Digital Communications: Theory, Techniques and Applications 2e is written for students of undergraduate degree programs in engineering for a course on digital communication. The second edition of this book treats spread spectrum communication techniques as an exclusive chapter. The book starts from the basics of signals and systems, builds the preliminary concepts through the chapters on probability and random process, and information theory, and then describes the core concepts such as digital coding, multiplexing and multiple access, modulation techniques, demodulation, error control coding and spread spectrum communication. The last chapter illustrates the concepts learnt in the earlier chapters through certain applications in optical, satellite, and wireless communication domains.