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

• US 7,835,431 B2
• Filed: 01/26/2010
• Issued: 11/16/2010
• Est. Priority Date: 01/07/2000
• Status: Expired due to Fees

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Aware Incorporated (Crowley Holdings Preferred LLC)
• Inventors: Belge, Murat
• Primary Examiner(s): Payne, David C
• Assistant Examiner(s): Perez, James M
• Application Number:
  US12/694,128
• Publication Number:
  US 20100142602A1
• Time in Patent Office: 294 Days
• Field of Search: 375/219, 375222-224, 375229-236, 379 22- 23, 379/337, 379/380, 379/400, 379/414, 455/73, 455/500.1, 455/557
• 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 method to estimate a loop length of a transmission line comprising:

estimating a first channel transfer function using one or more downstream signals from an initialization;

estimating a second channel transfer function using one or more upstream signals from the initialization, the initialization occurring between a first broadband multicarrier modem on a first end of the transmission line and a second broadband multicarrier modem on a second end of the transmission line, the one or more downstream signals from the initialization having been transmitted or received using a first multiplicity of discrete frequency carriers and the one or more upstream signals from the initialization having been transmitted or received using a second multiplicity of discrete frequency carriers;

determining a first theoretical channel transfer function;

determining a second theoretical channel transfer function;

comparing the first theoretical channel transfer function and the first estimated channel transfer function;

comparing the second theoretical channel transfer function and the second estimated channel transfer function;

determining a first estimated loop length of the transmission line based upon said comparison of the first theoretical channel transfer function and the first estimated channel transfer function; and

determining a second estimated loop length of the transmission line based upon said comparison of the second theoretical channel transfer function and the second estimated channel transfer function.

2. The method of claim 1, wherein the estimating of one or more of the first and second channel transfer functions uses a REVERB signal.

3. The method of claim 1, further comprising estimating a bridged tap length.

4. The method of claim 1, further comprising outputting one or more of the estimated loop lengths.

5. The method of claim 1, wherein one or more of the first and second estimated channel transfer functions include multiple sections with varying gauges.

6. The method of claim 1, wherein one or more of the first and second theoretical channel transfer functions include multiple sections with varying gauges.

7. The method of claim 1, wherein the method is performed on at least one of a single program general purpose computer, a program general purpose computer, a special purpose computer, a programmed microprocessor, a microcontroller and peripheral integrated circuit element, an ASIC or other integrated circuit, a digital signal processor, a hard wired electronic or logic circuit, a discrete element circuit, a programmable logic device, a PLD, a PLA, an FPGA, a PAL, and a modem.

8. A loop length estimation system comprising:

a controller; and

a loop length output device capable of;

estimating a first channel transfer function using one or more downstream signals from an initialization;

estimating a second channel transfer function using one or more upstream signals from the initialization, the initialization occurring between a first broadband multicarrier modem on a first end of a transmission line and a second broadband multicarrier modem on a second end of the transmission line, the one or more downstream signals from the initialization having been transmitted or received using a first multiplicity of discrete frequency carriers and the one or more upstream signals from the initialization having been transmitted or received using a second multiplicity of discrete frequency carriers;

determining a first theoretical channel transfer function;

determining a second theoretical channel transfer function;

comparing the first theoretical channel transfer function and the first estimated channel transfer function;

comparing the second theoretical channel transfer function and the second estimated channel transfer function;

determining a first estimated loop length of the transmission line based upon said comparison of the first theoretical channel transfer function and the first estimated channel transfer function; and

determining a second estimated loop length of the transmission line based upon said comparison of the second theoretical channel transfer function and the second estimated channel transfer function.

9. The system of claim 8, wherein the estimating of one or more of the first and second channel transfer functions uses a REVERB signal.

10. The system of claim 8, wherein the loop length output device is further capable of estimating a bridged tap length.

11. The system of claim 8, wherein the loop length output device is further capable of outputting one or more of the estimated loop lengths.

12. The system of claim 8, wherein one or more of the first and second estimated channel transfer functions include multiple sections with varying gauges.

13. The system of claim 8, wherein one or more of the first and second theoretical channel transfer functions include multiple sections with varying gauges.

14. The system of claim 8, wherein the loop length estimation system is implemented on at least one of a single program general purpose computer, a program general purpose computer, a special purpose computer, a programmed microprocessor, a microcontroller and peripheral integrated circuit element, an ASIC or other integrated circuit, a digital signal processor, a hard wired electronic or logic circuit, a discrete element circuit, a programmable logic device, a PLD, a PLA, an FPGA, a PAL, and a modem.