Granted Patent B2

US 8,102,970 · App. 11/489,131 · Granted Jan 24, 2012

Abstract

Claims (103)

1. A method of testing a communication line, the method comprising:

measuring a first voltage/current couple on the communication line including limiting current on the communication line to below a first current threshold during the measuring;

measuring a second voltage/current couple different from the first couple on the communication line including limiting current on the communication line to below a second current threshold during the measuring;

calculating a resistance based on the first couple and the second couple; and

terminating the method if a terminal device connected to the communication line goes to an off-hook state.

2. The method according to claim 1 , comprising:

determining that a connection to an erroneously connected element is present if the resistance is below a threshold value.

3. The method according to claim 2 , wherein the threshold value is at least 1 Megaohm.

4. The method according to claim 1 , comprising:

determining a further resistance between a known location and an element erroneously connected to the communication line based on the resistance.

5. The method of claim 4 , comprising:

determining a distance between the known location and the erroneously connected element based on the further resistance.

6. The method according to claim 1 , comprising:

continuously monitoring if the terminal device connected to the communication line goes to an off-hook state.

7. The method according to claim 1 , wherein the communication line comprises a pair of wires, the method comprising:

setting one wire of the pair of wires to a high impedance state; and

measuring the first couple and the second couple on the other wire of the pair of wires.

8. The method according to claim 1 , wherein measuring the first couple and measuring the second couple comprises controlling a line card to which the communication line is connected to perform the measuring.

9. The method according to claim 1 , wherein the first and the second current thresholds are different.

10. The method according to claim 1 , wherein the first and the second current thresholds are substantially the same.

11. The method according to claim 1 comprising:

setting the first and the second current thresholds below a threshold for off-hook detection for a terminal device.

12. The method according to claim 1 comprising:

setting the first and the second current thresholds significantly below a normal operating current limit.

13. A method of testing a communication line, the communication line comprising a first wire and a second wire, the method comprising:

setting the first wire to a high impedance state;

measuring a first voltage/current couple on the second wire including limiting current on the second wire to below a first current threshold during the measuring;

measuring a second voltage/current couple on the second wire including limiting current on the second wire to below a second current threshold during the measuring;

calculating a first resistance based on the first couple and the second couple;

setting the second wire to a high impedance state;

measuring a third voltage/current couple on the first wire including limiting current on the first wire to below the first current threshold during the measuring;

measuring a fourth voltage/current couple on the first wire including limiting current on the first wire to below the second current threshold during the measuring;

calculating a second resistance based on the third couple and the fourth couple;

evaluating whether at least one of the first wire and the second wire is connected to an erroneously connected element based on the first resistance and the second resistance; and

terminating the method if a terminal device connected to the communication line goes to an off-hook state.

14. The method according to claim 13 , wherein at least one of the measurements comprises setting a voltage on the respective wire and measuring a current on the respective wire.

15. The method according to claim 13 , wherein at least one the measurements comprises setting a current on the wire and determining a corresponding voltage of the respective wire.

16. The method according to claim 13 comprising:

setting the first and the second current thresholds below a threshold for off-hook detection for a terminal device.

17. The method according to claim 13 , comprising:

checking whether the communication line is used; and

delaying the measurements until the communication line is not used.

18. The method according to claim 13 , comprising:

measuring a third resistance between the first wire and a reference potential;

measuring a fourth resistance between the second wire and a reference potential; and

terminating the method if the third resistance and the fourth resistance correspond to expected resistance values.

19. The method according to claim 13 , comprising:

continuously monitoring if the terminal device connected to the communication line goes to an off-hook state.

20. The method according to claim 13 , comprising:

calculating a third resistance between a known location and an element erroneously connected to the communication line based on at least one of the first resistance and the second resistance.

21. An apparatus for testing a communication line, the apparatus comprising:

means for measuring voltage/current couples on the communication line;

means for limiting current on the communication line;

means for calculating a resistance based on measured voltage/current couples; and

means for controlling the means for measuring, the means for limiting, and the means for calculating such that, during a line testing, the following is performed:

measuring a first voltage/current couple on the communication line including limiting current on the communication line to below a first current threshold during the measuring;

measuring a second voltage/current couple on the communication line including limiting current on the communication line to below a second current threshold during the measuring;

calculating a resistance based on the first voltage/current couple and the second voltage/current couple; and

terminating the line testing if a terminal device connected to the communication line goes to an off-hook state.

