This book, covering the fundamentals of the theory of signals, systems and stochastic process, is intended to provide a firm understanding of the concepts, theories, processes and mathematical tools necessary for dealing with various kinds of signals and their interaction with systems. This knowledge forms the basis for the study of other engineering subjects such as circuit design, power systems, automatic control, communications, and signal processing. Although the contents have been structured keeping in view the requirements of JNTUH?s electronics and communication engineering undergraduate programme, it will also meet the requirements of the curriculum of most other technical universities in India.