Principles of Communications, systems, modulation, & Noise,

Textbook: Ziemer/Tranter, edition7, John Wiley.

In the first chapter, Fourier series of both trigonometric and exponential are presented. Fourier Transform as a generalization of Fourier series is developed that permits the transformation of both non-periodic and periodic signals. Discrete spectrum plots of Amplitude and phase of a periodic function provide a representation of the function's  frequency content.