This book is the result of several years of teaching and research at the Federal University of Campina Grande and Federal University of Pernambuco, Brazil. It is intended to serve as an introductory textbook for courses dealing with Communication Systems or Modulation Theory. The modulation theory is dealt with using stochastic processes, which is novel for undergraduate texts. The book is suitable for the under- graduate as well as the initial graduate levels of Electrical Engineering courses. .
