There are many valuable and useful books on electrical communication
(References 1-5 are some examples), but they have certain disadvantages
for the beginner. The more advanced books present some things in a basic
way, but they are very narrow for an introduction to communica- tion.
The introductory books are broader but still narrow by our stan- dards.
Further, they often pick things out of thin air rather than derive them.
This book is aimed at giving the beginner a basic understanding of a
wide range of topics which are essential in communication systems. These
include antennas and transmission, thermal noise and its consequences,
Fourier transforms, modulation and noise, sampling and pulse code
modulation, autocorrelation and power spectrum, optimum filtering,
gauss- ian noise and errors in digital transmission, data transmission,
limits on data rate including information theory and quantum limits, and
source encoding. We have not included communications traffic, switching,
and multiplexing, nor protocols for digital and computer communications.
For these, Reference 6 is excellent. In general, our book does not
discuss the circuits used for communication or the physics of radio
propagation. We assume that these will be taught in specialized courses,
but such courses are not prerequisites for this one. Chapter 1
introduces the transmission formula or antenna equation and antenna
directivity. Only a very basic sophomore physics knowledge of
electromagnetic theory is assumed. The radar equation is also treated.
