ABSTRACT
The technical world is becoming more and more digital because digital signals are very convenient for information processing. However, most physical phenomena are analogue and the sensors measure analogue quantities. For that reason, the digital signal processing is often realized in the following sequence: conversion of the analogue signal to digital form Ÿ digital signal processing Ÿ conversion of the digital signal back to the analogue one. The conversion is realized by the analogue-to-digital converters ADC while the reverse process is realized by digital to analogue converters DAC. The analogue signals are of continuous time – the value of such signal is determined in every instant of time. An example of the analogue signal is presented in Fig. 5.1a. The conversion of the analogue signal x(t) to the digital form is realized in such a way that in assumed moment of time the value of the signal x(n) is determined and represented by a number. We can say that the digital signal is determined in discrete time, which means that the value of the signal is known only in selected moments. Usually the
discrete time is realized by collecting the samples of the analogue signal at the constant interval called the period of sampling Ts (Fig. 5.1b).
