Shift-Invariant System However from the definition of the up-sampler M -nol x(n-m)/小n=mn+L,士2L… 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