Transfer function from amplitude response?

In summary, the paper describes a method for generating a polynomial g for the amplitude response of a filter that can have arbitrary flatness and roll-off characteristics. The transfer function can be easily determined from this polynomial, but the paper does not provide details on how to do so. However, the author has written a Mathematica notebook that can accomplish this task and is willing to share it with others.
  • #1
cuallito
95
1
Hi, in the paper I've attached, they give a method for generating a polynomial g for the amplitude response of a filter that gives arbitrary flatness and roll-off characteristics.

[tex]\frac{1}{\sqrt{1+g}}[/tex]

And then they say the transfer function can be easily determined from this, but they don't say how.

For example, they give an amplitude response

[tex]\frac{1}{\sqrt{1+10s^{8}-24w^{10}+15w^{12}}}[/tex]

and then they just say "then we will have the transfer function"

[tex]\frac{0.259}{s^{6}+2.392w^{5}+3.661s^{4}+2.755s^{3}+2.615s^{2}+1.162s+0.259}[/tex]

I know how to get the transfer function from the amplitude response for a standard filter like a butterworth or chebyshev, but for ones like this?
 

Attachments

  • takehisa98.pdf
    242.2 KB · Views: 519
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  • #2
Hey, I figured it out. I wrote a Mathematica note book that does it. Anyone want it?
 
  • #3
cuallito said:
Hey, I figured it out. I wrote a Mathematica note book that does it. Anyone want it?

Cool. Yes please, it would be fun to try out. Can you post it as an attachment?
 
  • #4
Yeah.
 

Attachments

  • p1_3.nb
    60.8 KB · Views: 474

1. What is a transfer function from amplitude response?

A transfer function from amplitude response is a mathematical representation of the relationship between the input and output of a system. It describes how the amplitude of the input signal is affected by the system and the resulting output amplitude.

2. How is a transfer function from amplitude response related to frequency response?

The transfer function from amplitude response and frequency response are closely related. The amplitude response is the magnitude of the system's output in response to a sinusoidal input at a given frequency, while the frequency response is a plot of the system's gain (amplitude response) versus frequency. The transfer function is the mathematical representation of the frequency response.

3. How is a transfer function from amplitude response obtained?

A transfer function from amplitude response can be obtained by taking the Fourier transform of the system's impulse response. This results in a complex-valued function that contains information about the magnitude and phase of the system's response to different frequencies. The amplitude response is then calculated by taking the absolute value of the transfer function.

4. What information can be obtained from a transfer function from amplitude response?

A transfer function from amplitude response provides information about the frequency-dependent gain and phase shift of a system. It can also be used to determine stability, bandwidth, and resonant frequencies of a system. Additionally, it can be used to design filters and equalizers for audio and signal processing applications.

5. How is a transfer function from amplitude response used in control systems?

In control systems, the transfer function from amplitude response is used to analyze and design systems that can regulate a desired output based on a given input. By understanding the frequency response of a system, engineers can design controllers that can compensate for the system's behavior and achieve desired performance metrics such as stability, response time, and disturbance rejection.

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