Represented by Analog signal is a function that is defined over a continuous range of time and in which the amplitude may assume a continuous range of values. Causal is a filter whose response at a specific instant is independent of subsequent values of the excitation. The response is related to the excitation by some rule of correspondence. Digital filter elements the basic building blocks of the digital filter are the Unit Delay , the Adder , and the Multiplier .
Digital signal is a function in which both time and amplitude are quantized .
Digital system operates on and produces digital signal s. Multiplier multiply its input by a constant. Quantization described the process of representing a variable by a set of distinct values. Quantized variable is a variable that may assume only distinct values. Time-invariant is a digital filter whose response to an arbitrary excitation does not depend on the time of the application of the excitation.