Patent US4859951A successfully refreshed from Google Patents.
US4859951A
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Detecting faults in transmission lines employing an echo cancellation signal
Assignee: British Telecommunications PLC
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Filing: 1987-10-21
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Granted: 1989-08-22
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Expires: 2007-10-21
Abstract
Abstract A variation in the cancellation coefficents of an echo cancelling modem indicate a change in the impedance of a line. In an echo canceller with T spaced samples (i.e. producing a cancellation signal at the data rate) the resolution is too poor to provide satisfactory identification of faults. A set of coefficients is stored and the sampling phase adjusted to produce a second set. This may be repeated producing eight sets in the preferred embodiment. A higher resolution picture of the line impedance is built up allowing comparisons with an earlier or optimum set of values. The test facility may be included in an operating modem providing line test facilities when not transmitting data.
Inventors
- 👤 Nigel G. Cole
- 👤 Peter F. Adams
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 23:33
CPC Classifications
H; H04; H04B; H04B3/00; H04B3/02; H04B3/20; H04B3/23; H04B3/231; G; G11; G11C; G11C27/00; G11C27/02; H04B3/46; H04B3/493
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
156 words
Fault detection apparatus for detecting faults in transmission lines comprising: transmitter means for supplying a sequence of output pulses to a wire, receiver means for receiving echoes of said pulses from said wire using a sample clock rate of 1/T and an adaptive cancellation processor arranged to produce a cancellation signal in response to each output pulse, said apparatus further including a fault detection processor, said fault detection processor being arranged to receive N sets of cancellation coefficients from said cancellation processor, each of said sets of cancellation coefficients being derived by adjusting the sample clock phase of the receiver means and hence of the cancellation signal by T/N, said fault detection processor interleaving said N sets of coefficients to derive an overall coefficient set representing line characteristics at N times sample rate 1/T, said overall set of coefficients being compared with a stored reference set to determine whether a fault has occurred on the line.
Claim 2
Dependent Claim
156 words
Fault detection apparatus for detecting faults in transmission lines comprising: transmitter means for supplying a sequence of output pulses to a wire, receiver means for receiving echoes of said pulses from said wire using a sample clock rate of 1/T and an adaptive cancellation processor arranged to produce a cancellation signal in response to each output pulse, said apparatus further including a fault detection processor, said fault detection processor being arranged to receive N sets of cancellation coefficients from said cancellation processor, each of said sets of cancellation coefficients being derived by adjusting the sample clock phase of the receiver means and hence of the cancellation signal by T/N, said fault detection processor interleaving said N sets of coefficients to derive an overall coefficient set representing line characteristics at N times sample rate 1/T, said overall set of coefficients being compared with a stored reference set to determine whether a fault has occurred on the line.
Claim 3
Dependent Claim
22 words
Fault detection apparatus according to Claim 1 in which the coefficients from each of said N sets are interleaved and displayed graphically.
Claim 4
Dependent Claim
17 words
Fault detection apparatus according to claim 1 in which said phase is adjusted seven times and N=8.
Claim 5
Independent Claim
106 words
A method of detecting faults in transmission lines comprising steps of: supplying a sequence of output pulses to a wire, receiving echoes of said pulses from said wire and producing a cancellation signal in response to each output pulse, adjusting the sample clock using a sample clock rate 1/T phase used to produce the cancellation signal (N - 1) times to produce N sets of cancellation coefficients, interleaving said N sets of cancellation coefficients to produce an overall set of cancellation coefficients at N times the sample clock rate and comparing said overall set of coefficients to determine whether a fault has occurred on the line.
Claim 6
Independent Claim
106 words
A method of detecting faults in transmission lines comprising steps of: supplying a sequence of output pulses to a wire, receiving echoes of said pulses from said wire and producing a cancellation signal in response to each output pulse, adjusting the sample clock using a sample clock rate 1/T phase used to produce the cancellation signal (N - 1) times to produce N sets of cancellation coefficients, interleaving said N sets of cancellation coefficients to produce an overall set of cancellation coefficients at N times the sample clock rate and comparing said overall set of coefficients to determine whether a fault has occurred on the line.
Claim 7
Dependent Claim
24 words
A method according to claim 4 in which the phase of the cancellation signal is adjusted relative to the phase of the output pulses.
Claim 8
Dependent Claim
22 words
A method according to claim 4 in which the relative phase is adjusted seven times to produce eight sets of cancellation coefficients.
Claim 9
Dependent Claim
15 words
A method according to claim 6 in which the coefficients are interleaved and displayed graphically.
Claim 10
Dependent Claim
111 words
Transmission line fault detecting apparatus comprising: transmitter means for launching repetitive pulses onto a transmission line; receiver means connected to receive resulting pulse echoes from said transmission line and to calculate a set of echo cancellation coefficients using supplied clock pulses of controllable phase and a transversal filter with tap spacings of T seconds; and a fault detection processor means for controllably changing the phase of said clock pulses by an increment of less than T seconds between successive cycles of calculation and storage of said cancellation coefficients thereby providing plural sets of stored coefficients which can be interleaved into a composite set having a resolution interval of less than T.
Claim 11
Dependent Claim
111 words
Transmission line fault detecting apparatus comprising: transmitter means for launching repetitive pulses onto a transmission line; receiver means connected to receive resulting pulse echoes from said transmission line and to calculate a set of echo cancellation coefficients using supplied clock pulses of controllable phase and a transversal filter with tap spacings of T seconds; and a fault detection processor means for controllably changing the phase of said clock pulses by an increment of less than T seconds between successive cycles of calculation and storage of said cancellation coefficients thereby providing plural sets of stored coefficients which can be interleaved into a composite set having a resolution interval of less than T.
Claim 12
Dependent Claim
96 words
Transmission line detecting method comprising: launching repetitive pulses onto a transmission line; receiving resulting pulse echoes from said transmission line and calculating a set of echo cancellation coefficients using supplied clock pulses of controllable phase and a transversal filter with tap spacings of T seconds; and controllably changing the phase of said clock pulses by an increment of less than T seconds between successive cycles of calculation and storage of said cancellation coefficients thereby providing plural set of stored coefficient which can be interleaved into a composite set having a resolution interval of less than T.
Claim 13
Dependent Claim
96 words
Transmission line detecting method comprising: launching repetitive pulses onto a transmission line; receiving resulting pulse echoes from said transmission line and calculating a set of echo cancellation coefficients using supplied clock pulses of controllable phase and a transversal filter with tap spacings of T seconds; and controllably changing the phase of said clock pulses by an increment of less than T seconds between successive cycles of calculation and storage of said cancellation coefficients thereby providing plural set of stored coefficient which can be interleaved into a composite set having a resolution interval of less than T.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-08-21 | 1993-02-20 | 1993-08-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-08-21 | 1997-02-20 | 1997-08-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-08-21 | 2001-02-20 | 2001-08-22 | $7700.00 | Window Closed / Lapsed |