Patent US3143602A successfully refreshed from Google Patents.
US3143602A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Multifrequency signal receiver
Assignee: AT&T Inc
•
Filing: 1961-05-19
•
Granted: 1964-08-04
•
Expires: 1981-05-19
Abstract
No abstract record available.
Inventors
- 👤 Charles G Morrison
- 👤 Douglas T Seward
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 21:00
CPC Classifications
H; H04; H04Q; H04Q1/00; H04Q1/18; H04Q1/30; H04Q1/44; H04Q1/444; H04Q1/45; H04Q1/453
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
143 words
IN A MULTIFREQUENCY SIGNAL RECEIVER INCLUDING A SIGNAL INPUT POINT AND A PLURALITY OF TUNED CIRCUITS, MEANS INCLUDING AN INPUT LIMITING STAGE AND AN OUTPUT LIMITING STAGE FOR CONVERTING TONE BURST INPUT SIGNALS APPLIED TO SAID INPUT POINT TO SUBSTANTIALLY SYMMETRICAL SQUARE WAVES AND FOR APPLYING SAID WAVES TO SAID TUNED CIRCUITS, AND MEANS FOR PROVIDING DUAL PROTECTION AGAINST FALSE OPERATION OF SAID RECEIVER BY NOISE AND SPEECH, SAID LAST NAMED MEANS COMPRISING MEANS FOR APPLYING A NEGATIVE FEEDBACK SIGNAL FROM THE OUTPUT OF SAID OUTPUT STAGE TO THE INPUT OF SAID INPUT STAGE, THE AMPLITUDE OF SAID FEEDBACK SIGNAL BEING DETERMINED JOINTLY BY THE AMPLITUDE AND FREQUENCY CHARACTERISTICS OF SAID INPUT SIGNALS AND BY THE IMPEDANCE CHARACTERISTICS OF SAID TUNED CIRCUITS, SAID FEEDBACK SIGNAL PERFORMING THEREBY A DUAL FUNCTION IN CONTROLLING THE SENSITIVITY OF SAID RECEIVER AND IN PREEMPHASIZING PRESELECTED NONSIGNALING FREQUENCIES.
Claim 2
Dependent Claim
143 words
IN A MULTIFREQUENCY SIGNAL RECEIVER INCLUDING A SIGNAL INPUT POINT AND A PLURALITY OF TUNED CIRCUITS, MEANS INCLUDING AN INPUT LIMITING STAGE AND AN OUTPUT LIMITING STAGE FOR CONVERTING TONE BURST INPUT SIGNALS APPLIED TO SAID INPUT POINT TO SUBSTANTIALLY SYMMETRICAL SQUARE WAVES AND FOR APPLYING SAID WAVES TO SAID TUNED CIRCUITS, AND MEANS FOR PROVIDING DUAL PROTECTION AGAINST FALSE OPERATION OF SAID RECEIVER BY NOISE AND SPEECH, SAID LAST NAMED MEANS COMPRISING MEANS FOR APPLYING A NEGATIVE FEEDBACK SIGNAL FROM THE OUTPUT OF SAID OUTPUT STAGE TO THE INPUT OF SAID INPUT STAGE, THE AMPLITUDE OF SAID FEEDBACK SIGNAL BEING DETERMINED JOINTLY BY THE AMPLITUDE AND FREQUENCY CHARACTERISTICS OF SAID INPUT SIGNALS AND BY THE IMPEDANCE CHARACTERISTICS OF SAID TUNED CIRCUITS, SAID FEEDBACK SIGNAL PERFORMING THEREBY A DUAL FUNCTION IN CONTROLLING THE SENSITIVITY OF SAID RECEIVER AND IN PREEMPHASIZING PRESELECTED NONSIGNALING FREQUENCIES.
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) | 1967-08-04 | 1968-02-03 | 1968-08-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1971-08-04 | 1972-02-03 | 1972-08-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1975-08-04 | 1976-02-03 | 1976-08-04 | $7700.00 | Window Closed / Lapsed |