US3870958A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Circuit for applying data signals across a microphone input circuit
Assignee: RCA Corp
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Filing: 1973-12-11
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Granted: 1975-03-11
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Expires: 1993-12-11
Abstract
Abstract A circuit for coupling audio tone data signals from a source at the input end of a transmitter to which is also coupled a microphone includes a negative feedback amplifier characterized by a D.C. voltage at the output that remains close to that at the input.
Inventors
- 👤 Chandos Arthur Rypinski
- 👤 Jaime Ernesto Pera
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 22:16
CPC Classifications
H; H04; H04M; H04M11/00; H04M11/06; H04M11/066
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
206 words
In a radio transmitter including a microphone connected by a transmission line to the modulation portion of the transmitter, an improved circuit for coupling audio tone data signals from a source across said transmission line in a manner to avoid D.C. transients associated with the coupling and decoupling of the data signals across the input end of said modulating portion of said transmitter comprising: an audio amplifier and an A.C. Coupling capacitor connected in series between said source and said input end of said modulating portion of said transmitter, a resistive load coupled across the output of said amplifier for presenting a high impedance to voice signals from said microphone, said amplifier including a negative feedback circuit and D.C. power coupling terminals for activating said amplifier, said amplifier characterized by a low output impedance when activated and a D.C. voltage at the output that remains close to that at the input such that the output voltage across said capacitor does not change materially with activation and deactivation of said amplifier to couple and decouple said data signal whereby said D.C. transient voltages are minimized, means coupled to said power coupling terminals for applying power to activate said amplifier and apply said data signals to said transmitter.
Claim 2
Dependent Claim
206 words
In a radio transmitter including a microphone connected by a transmission line to the modulation portion of the transmitter, an improved circuit for coupling audio tone data signals from a source across said transmission line in a manner to avoid D.C. transients associated with the coupling and decoupling of the data signals across the input end of said modulating portion of said transmitter comprising: an audio amplifier and an A.C. Coupling capacitor connected in series between said source and said input end of said modulating portion of said transmitter, a resistive load coupled across the output of said amplifier for presenting a high impedance to voice signals from said microphone, said amplifier including a negative feedback circuit and D.C. power coupling terminals for activating said amplifier, said amplifier characterized by a low output impedance when activated and a D.C. voltage at the output that remains close to that at the input such that the output voltage across said capacitor does not change materially with activation and deactivation of said amplifier to couple and decouple said data signal whereby said D.C. transient voltages are minimized, means coupled to said power coupling terminals for applying power to activate said amplifier and apply said data signals to said transmitter.
Claim 3
Dependent Claim
206 words
In a radio transmitter including a microphone connected by a transmission line to the modulation portion of the transmitter, an improved circuit for coupling audio tone data signals from a source across said transmission line in a manner to avoid D.C. transients associated with the coupling and decoupling of the data signals across the input end of said modulating portion of said transmitter comprising: an audio amplifier and an A.C. Coupling capacitor connected in series between said source and said input end of said modulating portion of said transmitter, a resistive load coupled across the output of said amplifier for presenting a high impedance to voice signals from said microphone, said amplifier including a negative feedback circuit and D.C. power coupling terminals for activating said amplifier, said amplifier characterized by a low output impedance when activated and a D.C. voltage at the output that remains close to that at the input such that the output voltage across said capacitor does not change materially with activation and deactivation of said amplifier to couple and decouple said data signal whereby said D.C. transient voltages are minimized, means coupled to said power coupling terminals for applying power to activate said amplifier and apply said data signals to said transmitter.
Claim 4
Dependent Claim
206 words
In a radio transmitter including a microphone connected by a transmission line to the modulation portion of the transmitter, an improved circuit for coupling audio tone data signals from a source across said transmission line in a manner to avoid D.C. transients associated with the coupling and decoupling of the data signals across the input end of said modulating portion of said transmitter comprising: an audio amplifier and an A.C. Coupling capacitor connected in series between said source and said input end of said modulating portion of said transmitter, a resistive load coupled across the output of said amplifier for presenting a high impedance to voice signals from said microphone, said amplifier including a negative feedback circuit and D.C. power coupling terminals for activating said amplifier, said amplifier characterized by a low output impedance when activated and a D.C. voltage at the output that remains close to that at the input such that the output voltage across said capacitor does not change materially with activation and deactivation of said amplifier to couple and decouple said data signal whereby said D.C. transient voltages are minimized, means coupled to said power coupling terminals for applying power to activate said amplifier and apply said data signals to said transmitter.
Claim 5
Dependent Claim
29 words
The combination claimed in claim 1 wherein said means includes timed means for deactivating said amplifier after a time period sufficient for the transmission of a desired data message.
Claim 6
Dependent Claim
14 words
The combination claimed in claim 2 wherein said timed means includes a pulse generator.
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) | 1978-03-10 | 1978-09-09 | 1979-03-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-03-10 | 1982-09-09 | 1983-03-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-03-10 | 1986-09-09 | 1987-03-11 | $7700.00 | Window Closed / Lapsed |