US4064370A
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US
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Time-division switching system
Assignee: AT&T Inc
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Filing: 1976-07-01
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Granted: 1977-12-20
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Expires: 1996-07-01
Abstract
Abstract A high-capacity low-blocking time-division switching system including a space-division switching network is disclosed for switching serial digital data words synchronously received on time multiplexed lines in a first code format wherein each data word occupies substantially an entire time multiplexed channel time period. In order to achieve high capacity and low blocking, the space-division switching network is physically large resulting in delays of the digital data words transmitted therethrough, which delays are significant when compared with the time duration of a time-division multiplex channel and which vary in accordance with the path selected. The communication paths through the stages of the space-division network are reconfigured each time-division multiplex channel time duration, but due to the transmission delays, the effective transmission period is less than the time duration of a channel. Accordingly, data words are converted to a second code format, in which a start code is associated with each data word, and transmitted to the space-division network in a period of time less than the duration of a time multiplexed channel. The start code is utilized to permit asynchronous reception at the network outputs which is necessitated by the variability of time delays through the network. Additionally, the outputs of the space-division network are reconverted to the first code format for synchronous transmission on an output time-division multiplexed line.
Inventors
- 👤 Homer Eugene Coonce
- 👤 Judson Bruce Synnott, III
- 👤 Austin Thomas Harty, deceased
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 22:28
CPC Classifications
H; H04; H04Q; H04Q11/00; H04Q11/04; H04Q11/06
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
186 words
In combination: timing means for generating a plurality of equally spaced timing signals defining time slots of fixed duration; a time division multiplex line carrying a plurality of channels of digital data words wherein the time duration of each channel is substantially equal to one of said time slots of fixed duration and wherein each digital data word is in a first format and occupies substantially an entire time multiplexed channel; a switching network having input and output terminals and comprising a plurality of switching elements; means for establishing communication paths through said switching network at a rate such that any given switching element may be used in any given communication path for a period of time less than or equal to one of said time slots of fixed duration; reformatting means for converting said digital data words from said first format to a second format; and means, responsive to said timing signals, for serially transmitting the data words in said second format to an input terminal of said switching network in a period of time less than one of said time slots of fixed duration.
Claim 2
Dependent Claim
186 words
In combination: timing means for generating a plurality of equally spaced timing signals defining time slots of fixed duration; a time division multiplex line carrying a plurality of channels of digital data words wherein the time duration of each channel is substantially equal to one of said time slots of fixed duration and wherein each digital data word is in a first format and occupies substantially an entire time multiplexed channel; a switching network having input and output terminals and comprising a plurality of switching elements; means for establishing communication paths through said switching network at a rate such that any given switching element may be used in any given communication path for a period of time less than or equal to one of said time slots of fixed duration; reformatting means for converting said digital data words from said first format to a second format; and means, responsive to said timing signals, for serially transmitting the data words in said second format to an input terminal of said switching network in a period of time less than one of said time slots of fixed duration.
Claim 3
Dependent Claim
80 words
Combination in accordance with claim 1 wherein said reformatting means operates in synchronism with the data words carried by said time-division multiplex line and comprises means for producing a second code format in which a start code is associated with each data word to facilitate asynchronous detection of data words in said second code format; and further comprising: a data word receiver connected to the output terminals of said switching network for asynchronously receiving data words in said second format.
Claim 4
Dependent Claim
52 words
The combination in accordance with claim 2 further comprising: means for converting said data words received by said data word receiver in said second format to said first format; and means for transmitting the data words in said first format, produced by said means for converting, on an output time-division multiplex line.
