Page 22 - EC8352 -SS-NOTES-by Prof.Bokhari ECE/MAMCET
P. 22
SUBJECT: EC8352- Signals and Systems
AUTHOR: M.SHAKUNTHALA, A.P/ECE/RMDEC
Dr.M.N.VIMAL KUMAR, AP/ECE/RMDEC
13. Determine whether the following systems are causal or not
( )
= + ( )
The given equation is differential equation and the output depends on past input. Hence the
given system is
14. Determine whether the following systems are causal or not
( ) = ( )
0 = (0) ⇒ present input
−1 = (−1) ⇒ present input
1 = (1) ⇒ present input
Since output depends on present input the given system is Causal system
15. Determine whether the following systems are stable or not
= − ( )
∞
Condition for stability ( ) < ∞
−∞
∞ ∞ ∞ ∞
−4 1
( ) = −4 ( ) = −4 = =
−4 4
−∞ −∞ 0 0
∞
∵ ( ) < ∞ the given system is
−∞
16. Determine whether the following systems are stable or not
= ( )
Let = , = ( )
⇒ = 3 ( )
∞
Condition for stability ( ) < ∞
=−∞
∞ ∞ ∞
( ) = 3 ( ) = 3 ( ) = 3
=−∞ =0 =0
∵ = 0 ≠ 0 = 1 = 0
∞
∵ ( ) < ∞ the given system is
=−∞
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