Causality Condition of a Discrete-Time LTI System A discrete-time LTI system is causal if and only if its impulse response hin is a causal sequence Example- The discrete-time system defined y]=a1x1n]+a2x[n-1]+3xn-2]+a4xn-3] is a causal system as it has a causal impulse response hn]}={(10234 Copyright C 2001, S.K. MitraCopyright © 2001, S. K. Mitra 10 Causality Condition of a Discrete-Time LTI System • A discrete-time LTI system is causal if and only if its impulse response {h[n]} is a causal sequence • Example - The discrete-time system defined by is a causal system as it has a causal impulse response [ ] [ ] [ 1] [ 2] [ 3] y n = 1 x n +2 x n − +3 x n − +4 x n − { [ ]} { } h n = 1 2 3 4 