4 The continuous time Fourier transform Fourier transform X(O x(te o di (t) X(oeo do 2元 or x(t>Xo) Relation between fourier series and Fourier transform X(lasko (Periodic signal X(o=T ak ko.so(Aperiodic signal4 The continuous time Fourier transform Fourier transform:      = =   + − + − −       x t X j e d X j x t e dt j t j t ( ) 2 1 ( ) ( ) ( ) Relation between Fourier series and Fourier transform:      =  = = = ( ) 0 0 ( ) | ( )| 1 Aperiodic signal (Periodic signal) k k k k X j T a X j T a       or x(t) X( j) ⎯F →