
2
B
bit rate Mbytes/s
B
channel bandwidth Hz
C
capacitance F
CIR carrier-to-interference ratio
CNR carrier-to-noise ratio
D
propagation delay s
Dl
spectral width Hz
Dt
pulse spread s
E
electric field intensity V/m
f
carrier frequency Hz
F
noise figure
g
(
t
) complex envelope
G
power gain of antenna dB
H
(
x
) entropy bit
h
quantum efficiency
I
polarization isolation dB
K
loop gain
m
(
t
) modulating signal
M
bit rate delay product
Symbol Quantity Unit
M
detector gain
m
rms modulation index
n
effective input current noise
density
N
number of equalizer coefficients
NF
noise ratio
P
power density W/m
P
probability of error
PE
preemphasis factor
q
interference reduction factor
r
distance m
R
L
input impedance
W
r
correlation coefficient
s
(
t
) modulated signal
S
throughput terabit/s
SNR signal-to-noise ratio
s
2
variance of noise samples
t
R
rise time s
t
o
sample time s
Z
fs
impedance of free space 120
p W
