This book addresses basic concepts on digital transmission, mainly pertaining to the physical layer of a digital communication system. However, these basic concepts are also intended to allow the reader to understand more advanced topics and the associated technology. Each topic is addressed in two different and complementary ways: theoretically and by simulation. The theoretical approach encompasses common subjects covering principles of digital transmission, like notions of probability and stochastic processes, signals and systems, baseband and passband signaling, signal-space representation, spread spectrum, multi-carrier and ultra wideband transmissions, carrier and symbol-timing recovery, information theory and errorcorrecting codes. The simulation approach also covers these subjects, but with focus on the capabilities of VisSim/Comm to help the reader fulfill the gap between the theory and its practical meaning. The presentation of the theory is made easier with the help of 357 illustrations. A total of 101 simulation files support the simulationoriented approach.