US5629628A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Instrument and method for testing local area network cables
Assignee: Fluke Corp
•
Filing: 1996-05-23
•
Granted: 1997-05-13
•
Expires: 2016-05-23
Abstract
Abstract An instrument and method for the troubleshooting and verification of copper-wire local area network (LAN) cable systems provides a series of resistance and capacitance measurements between all possible wire pairs using a pair of switch matrices and a software method for evaluating the measurements which are stored in a two-dimensional matrix. The stored measurements are evaluated against predetermined figures of merit and the decision pattern in matrix form is compared to that of a known good LAN cable system. Error messages responsive to mismatches are generated and presented to the operator via a user interface. Near-end cross talk (NEXT) isolation is evaluated using a mathematically calculated differential capacitance technique. Error messages are generated responsive to difference capacitance values larger than a figure of merit correlated to an acceptable level of NEXT isolation.
Inventors
- 👤 Mark E. Hinds
- 👤 Robert J. Lewandowski
- 👤 Thomas P. Locke
- 👤 Tzafrir Sheffer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 13:35
CPC Classifications
G; G01; G01R; G01R31/00; G01R31/08; H; H04; H04L; H04L43/00; H04L43/50; G01R31/50; G01R31/58
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
128 words
In a LAN cable test instrument, a method for determining a set of twisted-wire pairs within a LAN cable containing a plurality of wires, comprising: (a) measuring capacitance between each pair of said wires within said LAN cable to produce a set of capacitance measurement values; (b) selecting a subset of said set of capacitance measurement values which are substantially higher than all remaining capacitance measurement values; (c) comparing each of said capacitance measurement values in said subset with each of said remaining capacitance measurement values in said set to determine a minimum ratio of paired capacitance to unpaired capacitance wherein an error signal is generated if said minimum ratio is less than a predetermined figure of merit; and (d) displaying said twisted-wire pairs according to said subset.
Claim 2
Dependent Claim
128 words
In a LAN cable test instrument, a method for determining a set of twisted-wire pairs within a LAN cable containing a plurality of wires, comprising: (a) measuring capacitance between each pair of said wires within said LAN cable to produce a set of capacitance measurement values; (b) selecting a subset of said set of capacitance measurement values which are substantially higher than all remaining capacitance measurement values; (c) comparing each of said capacitance measurement values in said subset with each of said remaining capacitance measurement values in said set to determine a minimum ratio of paired capacitance to unpaired capacitance wherein an error signal is generated if said minimum ratio is less than a predetermined figure of merit; and (d) displaying said twisted-wire pairs according to said subset.
Claim 3
Dependent Claim
39 words
A method for determining a set of twisted-wire pairs within a LAN cable containing a plurality of wires according to claim 1 further comprising storing each of said capacitance measurement values in a memory means as a capacitance matrix.
Claim 4
Dependent Claim
35 words
A method for determining a set of twisted-wire pairs within a LAN cable containing a plurality of wires according to claim 2 further comprising generating a symbolic matrix containing indicator values according to said subset.
Claim 5
Dependent Claim
61 words
A method for determining a set of twisted-wire pairs within a LAN cable containing a plurality of wires according to claim 3 further comprising: (a) comparing a pattern formed by said symbolic matrix to an expected pattern of indicator values for a known good LAN cable; and (b) generating said error signal if said pattern does not match said expected pattern.
Claim 6
Dependent Claim
65 words
A method for determining a set of twisted-wire pairs within a LAN cable containing a plurality of wires according to claim 1 further comprising: (a) comparing each of said capacitance measurement values against a predetermined figure of merit for open circuits; and (b) generating said error signal if any of said capacitance measurement values are less than said predetermined figure of merit for open circuits.
Claim 7
Dependent Claim
199 words
In a LAN cable test instrument, a method for evaluating near-end cross-talk between first and second twisted-wire pairs in a LAN cable, comprising: (a) measuring capacitances between a first wire of said first twisted-wire pair and one wire of said second twisted-wire pair and between a second wire of said first twisted-wire pair and one wire of said second twisted-wire pair within said LAN cable to produce first and second capacitance measurement values; (b) measuring capacitances between a first wire of said first twisted-wire pair and another wire of said second twisted-wire pair and between a second wire of said first twisted-wire pair and another wire of said second twisted-wire pair within said LAN cable to produce third and fourth capacitance measurement values; (c) calculating a first capacitance difference value between said first and second measurement values; (d) calculating a second capacitance difference value between said third and fourth measurement values; (e) comparing said first and second capacitance difference values to a predetermined figure of merit correlated to an acceptable level of near-end cross-talk; and (f) generating an error signal if at least one of said first and said second capacitance difference values exceeds said predetermined figure of merit.
Claim 8
Dependent Claim
199 words
In a LAN cable test instrument, a method for evaluating near-end cross-talk between first and second twisted-wire pairs in a LAN cable, comprising: (a) measuring capacitances between a first wire of said first twisted-wire pair and one wire of said second twisted-wire pair and between a second wire of said first twisted-wire pair and one wire of said second twisted-wire pair within said LAN cable to produce first and second capacitance measurement values; (b) measuring capacitances between a first wire of said first twisted-wire pair and another wire of said second twisted-wire pair and between a second wire of said first twisted-wire pair and another wire of said second twisted-wire pair within said LAN cable to produce third and fourth capacitance measurement values; (c) calculating a first capacitance difference value between said first and second measurement values; (d) calculating a second capacitance difference value between said third and fourth measurement values; (e) comparing said first and second capacitance difference values to a predetermined figure of merit correlated to an acceptable level of near-end cross-talk; and (f) generating an error signal if at least one of said first and said second capacitance difference values exceeds said predetermined figure of merit.
Claim 9
Dependent Claim
35 words
A method for evaluating near-end cross-talk between first and second twisted-wire pairs in a LAN cable according to claim 6 further comprising generating a capacitance difference matrix from said first and second capacitance difference values.
Claim 10
Dependent Claim
17 words
In a LAN cable test instrument according to claim 6 further comprising visually displaying said error signal.
Claim 11
Dependent Claim
110 words
In a LAN cable test instrument, a method for evaluating near-end cross-talk between a twisted-wire pair and a conductor in a LAN cable, comprising: (a) measuring capacitances between a first wire of said first twisted-wire pair and said conductor and between a second wire of said first twisted-wire pair and said conductor to produce first and second capacitance measurement values; (b) calculating a capacitance difference value between said first and second measurement values; (c) comparing said capacitance difference value to a predetermined figure of merit correlated to an acceptable level of near-end cross-talk; and (f) generating an error signal if said capacitance difference value exceeds said predetermined figure of merit.
Claim 12
Dependent Claim
110 words
In a LAN cable test instrument, a method for evaluating near-end cross-talk between a twisted-wire pair and a conductor in a LAN cable, comprising: (a) measuring capacitances between a first wire of said first twisted-wire pair and said conductor and between a second wire of said first twisted-wire pair and said conductor to produce first and second capacitance measurement values; (b) calculating a capacitance difference value between said first and second measurement values; (c) comparing said capacitance difference value to a predetermined figure of merit correlated to an acceptable level of near-end cross-talk; and (f) generating an error signal if said capacitance difference value exceeds said predetermined figure of merit.
Claim 13
Dependent Claim
17 words
In a LAN cable test instrument according to claim 9 further comprising visually displaying said error signal.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2000-05-12 | 2000-11-11 | 2001-05-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-05-12 | 2004-11-11 | 2005-05-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-05-12 | 2008-11-11 | 2009-05-13 | $7700.00 | Window Closed / Lapsed |