Figure 2. 1 Graphical representation of a discrete-time signal -2J 2 7891011 9-8-7-6-54-3-2-10123456 Abscissa: continuous line x[n: is defil ned on ly at dis iscrete instants 6 1/30/2021 Zhongguo Liu_ Biomedical Engineering_ Shandong Univ6 1/30/2021 Zhongguo Liu_Biomedical Engineering_Shandong Univ. Figure 2.1 Graphical representation of a discrete-time signal Abscissa: continuous line : is defined only at discrete instants xn