ABSTRACT
A signal can be defined as a single-valued function of time that conveys information. Time is the independent variable, and for every value of time the function which is the dependent variable must have a unique value. A random signal is one in which there is uncertainty about the value of the function until it occurs. The uncertainty lies in which deterministic waveform from the collection of signals ensemble occurs. A signal which is a continuous function of time and whose amplitude is continuous as well is called an analog signal. Consider the conversion of sound and light waves into an electrical signal such as the output of a carbon microphone or a photovoltaic cell. A digital signal is one in which the independent variable, that is, time, and the dependent variables take on a finite set of discrete values. The output of a digital computer is an example of such signals. Shannon’s theorem relates information and bandwidth.
