Patent US3567873A successfully refreshed from Google Patents.
US3567873A
Expired / Lapsed
US
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Echo-suppression and noise-elimination system for telephone circuits
Assignee: Consiglio Nazionale delle Richerche
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Filing: 1967-12-22
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Granted: 1971-03-02
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Expires: 1987-12-22
Abstract
Abstract An incoming and an outgoing telephone channel, connected to a local line via a hybrid coil, are each provided with a multiplicity of parallel branch paths including respective bandpass filters selecting different subbands in a band of voice frequencies to be transmitted or received, the filters of each channel being in series with respective relay contacts so controlled in response to incoming voice signals that subbands whose frequencies predominate in the incoming signal are selectively received by the local line while being blocked in the outgoing channel for the suppression of echoes. The selective opening of some relay contacts may be limited to periods of twoway communication, with the aid of a monitoring circuit responding to the concurrent presence of different frequencies in the two channels; alternatively, the monitoring circuit may be responsive to a single pilot frequency which is suppressed at the receiving side of the hybrid coil so that its presence in the outgoing channel can be due only to a voice signal originating at the local station.
Inventors
- 👤 Bruno Peroni
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 12:05
CPC Classifications
H; H04; H04B; H04B3/00; H04B3/02; H04B3/20; H04B3/21
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
131 words
In a telecommunication system comprising a local line, an incoming signal path, an outgoing signal path, and a coupling network operatively interconnecting said line for the transmission of signals within a predetermined frequency band between a local station and a remote station, the combination therewith of: a multiplicity of band-pass filters connected in parallel in said outgoing path for selecting different subbands within said frequency band for transmission between said stations; a multiplicity of switch means respectively inserted in series with said filters for selectively blocking the transmission of said subbands over said outgoing path; and detector means connected to said incoming path for ascertaining the predominance of signal energy in certain of said subbands and controlling said switch means to block transmission of the last-mentioned subbands over said outgoing path.
Claim 2
Dependent Claim
131 words
In a telecommunication system comprising a local line, an incoming signal path, an outgoing signal path, and a coupling network operatively interconnecting said line for the transmission of signals within a predetermined frequency band between a local station and a remote station, the combination therewith of: a multiplicity of band-pass filters connected in parallel in said outgoing path for selecting different subbands within said frequency band for transmission between said stations; a multiplicity of switch means respectively inserted in series with said filters for selectively blocking the transmission of said subbands over said outgoing path; and detector means connected to said incoming path for ascertaining the predominance of signal energy in certain of said subbands and controlling said switch means to block transmission of the last-mentioned subbands over said outgoing path.
Claim 3
Dependent Claim
64 words
The combination defined in claim 1, further comprising a multiplicity of second band-pass filters connected in parallel in said incoming path between said detector means and said coupling network, and a multiplicity of second switch means respectively inserted in series with said second filters for selectively blocking the transmission of subbands other than said last-mentioned subbands from said incoming path to said local line.
Claim 4
Dependent Claim
72 words
The combination defined in claim 2 wherein said incoming path is normally open-circuited in the vicinity of said coupling network, said second switch means being associated with respective switch means of the first-mentioned multiplicity to form pairs of switches operable to connect the associated filter in said incoming path upon blocking the transmission of its subband over said outgoing path, thereby facilitating selective reception of the corresponding subband by said local line.
Claim 5
Dependent Claim
59 words
The combination defined in claim 3, further comprising monitoring means connected to both said paths for ascertaining the concurrent presence of different frequencies therein, indicative of two-way communication over said paths, said detector means being responsive to said monitoring means for operating said switch means to block any of said subbands only in the event of said concurrent presence.
Claim 6
Dependent Claim
29 words
The combination defined in claim 4 wherein said monitoring means comprises a logic network with input connections to said outgoing path beyond said filters and to said detector means.
Claim 7
Dependent Claim
62 words
The combination defined in claim 4 wherein said monitoring means comprises band-stop means centered on a predetermined frequency and connected between said incoming path and said coupling network, first frequency-selector means responsive to said predetermined frequency and connected to said incoming path ahead of said band-stop means, and second frequency-selector means responsive to said predetermined frequency and connected to said outgoing path.
Claim 8
Dependent Claim
22 words
The combination defined in claim 6 wherein said second frequency selector means is connected to said outgoing path ahead of said filters.
Claim 9
Dependent Claim
29 words
The combination defined in claim 1 wherein said detector means comprises a set of parallel-connected filters and a set of level detectors connected in the outputs of said filters.
Claim 10
Dependent Claim
122 words
In a telecommunication system comprising an incoming signal path for the transmission of signals from a remote station to a local station, the combination therewith of a multiplicity of band-pass filters connected in parallel in said path for selecting different subbands within a band of frequencies to be transmitted, a multiplicity of switch means respectively inserted in series with said filters for selectively blocking the transmission of their respective subbands to said local station, and detector means connected to said incoming path ahead of said filters and of said switch means for ascertaiNing the predominance of signal energy in certain of said subbands and controlling said switch means to block transmission in the remaining subbands, thereby reducing noise accompanying an incoming signal.
Claim 11
Dependent Claim
122 words
In a telecommunication system comprising an incoming signal path for the transmission of signals from a remote station to a local station, the combination therewith of a multiplicity of band-pass filters connected in parallel in said path for selecting different subbands within a band of frequencies to be transmitted, a multiplicity of switch means respectively inserted in series with said filters for selectively blocking the transmission of their respective subbands to said local station, and detector means connected to said incoming path ahead of said filters and of said switch means for ascertaiNing the predominance of signal energy in certain of said subbands and controlling said switch means to block transmission in the remaining subbands, thereby reducing noise accompanying an incoming signal.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-03-01 | 1974-08-31 | 1975-03-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-03-01 | 1978-08-31 | 1979-03-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-03-01 | 1982-08-31 | 1983-03-02 | $7700.00 | Window Closed / Lapsed |