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title of Microwave Electronic Circuit Technology. In particular, there is no
discussion of transistor circuits or other active devices. To reflect this in the
title, I would suggest the inclusion of the word passive.
R. SLOAN Department of Electrical Engineering and Electronics, UMIST
Fiber-Optic Communication Systems, 2nd Ed.: G. P. AGRAWAL
(1. Wiley, 1997, 555 pp., £50)
This book is a timely update of the very good first edition produced in 1992.
Thus in my review I have made a special attempt to indicate the places where
significant changes have occurred. To a large extent, the book has maintained
its previous structure and many of the alterations are incremental. However,
because the clearer style of printing has been used and the section layout has
been improved, the difference appears greater than it actually is. The book
covers an extremely large range of topics and provides an excellent starting
point for graduate students in optical fibre communications.
Chapter 1 provides an introductory overview of fibre systems plus some
basic communication principles and is largely the same as the first edition.
The changes made reflect progress in the installation of optical fibre systems,
for example the TAT undersea series. Additionally, the SONET/SDH standards,
now firmly established, are given in tabular form. In common with all the
following chapters, the references have been updated and increased in number.
The second chapter is concerned with the characteristics of the optical fibre
as a transmission channel and contains material on physical manufacture, loss
mechanisms, propagation and dispersion. The characteristics of some commer-
cial fibres have been added in a table, to reflect the fact that fibre is now an
established and routinely used medium. Also there is a topical retitling of the
section on polarisation mode dispersion, now a major area of research in
high-speed systems, for which new references have been added.
Chapter 3 covers the area of optical transmitters and includes light emitting
diodes (LED), lasers and the design of transmitters. There are some new
sections covering recent advances in source technology, for example the use of
cavity effects to produce tunable, resonantly enhanced LEDs. This is comple-
mented within the laser section of the chapter by discussion of multisection
distributed feedback and superstructure lasers for tuning. There is a short
paragraph on the topical area of vertical cavity surface emitting lasers, which
have taken on importance for low cost and interconnection applications. The
performance improvements resulting from the integration of lasers and driving
circuitry to form optoelectronic integrated circuits are also indicated.
Receivers form the basis of chapter 4, being the natural complement to the
previous chapter. The initial portion covers detectors in a logical and straight-
forward fashion, that is pn diodes, pin diodes, avalanche photodiodes (APDs)
and metal-semiconductor-metal devices. The last of these is an addition since
the first edition and enables discussion of an integrated receiver structure.
Within the pin and APD sections, there are tables of common material
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characteristics and structures. There is then a sizeable chunk concerning
receiver design and performance at an introductory level using the gaussian
approximation only.
The fifth chapter covers the design and performance of optical systems, both
long haul and local area. A section on long haul systems with in-line optical
amplifiers has been added plus details of fibre links installed in recent years.
Additionally, there is new data concerning reflection feedback and noise
including consideration of the expanding area of vertical cavity lasers.
Coherent communications are treated in chapter 6, which is largely
unchanged in this edition, reflecting the slowdown in this field as a result of
the impact of optical amplifiers on the performance of direct detection systems
in recent years. The sections within the chapter cover the essential features of
coherent systems: modulation and demodulation, error rates and perform-
ance limits.
Chapter 7 is concerned with multiplexing and is a very good introduction
to the growing range of techniques available for sharing optical bandwidth
between many users. A system categorisation, distinguishing between point-to-
point, distribution and multiple access networks comes first. This allows a
rapid tour of the topical issues, such as passive optical networks (PONs) and
hybrid fibre coaxial technology, to be made. After this, sections concerning
wavelength division multiplexing (WDM) are considerable, particularly the
coverage of WDM components. This is wholly justified, as there has been a
huge amount of research effort in this field since the first edition. In addition,
the concepts and implementations of optical time division multiplexing are
reviewed. Subcarrier multiplexing (SCM) warrants a reasonable section in
which coverage of analogue systems and digital coherent SCM is presented.
The final section on code division multiplexing is rather disappointing, despite
the statement contained in it that the area has been the subject of considerable
interest in the 1990s.
Chapter 8 covers optical amplification, describing the principles, semi-
conductor devices, fibre-based amplifiers and system applications. The area
has undergone considerable change since the first edition of the book and this
is reflectedwithin the chapter. There is a completely new part on praseodymium
doped fibres, which have recently reached maturity. Optical preamplification
has likewise made great strides over this time and the insertion of a paragraph
to indicate this begins a final section that has been substantially reorganised.
The impact of dispersion and nonlinearities are discussed since these have been
major areas of research in the 1990s; likewise the efforts in gain flattening for
WDM systems produce a short section but almost thirty references for the
interested reader.
The ninth chapter is completely new and extremely timely. It reviews the
area of dispersion compensation, which has expanded now that fibre communi-
cations has moved to a situation where dispersion, rather than attenuation, is
the major limit in high speed transmission. This has led to the development of
many dispersion compensation schemes during the 1990s based on both pre-
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and post-compensation. These are well summarised, with 139 references for
readers to pursue any topic further.
The tenth and final chapter concerns soliton-based communications begin-
ning with the soliton physics and progressing to a very substantial treatment
of soliton-based communication systems. This chapter has been greatly
expanded to reflect the research effort that has occurred in this area since the
first edition. The number of pages has been more than doubled and the
references have grown in proportion to number in excess of two hundred. A
section discussing the fundamentals of soliton-based transmission covers, inter
alia, the transmission of information using solitons, methods for soliton
generation and soliton amplification. Soliton system design is tackled via the
average soliton approach, with subsequent discussion ofjitter and experimental
progress. The final two sections extend the coverage to high capacity and
WDM soliton systems.
There is a selection of problems at the end of each chapter but no solutions
are provided. Although the inclusion of full worked answers is not perhaps
appropriate to a mainly graduate level text, the addition of numerical answers
would be helpful. For those in possession of the first edition, I think the
balance just tips in favour of a purchase unless funds are very short. Other
readers searching for a wide ranging and up to date view of fibre-optic
communication systems would do well to purchase this book.
MARK LEESON Department oj Electrical and Electronic Engineering,
Manchester Metropolitan University
Phase-Locked Loops - principles and practice: P. V. BRENNAN
(Macmillan, 1996,204 pp., £22 hardback)
The slim volume is a concise guide to the theory and design of phase-locked
loops. It is written from an engineering viewpoint, and it is liberally illustrated
with block and circuit diagrams, waveform and phasor diagrams, some
photographs, tables of results and graphical responses. The book is aimed at
design engineers and the more advanced students of electronics and tele-
communications. Laplace transforms are used throughout to analyse system
performance as required.
There are nine chapters in all, as follows:
• Chapter 1 (Introduction) describes the basic phase-locked loop (PLL) with
its 'curious' blend of both analogue and digital techniques. A few basic
applications are mentioned to whet the reader's appetite and to generate
initial interest.
• Chapter 2 (Loop Components) then describes the four basic loop-
components (viz. the phase detector, the loop filter, the voltage-controlled
oscillator, and the frequency divider) in detail, along with their behaviour
and characteristics.
• Chapter 3 (Loop Basics) explains how a PLL may be designed using
standard control-systems techniques. Some basic loop filters and their
responses are considered, and then analysed mathematically. Some
