Patent EP0454926A2 successfully refreshed from Google Patents.
EP0454926A2
Expired / Lapsed
EP
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Drop testing in fiber to the home systems
Assignee: AT&T Inc
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Filing: 1990-12-17
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Granted: —
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Expires: 2010-12-17
Abstract
Abstract Disclosed is a means for testing drop wires (18) in digital loop systems which employ optical fiber up to a distant terminal (16) near the subscriber's premises. A test module (20) is provided at the distant terminal to determine the presence or absence of faults on the wires to the customer premises. The results of the test are transmitted via an optical data link (17) to the remote terminal (12) where the results can be accessed by a loop tester (15) at the central office.
Inventors
- 👤 Michael Eugene Burke
- 👤 Samuel Colodner
- 👤 Huy Tho Luu
- 👤 Steven Philip Saneski
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-02 16:09
CPC Classifications
H; H04; H04B; H04B10/00; H04B10/07; H04M; H04M3/00; H04M3/22; H04M3/26; H04M3/28; H04M3/30; H04M3/302; H04M3/303; G; G01; G01R; G01R31/00; G01R31/50; G01R31/52; G01R31/54; G01R31/58
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
67 words
A digital loop transmission system comprising: a central office terminal (11); a remote terminal (12) optically and electrically coupled to the central office terminal; a distant terminal (16) optically coupled to the remote terminal; and CHARACTERIZED BY means (20 and 21) in the distant terminal for testing electrical wires extending beyond the distant terminal and for optically transmitting the results of said test to the remote terminal.
Claim 2
Dependent Claim
42 words
The system according to claim 1 further comprising means (e.g., K 5C , K 6C , K 7C and R₁₀₁, R₁₀₂, R₁₀₃) in the remote terminal for converting said results into characteristic resistances which can be electrically accessed by a loop tester.
Claim 3
Dependent Claim
42 words
The system according to claim 1 wherein the testing means includes means (FIGS. 3 and 4) for detecting leakage in the wires, the presence of a ringer circuit coupled to the wires and an off-hook condition of equipment coupled to the wires.
Claim 4
Dependent Claim
43 words
The system according to claim 3 wherein the testing means includes means (100, 101) for generating a constant current of two different values and means (e.g., 104, 105, R₁₅, R₁₆, R₂₄, R₂₅, Q₇-Q₁₀) for determining the resistance of the wires at these values.
Claim 5
Dependent Claim
29 words
The system according to claim 1 wherein the testing means includes a bridge circuit (R₁₅, R₁₆, R₂₄, R₂₅) for comparing the resistance on the wires with a known resistance.
Claim 6
Dependent Claim
43 words
The system according to claim 1 further comprising means (201) for producing a data signal comprising a predetermined bit length in response to said tests and for combining that signal with other data from the distant terminal for transmission to the remote terminal.
Claim 7
Dependent Claim
37 words
The system according to claim 1 wherein the characteristic resistances are generated by a resistor delta (FIG. 8) including fixed resistances (R₁₀₀ and R₁₀₅) between each wire and ground, and a variable resistance between the two wires.
Claim 8
Dependent Claim
66 words
The system according to claim 7 wherein the variable resistance is generated by a plurality of resistors (R₁₀₁-R₁₀₃) coupled in series between the two wires and individual switches (K 5C -K 7C ) coupled in parallel to each of said resistors, said switches being responsive to the signal transmitted by the testing means to electrically couple one or more of said resistors between the two wires.
Claim 9
Dependent Claim
73 words
A circuit for electrically testing a pair of wires CHARACTERIZED BY circuit means (100, 101) for generating a constant current having at least two values; a bridge circuit (R₁₅, R₁₆, R₂₄, R₂₅) having two legs and including means (Q₇-Q₁₀) for comparing voltages at the two legs of the circuit; and means (K 1B , K 1C , K₂) for coupling at least one of said wires to a leg of the bridge circuit.
Claim 10
Dependent Claim
34 words
The circuit according to claim 9 further comprising switching means (104, 105) for alternatively coupling two resistors (R₂₄, R₂₅) to the leg of the bridge circuit coupled to at least one of said wires.
Claim 11
Dependent Claim
38 words
The circuit according to claim 9 further comprising means (e.g., (R₄₄-R₄₇, 120, 114) for comparing the voltage across the wires to a predetermined maximum value prior to coupling at least one of said wires to the bridge circuit.
Claim 12
Dependent Claim
35 words
The circuit according to claim 9 further comprising means (115) for producing a digital output signal having a predetermined bit length, said signal based at least in part on the output of the comparing means.
Claim 13
Dependent Claim
67 words
The circuit according to claim 9 wherein the circuit means for generating a constant current comprises an operational amplifier (102) with one input grounded and the other input coupled to a source of reference voltage, and a feedback loop to said other input comprising a pair of bipolar transistors (Q₁, Q₂) and a resistor (R₆) through which a constant current is drawn when said transistors are enabled.
Claim 14
Dependent Claim
33 words
The circuit according to claim 13 wherein the source of reference voltage is provided alternatively through a pair of switches (100, 101) having different resistors (R₂, R₃) at the output of the switches.
Claim 15
Dependent Claim
52 words
The circuit according to claim 9 wherein the means for comparing voltages comprises a differential amplifier having two legs and including Darlington-coupled bipolar transistors (Q₇, Q₈ and Q₉, Q₁₀) and a resistor (R₁₈ and R₁₉) in different legs, each leg being coupled to a current source (Q 5 , Q 6 ).
Claim 16
Dependent Claim
28 words
The circuit according to claim 9 further comprising means (106) for coupling a zener diode (D₂) of a particular breakdown voltage to a leg of the bridge circuit.
Claim 17
Dependent Claim
31 words
The circuit according to claim 10 further comprises means (C₁₀) for storing the voltage generated at a leg of the bridge circuit when one of said two resistors is coupled thereto.
Claim 18
Dependent Claim
55 words
The circuit according to claim 17 further comprising an operational amplifier (107) with one input coupled through a switch (117) to a leg of the bridge circuit and the other input coupled to a pair of resistors so as to produce a signal if the resistance of the wires is greater than a predetermined value.
Claim 19
Dependent Claim
33 words
The circuit according to claim 18 further comprising a comparator element (110) with one input coupled to the output of said operational amplifier and the other input coupled to said voltage storing means.
Claim 20
Dependent Claim
74 words
The circuit according to claim 9 further comprising reference capacitors (C₈, C₁₈) coupled through a switch (111) to a node of said bridge circuit, means (112) for charging said capacitors and any capacitors on the wires to the same voltage, and means (117, R₂₆, R₂₇ and R₁₆) for discharging said capacitors and said capacitors on the line so that the amount of charge stored is compared by the comparing means of the bridge circuit.
References Cited (Backward Citations)
No citation records indexed.
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