Signals and Systems

Signals are physical variables or quantities measured at various parts of a system, which when processed yield the desired information. A wide variety of signals are often encountered in describing many practical systems. Electrical signal, in form of current and voltage, is the most easily measured quantity, hence the need to use sensors and transducers to transform other non-electrical quantity into electrical signals. These signals must be processed by appropriate techniques if desirable results are to be obtained. Several methods of signal representation, suitable for effective signal processing in both time and frequency domains, are discussed in this section.