For one/two-semester, senior/graduate-level First Communications courses in Communication Systems and Digital Communication in the department of electrical engineering for electrical engineering students. Using three parallel approaches-rigorous mathematical, graphical, and intuitive-this text offers students a practical and deep understanding of communication systems. Emphasis on the theme of cost vs. performance tradeoffs throughout the book provides a framework and motivation for all the topics examined in it. Fundamentals of frequency domain analysis are reinforced through graphical techniques and communications-oriented examples.