Patent US3576402A successfully refreshed from Google Patents.
US3576402A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Circuit for coin telephone set in mobile radio telephone system
Assignee: AT&T Inc
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Filing: 1968-03-13
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Granted: 1971-04-27
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Expires: 1988-03-13
Abstract
Abstract In a coin telephone set adapted for use in a mobile radio telephone system that provides phone service on trains, for example, signaling reliability is enhanced by the employment of means including a timing circuit for ensuring the transmission of multifrequency dial signals of limited duration irrespective of the duration of the manual actuation of the dial.
Inventors
- 👤 Gerald P Baker
- 👤 John E Edington
- 👤 Ralston H Robertson Jr
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 08:45
CPC Classifications
H; H04; H04W; H04W88/00; H04W88/02; H04M; H04M17/00; H04M17/02; H04M17/023
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
119 words
A mobile telephone set comprising, in combination, multifrequency dial signal generating means including pushbuttons, means for applying voice current from said set and signals from said dial to a radio transmitter, and means for limiting the duration of signals from said dial to a period equal to the duration of the operation of one of said pushbuttons or to a preselected duration, whichever is shorter, whereby spurious signaling resulting from gaps and fading in unduly long signals is avoided, said signal generating means including a multifrequency oscillator having frequency determining elements and an active element and said limiting means including a monostable multivibrator and a transistor switch connected in tandem between said frequency determining elements and said active element.
Claim 2
Dependent Claim
119 words
A mobile telephone set comprising, in combination, multifrequency dial signal generating means including pushbuttons, means for applying voice current from said set and signals from said dial to a radio transmitter, and means for limiting the duration of signals from said dial to a period equal to the duration of the operation of one of said pushbuttons or to a preselected duration, whichever is shorter, whereby spurious signaling resulting from gaps and fading in unduly long signals is avoided, said signal generating means including a multifrequency oscillator having frequency determining elements and an active element and said limiting means including a monostable multivibrator and a transistor switch connected in tandem between said frequency determining elements and said active element.
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) | 1974-04-26 | 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 |