Obtaining Step Response for Linear Systems in Sinusoidal Frequency Domain

In summary, the transfer function of a linear system in the sinusoidal frequency domain is a complex function of the angular frequency ω. To obtain the step response, you need to know the relationship between the transfer function and the impulse response, and the relationship between the impulse response and the step response. One method of obtaining the impulse response is by using the real part of the transfer function, R(ω), and integrating it with respect to ω. This method was described in a 1959 publication by Victor S. Levadi.
  • #1
Boudy
7
1
The transfer function of a linear system is known in the sinusoidal frequency domain. It is given in its final form as a complex function of the angular frequency ω (not jω ). How to obtain the step response?
Thanks in advance.
 
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  • #2
In order to figure this out you need to know two things:

1. The relationship between the transfer function and the impulse response

2. The relationship between the impulse response and the step response

Hopefully this points you in the correct direction.

jason
 
  • #3
How would you normally obtain the step response given the transfer function?
Note: If you have ##s=j\omega## - then ##f(\omega) = f(-js)## right?

If you prefer, you can Fourier transform back to time domain, then transfer to frequency domain like you are used to.
 
  • #4
Dear friends:
Thanks for your kind comments. In the meantime I could find a direct straightforward answer in the 1959 publication:

SIMPLIFED METHOD OF DETERMINING TRANSIENT RESPONSE
FROM FREQUENCY RESPONSE OF LINEAR NETWORKS AND SYSTEMS

By: Victor S . Levadi

Thanks again.
Boudy
 
  • #5
Excellent - perhaps you could summarize what you found?
 
  • #6
In order to find the Impulse response , f(t), you need only the real part , R(ω),of the transfer function
F(j ω).
According to the mentioned paper:
f(t)= (2/π).R(ω).cos(tω) dω
The limits of integration are from zero to infinity.
Best regards
 
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Likes Simon Bridge

What is the purpose of obtaining step response for linear systems in sinusoidal frequency domain?

The purpose of obtaining step response for linear systems in sinusoidal frequency domain is to analyze the behavior of a system in response to a step input in the frequency domain. This allows for the identification of the system's stability, damping, and resonance characteristics, which are important in understanding and controlling the system's behavior.

What is a step response and how is it different from frequency response?

A step response is the output of a system in response to a sudden change in the input, such as a step function. This is different from frequency response, which shows the relationship between input and output signals at different frequencies. Step response is typically used to analyze the transient behavior of a system, while frequency response is used to analyze the steady-state behavior.

How is the step response obtained for a linear system in sinusoidal frequency domain?

The step response for a linear system in sinusoidal frequency domain can be obtained by converting the system's transfer function from the time domain to the frequency domain using the Laplace transform. Then, the transfer function can be evaluated at different frequencies to obtain the system's response. This response can then be plotted on a graph to analyze the system's behavior.

What are the advantages of obtaining step response in sinusoidal frequency domain?

Obtaining step response in sinusoidal frequency domain has several advantages, including the ability to analyze the system's stability, damping, and resonance characteristics, as well as the ability to easily compare the response of different systems. Additionally, it allows for the identification of any frequency components present in the response, which can provide insight into the system's behavior.

Are there any limitations to obtaining step response in sinusoidal frequency domain?

One limitation of obtaining step response in sinusoidal frequency domain is that it assumes the system is linear and time-invariant. This may not be the case in real-world systems, which can exhibit nonlinear and time-varying behavior. Additionally, the step response may not accurately represent the system's behavior if the input signal is not a true step function.

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