Systems and methods for loop length and bridged tap length determination of a transmission line

• US 6,865,221 B2
• Filed: 01/08/2001
• Issued: 03/08/2005
• Est. Priority Date: 01/07/2000
• Status: Expired due to Term

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Aware Incorporated (Crowley Holdings Preferred LLC)
• Inventors: Belge, Murat
• Primary Examiner(s): Chin, Stephen
• Assistant Examiner(s): Vartanian, Harry
• Application Number:
  US09/755,172
• Publication Number:
  US 20010043647A1
• Time in Patent Office: 1,520 Days
• Field of Search: 375/222, 375/224
• US Class Current: 375/222
• CPC Class Codes: H04B 3/46 Monitoring; Testing
• CPC Class Codes: H04B 3/493 Testing echo effects or singing
• CPC Class Codes: H04L 1/004 by using forward error control H04L1/0618 takes precedence; coding, decoding or code conversion, for error detection or correction H03M13/00
• CPC Class Codes: H04L 1/24 Testing correct operation
• CPC Class Codes: H04L 1/245 by using the properties of transmission codes
• CPC Class Codes: H04L 25/0202 Channel estimation
• CPC Class Codes: H04L 25/0216 with estimation of channel length
• CPC Class Codes: H04L 43/50 Testing arrangements
• CPC Class Codes: H04L 5/1438 Negotiation of transmission parameters prior to communication modified according to link quality H04L1/0001
• CPC Class Codes: H04M 3/085 Fault locating arrangements
• CPC Class Codes: H04M 3/2209 for lines also used for data transmission
• CPC Class Codes: H04M 3/2227 Quality of service monitoring
• CPC Class Codes: H04M 3/306 for frequencies above the voice frequency, e.g. xDSL line qualification test methods, test equipment and test arrangements for subscriber lines using xDSL modems H04M3/304; systems modifying transmission characteristics according to link quality H04L1/0001; monitoring and/or testing of line transmission systems H04B3/46

Abstract

Through the use of a least squares minimization concept, the loop length, the number of bridged taps and length of the bridged taps on a transmission line can be determined from readily available modem data. In particular, the loop length, the number of bridge taps and the length of bridged taps can be estimated by comparing a measured frequency domain channel impulse response of the transmission line to a model of a loop that is comprised of multiple sections and multiple bridge taps.

Claims

1. A loop length and bridged tap length estimation system comprising:

a central office (CO) modem;

a customer-premises equipment (CPE) modem;

a channel impulse response device that determines a channel impulse response for a transmission line based on signals transmitted during initialization of the CO modem and CPE modem;

a modeling device that determines a theoretical channel impulse response; and

a loop length and bridged tap determination device that determines a loop length and at least one bridged tap length based on a comparison of the channel impulse response and the theoretical channel impulse response.

2. The system of claim 1, wherein the comparison is based on an error minimization function.

3. The system of claim 2, where the error minimization function is a least squares minimization.

4. The system of claim 1, further comprising an impedance determination device that determines at least one of a transmit impedance of the CPE modem and a receive impedance of the CO modem.

5. The system of claim 1, further comprising a modem identification determining device that determines at least one of an identification of the CPE modem and an identification of the CO modem.

6. The system of claim 1, wherein the theoretical channel impulse response comprises variables representing a load and a source impedance.

7. The system of claim 1, where the channel impulse response is estimated based on a measured reverb signal.

8. The system of claim 1, wherein the transmission line comprises at least one of at least one wire gauge and at least one bridged tap.

9. The system of claim 1, wherein the transmission line is used for multicarrier modulation communications.

10. A method for determining a loop length and at least one bridged tap for a transmission line comprising:

initializing a central office (CO) modem and a customer-premises equipment (CPU) modem;

estimating a channel impulse response based on signals transmitted during the initialization step;

determining a theoretical channel impulse response;

comparing the theoretical channel impulse response and the estimated channel impulse response; and

determining the loop length and at least one bridged tap based on an error minimization function.

11. The method of claim 10, further comprising determining a transfer function of the transmission line based on a reverb signal.

12. The method of claim 11, wherein the transfer function is determined based on averaging a predetermined number of consecutive frames of the reverb signal.

13. The method of claim 10, further comprising determining a frequency domain propagation function for at least one wire gauge.

14. The method of claim 10, further comprising determining at least one of a calibrated and a compensated reverb signal in the frequency domain.

15. The method of claim 10, further comprising determining the frequency domain impedance of at least one wire gauge.

16. The method of claim 10, further comprising determining a transmit impedance of the CPE modem.

17. The method of claim 10, further comprising determining a receive impedance of the CO modem.

18. The method of claim 10, further comprising determining a matrix representing a frequency domain response for a predetermined portion of the transmission line.

19. The method of claim 10, further comprising determining a matrix representing a response of the at least one bridged tap.

20. The method of claim 10, further comprising determining a matrix representing an analog front end circuit for a source and a load path.

21. The method of claim 10, further comprising determining an identification of at least one of the CO modem and the CPE modem.

22. The method of claim 10, further comprising outputting an estimated loop length of the transmission line.

23. The method of claim 10, further comprising outputting an estimated bridged tap length for the transmission line.

24. An information storage media comprising information that determines a loop length and at least one bridged tap for a transmission line comprising:

information that initializes a central office (CO) modem and a customer-premises equipment (CPE) modem;

information that estimates a channel impulse response based on signals transmitted during the initialization;

information that determines a theoretical channel impulse response;

information that monitors a difference between the theoretical channel impulse response and the estimated channel impulse response; and

information that determines the loop length and at least one bridged tap based on an error minimization function.

25. The information storage media of claim 24, further comprising information that determines a transfer function of the transmission line based on a reverb signal.

26. The information storage media of claim 25, wherein the transfer function is determined based on averaging a predetermined number of consecutive frames of the reverb signal.

27. The information storage media of claim 24, further comprising information that determines a frequency domain propagation function for at least one wire gauge.

28. The information storage media of claim 24, further comprising information that determines at least one of a calibrated and a compensated reverb signal in the frequency domain.

29. The information storage media of claim 24, further comprising information that determines the frequency domain impedance of at least one wire gauge.

30. The information storage media of claim 24, further comprising information that determines a transmit impedance of the CPE modem.

31. The information storage media of claim 24, further comprising information that determines a receive impedance of the CO modem.

32. The information storage media of claim 24, further comprising information that determines a matrix representing a frequency domain response for a predetermined portion of the transmission line.

33. The information storage media of claim 24, further comprising information that determines a matrix representing a response of the at least one bridged tap.

34. The information storage media of claim 24, further comprising information that determines a matrix representing an analog front end circuit for a source and a load path.

35. The information storage media of claim 24, further comprising information that determines an identification of at least one of the CO modem and the CPE modem.

36. The information storage media of claim 24, further comprising information that outputs an estimated loop length of the transmission line.

37. The information storage media of claim 24, further comprising information that outputs an estimated bridged tap length for the transmission line.