Claim 5
Dependent Claim
301 words
In combination: timing means for generating a plurality of equally spaced timing signals defining time slots of fixed duration; an input time-division multiplex line carrying a plurality of channels of digital data words wherein the time duration of each channel is substantially equal to one of said time slots of fixed duration and wherein each digital data word is in a first format and occupies substantially an entire time multiplexed channel; a switching network having input and output terminals and comprising a plurality of switching elements; means for establishing communication paths through said switching network at a rate such that any given switching element may be used in any given communication path for a period of time less than or equal to one of said time slots of fixed duration; first formatting means for converting said digital data words from said first format to a second format wherein each data word includes a start code; means, responsive to said timing signals, for serially transmitting the data words in said second format to an input terminal of said switching network in a period of time less than one of said time slots of fixed duration; receive means, connected to the output terminals of said switching network, responsive to said start code for receiving the data words in said second format; second formatting means for converting the data words in said second word format received by said receive means to said first format; and retransmission means for transmitting said data words in said first format from said second formatting means on output time-division multiplex lines wherein the time duration of each channel of said output time-division multiplex lines is substantially equal to one of said time slots of fixed duration and wherein each digital data word occupies substantially an entire time multiplex channel.
Claim 6
Dependent Claim
301 words
In combination: timing means for generating a plurality of equally spaced timing signals defining time slots of fixed duration; an input time-division multiplex line carrying a plurality of channels of digital data words wherein the time duration of each channel is substantially equal to one of said time slots of fixed duration and wherein each digital data word is in a first format and occupies substantially an entire time multiplexed channel; a switching network having input and output terminals and comprising a plurality of switching elements; means for establishing communication paths through said switching network at a rate such that any given switching element may be used in any given communication path for a period of time less than or equal to one of said time slots of fixed duration; first formatting means for converting said digital data words from said first format to a second format wherein each data word includes a start code; means, responsive to said timing signals, for serially transmitting the data words in said second format to an input terminal of said switching network in a period of time less than one of said time slots of fixed duration; receive means, connected to the output terminals of said switching network, responsive to said start code for receiving the data words in said second format; second formatting means for converting the data words in said second word format received by said receive means to said first format; and retransmission means for transmitting said data words in said first format from said second formatting means on output time-division multiplex lines wherein the time duration of each channel of said output time-division multiplex lines is substantially equal to one of said time slots of fixed duration and wherein each digital data word occupies substantially an entire time multiplex channel.
Claim 7
Dependent Claim
56 words
The combination in accordance with claim 4 wherein: said first formatting means includes control means for controlling said first formatting means to operate in synchronism with the data words on said input time multiplex line; and said receive means responds to said start code by receiving data words in said second format in an asynchronous manner.
Claim 8
Dependent Claim
241 words
In combination: timing means for generating a series of equally spaced timing signals defining time slots of fixed duration; a source of digital words; a storage means for storing said digital words; means for serially transmitting said digital words from said source to said storage means at a first bit rate; a switching network comprising input and output terminals for selectively completing time-division communication paths between said input and said output terminals wherein said communication paths exhibit transmission delays of significant duration with respect to one of said word time slots and which time delays vary in accordance with the communication path selected; means for controlling said switching network to establish communication paths such that the holding time for any point along said communication path is less than or equal to one of said time slots; reformatting means for reading digital words from said storage means and for concatenating a start code to the beginning thereof; means responsive to said timing signals for serially transmitting each of said digital words and its associated start code obtained from said reformatting means to the inputs of said switching network at a second bit rate and within a period of time less than or equal to one of said time slots, said second bit rate being faster than said first bit rate; and receive means connected to the output terminals of said switching network responsive to said start code for receiving said digital words.
Claim 9
Dependent Claim
241 words
In combination: timing means for generating a series of equally spaced timing signals defining time slots of fixed duration; a source of digital words; a storage means for storing said digital words; means for serially transmitting said digital words from said source to said storage means at a first bit rate; a switching network comprising input and output terminals for selectively completing time-division communication paths between said input and said output terminals wherein said communication paths exhibit transmission delays of significant duration with respect to one of said word time slots and which time delays vary in accordance with the communication path selected; means for controlling said switching network to establish communication paths such that the holding time for any point along said communication path is less than or equal to one of said time slots; reformatting means for reading digital words from said storage means and for concatenating a start code to the beginning thereof; means responsive to said timing signals for serially transmitting each of said digital words and its associated start code obtained from said reformatting means to the inputs of said switching network at a second bit rate and within a period of time less than or equal to one of said time slots, said second bit rate being faster than said first bit rate; and receive means connected to the output terminals of said switching network responsive to said start code for receiving said digital words.
