There are some very strong similarities and also some very important dif-
ferences between discrete-time signals and systems and continuous-time sig-
nals and systems. Discussing both classes together provides an opportunity to
share intuition and to use both the similarities and the differences as a further
emphasis of important concepts. Furthermore, as we will see as the course
proceeds, current technology provides an important mechanism-through
the concept of sampling-for converting between continuous-time and dis-
crete-time signals. It is often very advantageous to process continuous-time
signals by first converting them to discrete time.