Method for whitening colored noise in a communication system
View Patent ↗A filter settings generation operation includes sampling colored noise present at the input of a receiver to produce a sampled signal. The sampled signal is spectrally characterized across a frequency band of interest to produce a spectral characterization of the sampled signal. This spectral characterization may not include a signal of interest. The spectral characterization is then modified to produce a modified spectral characterization. Filter settings are then generated based upon the modified spectral characterization. Finally, the input present at the receiver is filtered using the filter settings when the signal of interest is present to whiten colored noise that is present with the signal of interest. In modifying the spectral characterization, pluralities of spectral components of the spectral characterization are independently modified to produce the modified spectral characterization. Modifications to the spectral characterization may be performed in the frequency domain and/or the time domain. Particular modifications include amplifying spectral components, weighting spectral components based upon prior spectral components, and averaging spectral components with prior spectral components.
1. In a communication network, a method for whitening colored noise present at the input of a receiver, the method comprising:
sampling colored noise present at the input of the receiver during a sampling interval to produce a sampled signal;
spectrally characterizing the sampled signal across a frequency band of interest to produce a spectral characterization of the sampled signal;
modifying the spectral characterization of the sampled signal to produce a modified spectral characterization, wherein:
the modified spectral characterization is based upon the spectral characterization and prior spectral characterizations; and
wherein in modifying the spectral characterization, spectral components of the spectral characterization are averaged with corresponding spectral components of prior spectral characterizations;
generating filter settings based upon the modified spectral characterization; and
when a signal of interest and colored noise are present at the input of the receiver, filtering the input using the filter settings to whiten the colored noise at the input.
2. The method of claim 1 , wherein in modifying the spectral characterization of the sampled signal to produce the modified spectral characterization, a plurality of spectral components of the spectral characterization are modified.
3. The method of claim 1 , wherein in modifying the spectral characterization of the sampled signal to produce the modified spectral characterization, the modified spectral characterization is based upon the spectral characterization and at least one of:
a characterization of the noise power of the spectral characterization;
a prior spectral characterization; and
a characterization of the noise power of the prior spectral characterization.
4. In a communication network, a method for whitening colored noise present at the input of a receiver, the method comprising:
sampling colored noise present at the input of the receiver during a sampling interval to produce a sampled signal;
spectrally characterizing the sampled signal across a frequency band of interest to produce a spectral characterization of the sampled signal;
discarding the spectral characterization when a characterization of the noise power of the spectral characterization exceeds a threshold;
modifying the spectral characterization of the sampled signal to produce a modified spectral characterization by folding the spectral characterization to decrease the bandwidth of the spectral characterization;
generating filter settings based upon the modified spectral characterization; and
when a signal of interest and colored noise are present at the input of the receiver, filtering the input using the filter settings to whiten the colored noise at the input.
5. The method of claim 4 , wherein in modifying the spectral characterization of the sampled signal to produce the modified spectral characterization, a plurality of spectral components of the spectral characterization are modified.
6. The method of claim 4 , wherein modifying the spectral characterization of the sampled signal to produce the modified spectral characterization further includes amplifying each of the plurality of spectral components of the spectral characterization by one of a plurality of gain factors.
7. The method of claim 6 , further comprising applying a gain factor to a particular spectral component, the gain factor based upon the magnitude of the spectral component.
8. The method of claim 7 , wherein the gain factor to be applied to the particular spectral component is also based upon the magnitudes of other of the spectral components of the spectral characterization.
9. The method of claim 7 , wherein the gain factor to be applied to the particular spectral component is also based upon a characterization of the noise power of the spectral characterization.
10. The method of claim 4 , wherein modifying the spectral characterization of the sampled signal to produce the modified spectral characterization is further based upon the spectral characterization and at least one of:
a characterization of the noise power of the spectral characterization;
a prior spectral characterization; and
a characterization of the noise power of the prior spectral characterization.
11. The method of claim 4 , wherein modifying the spectral characterization of the sampled signal to produce the modified spectral characterization is further based upon:
a characterization of the noise power of the spectral characterization and characterizations of the noise power of the prior spectral characterizations; and
when the characterization of the noise power of the spectral characterization is above average as compared to characterizations of the noise power of prior spectral characterizations, the spectral components of the spectral characterization are de-weighted in determining the spectral components of the modified spectral characterization.
12. The method of claim 4 , further comprising modifying the filter settings to compensate for the folding of the spectral characterization.
13. The method of claim 4 , wherein the sampling is performed when the signal of interest is not present at the input of the receiver.
14. The method of claim 4 , wherein:
the sampling is performed while the signal of interest is present at the input of the receiver; and
the method further comprises removing the signal of interest from the sampled signal.
15. The method of claim 4 , wherein modifying the spectral characterization of the sampled signal to produce a modified spectral characterization is performed in the frequency domain.
16. The method of claim 4 , wherein modifying the spectral characterization of the sampled signal to produce a modified spectral characterization is performed in the time domain.
17. The method of claim 4 , wherein modifying the spectral characterization of the sampled signal to produce a modified spectral characterization is performed both in the frequency domain and in the time domain.
18. The method of claim 4 , further comprising discarding the spectral characterization when a characterization of the noise power of the spectral characterization exceeds a threshold.
19. The method of claim 4 , wherein the network comprises a home phone line network.