Method for diagnosing performance problems in cabling

• US 6,433,558 B1
• Filed: 05/11/2000
• Issued: 08/13/2002
• Est. Priority Date: 05/13/1999
• Status: Active Grant

• Current Assignee: Microtest, Inc. (NetScout Systems Incorporated)
• Original Assignee: Microtest, Inc. (NetScout Systems Incorporated)
• Inventors: Tonti, James G., Sciacero, James R.
• Primary Examiner(s): Le, N.
• Assistant Examiner(s): Nguyen, Vincent Q.
• Application Number:
  US09/569,005
• Time in Patent Office: 824 Days
• Field of Search: 324/543, 324/628, 324/603, 324/602, 324/605, 324/612, 324/607, 324/622, 324/623
• US Class Current: 324/628
• CPC Class Codes: G01R 31/083 in cables, e.g. underground
• CPC Class Codes: G01R 31/11 using pulse reflection methods

Abstract

The present invention provides methods for using time domain analysis of NEXT, Return Loss and the like, in conjunction with the application of time or distance referenced limits to verify and determine compliance of the performance requirements of connections in a typical link. Time domain analysis of NEXT, Return Loss data and the like, suitably provides the performance characteristics of a link as a function of time or distance. When coupled with time or distance performance curves for connections, it can be determined if the transmission fault is at a connection or in the cable. The time limit curves for connections can be generated based on the frequency domain performance requirements for connecting hardware of a specific level of performance. The connection time limit curves thus provide an interpretation means to determine if the connection is within performance standards, allowing improved isolation of the fault condition.

Claims

1. A method for determining limits for use in cabling diagnostics, comprising:

(a) determining desired performance limits for a component in a reference cable link;

(b) setting a location variable to said component to an initial reference point;

(c) obtaining a performance characteristic at said location variable;

(d) moving said location variable an incremental amount to reset said location variable; and

(e) repeating steps (c)-(d) along the length of said reference cable link until a desired limit is obtained.

2. The method according to claim 1 wherein said location variable is at least one of a spatial variable or a temporal variable.

3. The method according to claim 1 further comprising the step (e) of comparing said performance characteristics of said component to said desired performance limits and outputting a result of said comparison.

4. The method according to claim 1 further comprising the step (e) of determining whether said performance characteristic exceeds said performance limits.

5. The method according to claim 1 wherein said obtaining step further comprises calculating a time domain performance characteristic by measuring said performance characteristic at said reference point.

6. The method according to claim 1 wherein said obtaining step further comprises calculating a time domain performance characteristic by mathematically calculating said performance characteristic at said reference point.

7. The method according to claim 1 wherein said obtaining step further comprises calculating a time domain performance characteristic by simulating said performance characteristic at said reference point.

8. The method according to claim 1 wherein said obtaining step further comprises generating a time domain performance characteristic by performing an Inverse Fourier Transformation on said performance characteristic at said reference point.

9. The method according to claim 1 wherein said performance characteristic is a reflection characteristic reading.

10. The method according to claim 9 wherein said reflection characteristic reading is a return loss reading.

11. The method according to claim 1 wherein said performance characteristic is a signal coupling characteristic.

12. The method according to claim 11 wherein said signal coupling characteristic is a cross-talk reading.

13. The method according to claim 12 wherein said cross-talk reading characteristic is a near end cross-talk reading.

14. A method for determining limits used in diagnosing cabling, comprising:

(a) determining desired performance limits for a component in a reference cable link;

(b) setting a location variable to a predetermined distance from a reference point;

(c) calculating a frequency performance characteristic at said location variable;

(d) transforming said frequency performance characteristic into a time domain performance characteristic;

(e) adding an incremental amount to said location variable to reset said location variable; and

(f) repeating steps (c)-(e) along the length of said reference cable link.

15. The method according to claim 14 wherein said location variable is at least one of a spatial variable and a temporal variable.

16. The method according to claim 14 further comprising the step (g) of comparing said time domain performance characteristics to said desired performance limits.

17. The method according to claim 14 further comprising the step (g) of determining whether said time domain performance characteristic exceeds said desired performance limits.

18. The method according to claim 14 wherein said obtaining step further comprises calculating a time domain performance characteristic by measuring said performance characteristic at said reference point.

19. The method according to claim 14 wherein said obtaining step further comprises calculating a time domain performance characteristic by mathematically calculating said performance characteristic at said reference point.

20. The method according to claim 14 wherein said obtaining step further comprises calculating a time domain performance characteristic by simulating said performance characteristic at said reference point.

21. The method according to claim 14 wherein said obtaining step further comprises generating a time domain performance characteristic by performing an Inverse Fourier Transformation on said performance characteristic at said reference point.

22. The method according to claim 14 wherein said performance characteristic is a signal coupling characteristic.

23. The method according to claim 14 wherein said performance characteristic is a reflection characteristic reading.

24. The method according to claim 14 wherein said reflection characteristic reading is a return loss reading.

25. The method according to claim 22 wherein said signal coupling characteristic is a cross-talk reading.

26. The method according to claim 25 wherein said cross-talk characteristic is a near end cross-talk reading.