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Signals and Systems - Engineering

Q1:

The range of value "a" for which system will be stable. If impulse response of DT system is = an ∪[n]

A a > 1

B a < 1

C 1 < a < ∞

D -1 < a < 1

ANS:D - -1 < a < 1

Given n(n) = an ∪(n) ROC is |z| > a open the mod function when z > 0 ⇒ z > a z < 0 ⇒ - z > a or ⇒ z < - a For stability ROC must include unit circle, so |z| > a or - a < z < + a or -1 < a < + 1.