This book is about the transmission of digital data through time and space, as it is
practiced in the sophisticated systems of today. Since the ideas behind today’s designs
can be subtle, theory and concepts play a major role, but engineering practices
and judgments are an essential part of the story as well and need equal prominence.
This book seeks to combine a clear conceptual grounding with an engineering attitude.
Digital transmission is not an elementary subject. The author remembers learning
both digital communication theory and computer programming in the mid-
1960s, and being told that these were hard subjects that could not be taught but
rather must simply be absorbed. Both were new at the time. Since then we have
learned how to teach them, fortunately. Programming turned out to be rather easy,
and as it turned out, children could learn it and even get into mischief with it. Digital
transmission, on the other hand, is still an advanced discipline. After 30 or more
years, it is accessible to the same persons it was in the 1960s, namely, students and
practicing engineers with at least 4–5 years’ training.