The second edition of this accessible book provides readers with an introductory treatment of communication theory as applied to the transmission of information-bearing signals. While it covers analog communications, the emphasis is placed on digital technology. It begins by presenting the functional blocks that constitute the transmitter and receiver of a communication system. Readers will next learn about electrical noise and then progress to multiplexing and multiple access techniques. ?? Introduction. ?? Fourier Representation of Signals and Systems. ?? Amplitude Modulation. ?? Angle Modulation. ?? Pulse Modulation: Transition from Analog to Digital Communications. ?? Baseband Data Transmission. ?? Digital Band-Pass Modulation Techniques. ?? Random Signals and Noise. ?? Noise in Analog Communications. ?? Noise in Digital Communications. ?? System and Noise Calculations. Appendix 1: Power Ratios and Decibel. Appendix 2: Fourier Series. Appendix 3: Bessel Functions. Appendix 4: The Q-Function and Its Relationship to the Error Function. Appendix 5: Schwarz's Inequality. Appendix 6: Mathematical Tables. Appendix 7: MATLAB Scripts for Computer Experiments to Problems in Chapters 7-10. Appendix 8: Answers to Drill Problems.