US3749857A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Cable testing device for long-distance cables, particularly for occupied cables
Assignee: ROSE W KG DT
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Filing: 1971-10-27
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Granted: 1973-07-31
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Expires: 1991-10-27
Abstract
Abstract A cable testing device including an oscillator designed to operate at a constant frequency and arranged to be selectively interconnected to one end of pairs of conductors in a long distance telephone cable through a transformer. Optical and/or acoustic signal generators are connected to windings on the transformer and to the pairs of conductors at their other ends at the opposite end of the cable. The signal generators permit resistance values of a known pair of conductors to be compared to resistance values of conductors tested one by one in conjunction with a return conductor of known value. These signal generators can be electrical meters or may involve a switching stage which is associated with the transformer to switch a wireless signal generator or a summing device, such as a multivibrator.
Inventors
- 👤 T Konig
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 06:23
CPC Classifications
H; H04; H04M; H04M3/00; H04M3/22; H04M3/26; H04M3/28; G; G01; G01R; G01R31/00; G01R31/50; G01R31/58; G01R31/60
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
321 words
Circuitry for testing for the proper connection of an individual conductor in a telephone cable having a plurality of conductors by providing an indication of the relation between a preselected resistance value and the resistance value of a conductive test path which includes a test portion and a return conductive portion, the test circuit comprising in combination: a. a first transformer having a primary winding and first and second secondary windings, said first secondary winding being connected across the conductive test path; b. controllable oscillator means having an output connected to said primary winding of said first transformer so that the conductive test path is inductively coupled to the output of said oscillator means, said oscillator means being switchable between an inoperative state and an operative state in which it produces a test signal having a constant frequency lying below the lower listening threshold of the telephone system, said oscillator means including control means responsive to the resistance of the conductive test path for switching said oscillator means to its operative state so as to enable it to oscillate only when the resistance of the conductive test path is above the preselected value; c. adjustable resistance means, connected in the conductive test path to be in series with said first secondary winding of said transformer and the individual conductor to be tested, for providing a resistance in the conductive test path of a value such that the total resistance of the conductive test path is approximately equal to the preselected resistance value when the test portion of the conductive test path consists of an individual operative conductor; d. a signal generator coupled to the output of said oscillator means for providing an indication signal only when said oscillator means is in a selected one of its states; and e. switching means connected to said second secondary winding and responsive to the output from said oscillator means for controlling said signal generator.
Claim 2
Dependent Claim
321 words
Circuitry for testing for the proper connection of an individual conductor in a telephone cable having a plurality of conductors by providing an indication of the relation between a preselected resistance value and the resistance value of a conductive test path which includes a test portion and a return conductive portion, the test circuit comprising in combination: a. a first transformer having a primary winding and first and second secondary windings, said first secondary winding being connected across the conductive test path; b. controllable oscillator means having an output connected to said primary winding of said first transformer so that the conductive test path is inductively coupled to the output of said oscillator means, said oscillator means being switchable between an inoperative state and an operative state in which it produces a test signal having a constant frequency lying below the lower listening threshold of the telephone system, said oscillator means including control means responsive to the resistance of the conductive test path for switching said oscillator means to its operative state so as to enable it to oscillate only when the resistance of the conductive test path is above the preselected value; c. adjustable resistance means, connected in the conductive test path to be in series with said first secondary winding of said transformer and the individual conductor to be tested, for providing a resistance in the conductive test path of a value such that the total resistance of the conductive test path is approximately equal to the preselected resistance value when the test portion of the conductive test path consists of an individual operative conductor; d. a signal generator coupled to the output of said oscillator means for providing an indication signal only when said oscillator means is in a selected one of its states; and e. switching means connected to said second secondary winding and responsive to the output from said oscillator means for controlling said signal generator.
Claim 3
Dependent Claim
23 words
A circuit as defined in claim 1 wherein said oscillator means oscillates at a frequency of approximately 185 Hz in its operative state.
