US3573630A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Time variable alert tone circuit for personal radio paging systems
Assignee: AT&T Inc
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Filing: 1968-09-30
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Granted: 1971-04-06
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Expires: 1988-09-30
Abstract
Abstract The present invention concerns a method for varying over a period of time the alert tone in a personal radio-paging receiver making extensive use of signal voltages already present in the circuit and decreasing the overall drain on the receiver supply battery.
Inventors
- 👤 Steven M Baer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 17:57
CPC Classifications
G; G08; G08B; G08B3/00; G08B3/10; G08B3/1008; G08B3/1016; G08B3/1025
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
119 words
A time variable alert tone circuit for a personal radiopaging receiver comprising a circuit having an OFF state and capable of being triggered into an unstable ON state, means responsive to a signal indicating that said receiver is being paged for triggering said circuit into said ON state, means for deriving from said ON state a first DC signal for a given time period, means for deriving from said ON state a second DC signal having an amplitude that varies monotonically during said period, means responsive to said first signal for producing an audible indication that said receiver is being paged, and means responsive to said second signal for increasing the amplitude of said audible indication during said period.
Claim 2
Dependent Claim
119 words
A time variable alert tone circuit for a personal radiopaging receiver comprising a circuit having an OFF state and capable of being triggered into an unstable ON state, means responsive to a signal indicating that said receiver is being paged for triggering said circuit into said ON state, means for deriving from said ON state a first DC signal for a given time period, means for deriving from said ON state a second DC signal having an amplitude that varies monotonically during said period, means responsive to said first signal for producing an audible indication that said receiver is being paged, and means responsive to said second signal for increasing the amplitude of said audible indication during said period.
Claim 3
Dependent Claim
80 words
A circuit as defined in claim 1 wherein the means responsive to said signal indicating that said receiver is being paged for producing said first and second signals comprises a monostable multivibrator, said first signal being derived from a point in said multivibrator where the output voltage is a DC pulse of substantially constant amplitude over said time period, and said second signal being derived from a point in said multivibrator where the output voltage varies monotonically during said period.
Claim 4
Dependent Claim
38 words
A circuit as defined in claim 2 wherein said amplitude of said second signal decreases monotonically during said period in combination with a voltage inverter stage, said inverter stage deriving its supply voltage from said first DC signal.
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) | 1974-04-05 | 1974-10-05 | 1975-04-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-04-05 | 1978-10-05 | 1979-04-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-04-05 | 1982-10-05 | 1983-04-06 | $7700.00 | Window Closed / Lapsed |