Claim 10
Dependent Claim
170 words
In combination: a first digital transmitter for transmitting serial data words in time separated channels in a first code format wherein each data word in said first code format occupies substantially an entire one of said channels; a first digital data receiver, operating in synchronism with said first digital data transmitter, for receiving data words in said first code format and for converting said data words to a second code format wherein each data word includes a start code; a switching network having a plurality of input and output terminals; a second digital data transmitter connected to said first digital data receiver for serially transmitting date words in said second format to an input terminal of said switching network in a period of time less than one of said time separated channels; and a second digital data receiver connected to an output terminal of said switching network responsive to said start code for receiving data words in said second code format asynchronously with respect to said second digital data transmitter.
Claim 11
Dependent Claim
170 words
In combination: a first digital transmitter for transmitting serial data words in time separated channels in a first code format wherein each data word in said first code format occupies substantially an entire one of said channels; a first digital data receiver, operating in synchronism with said first digital data transmitter, for receiving data words in said first code format and for converting said data words to a second code format wherein each data word includes a start code; a switching network having a plurality of input and output terminals; a second digital data transmitter connected to said first digital data receiver for serially transmitting date words in said second format to an input terminal of said switching network in a period of time less than one of said time separated channels; and a second digital data receiver connected to an output terminal of said switching network responsive to said start code for receiving data words in said second code format asynchronously with respect to said second digital data transmitter.
Claim 12
Dependent Claim
68 words
The combination in accordance with claim 7 further including: reformatting means connecting to said second digital data receiver for converting the data words received by said second digital data receiver in said second code format to said first code format and for transmitting said data words in said first code format; and means for receiving said data words from said reformatting means in synchronism with said reformatting means.
Claim 13
Dependent Claim
236 words
In combination: a first digital transmitter for transmitting serial data words in time separated channels in a first code format wherein each data word digit in said first code format comprises two digit portions and each data word occupies substantially an entire one of said time separated channels; a first digital data receiver, operating in synchronism with said first digital data transmitter, for receiving data words in said first code format and for converting said data words to a second code format wherein each data word digit comprises one digit portion and each data word includes a start code; a high-capacity switching network having a plurality of input and output terminals with a plurality of serially connected networdk stages therebetween; control means for establishing communication paths between said input and output terminals of said switching network by establishing paths through said serially connected network stages in sequence and overlapped in time; a second digital data transmitter connected to said first digital data receiver for serially transmitting data words in said second format to an input terminal of said switching network in a period of time approximately 5/8 of the time duration of one of said time separated channels; and a second digital data receiver connected to an output terminal of said switching network responsive to said start code for receiving data words in said second code format asynchronously with respect to said second digital data transmitter.
Claim 14
Dependent Claim
236 words
In combination: a first digital transmitter for transmitting serial data words in time separated channels in a first code format wherein each data word digit in said first code format comprises two digit portions and each data word occupies substantially an entire one of said time separated channels; a first digital data receiver, operating in synchronism with said first digital data transmitter, for receiving data words in said first code format and for converting said data words to a second code format wherein each data word digit comprises one digit portion and each data word includes a start code; a high-capacity switching network having a plurality of input and output terminals with a plurality of serially connected networdk stages therebetween; control means for establishing communication paths between said input and output terminals of said switching network by establishing paths through said serially connected network stages in sequence and overlapped in time; a second digital data transmitter connected to said first digital data receiver for serially transmitting data words in said second format to an input terminal of said switching network in a period of time approximately 5/8 of the time duration of one of said time separated channels; and a second digital data receiver connected to an output terminal of said switching network responsive to said start code for receiving data words in said second code format asynchronously with respect to said second digital data transmitter.
References Cited (Backward Citations)
US3736381A
Cited
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-12-19 | 1981-06-20 | 1981-12-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-12-19 | 1985-06-20 | 1985-12-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-12-19 | 1989-06-20 | 1989-12-20 | $7700.00 | Window Closed / Lapsed |