Systems and methods for reducing noise in ADSL transmissions

1. A method for processing asymmetric digital subscriber line (ADSL) signals, comprising:

receiving a signal comprising a continuous ADSL signal and transient noise;

applying a wavelet transform operation to the received signal;

estimating the signal level in wavelet space by way of the equation

Signal

=

∑

n

2

+

1

n

⁢



X

w

⁢

n

0.6745



n

,

where “n” represents number of frequency bins for the continuous ADSL signal and x w is value of the wavelet transform of the received signal;

using the signal level estimate to determine an amplitude threshold;

applying the amplitude threshold to the wavelet transformed signal;

discarding a portion of the wavelet transformed signal at or below the threshold to obtain a resulting signal;

applying an inverse wavelet transform operation to the resulting signal to obtain a replica signal corresponding to the noise; and

subtracting the replica signal from the received signal to obtain the ADSL signal.

2. A method for processing an asymmetric digital subscriber line (ADSL) signal, comprising:

receiving the signal comprising a continuous ADSL signal and transient noise;

isolating the transient noise in the signal by:

applying wavelet processing to the signal to obtain a wavelet processed signal,

estimating the signal level in wavelet space by way of the equation

Signal

=

∑

n

2

+

1

n

⁢



X

w

⁢

n

0.6745



n

,

where “n” represents number of frequency bins for the continuous ADSL signal and x w is value of the wavelet transform of the received signal,

using the signal level estimate to determine an amplitude threshold,

applying the amplitude threshold to the wavelet processed signal,

discarding a portion of the wavelet processed signal at or below the threshold to obtain a resulting signal, and

applying inverse wavelet processing to the resulting signal to obtain the isolated transient noise; and

retrieving the continuous ADSL signal from the signal using the isolated transient noise.

3. The method of claim 2 wherein the retrieving includes:

subtracting the isolated transient noise from the signal.

4. The method of claim 2 further comprising:

separating the retrieved ADSL signal into a voice signal and a data signal.

5. A system for processing asymmetric digital subscriber line (ADSL) signals, comprising:

means for receiving one or more signals, each one of the one or more signals comprising a continuous ADSL signal and transient noise;

means for detecting the noise in the one or more signals including:

means for applying wavelet transform processing to the signal to produce a plurality of wavelet coefficients,

means for estimating the signal level in wavelet space by way of:

Signal

=

∑

n

2

+

1

n

⁢



X

w

⁢

n

0.6745



n

,

where “n” represents number of frequency bins for the continuous ADSL signal and x w is value of a wavelet transform of one of the one or more received signals,

means for using the signal level estimate to determine an amplitude threshold, and

means for comparing the plurality of wavelet coefficients to the amplitude threshold; and

means for retrieving the continuous ADSL signal from each one of the one or more signals using the detected noise.

6. The system of claim 5 wherein the means for detecting further includes:

means for discarding one or more of the plurality of wavelet coefficients at or below the threshold to obtain a resulting set of wavelet coefficients, and

means for applying inverse wavelet transform processing to the resulting set of wavelet coefficients to detect the noise.

7. A system for processing an asymmetric digital subscriber line (ADSL) signal, comprising:

logic configured to receive the signal comprising a continuous ADSL signal and transient noise;

logic configured to isolate the transient noise in the signal using a multi-scale transformation operation by being configured to

apply wavelet processing to the signal to obtain a wavelet processed signal,

estimate the signal level in wavelet space by way of the equation

Signal

=

∑

n

2

+

1

n

⁢



X

w

⁢

n

0.6745



n

,

where “n” represents number of frequency bins for the continuous ADSL signal and x w is value of the wavelet transform of the signal,

use the signal level estimate to determine an amplitude threshold,

apply the amplitude threshold to the wavelet processed signal,

discard a portion of the wavelet processed signal at or below the threshold to obtain a resulting signal, and

apply inverse wavelet processing to the resulting signal to obtain the isolated transient noise; and

logic configured to obtain the continuous ADSL signal from the signal using the isolated transient noise.

8. The system of claim 7 wherein the logic configured to obtain the ADSL signal is configured to:

subtract the isolated transient noise from the signal.

9. A system for processing an asymmetric digital subscriber line (ADSL) signal, comprising:

logic configured to receive the signal comprising a continuous ADSL signal and transient noise; and

logic configured to suppress the noise in the signal using a wavelet transformation operation including:

logic configured to isolated the noise by: (1) applying wavelet processing to the signal to obtain a wavelet processed signal, (2) estimating the signal level in wavelet space, (3) using the signal level estimate to determine an amplitude threshold, (4) applying the amplitude threshold to the wavelet processed signal, (5) discarding a portion of the wavelet processed signal at or below the threshold to obtain a resulting signal, and (6) applying inverse wavelet processing to the resulting signal to obtain the isolated noise; and

logic configured to subtract the isolated noise from the signal to retrieve the continuous ADSL signal;

wherein the logic for estimating signal level in wavelet space relies on the equation

Signal

=

∑

n

2

+

1

n

⁢



X

w

⁢

n

0.6745



n

,

where “n” represents number of frequency bins for the continuous ADSL signal and x w is value of the wavelet transform of the received signal.

10. A noise suppression device comprising:

first logic configured to receive a signal comprising a continuous asymmetric digital subscriber line (ADSL) signal and transient noise;

second logic configured to isolate the noise in the received signal wherein, when isolating the noise, the second logic is configured to:

apply wavelet processing to the received signal to obtain a wavelet processed signal,

estimate the signal level in wavelet space by way of the equation

Signal

=

∑

n

2

+

1

n

⁢



X

w

⁢

n

0.6745



n

,

where “n” represents number of frequency bins for the continuous ADSL signal and x w is value of the wavelet transform of the received signal,

use the signal level estimate to determine an amplitude threshold,

apply the amplitude threshold to the wavelet processed signal,

discard a portion of the wavelet processed signal at or below the threshold to obtain a resulting signal, and

apply inverse wavelet processing to the resulting signal to obtain the isolated noise; and

third logic configured to subtract the isolated noise from the received signal to obtain the continuous ADSL signal.