Methods for performing channel diagnostics

1. A method of determining information about a communication channel using an adaptive filter coupled to the channel, the adaptive filter including adaptive filter coefficients, comprising:

a) comparing the filter coefficients to filter coefficient thresholds;

b) determining if one of a communication link and a channel fault exists, and if a channel fault exists determining if one of,

i) a cable open condition exists in the channel, and

ii) a cable short condition exists in the channel; and

c) indicating whether the channel is one of linked, open, and shorted;

d) determining when a given filter coefficient one of meets and exceeds a corresponding filter coefficient threshold;

e) comparing only a further subset of filter coefficients to corresponding ones of a subset of the filter coefficient thresholds;

f) identifying a largest one of the given filter coefficient and the further subset of filter coefficients; and

g) determining the channel length based on the largest coefficient identified in the previous step.

2. The method of claim 1 , wherein step (a) further comprises:

comparing the filter coefficients to corresponding filter coefficient thresholds in an order of increasing filter time delay associated with each of the filter coefficients.

3. The method of claim 1 , wherein the thresholds include thresholds indicative of a channel length.

4. The method of claim 1 , further comprising performing curve fitting for the length of the channel using a polynomial algorithm.

5. The method of claim 1 , further comprising performing curve fitting for the length of the channel using a set of polynomial algorithms.

6. The method of claim 1 , wherein the filter coefficient thresholds include varying thresholds.

7. The method of claim 1 , wherein the filter coefficient thresholds include varying thresholds that follow a staircase of values.

8. The method of claim 1 , further comprising, prior to step (a):

bypassing a filter convergence operation that converges the set of filter coefficients if a valid communication link exists.

9. The method of claim 1 , wherein if the channel is linked, further comprising:

h) determining a length of the channel.

10. The method of claim 9 , wherein step h) comprises:

i) determining a number of taps for the channel, wherein the number of taps is indicative of the length of the channel.

11. The method of claim 1 , wherein if the channel fault exists, further comprising:

h) determining a distance to the channel fault.

12. The method of claim 11 , wherein step h) comprises:

determining a number of taps before a spike in a filter coefficient value, wherein the number of taps is indicative of the distance to the channel fault.

13. The method of claim 11 , further comprising, prior to step (a):

converging the set of filter coefficients.

14. The method of claim 1 , wherein before step b) further comprises:

determining a polarity of a filter coefficient corresponding to a spike in the filter coefficients.

15. The method of claim 14 , wherein when the polarity is positive, the cable open condition exists.

16. The method of claim 14 , wherein when the polarity is negative, the cable short condition exists.

17. A method of determining information about a communication channel using an adaptive filter coupled to the channel, the adaptive filter including adaptive filter coefficients, comprising:

a) comparing the filter coefficients to filter coefficient thresholds;

b) determining if one of a communication link and a channel fault exists, and if a channel fault exists determining if one of,

i) a cable open condition exists in the channel, and

ii) a cable short condition exists in the channel;

c) indicating whether the channel is one of linked, open, and shorted;

d) determining when a given filter coefficient either one of meets and exceeds a corresponding filter coefficient threshold;

e) comparing only a further subset of filter coefficients to corresponding ones of a subset of the filter coefficient thresholds;

f) identifying a largest one of the given filter coefficient and the further subset of filter coefficients; and

g) determining a distance to the channel fault based on the largest coefficient identified in step f).

18. The method of claim 17 , wherein step (a) further comprises:

comparing the filter coefficients to corresponding ones of filter coefficient thresholds in an order of decreasing filter time delay associated with each of the filter coefficients.

19. The method of claim 17 , further comprising:

h) adjusting values of the thresholds; and

i) repeating the steps d) through t) for the adjusted thresholds.

20. The method of claim 17 , wherein the thresholds include thresholds indicative of a channel fault.

21. The method of claim 17 , further comprising performing curve fitting for the distance to the channel fault using a polynomial algorithm.

22. The method of claim 17 , further comprising performing curve fitting for the distance to the channel fault using a set of polynomial algorithms.

23. The method of claim 17 , wherein the filter coefficient thresholds include varying thresholds.

24. The method of claim 17 , wherein the filter coefficient thresholds include varying thresholds that follow a staircase of values.

25. The method of claim 17 , further comprising, prior to step (a):

bypassing a filter convergence operation that converges the set of filter coefficients if a valid communication link exists.

26. The method of claim 17 , further comprising:

h) producing a sampled signal from a received signal via the channel using a candidate sampling phase;

i) converging the filter coefficients based on the candidate sampling phase;

j) comparing the converged filter coefficients to filter coefficient thresholds; and

k) determining a largest filter coefficient among one or more excessive filter coefficients that exceed corresponding coefficient thresholds.

27. The method of claim 26 , further comprising:

l) repeating steps h) through k) using different candidate sampling phases, thereby determining one or more largest filter coefficients for one or more respective candidate sampling phases; and

m) selecting as a best sampling phase the candidate sampling phase corresponding to a largest one of all of the largest filter coefficients.

28. The method of claim 17 , wherein if the channel is linked, further comprising:

h) determining a length of the channel.

29. The method of claim 28 , wherein step h) comprises:

i) determining a number of taps for the channel, wherein the number of taps is indicative of the length of the channel.

30. The method of claim 17 , wherein if the channel fault exists, further comprising:

h) determining a distance to the channel fault.

31. The method of claim 30 , wherein step h) comprises:

determining a number of taps before a spike in a filter coefficient value, wherein the number of taps is indicative of the distance to the channel fault.

32. The method of claim 30 , further comprising, prior to step (a):

converging the set of filter coefficients.

33. The method of claim 17 , wherein before step b) further comprises:

determining a polarity of a filter coefficient corresponding to a spike in the filter coefficients.

34. The method of claim 33 , wherein when the polarity is positive, the cable open condition exists.

35. The method of claim 33 , wherein when the polarity is negative, the cable short condition exists.

36. A method of determining information about a communication channel using an adaptive filter coupled to the channel, the adaptive filter including adaptive filter coefficients, comprising:

a) comparing the filter coefficients to filter coefficient thresholds;

b) determining if one of a communication link and a channel fault exists, and if a channel fault exists determining if one of,

i) a cable open condition exists in the channel, and

ii) a cable short condition exists in the channel; and

c) indicating whether the channel is one of linked, open, and shorted, and if the channel is linked determining a length of the channel;

d) performing post-processing techniques, such that a determination is made whether the length of the cable is within a predetermined range;

i) re-determining the length of the cable and indicating the length of the cable is indeterminable when the length of the cable is outside the predetermined range.

37. A method of determining information about a communication channel using an adaptive filter coupled to the channel, the adaptive filter including adaptive filter coefficients, comprising:

a) comparing the filter coefficients to filter coefficient thresholds;

b) determining if one of a communication link and a channel fault exists, and if a channel fault exists determining if one of,

i) a cable open condition exists in the channel, and

ii) a cable short condition exists in the channel;

c) indicating whether the channel is one of linked, open, and shorted, and if the channel fault exists determining a distance to the channel fault;

d) perform post-processing techniques, such that a determination is made whether the distance to the cable fault is within a predetermined range, and if the distance to the cable fault is outside the predetermined range doing one of,

i) re-determining the distance to the cable fault; and

ii) indicating the distance to the cable fault is indeterminable.