Study the autocorrelation function

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Discussion Overview

The discussion revolves around the autocorrelation function, its properties, and methods for calculating it, particularly in the context of specific equations involving derivatives. Participants seek resources for study and engage in mathematical reasoning related to the definition and computation of the autocorrelation function.

Discussion Character

  • Exploratory
  • Technical explanation
  • Mathematical reasoning
  • Homework-related

Main Points Raised

  • One participant requests resources for studying the autocorrelation function and its properties in detail.
  • Several links to Wikipedia and other resources are provided, but the original requester seeks additional free e-book downloads.
  • A participant presents a specific equation for which they want to find the autocorrelation function, indicating difficulty with the provided links.
  • Another participant suggests a method to compute the autocorrelation function using limits and integrals, referencing the definition of the autocorrelation function.
  • There is a discussion about the integration of specific functions and the application of limits in the context of the autocorrelation function.
  • Participants engage in correcting and refining earlier mathematical claims, including the limits of integration and the form of the functions involved.
  • Questions arise about the autocorrelation function for different derivatives of the function H(t), and whether such cases fit the definition of autocorrelation.
  • Some participants express uncertainty about how to proceed with calculations for higher derivatives and the general case for arbitrary n.

Areas of Agreement / Disagreement

Participants generally agree on the definition of the autocorrelation function and the methods to compute it, but there are multiple competing views regarding the application of these methods to specific cases, particularly concerning the derivatives of functions and the validity of certain integrals. The discussion remains unresolved on some aspects, particularly regarding the general case for arbitrary n.

Contextual Notes

Limitations include unresolved mathematical steps, particularly in deriving integrals for higher derivatives and the specific conditions under which the autocorrelation function is defined. There is also ambiguity regarding the application of the autocorrelation function to combinations of different derivatives.

  • #31
EnumaElish said:
My best understanding is this:
You are trying to find the autocorrelation coefficient of a signal. http://en.wikipedia.org/wiki/Autocorrelation#Signal_processing

You need to first determine the Rff(T) function.

Then you'd like to convert it into an AC coefficient as: r(T) = [Rff(T) - Meanf(T)^2]/Varf(T). http://en.wikipedia.org/wiki/Autocovariance (look under "Normalization")

Am I close?

yes, exactly! My points are to determine the mean and variance.
So, as I understand from your comments that if I will find the correlation coefficient then I can determine the mean and variance.
 
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  • #32
No. Typically you need to:
1. Calculate the mean
2. Calculate the variance
3. Calculate Rff
4. Put 1, 2, 3 together to calculate r (the corr. coeff.).

Is this helpful? If not, why not?
 
  • #33
EnumaElish said:
No. Typically you need to:
1. Calculate the mean
2. Calculate the variance
3. Calculate Rff
4. Put 1, 2, 3 together to calculate r (the corr. coeff.).

Is this helpful? If not, why not?

Yes, it’s fine. I agree.
But I think I should start with determining Rff(T) and after that the mean and variance.
Is that’s right?
 
  • #34
Any order would be fine.
 

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