Chapter 10 The z-transform 510.2 The Region of Convergence for the Z-Transform Property 1: The roc of X(z consists of a ring in the z-plane centered about the origin x(a)=FkInI Property 2: The roc does not contain any poles.9 Chapter 10 The Z-Transform §10.2 The Region of Convergence for the Z-Transform Property 1: The ROC of X(z) consists of a ring in the z-plane centered about the origin. ( )     n X z x n r − =F   n n x n r + − =−    Property 2: The ROC does not contain any poles