"Communication Systems is based on the syllabi of the various universities, covering all the theoretical and mathematical aspects related to topics. The language used in explaining various concepts is extremely simple and understandable. Since proper understanding of the subject would involve a serious attempt to solve a variety of problems, a wide variety of problems with their step by step solutions are provided for every concept. This book will serve the purpose of a text to engineering students of degree, diploma AMIE and a useful reference for students preparing for GATE, UPSC and other technical competitive exams. Keeping above points in mind this book has been developed right from the basic principles of the communication system and to its zenith in the development of analog communication techniques so far. A set of questions has been given at the end for the readers to increase their understanding of the subject and to encourage further reading. "