System and method for linear distortion estimation by way of equalizer coefficients

1. A method for estimating channel distortion in a communications channel including an adaptive equalizer, comprising:

determining one or more adaptive filter coefficients h 1 (n) associated with a signal by the adaptive equalizer;

normalizing the determined one or more adaptive filter coefficients to unit energy; and

differencing the normalized one or more adaptive filter coefficients with an ideal response h 0 (n) of the communications channel, the differencing producing an error sequence h 2 (n).

2. The method of claim 1 , further comprising determining an energy of the error sequence.

3. The method of claim 1 , further comprising:

converting the error sequence to frequency domain, the converting producing a frequency response H 2 (k) of the error sequence; and

removing a delay offset of the frequency response to produce a delayed offset response H 3 (k).

4. The method of claim 3 , further comprising:

(i) summing the delayed offset response and an ideal channel frequency response and (ii) inverting the sum to produce an inverted response H 4 (k);

normalizing the inverted response to unit power, thus producing a normalized response H 5 (k); and

removing a phase offset from the normalized inverted response, the removing producing an estimated channel response H 6 (k).

5. The method of claim 4 , further comprising:

differencing the estimated channel response H 6 (k) with the ideal channel frequency response, the differencing producing an error filter response H 7 (k); and

determining an error power of the difference.

6. The method of claim 3 , wherein the converting is based upon a fast Fourier transform of the error sequence.

7. The method of claim 3 , wherein the converting is based upon (i) padding the error sequence with zeros and (ii) applying a fast Fourier transform (FFT) to the padded error sequence.

8. The method of claim 7 , wherein the FFT includes at least 4096 samples.

9. A method for estimating channel distortion in a communications channel including an adaptive equalizer, comprising:

receiving data within the communications channel and converging taps of the adaptive equalizer when the data is received;

determining a sum of tap power values, the sum including a power of a main tap;

normalizing the taps to unity power;

determining a difference filter from the normalized taps; and

summing a power of taps of the difference filter.

10. An apparatus for estimating channel distortion in a communications channel including an adaptive equalizer, comprising:

means for determining one or more adaptive filter coefficients h 1 (n) associated with a signal by the adaptive equalizer;

means for normalizing the determined one or more adaptive filter coefficients to unit energy; and

means for differencing the normalized one or more adaptive filter coefficients with an ideal response h 0 (n) of the communications channel, the differencing producing an error sequence h 2 (n).

11. The apparatus of claim 10 , further comprising means for determining an energy of the error sequence.

12. The apparatus of claim 10 , further comprising:

means for converting the error sequence to frequency domain, the converting producing a frequency response H 2 (k) of the error sequence; and

means for removing a delay offset of the frequency response to produce a delayed offset response H 3 (k).

13. The apparatus of claim 12 , further comprising:

means for (i) summing the delayed offset response and an ideal channel frequency response and (ii) inverting the sum to produce an inverted response H 4 (k);

means for normalizing the inverted response to unit power, thus producing a normalized response H 5 (k); and

means for removing a phase offset from the normalized inverted response, the removing producing an estimated channel response H 6 (k).

14. The apparatus of claim 13 , further comprising:

means for differencing the estimated channel response H 6 (k) with the ideal channel frequency response, the differencing producing an error filter response H 7 (k); and

means for determining an error power of the difference.