Cross-correlation of white noise process with its conjugate

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SUMMARY

The discussion focuses on the properties of white Gaussian noise (WGN) processes, specifically the expected value of the product of samples from the process. It establishes that for a complex white noise process, E[w[n1] w*[n2]] equals 0, similar to the case for real white noise where E[w[n1] w[n2]] also equals 0. The key conclusion is that the ensemble average of the auto-correlation function for WGN is zero, regardless of whether the process is real or complex.

PREREQUISITES
  • Understanding of white Gaussian noise (WGN) processes
  • Knowledge of expected value and auto-correlation functions
  • Familiarity with complex random processes
  • Basic concepts of signal processing
NEXT STEPS
  • Study the properties of complex random processes in signal processing
  • Learn about the implications of auto-correlation functions in WGN
  • Explore the concept of ensemble averages in stochastic processes
  • Investigate the effects of time-reversal on signal properties
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Signal processing engineers, researchers in stochastic processes, and students studying random processes will benefit from this discussion.

nitisha
If w[n] are samples of the white gaussian noise process, I know that
E[w[n1] w[n2]] = 0 for a WGN process.

what would the following expression lead to:

E[w[n1] w*[n2]] = ?

Would it also be zero?

Thanks a lot!
 
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nitisha said:
If w[n] are samples of the white gaussian noise process, I know that
E[w[n1] w[n2]] = 0 for a WGN process.

what would the following expression lead to:

E[w[n1] w*[n2]] = ?

Would it also be zero?

Thanks a lot!
Welcome to the PF. :smile:

What do you think the answer is and why? Also, is this for homework?
 
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Are you talking about complex white noise where the real and imaginary parts are uncorrelated white noise processes? If so, the expected value should be 0.
 
If you reverse the samples in the time domain, you get the conjugate, = negative phase, in the frequency domain.

Why does it matter if a Gaussian white noise is played forwards or backwards in time?
 
Thanks all! Got the answer.

If white noise is a complex random process, we say that E[w[n1] w*[n2]] = 0;
If it is a real random process, we say that E[w[n1] w[n2]] = 0

Generally speaking, the ensemble average of the auto-correlation function at times n1 and n2 of a WGN process is 0.
 
Most likely this can only be answered by an "old timer". I am making measurements on an uA709 op amp (metal can). I would like to calculate the frequency rolloff curves (I can measure them). I assume the compensation is via the miller effect. To do the calculations I would need to know the gain of the transistors and the effective resistance seen at the compensation terminals, not including the values I put there. Anyone know those values?

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