22. The apparatus according to claim 21 , wherein during the line testing, the following is performed:

deciding that a connection to an erroneously connected element is present if the resistance is below a threshold value.

23. The apparatus according to claim 22 , wherein the threshold value is at least 1 Megaohm.

24. The apparatus according to claim 21 , wherein during the line testing, the following is performed:

calculating a further resistance between a known location and an element erroneously connected to the communication line based on the resistance.

25. The apparatus according to claim 24 , wherein during the line testing, the following is performed:

calculating a distance between the known location and the erroneously connected element based on the further resistance.

26. The apparatus according to claim 21 , wherein during the line testing, the following is performed:

continuously monitoring if the terminal device connected to the communication line goes to an off-hook state.

27. The apparatus according to claim 21 , wherein the communication line comprises a pair of wires, wherein during the line testing, the following is performed:

setting one wire of the pair of wires to a high impedance state; and

measuring the first couple and the second couple on the other wire of the pair of wires.

28. The apparatus according to claim 21 , wherein the measuring the first couple and measuring the second couple comprises controlling a line card to which the communication line is connected to perform the measuring.

29. An apparatus configured to test a communication line, the apparatus comprising:

at least one adjustable source comprising at least one of an adjustable voltage source and an adjustable current source;

at least one current limiter configured to limit current on the communication line;

at least one meter comprising at least one of a current meter and a voltage meter; and

a control unit operatively coupled to the at least one adjustable source and the at least one meter, the control unit having a test mode, wherein, when the test mode of the control unit is activated, the control unit is configured to control the at least one adjustable source, and the at least one current limiter, and the at least one meter to:

measure a first voltage/current couple on the communication line and limit current on the communication line to below a first current threshold during the measuring of the first voltage/current couple;

measure a second voltage/current couple different from the first couple on the communication line and limit current on the communication line to below a second current threshold during the measuring of the second voltage/current couple;

calculate a resistance based on the first couple and the second couple; and

terminate the test of the communication line if a terminal device connected to the communication line goes to an off-hook state.

30. The apparatus according to claim 29 , wherein the at least one adjustable source and the at least one meter are implemented in a line card.

31. The apparatus according to claim 29 , wherein the communication line comprises a first wire and a second wire.

32. The apparatus according to claim 29 , wherein the measuring comprises setting a voltage and measuring a current.

33. The apparatus according to claim 29 , wherein the measuring comprises setting a current and measuring a voltage.

34. The apparatus according to claim 29 , wherein the control unit is configured to set the first current and the second current thresholds below a threshold for off-hook detection for a terminal device.

35. A central office equipment comprising:

at least one line card comprising a current limiter configured to limit current on a communication line and a subscriber line interface configured to be coupled to the communication line and a coder/decoder; and

a programmable control unit coupled to the line card and comprising storage configured to store a program comprising a test procedure, wherein, when the test procedure is run, the following is performed:

measure a first voltage/current couple on the communication line and limit current on the communication line to below a first current threshold during the measuring of the first voltage/current couple;

measure a second voltage/current couple on the communication line and limit current on the communication line to below a second current threshold during the measuring of the second voltage/current couple;

calculate a resistance based on the first couple and the second couple; and

terminate the test procedure if a terminal device connected to the communication line goes to an off-hook state.

36. The central office equipment according to claim 35 , wherein, when the test procedure is run, the following is performed:

determine that a connection to an erroneously connected element is present if the resistance is below a threshold value.

37. The central office equipment according to claim 35 , wherein the threshold value is at least 1 Megaohm.

38. The central office equipment according to claim 35 , wherein, when the test procedure is run, the following is performed:

calculate a resistance between a known location and an element erroneously connected to the communication line based on the resistance.

39. The central office equipment according to claim 35 , wherein, when the test procedure is run, the following is performed:

continuously monitor if the terminal device connected to the communication line goes to an off-hook state.

40. The central office equipment according to claim 35 , wherein the communication line comprises a pair of wires, wherein, when the test procedure is run, the following is performed:

set one wire of the pair of wires to a high impedance state; and

measure the first couple and the second couple on the other wire of the pair of wires.

Assignments (10)