Shift-Invariant System However from the definition of the up-sampler 1-1 =x(m-m),n=mn土Lm士2L,… 0 otherwise ≠ Hence, the up-sampler is a time-varying system Copyright C 2001, S K MitraCopyright © 2001, S. K. Mitra 18 Shift-Invariant System • However from the definition of the up-sampler • Hence, the up-sampler is a time-varying system [ ] u n no x − − = = , otherwise [( )/ ], , , ,..... 0 x n no L n no no L no 2L [ ] x1,u n