ABSTRACT
Filters are generally classified into three broad classes: continuous-time, sampled-data, and discrete-time filters depending on the type of signal being processed by the filter. Therefore, the concepts of signals are fundamental in the design of filters. In real-world signals, often referred to as analog signals, both amplitude and time are continuous. These types of signals cannot be processed by digital machines unless they have been converted into discrete-time signals. In contrast, a digital signal is characterized by discrete signal values that are defined only at discrete points in time. A digital filter is a circuit or a computer program that computes a discrete output sequence from a discrete input sequence. Digital filters belong to the class of discrete-time linear time-invariant systems, which are characterized by the properties of causality, recursibility, and stability, and may be characterized in the time domain by their impulse response and in the transform domain by their transfer function.
