Engineers are professional inventors, researchers, and developers. Education imbues each engineer
with discipline-specific knowledge. Combining the different disciplines allows engineers to solve
more complex problems.
Our original effort in writing this book was to create a starting point for those in
the business community who did not have a high level of technical expertise but
needed to have some understanding of the technical functions of their information
and communication technologies (ICT) in a corporate environment. As was true
with the first edition of this book, if you are already an engineer, find some other
form of pleasure reading—this text is not designed for you!
This book is intended for the graduate or advanced undergraduate
engineer. The primary motivation for developing the text was to present a
complete tutorial of phase-locked loops with a consistent notation. I believe
this is critical for the practicing engineer who uses the text as a self-study
guide.
Until the mid-1990s most readers would probably not have even come across the term soft-
ware defined radio (SDR), let alone had an idea what it referred to. Since then SDR has made
the transition from obscurity to mainstream, albeit still with many different understandings of
the terms – software radio, software defined radio, software based radio, reconfigurable radio.
The serious study of the practice of how to determine the appropriate content of a
specification is a seldom-appreciated pastime. Those who have the responsibility to
design a product would prefer a greater degree of freedom than permitted by the con-
tent of a specification. Many of those who would manage those who would design
a product would prefer to allocate all of the project funding and schedule to what
they consider more productive labor. These are the attitudes, of course, that doom a
project to defeat but they are hard to counter no matter how many times repeated by
design engineers and managers. A system engineer who has survived a few of these
experiences over a long career may retire and forget the past but we have an endur-
ing obligation to work toward changing these attitudes while trying to offer younger
system engineers a pathway toward a more sure success in requirements analysis and
specification publishing.
When thinking about mobile radio engineers there is a tendency to
assume that the engineering function relates solely to the technical
aspects of the network, such as the equipment design or the network
design. That is certainly a key part of the role of a mobile radio engineer.
However,increasinglyengineersarerequiredtointeractwithprofession-
als from other divisions. The “complete wireless professional” should
know about mobile networks; fixed networks; other types of mobile
systems; regulatory and government policy; the requirements of the
users; and financial, legal, and marketing issues.
When thinking about mobile radio engineers there is a tendency to
assume that the engineering function relates solely to the technical
aspects of the network, such as the equipment design or the network
design. That is certainly a key part of the role of a mobile radio engineer.
However,increasinglyengineersarerequiredtointeractwithprofession-
als from other divisions.
Since the original publication of Manual 74 in 1991, and the preceding
“Guidelines for Transmission Line Structural Loading” in 1984, the
understanding of structural loadings on transmission line structures has
broadened signifi cantly. However, improvements in computational capa-
bility have enabled the transmission line engineer to more easily deter-
mine structural loadings without properly understanding the parameters
that affect these loads. Many seasoned professionals have expressed
concern for the apparent lack of recent information on the topic of struc-
tural loadings as new engineers enter this industry. The Committee on
Electrical Transmission Structures is charged with the responsibility to
report, evaluate, and provide loading requirements of transmission struc-
tures. This task committee was therefore formed to update and revise the
1991 manual.
December 2007, San Jose, California: It seems a long time ago.
I walked into a big networking company to head their small
Power over Ethernet (PoE) applications team. Surprisingly,
I hardly knew anything about PoE prior to that day, having been a
switching-power conversion engineer almost all my life. But it
seemed a great opportunity to widen my horizons. As you can see,
one notable outcome of that seemingly illogical career choice five
years ago is the book you hold in your hands today. I hope this small
body of work goes on to prove worthy of your expectations and also
of all the effort that went into it. Because, behind the scenes, there is a
rather interesting story to relate—about its backdrop, intertwined
with a small slice of modern PoE history, punctuated by a rather res-
tive search for our roots and our true heroes, one that takes us back
almost two centuries
