Contents
What is noise whitening?
The noise (and other additive distortions) usually has non-flat amplitude spectrum. The noise whitening module equalizes the spectrum of the signal, making it similar to the white noise spectrum. The noise estimate is calculated as a smoothed (low-pass filtered) noise spectrum averaged in all segments. …
What does whitening a signal mean?
The transformation is called “whitening” because it changes the input vector into a white noise vector. …
How do you whiten data?
Whitening a data matrix follows the same transformation as for random variables. An empirical whitening transform is obtained by estimating the covariance (e.g. by maximum likelihood) and subsequently constructing a corresponding estimated whitening matrix (e.g. by Cholesky decomposition).
What is Decorrelation time?
Decorrelation time is the time for a correlation between the initial image and the subsequently captured image to drop to 50%.
Which is the formula for the whitening filter?
The whitening filter is defined such that h b ( t) ∗ h w ( t) = δ ( t), hence: (42) h w ( t) = F − 1 { 1 H b ( j ω) } = 1 k f R ( k r δ ( t) + d δ ( t) d t). As shown in Fig. 6, the proposed whitening filter is a weighted summation of a differentiator and the signal. Fig. 6.
Why do we need an adaptive whitening filter?
Another reason for considering an adaptive approach to signal whitening is the fact that the SNR changes with contraction level. Since a large number of motor units are active during stronger contractions, the muscular activity dominates relative to the noise of nonmuscular origin so that the SNR of the EMG signal is high.
Why do we need to use spectral whitening?
Spectral whitening is usually an attempt to make the spectrum of the signal “more uniform”. One reason this might be a good thing to do is that it can have the effect of making the autocorrelation of the signal “narrower” (and closer to a Dirac delta, for discrete-time signals).
Which is the left inverse of the whitening filter?
One can observe that the whitening filter W[z] corresponds to a left inverse of AI[z] in Theorem 8.7. The whitening filter can thus be looked for in the set of FIR filters. Thanks to Proposition 8.6, the degree of the whitening filter should not exceed N deg AI[z] − 1 ≤ N deg A[z] − 1.