US5063585A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Telephone subscriber line fault detector
Assignee: Nokia Bell Labs
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Filing: 1990-09-27
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Granted: 1991-11-05
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Expires: 2010-09-27
Abstract
Abstract The present invention relates to a method for distinguishing between an open conductor and a proper termination of a telephone subscriber loop which is terminated with a telephone which does not conform to the ringer-equivalence standard of the FCC Rules. In this invention a telephone subscriber loop can be tested for an open or for a termination by a customer provided equipment telephone by obtaining a first ratio of the tip-to-ground impedance relative to the tip-to-ring impedance; and a second ratio of the ring-to-ground impedance relative to the tip-to-ring impedance, and comparing each of these ratios relative to a fixed ratio value. If the measured ratios are substantially equal to or greater than the fixed ratio value, the subscriber loop is terminated with a customer provided equipment telephone. The fixed value may be dependent upon the length of the loop and whether or not a maintenance termination unit is present in the loop.
Inventors
- 👤 Roy A. Shapiro
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 22:01
CPC Classifications
H; H04; H04M; H04M3/00; H04M3/22; H04M3/26; H04M3/28; H04M3/30
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
103 words
A method of testing a telephone subscriber loop having a tip conductor and a ring conductor for a customer provided equipment telephone termination comprising the steps of measuring the impedance between the tip conductor and a ground terminal, measuring the impedance between the ring conductor and the ground terminal, measuring the impedance between the tip conductor and the ring conductor, comparing the tip-ground impedance and ring-ground impedance with the tip-to-ring impedance to obtain two ratio values; and comparing said two ratio values with a fixed ratio value to determine the presence of a customer provided equipment telephone termination on said telephone subscriber loop.
Claim 2
Independent Claim
103 words
A method of testing a telephone subscriber loop having a tip conductor and a ring conductor for a customer provided equipment telephone termination comprising the steps of measuring the impedance between the tip conductor and a ground terminal, measuring the impedance between the ring conductor and the ground terminal, measuring the impedance between the tip conductor and the ring conductor, comparing the tip-ground impedance and ring-ground impedance with the tip-to-ring impedance to obtain two ratio values; and comparing said two ratio values with a fixed ratio value to determine the presence of a customer provided equipment telephone termination on said telephone subscriber loop.
Claim 3
Dependent Claim
24 words
The method of claim 1 further comprising the step of determining the length of said telephone subscriber loop to determine said fixed ratio value.
Claim 4
Dependent Claim
27 words
The method of claim 2 further comprising the step of determining if said telephone subscriber loop has a maintenance termination unit for determining the fixed ratio value.
Claim 5
Dependent Claim
53 words
The method of claim 1 further comprising the step of comparing said two ratio values with a fixed ratio value of substantially 3:1, and identifying a telephone subscriber loop as having a customer provided equipment telephone termination when said two ratio values are substantially equal to or more than said fixed ratio value.
Claim 6
Dependent Claim
52 words
The method of claim 1 further comprising the step of comparing said two ratio values with a fixed ratio value of substantially 4:1, and identifying a telephone subscriber loop as having a customer provided equipment termination when said two ratio values are substantially equal to or more than said fixed ratio value.
Claim 7
Dependent Claim
52 words
The method of claim 1 further comprising the step of comparing said two ratio values with a fixed ratio value of substantially 6:1, and identifying a telephone subscriber loop as having a customer provided equipment termination when said two ratio values are substantially equal to or more than said fixed ratio value.
Claim 8
Dependent Claim
17 words
The method of claim 5 wherein said loop is substantially equal to or greater than 60K feet.
Claim 9
Dependent Claim
13 words
The method of claim 6 wherein said loop includes a maintenance termination unit.
References Cited (Backward Citations)
US4292480A
Cited
US4845737A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-11-04 | 1995-05-06 | 1995-11-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-11-04 | 1999-05-06 | 1999-11-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-11-04 | 2003-05-06 | 2003-11-05 | $7700.00 | Window Closed / Lapsed |