Claim 4
Dependent Claim
24 words
A circuit as defined in claim 1 wherein said switching means interrupts the circuit of said signal generator when said oscillator means is oscillating.
Claim 5
Dependent Claim
35 words
A circuit as defined in claim 1 wherein said second secondary winding of said first transformer has a greater number of turns than said primary winding of said first transformer connected to said oscillator means.
Claim 6
Dependent Claim
39 words
A circuit as defined in claim 1 wherein said switching means constitutes a circuit arrangement which causes said signal generator to be switched off when said oscillator means is oscillating and switched on when said oscillator means is inoperative.
Claim 7
Dependent Claim
57 words
A circuit as defined in claim 1 wherein said oscillator means is a feedback transistor oscillator operating according to the phase shift principle and includes a transistor producing oscillations at a frequency which lies below the lower listening threshold of the telephone system and resistance means for setting the operating point and oscillating amplitude of said transistor.
Claim 8
Dependent Claim
187 words
A circuit as defined in claim 1 further comprising a second trAnsformer having a primary winding and two series connected secondary windings, a first earphone headset and a second earphone headset, and wherein said signal generator is a summing device whose output is connected to said primary winding of said second transformer, said first headset is connected to said primary winding of said second transformer and in parallel with said summing device, the return conductive portion is constituted by a free pair of conductors symmetrically connected to said secondary windings of said second transformer, said first secondary winding of said first transformer is connected to the return conductive path at a point of symmetry of the circuit formed by the free pair of conductors and said two series connected secondary windings of said second transformer and said second headset is connected in the conductive test path, at a side remote from said oscillator means, between the individual conductor to be tested and a point of symmetry of the circuit formed by the free pair of conductors and said two series connected secondary windings of said second transformer.
Claim 9
Dependent Claim
32 words
A circuit as defined in claim 7 further comprising capacitors each connected in series with a respective one of the conductors of the free pair of conductors of the return conductive portion.
Claim 10
Dependent Claim
14 words
A circuit as defined in claim 7 wherein said summing device is a multivibrator.
Claim 11
Dependent Claim
32 words
A circuit as defined in claim 7 further comprising capacitors connected to both ends of the individual conductor to be tested and in series therewith to protect the device against extraneous voltages.
Claim 12
Dependent Claim
31 words
A circuit as defined in claim 7 wherein said oscillator means includes a resistor, a Zener diode, and a capacitor connected to stabilize a voltage supply connected to said oscillator means.
Claim 13
Dependent Claim
58 words
A circuit as defined in claim 7 further comprising: a telephone set consisting of a microphone and a headset connected to said multivibrator, a first switch connected to open and close the microphone circuit, a second switch connected to open and close the ringing circuit and a third switch connected to switch the test circuit on and off.
Claim 14
Dependent Claim
56 words
A circuit as defined in claim 12 further comprising a fourth switch associated with said third switch to function as a terminal switch for simultaneously turning off the test circuit with its one terminal and through its other terminal short-circuiting the individual conductor to be tested with the center tap of the symmetrically connected free conductors.
Claim 15
Dependent Claim
22 words
A circuit as defined in claim 12 wherein said microphone circuit includes a resistor connected to protect said microphone against excess currents.
Claim 16
Dependent Claim
16 words
A circuit as defined in claim 12 further comprising a listening amplifier associated with said headset.
Claim 17
Dependent Claim
17 words
A circuit as defined in claim 12 further comprising a noise killer rectifier associated with said headset.
Claim 18
Dependent Claim
46 words
A circuit as defined in claim 1 wherein said signal generator is a radio signal generator and further comprising a radio signal receiver connected to receive the signal from said radio signal generator and disposed at the other ends of the conductive test path being tested.
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) | 1976-07-30 | 1977-01-29 | 1977-07-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-07-30 | 1981-01-29 | 1981-07-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-07-30 | 1985-01-29 | 1985-07-31 | $7700.00 | Window Closed / Lapsed |