US3784756A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Subscriber loop range extender
Assignee: AT&T Inc
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Filing: 1972-12-15
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Granted: 1974-01-08
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Expires: 1992-12-15
Abstract
Abstract This disclosure relates to a range extender having a through transmission path, a voice transmission path including a repeater, a relay for transferring back and forth between paths and a dual mode, loop current detector. In the idle state, the current detector is in a ''''slow'''' mode for the purpose of preventing (spurious) operation of the detector, except in response to an off-hook current flow. The transfer relay connects the repeater to the loop immediately after an off-hook is detected and the current detector is switched to its ''''fast'''' mode in preparation for dialing pulsing. The repeater normally remains connected to the loop for the duration of the call, even over dial pulsing. Dial pulsing is therefore repeated via the repeater, and not shunt aided. The dial pulses are detected by the fast current detector and the office loop is opened and closed through the repeater, which, from the office side, looks like a low resistance (1K) to low frequencies.
Inventors
- 👤 J Nemchik
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 23:18
CPC Classifications
H; H04; H04M; H04M19/00; H04M19/001; H04M19/006
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
212 words
A range extender for long subscriber loops interconnecting subscriber telephone sets to a central office comprising a through transmission path, a voice transmission path including an amplifier means, relay means for transferring back and forth between paths to establish a loop connection through said through transmission path or said voice transmission path, loop current detector means coupled to said loop and having two modes of operation, said detector means being normally in a slow detection mode to inhibit the detection of current in said loop except that due to an off-hook condition of the subscriber set, control means responsive to a current detection output signal from said detector means to enable said relay means to connect said amplifier means to said loop and to switch said current detector means to a fast detection mode for rapid detection of dial pulses, said control means serving to maintain said relay means in the enabled state for a predetermined period after a termination of said current detection output signal, said predetermined period being substantially longer than the longest possible dial break, and second relay means responsive to the detection of dial pulses by said detector means in its fast detection mode to open and close the office side of the loop through said amplifier means.
Claim 2
Dependent Claim
212 words
A range extender for long subscriber loops interconnecting subscriber telephone sets to a central office comprising a through transmission path, a voice transmission path including an amplifier means, relay means for transferring back and forth between paths to establish a loop connection through said through transmission path or said voice transmission path, loop current detector means coupled to said loop and having two modes of operation, said detector means being normally in a slow detection mode to inhibit the detection of current in said loop except that due to an off-hook condition of the subscriber set, control means responsive to a current detection output signal from said detector means to enable said relay means to connect said amplifier means to said loop and to switch said current detector means to a fast detection mode for rapid detection of dial pulses, said control means serving to maintain said relay means in the enabled state for a predetermined period after a termination of said current detection output signal, said predetermined period being substantially longer than the longest possible dial break, and second relay means responsive to the detection of dial pulses by said detector means in its fast detection mode to open and close the office side of the loop through said amplifier means.
Claim 3
Dependent Claim
26 words
A range extender as defined in claim 1 wherein said amplifier means presents a low resistance at low frequencies to the office side of the loop.
Claim 4
Dependent Claim
32 words
A range extender as defined in claim 2 wherein said office side of the loop is opened and closed by said second relay means with a predetermined delay to provide noise immunity.
Claim 5
Dependent Claim
31 words
A range extender as defined in claim 3 including dynamic hysteresis means for maintaining the second relay means in its enabled or disabled state for a predetermined minimum period of time.
Claim 6
Dependent Claim
31 words
A range extender as defined in claim 1 including means for detecting an automatic number identification (ANI) tip party test and for rapidly disabling the first-recited relay means in response thereto.
Claim 7
Dependent Claim
40 words
A range extender as defined in claim 5 wherein the tip party test detection means comprises an optoelectronic coupler with a light emitting diode connected to said amplifier means to detect when the current through the latter goes to zero.
Claim 8
Dependent Claim
54 words
A range extender as defined in claim 6 wherein said tip party test detection means includes logic means for coupling the output signal from said optoelectronic coupler to the first-recited relay means, said logic means serving to disable said first-recited relay means in response to, and only in response to, said tip party test.
References Cited (Backward Citations)
US3671676A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-01-07 | 1977-07-09 | 1978-01-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-01-07 | 1981-07-09 | 1982-01-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-01-07 | 1985-07-09 | 1986-01-08 | $7700.00 | Window Closed / Lapsed |