Lee & Varaiya: Structure and Interpretation of Signals and Systems
This book introduces the mathematical models used to design and understand signals and systems. It is intended for students interested in developing a deep understanding of how to digitally create and manipulate signals to measure and control the physical world and to enhance human experience and communication.
Berkeley Course
This book is used at Berkeley in EECS 20n,
an undergraduate class introducing signals and systems
to majors in electrical engineering and computer sciences.
The course website is
http://ptolemy.eecs.berkeley.edu/eecs20/.