Flashcards
LTI
Cards in this deck (14)
- 1Memoryless systemA system is said to be memoryless if the output at any time depends on only the input at that same time.
- 2Causal systemThe output depends on past and current inputs but not future inputs
It means y(n) is a function of x(n), x(n-1), x(n-2), x(n-3).. - 3Non-Causal systemA system whose present response depends on future values of the inputs is called as a non-causal system.
y is a function of x(n+1), x(n+2), x(n+3).. - 4What is the condition for stability for continuous time linear time-invariant (LTI) system?bounded input -> bounded output
The impulse response must be absolutely integrable. - 5What is the condition for stability for discrete time linear time-invariant (LTI) system?the impulse response be absolutely summable
- 6Linear systemit obeys the principle of superposition
a*x1 + b*x2 = a*y1 + b*y2 - 7What is the impulse response?A system's impulse response (often annotated as h(t) for continuous-time systems or h[n] for discrete-time systems) is defined as the output signal that results when an impulse* is applied to the system input.
*For continuous-time systems, this is the Dirac delta function δ(t). - 8Why is the impulse response useful?For both discrete- and continuous-time systems, the impulse response is useful because it allows us to calculate the output of these systems for any input signal; the output is simply the input signal convolved with the impulse response function.
- 9How do you test BIBO stability with Laplace?H(s) is BIBO stable iff;
- H(s) is proper
- all poles of H(s) have neg. parts - 10When is H(s) proper?m>n: more zeros than poles => unstable
m=n: proper
m - 11When analyzing stability with Laplace-transform, what are "zeros" and "poles" referring to?Zeros are roots in the numerator (täljare).
Poles are roots in the denominator (nämnare). - 12How is the unit step function defined?
- 13TriangelolikhetenABS(x+y) <= ABS(x) + ABS(y)
- 14h(t) for a causal LTIC systemh(t)=0 for t<0
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- Sigsys Flashcards on LTI, created by Emma Tysk on 27/12/2017.
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- Emma Tysk
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