US3757228A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Circuit for automatic search tuning in radio receivers
Assignee: Deutsche Thomson OHG
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Filing: 1971-09-09
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Granted: 1973-09-04
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Expires: 1991-09-09
Abstract
Abstract An automatic tuning circuit for a receiver which has a switch for initiating a search for a station delivering a signal exceeding a threshold level. The circuit is designed to maintain lock-on to such a station even when the received signal momentarily fades. A modification of the circuitry permits reversible tuning across the broadcast band. Fine tuning is achieved by a ratio detector which generates an error signal dependent upon frequency deviation.
Inventors
- 👤 O Klank
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 21:42
CPC Classifications
H; H03; H03J; H03J7/00; H03J7/18; H03J7/20; H03J7/24; H03J7/26
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
294 words
In an automatic search tuning circuit for tuning the tunable capacitance diode of the resonant circuit of a radio receiver, the search tuning circuit including a capacitor means for providing an output signal for tuning the tunable capacitance diode, said capacitor means being well insulated to prevent loss of the charge thereon, an electronic switching means having an output connected to the capacitor means for providing a signal for charging the capacitor means, a control voltage generator means for producing a first output voltage signal at a first output when a signal received by the radio receiver exceeds a minimum value of field intensity, a first switchable control means having its output connected to a first input of the electronic switching means, a search tuning actuator means connected to the first switchable control means for switching it into a first state and means for connecting the first output of the control voltage generator means to the first switchable control means for switching it into a second state, the improvement wherein said first switchable control means produces an output signal sufficient to fully drive said electronic switching means only when in its first state, said control voltage generator means produces, at a second output, a second output voltage which is S-shaped in dependence on the frequency deviation of the radio receiver and said electronic switching means includes a first transistor having first and second control electrodes, said first control electrode constituting said first input of said electronic switching means connected to the output of said first switchable control means and said second control electrode being connected to said second output of said control voltage generator means for driving said first transistor so as to continue to charge said capacitor means for effecting automatic fine tuning.
Claim 2
Dependent Claim
294 words
In an automatic search tuning circuit for tuning the tunable capacitance diode of the resonant circuit of a radio receiver, the search tuning circuit including a capacitor means for providing an output signal for tuning the tunable capacitance diode, said capacitor means being well insulated to prevent loss of the charge thereon, an electronic switching means having an output connected to the capacitor means for providing a signal for charging the capacitor means, a control voltage generator means for producing a first output voltage signal at a first output when a signal received by the radio receiver exceeds a minimum value of field intensity, a first switchable control means having its output connected to a first input of the electronic switching means, a search tuning actuator means connected to the first switchable control means for switching it into a first state and means for connecting the first output of the control voltage generator means to the first switchable control means for switching it into a second state, the improvement wherein said first switchable control means produces an output signal sufficient to fully drive said electronic switching means only when in its first state, said control voltage generator means produces, at a second output, a second output voltage which is S-shaped in dependence on the frequency deviation of the radio receiver and said electronic switching means includes a first transistor having first and second control electrodes, said first control electrode constituting said first input of said electronic switching means connected to the output of said first switchable control means and said second control electrode being connected to said second output of said control voltage generator means for driving said first transistor so as to continue to charge said capacitor means for effecting automatic fine tuning.
Claim 3
Dependent Claim
125 words
A circuit as defined in claim 1 wherein said first switchable control means includes a second capacitor and a third transistor having its collector-emitter path connected in parallel with said second capacitor, a charging circuit connected to said second capacitor for charging said second capacitor to a predetermined voltage level upon actuation of said search tuning actuator means thereby switching said first switchable control means into its first state; the voltage across said second capacitor constituting the output signal of said first switchable control means; the first output of said control voltage generator means is connected to said first switchable control means via the base electrode of said third transistor for actuating said third transistor so as to enable said second capacitor to be discharged.
Claim 4
Dependent Claim
26 words
A circuit as defined in claim 1 wherein said control voltage generator means includes a ratio detector for producing the second output signal having an S-shape.
Claim 5
Dependent Claim
131 words
A circuit as defined in claim 1 further comprising: a reverse search tuning actuator means; a second switchable control means; a second transiStor having its collector-emitter path connected in parallel with said capacitor means for slowly discharging the signal across said capacitor means and having its base electrode connected with the output of said second switchable control means; said reverse search tuning actuator means being connected to said second switchable control means for switching it into a first state; means for connecting the first output signal of said control voltage generator means to said second switchable control means for switching said second switchable control means into a second state; and said second switchable control means produces an output sufficient to fully drive said second transistor only when in its first state.
Claim 6
Dependent Claim
171 words
A circuit as defined in claim 4 wherein each of said first and second switchable control means includes a respective second capacitor and a decoupling diode and both of said first and second switchable control means include a common third transistor having its collector-emitter path connected in parallel with each of said second capacitors via said respective decoupling diode, a charging circuit connected to both of said second capacitors for charging a respective one of said second capacitors to a predetermined voltage level upon actuation of said search tuning actuator and said reverse search tuning actuator, respectively, thereby switching said first and second switchable control means, respectively, into their first state; the voltage across each of said second capacitors constituting the respective output signals of said first and second switchable control means; the first output of said control voltage generator means is connected to said switchable control means via the base electrode of said third transistor for actuating said third transistor so as to enable said second capacitors to be discharged.
Claim 7
Dependent Claim
51 words
A circuit as defined in claim 4 wherein the base electrode of said second transistor is connected to the second output of said control voltage generator means for driving said second transistor so as to continue to discharge said capacitor means to effect automatic fine tuning of the tunable capacitance diodes.
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) | 1976-09-03 | 1977-03-05 | 1977-09-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-09-03 | 1981-03-05 | 1981-09-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-09-03 | 1985-03-05 | 1985-09-04 | $7700.00 | Window Closed / Lapsed |