The first part (Deterministic Signals) of the course deals with the basic understanding of Fourier analysis techniques for analog and digital signals. Such concepts are applied to the study of one-dimensional linear systems, with specific emphasis to problems related to the field of communication systems. The second part of the course is specifically devoted to an introduction to the field of probability and random processes that bridges the gap towards the applications taught in third-year courses. These concepts allows the student to understand the fundamentals of the communication systems and their applications.