2.1.3 Basic sequences I Unit sample sequence 0 H≠0 n 2. The unit step sequence ≥0 0n<0 3. The rectangular sequence RIn 0≤n<N-1 other N-1 n10 1. Unit sample sequence 2.1.3 Basic sequences 2．The unit step sequence 0 0 0 1 [ ]  =    = n n  n 0 0 0 1 [ ]      = n n u n 1 u[n] 0 n 1 δ[n] 0 n 3．The rectangular sequence 1 R[n] 0 N-1 n other n N R n N 0 1 0 1 [ ]   −    =