This document discusses different types of signals including analog and digital signals as well as periodic and aperiodic signals. It includes figures showing the transformation of information to signals, examples of analog and digital clocks, definitions of analog and digital signals, periodic signals represented by a sine wave, and the definition of aperiodic signals.

2. Figure 4-1 WCB/McGraw-Hill  The McGraw-Hill Companies, Inc., 1998 Transformation of Information to Signals

3. Figure 4-2 WCB/McGraw-Hill  The McGraw-Hill Companies, Inc., 1998 Analog and Digital Clocks

4. Figure 4-3 WCB/McGraw-Hill  The McGraw-Hill Companies, Inc., 1998 Analog and Digital Signals

5. Figure 4-4 WCB/McGraw-Hill  The McGraw-Hill Companies, Inc., 1998 Periodic Signals

6. Figure 4-5 WCB/McGraw-Hill  The McGraw-Hill Companies, Inc., 1998 Aperiodic Signals

7. Figure 4-6 WCB/McGraw-Hill  The McGraw-Hill Companies, Inc., 1998 Sine Wave