USRE27864E
Expired / Lapsed
US
⏱️ 0.0 years remaining
Closed loop test method and apparatus fof duplex data transmission modem
Assignee: —
•
Filing: 1972-06-29
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Granted: 1974-01-01
•
Expires: 1992-06-29
Abstract
Abstract A DUPLEX DATA TRANSMISSION MODEM IS PROVIDED HAVING FACILITIES FOR TRANSMITTING DATA ON EITHER A CALL ORIGINATE FREQUENCY F1 OR A CALL ANSWER FREQUENCY F2 WHILE SIMULTANEOUSLY RECEIVING DATA ON A CALL ORIGINATE FREQUENCY F2 AND A CALL ANSWER FREQUENCY F1. CONTROL APPARATUS IS PROVIDED IN THE MODEM FOR CLOSED LOOP TESTING WHEREIN THE MODEM RECEIVER IS FORCED TO RECEIVE THE NORMAL OUTGOING DATA MODULATED CARRIER SIGNAL AND RETURN THE DATA SIGNAL BACK TO THE INCOMING LINE AND THEREBY PROVIDE LOOPBACK ON THE ANALOG OR TONE SIDE OF THE TELEPHONE LINE INTERFACE.
Inventors
No inventors recorded.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 18:20
CPC Classifications
H; H04; H04L; H04L27/00; H04L27/10
Claims Analysis
Total Claims: 0
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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) | 1976-12-31 | 1977-07-02 | 1978-01-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-12-31 | 1981-07-02 | 1982-01-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-12-31 | 1985-07-02 | 1986-01-01 | $7700.00 | Window Closed / Lapsed |