US4169215A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Signal limiting circuit
Assignee: AT&T Inc
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Filing: 1978-08-14
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Granted: 1979-09-25
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Expires: 1998-08-14
Abstract
Abstract The disclosed signal limiting circuit is bridged on to a bidirectional communication path (T, R) and functions to selectively attenuate excessive signals (2V A ) being transmitted in a predetermined direction on the bidirectional communication path. This is accomplished by a signal discriminator circuit (100) which separates the excessive signal (2V A ) from the plurality of signals appearing on the communication path (T, R). The signal discriminator circuit (100) also inverts the isolated excessive signal, passes it through an attenuator (102) to a signal injection circuit (103) which injects a controlled amount of the 180 degrees out-of-phase isolated excessive signal back on the communication path (T, R) to cancel out a portion of the excessive signal, thereby providing selective attenuation of the excessive signal.
Inventors
- 👤 Dennis B. James
- 👤 John F. O'Neill
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 16:34
CPC Classifications
H; H04; H04M; H04M1/00; H04M1/738; H04M1/74; H04M1/745; H04B; H04B3/00; H04B3/02; H04B3/04
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
146 words
A selective signal limiting circuit for attenuating one (2V A ) of a plurality of signals appearing on a communication path (T, R) CHARACTERIZED IN THAT said signal limiting circuit comprises: signal isolation means (100) for separating and inverting said one signal (2V A ) from said plurality of signals appearing on said communication path (T, R); gain control means (102) for attenuating said separated inverted one signal (-2V A ); signal injection means (103) for applying said attenuated separated inverted one signal to said communication path (T, R) to cancel a portion of said one signal (2V A ) appearing thereon; means for detecting (104-4, 147-55) the presence of network control signals in said one signal (2V A ); and means responsive to said detection means (140-4, 147-55) for disabling (156-9) said gain control means (102) to prevent the attenuation of said network control signals.
Claim 2
Dependent Claim
146 words
A selective signal limiting circuit for attenuating one (2V A ) of a plurality of signals appearing on a communication path (T, R) CHARACTERIZED IN THAT said signal limiting circuit comprises: signal isolation means (100) for separating and inverting said one signal (2V A ) from said plurality of signals appearing on said communication path (T, R); gain control means (102) for attenuating said separated inverted one signal (-2V A ); signal injection means (103) for applying said attenuated separated inverted one signal to said communication path (T, R) to cancel a portion of said one signal (2V A ) appearing thereon; means for detecting (104-4, 147-55) the presence of network control signals in said one signal (2V A ); and means responsive to said detection means (140-4, 147-55) for disabling (156-9) said gain control means (102) to prevent the attenuation of said network control signals.
Claim 3
Dependent Claim
32 words
The invention of claim 1 CHARACTERIZED IN THAT said signal limiting circuit additionally includes reset means (145-6, 160-175) for disabling said disabling means (156-9) upon the termination of said network control signals.
Claim 4
Dependent Claim
67 words
The invention of claim 1 CHARACTERIZED IN THAT said signal isolation means (100) includes: summation means (110-117) for obtaining both the sum and the difference of the signals appearing on said communication path (T, R); combination means (118-119) for combining said sum and said difference to isolate said one signal (2V A ); and inversion means (120, 121) for inverting said isolated one signal (2V A ).
Claim 5
Dependent Claim
167 words
In a communication system, wherein a first circuit (199) is connected to a second circuit by a communication path (T, R), a signal limiting circuit for selectively attenuating signals (2V A ) from said first circuit (199), when said first circuit signals (2V A ) exceed a predetermined threshold, CHARACTERIZED IN THAT said signal limiting circuit comprises: signal isolation means (100) for separating and inverting said first circuit signals (2V A ) from signals from said second circuit (2V B ) appearing on said communication path (T, R); comparison means (129-37) for generating an enable signal when said separated inverted first circuit signal (-2V A ) exceeds a predetermined threshold; gain control means (122) responsive to said comparison means (129-37) enable signal for attenuating said separated inverted first circuit signal (-2V A ); and signal injection means (103) for applying said attenuated separated inverted first circuit signal to said communication path (T, R) to cancel a portion of said first circuit signal (2V A ) appearing thereon.
Claim 6
Dependent Claim
167 words
In a communication system, wherein a first circuit (199) is connected to a second circuit by a communication path (T, R), a signal limiting circuit for selectively attenuating signals (2V A ) from said first circuit (199), when said first circuit signals (2V A ) exceed a predetermined threshold, CHARACTERIZED IN THAT said signal limiting circuit comprises: signal isolation means (100) for separating and inverting said first circuit signals (2V A ) from signals from said second circuit (2V B ) appearing on said communication path (T, R); comparison means (129-37) for generating an enable signal when said separated inverted first circuit signal (-2V A ) exceeds a predetermined threshold; gain control means (122) responsive to said comparison means (129-37) enable signal for attenuating said separated inverted first circuit signal (-2V A ); and signal injection means (103) for applying said attenuated separated inverted first circuit signal to said communication path (T, R) to cancel a portion of said first circuit signal (2V A ) appearing thereon.
Claim 7
Dependent Claim
39 words
The invention of claim 4 CHARACTERIZED IN THAT said gain control means (122) is responsive to the absence of said comparison means (129-37) enable signal for blocking said separated inverted first circuit signal from said signal injection means (103).
Claim 8
Dependent Claim
114 words
The invention of claim 5 CHARACTERIZED IN THAT said signal limiting circuit additionally comprises: means for detecting (140-4, 147-55) the presence of network control signals in said first circuit signals (2V A ); reset means (145-6, 160-175) for resetting said detection means (140-4, 147-55) upon the termination of said network control signals in said first circuit signals (2V A ); and wherein said comparison means (129-37) is responsive to said detection means (140-4, 147-55) determining the presence of network control signals in said first circuit signals (2V A ) for removing said comparison means (129-37) enable signal, thereby blocking said separated inverted first circuit signal (-2V A ) from said signal injection means (103).
Claim 9
Dependent Claim
101 words
The invention of claim 4 CHARACTERIZED IN THAT said signal isolation means (100) includes: summation means (110-117) for obtaining both the sum (V A +V B ) and the difference (V A +V B ) of said first circuit signals (2V A ) and said second circuit signals (2V B ) appearing on said communication path (T, R); combining means (118-119) for combining said sum (V A +V B ) and said difference (V A -V B ) to isolate said first circuit signals (2V A ); and inversion means (120-1) for inverting said isolated first circuit signals (2V A ).
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) | 1982-09-24 | 1983-03-26 | 1983-09-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-09-24 | 1987-03-26 | 1987-09-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-09-24 | 1991-03-26 | 1991-09-25 | $7700.00 | Window Closed / Lapsed |