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

• US 8,958,466 B2
• Filed: 03/27/2014
• Issued: 02/17/2015
• Est. Priority Date: 01/07/2000
• Status: Expired due to Fees

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Belge, Murat
• Primary Examiner(s): Ahn, Sam K
• Assistant Examiner(s): Perez, James M
• Application Number:
  US14/227,827
• Publication Number:
  US 20140211836A1
• Time in Patent Office: 327 Days
• Field of Search: 375/219, 375/222, 375/224, 375/259, 375/260, 375/295, 375/316, 375/346, 375/354, 375/358, 375/377, 379/1.01, 379/1.03, 379/1.04, 379 22- 24, 379/27.01, 379/27.03, 379/28, 379 2901- 2902, 379/29.09
• 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 modem-based upstream data loop length and bridged tap length estimation system comprising:

a reverb signal determination device configured to determine a measured transfer function by averaging a plurality of consecutive frames of a reverb signal;

a controller configured to determine a frequency domain propagation function for a specified wire gauge input from a storage device;

an impedance determination device configured to determine a frequency domain impedance of the specified wire gauge;

the controller further configured to;

determine a transmit impedance of a customer-premises equipment, CPE, modem;

determine a receive impedance of a central office, CO, modem;

determine a matrix representing frequency domain responses of a plurality of sections of the loop, the matrix further including a frequency response of a bridged tap, and an F^S matrix and an F^L matrix respectively representing analog front end circuitry for source (TX) and load (RX) paths;

estimate an actual transfer function (H) based on the frequency domain responses of the plurality of sections of the loop, the frequency response of the bridged tap, the F^S matrix, and the F^L matrix; and

input a calibrated and a compensated reverb signal in the frequency domain, and a reference gauge of a wire from the storage device; and

a modem identification determining device configured to determine an identification of the CO modem collecting the reverb signal, and the identification of the CPE modem transmitting the reverb signal,

wherein since the number of elements in a receive function is known, the controller is further configured to minimize a difference between the actual transfer function and the measured transfer function, and output, with the cooperation of a loop length output device and a bridged tap output device, the estimated loop length and the estimated bridged tap length, respectively.

2. The system of claim 1, wherein the loop includes a communication line and an assumption is made that the communication line is not perfectly terminated.

3. The system of claim 1, further comprising the CO or CPE modem being initialized.

4. The system of claim 1, wherein the specified wire gauge is input to the storage device.

5. The system of claim 1, wherein a transmission line connects the CO modem and the CPE modem.

6. The system of claim 1, wherein the estimated loop length and the estimated bridged tap length are also applicable to a downstream direction.

7. The system of claim 1, wherein the loop length output device outputs the estimated loop length to one or more of a computer, a laptop, a terminal, and a transmission line testing device.

8. The system of claim 1, wherein the bridged tap output device outputs the estimated bridged tap length to one or more of a computer, a laptop, a terminal, and a transmission line testing device.

9. A modem-based upstream data loop length and bridged tap length estimation method comprising:

determining a measured transfer function by averaging a plurality of consecutive frames of a reverb signal;

determining a frequency domain propagation function for a specified wire gauge input from a storage device;

determining a frequency domain impedance of the specified wire gauge;

determining a transmit impedance of a customer-premises equipment, CPE, modem;

determining a receive impedance of a central office, CO, modem;

determining a matrix representing frequency domain responses of a plurality of sections of the loop, the matrix including a frequency response of a bridged tap, and an F^S matrix and an F^L matrix respectively representing analog front end circuitry for source (TX) and load (RX) paths;

determining an actual transfer function (H) based on the frequency domain responses of the plurality of sections of the loop, the frequency response of the bridged tap, the F^S matrix, and the F^L matrix; and

inputting a calibrated and a compensated reverb signal in the frequency domain, and a reference gauge of a wire from the storage device; and

determining an identification of the CO modem collecting the reverb signal, and the identification of the CPE modem transmitting the reverb signal,

wherein since the number of elements in a receive function is known, a difference between the actual transfer function and the measured transfer function may be determined, and the estimated loop length and the estimated bridged tap length are output respectively by a loop length output device and a bridged tap output device.

10. The method of claim 9, wherein the loop includes a communication line and an assumption is made that the communication line is not perfectly terminated.

11. The method of claim 9, further comprising the CO or CPE modem being initialized.

12. The method of claim 9, wherein the specified wire gauge is input to the storage device.

13. The method of claim 9, wherein a transmission line connects the CO modem and the CPE modem.

14. The method of claim 9, wherein the estimated loop length and the estimated bridged tap length are also applicable to a downstream direction.

15. The method of claim 9, wherein the loop length output device outputs the estimated loop length to one or more of a computer, a laptop, a terminal, and a transmission line testing device.

16. The method of claim 9, wherein the bridged tap output device outputs the estimated bridged tap length to one or more of a computer, a laptop, a terminal, and a transmission line testing device.