Can't find inverse Z transform

In summary, the conversation is about converting a Laplace transfer function to a Z transform, and using the "displacement rule" to find the inverse Z transform. The conversation also mentions the use of reference 17 and the delta function in transformations. The solution involves putting all components under one fraction sign and multiplying by Z^-1 until only Z^- terms remain.
  • #1
Addez123
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Homework Statement


I got the laplace transfer function H(s) = 1/(s + 2) and I'm suppose to find the inverse Z transform by first converting to H(z) by s = Ts/2*(z-1)/(z+1)
Then do inverse Z-transform using the "displacement rule" - Never heard of.

Homework Equations


H(s) = 1/(s + 2)
s = Ts/2*(z-1)/(z+1)

3. The Attempt at a Solution

I can't get any serious answer, and the partial z-inverse that I manage to find it's incredibly complicated (see image).
Namnl_s.png

What is this 'displacement rule' and how do I use it here?
 
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  • #2
I don't have reference 17 (James G. Advanced modern engineering mathematics. Reading: Addison-Wesley; 1993.) that they refer to, but it looks like this paper ( https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5240402/ ) uses it to associate the scaled/shift inside δ(γk-λtot(t)) of equation 13 with (1/γ)ztot(t)/γ in equation 15.
Conversions like that are fairly common in transformations involving the delta function.
 
  • #3
The solution was to, after replacing 's' with the Z components, then put all under one fraction sign (no plus in nominator). Then multiply with Z^-1 in bottom and top until you got only Z^- terms. This = Y(x)/X(x) which can then be translated back to y[n] and y[n-1] = Z^-1*Y(x)
 

1. Why is it important to find the inverse Z transform?

The inverse Z transform is important because it allows us to convert a complex function in the Z domain into a time domain function, which is more easily understood and can be used for practical applications.

2. What are the common methods used to find the inverse Z transform?

The most common methods used to find the inverse Z transform are the partial fraction expansion, the long division method, and the residue method. Each method has its own advantages and is suitable for different types of functions.

3. What are the challenges in finding the inverse Z transform?

One of the main challenges in finding the inverse Z transform is that there is no single method that can be applied to all types of functions. Each method has its limitations and may not work for certain types of functions. Additionally, the inverse Z transform can sometimes result in complex and lengthy calculations.

4. Can the inverse Z transform be calculated analytically?

In some cases, the inverse Z transform can be calculated analytically using known formulas or tables. However, for more complex functions, numerical methods such as the inverse discrete-time Fourier transform (IDTFT) or the inverse Laplace transform may be used.

5. How can I check if my inverse Z transform result is correct?

One way to check if your inverse Z transform result is correct is to apply the forward Z transform to the result and see if it matches the original function. Additionally, you can also use software or online tools to verify your result or compare it with known solutions.

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