Impulse response function & Laplace transforms

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SUMMARY

The discussion centers on solving for the output of a system given its impulse response function H(s) = 1/(s² + s + 1) and input x(t) = sin²(t-1)U(t-1). The user correctly identifies that Y(s) = H(s)X(s) and attempts to find X(s) as X(s) = 2e^(-s)/(s² + 4). However, they encounter difficulties in finding the inverse Laplace transform and consider using the convolution integral as an alternative method. The suggested approach involves using partial fractions to simplify Y(s) before finding y(t).

PREREQUISITES
  • Understanding of Laplace transforms and their properties
  • Familiarity with impulse response functions in control systems
  • Knowledge of convolution integrals for signal processing
  • Ability to perform partial fraction decomposition
NEXT STEPS
  • Study the process of finding inverse Laplace transforms using partial fractions
  • Learn about convolution integrals and their application in system output analysis
  • Explore the properties of impulse response functions in linear time-invariant systems
  • Review examples of signal transformations using Laplace methods
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Students and professionals in electrical engineering, control systems, and signal processing who are working with Laplace transforms and impulse response functions.

magnifik
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i am given the Laplace transform of an impulse response function, as well as its input. i am supposed to find its output.

H(s) = 1/s2 + s + 1
x(t) = sin2(t-1)U(t-1)

what i have done so far is the following:
i know that Y(s) = H(s)X(s) and from this i can easily find y(t)
so i found X(s) since H(s) is already given...this may be wrong
X(s) = 2e-s/s2 + 4

then i found Y(s)
Y(s) = 2e-s/(s2 + s + 1)(s2 + 4)
then i know that y(t) should be 2y(t-1) because of the e-s time shifting

but i am stuck here... is there a better way to solve this problem using Convolution integral or any other way? i know how to do both the partial fractions method and convolution integral but i keep getting stuck. i think i have set up the problem wrong, perhaps in the X(s) solution
 
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Yes it will be messy all ways!
 
If you want to continue with what you started, ignore the exponential factor for now and find the inverse Laplace transform of

\frac{2}{(s^2+s+1)(s^2+4)}

Start by using partial fractions to get separate terms:

\frac{2}{(s^2+s+1)(s^2+4)} = \frac{As+B}{s^2+s+1}+\frac{Cs+D}{s^2+4}


The more painful way of finding y(t) would be to find h(t) from H(s) and then convolve x(t) and h(t).
 

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