World has come very close due to rapid advancements in communication technologies. High speed computers and microprocessors, broadband communication channels, satellites, fiber optic cables have made communication very effective in wide range of applications. This book mainly describes basic principles of Communication Theory. This book is useful for Students studying Information Technology, ECE of Anna University , Affiliated Colleges & other Universities. Contents : Preface Acknowledgement Introduction Unit 1 - Amplitude Modulation Unit 2 - Angle Modulation Unit 3 - Random Process Unit 4 - Noise Characterisation Unit 5 - Sampling and Quantization University Questions