US4306303A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Switching of digital signals
Assignee: Post Office
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Filing: 1978-11-07
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Granted: 1981-12-15
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Expires: 1998-11-07
Abstract
Abstract A digital switching device of the stored program type operating under the control of a central control unit has a multiplexing stage for multiplexing signals from a plurality of ports, an input time switching stage which receives multiplexed signals from the multiplexing stage and outputs them in appropriate time slots, an interface unit connecting the input time switching stage to an output time switching stage and a demultiplexing stage which demultiplexes signals from the output time switching stage for transmission to said ports. The interface unit is an interchangeable unit which either provides a direct connection between the input and output time switching stages or comprises a space switching stage.
Inventors
- 👤 John H. M. Hardy
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 14:40
CPC Classifications
H; H04; H04Q; H04Q11/00; H04Q11/04; H04Q11/0407
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
160 words
A digital switching device for switching digital signals between plural input/output ports under the control of a central control unit, said switching device comprising: multiplexing means for multiplexing signals from a plurality of said ports, an input time switching stage means arranged to receive multiplexed signals from the multiplexing means and to output said signals in appropriate time slots under the control of the central control unit, an interface unit means for connecting the input time switching stage means to an output time switching stage, and demultiplexing means connected for demultiplexing signals passed through said interface unit means for transmission to said ports, said interface unit means being a unit which comprises a space switching stage, said input and output time switching stage means each including connection store means and said space switching stage means including comparing means arranged to compare the contents of said connection store means, the operation of the space switching stage being determined by said comparison.
Claim 2
Dependent Claim
160 words
A digital switching device for switching digital signals between plural input/output ports under the control of a central control unit, said switching device comprising: multiplexing means for multiplexing signals from a plurality of said ports, an input time switching stage means arranged to receive multiplexed signals from the multiplexing means and to output said signals in appropriate time slots under the control of the central control unit, an interface unit means for connecting the input time switching stage means to an output time switching stage, and demultiplexing means connected for demultiplexing signals passed through said interface unit means for transmission to said ports, said interface unit means being a unit which comprises a space switching stage, said input and output time switching stage means each including connection store means and said space switching stage means including comparing means arranged to compare the contents of said connection store means, the operation of the space switching stage being determined by said comparison.
Claim 3
Dependent Claim
75 words
A digital switching device as in claim 1 wherein said input and output time switching stages each include: first and second sections, one section associated with a first group of ports and the other section associated with the remainder of the ports, each section of each stage having its own connection store means, and said space switching stage being operable to connect either input time switching stage section to either output time switching stage section.
Claim 4
Dependent Claim
139 words
A digital switching device as in claim 2 wherein said space switching stage comprises: first comparing means for comparing the contents of the connection store means of said first input time switching stage section with the contents of the connection store means of said first output time switching stage section, second comparing means for comparing the contents of the connection store means of said second input time switching stage section with the contents of the connection store means of the second output time switching stage section, switches associated with each comparing means, and means linking said switches, the arrangement being such that said comparing means controls operation of the switches such that a given input switching stage section is connected to a given output switching stage section according to the result of said comparison of connection store means contents.
Claim 5
Dependent Claim
14 words
A digital switching device as in claim 3 wherein each switch comprises a crosspoint.
Claim 6
Dependent Claim
141 words
A digital switching device as in claim 2 wherein each said input time switching stage section comprises: a first data store having a data input, a serial-to-parallel converter connected to the data input of said store, said converter being arranged to receive data signals from said first stage, and a connection store means which is operative under the control of said central control unit to provide address signals to said first data store to control read out of data signals from said first data store, and each said output time switching stage comprises a second data store, a parallel-to-serial converter connected to receive data from said data store, and said connection store means operative under the control of the central control unit to provide address signals to said second data store to control reading of data from said second data store.
Claim 7
Dependent Claim
31 words
A digital switching device as claimed in any of claims 1, 2, 3, 4 or 5 wherein said device is a PABX and said data signals are digitally encoded speech samples.
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) | 1984-12-14 | 1985-06-15 | 1985-12-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-12-14 | 1989-06-15 | 1989-12-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-12-14 | 1993-06-15 | 1993-12-15 | $7700.00 | Window Closed / Lapsed |