Page 36 - Fundamentals of Communications Systems

1.2 Chapter One

gripped the world’s major technology innovation centers. The invention of the
semiconductor transistor and the impact of Moore’s law have spurred the march
of innovation since the early 1980s. The evolving power of the microprocessor,
the embedded computer, and the signal processor has enabled algorithms, that
were considered preposterous at their formulation, to see cost-effective imple-
mentation. Distilling this 150 plus years of innovation into a small part of an
engineering curriculum is a challenge but one this book arrogantly attempts.
The relative growth rate of electronic communications is phenomenal. Con-
sider, for example, transatlantic transmission of information using undersea
cables. This system has gone from roughly 10 bits/s in 1866 to roughly 10 12 bits/s
in the year 2000 [Huu03]. The world community has gone in a very short period
of time from accepting message delivery delays of weeks down to seconds. The
period from 1850–1900 was one filled with remarkable advances in technol-
ogy. It is noteworthy that the advances in communications prior to 1900 can
almost all be attributed to a single individual or invention. This started to
change as technology became more complex in the 1900s. Large corporations
and research labs began to be formed to support the large and complex sys-
tems that were evolving. The evolution of these technologies and the personal-
ities involved in their development are simply fascinating. Several books that
are worth some reading if you are interested in the history of the field are
[Huu03, Bur04, SW49, Bra95, Les69]. It is a rare invention that has an uncon-
tested claim to ownership. These intellectual property disputes have existed
from the telegraph up until modern times, but the tide of human innovation
seems to be ever rising in spite of who gets credit for all the advances.
The ability to communicate has been markedly pushed by advances in tech-
nology but this book is not about technology. From the invention of the mi-
crophone, to the electric motor, to the electronic tube, to the transistor, and
to the laser, engineers and physicists have made great technological leaps for-
ward. These technological leaps have made great advances in communications
possible. As technology has advanced, the job of an engineer has become multi-
faceted and specialized over time. What once was a field where nonexperts
1
could contribute prior to 1900 became a field where great specialization was
needed in the post 1900 era. Two areas of specialization formed through the
1900s: the devices engineer and the systems engineer. The devices engineer is
focused on designing technology to complete certain tasks. Devices engineers,
for example, build antennas, amplifiers, and/or oscillators are heavily involved
with current technology. Systems engineers try to put devices together in a way
that will work as a system to achieve an overall goal. System engineers try to
form mathematical models for how systems operate and use these models to
design and specify systems. This text is written with a systems engineering
perspective. In fact, as a reflection of this focus, this book has exactly one cir-
cuit diagram. This is not an academic shortcoming of this book as the author,

1 For example, Samuel Morse of Morse code and telegraph systems fame in the United States
was a professor in the liberal arts.