US3576399A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Scanning means for central-controlled switching systems
Assignee: International Standard Electric Corp
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Filing: 1968-01-09
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Granted: 1971-04-27
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Expires: 1988-01-09
Abstract
Abstract A last look scanning technique is used to detect changes occurring on a line. To avoid a continuous report of ''''no change'''' to a centralized data processor, a decentralized detector looks at each line during the appropriate scan time slot. Only if there is a change does the decentralized detector communicate with the central processing equipment.
Inventors
- 👤 Hans Schweitzer
- 👤 Helmut Willrett
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 08:24
CPC Classifications
H; H04; H04Q; H04Q3/00; H04Q3/42; H04Q3/54
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
136 words
In a central control switching system, a first matrix having connection to a plurality of subscribers lines, a second matrix having like representation for said plurality of subscribers lines, said second matrix including storage elements at each of said representations, scanning means having connection to both of said matrices for simultaneously interrogating both of said matrices, means responsive to one or more changes in condition at the lines connected to said first matrix for thereafter transmitting like indications of said changes to the representative storage elements of said second matrix to store indications of such changes, means connected to both said matrices and responsive to the simultaneous scan for comparing indications received from said both matrices and means responsive to a difference in said comparison for transmitting a signal of said change to a central control.
Claim 2
Dependent Claim
136 words
In a central control switching system, a first matrix having connection to a plurality of subscribers lines, a second matrix having like representation for said plurality of subscribers lines, said second matrix including storage elements at each of said representations, scanning means having connection to both of said matrices for simultaneously interrogating both of said matrices, means responsive to one or more changes in condition at the lines connected to said first matrix for thereafter transmitting like indications of said changes to the representative storage elements of said second matrix to store indications of such changes, means connected to both said matrices and responsive to the simultaneous scan for comparing indications received from said both matrices and means responsive to a difference in said comparison for transmitting a signal of said change to a central control.
Claim 3
Dependent Claim
59 words
In a system as claimed in claim 1, wherein there are scan control means, and wherein said last mentioned transmitting means comprises a plurality of AND circuits, a first input to said AND circuits, connected to the output of said scan control means, and a second input to said AND circuits connected to the output of said comparing means.
Claim 4
Dependent Claim
38 words
In a system as claimed in claim 2, wherein a further connection is made to said central control from said comparing means in parallel with an AND circuit output for indicating the direction of change of said 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) | 1974-04-26 | 1974-10-26 | 1975-04-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-04-26 | 1978-10-26 | 1979-04-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-04-26 | 1982-10-26 | 1983-04-27 | $7700.00 | Window Closed / Lapsed |