Patent US4373209A successfully refreshed from Google Patents.
US4373209A
Expired / Lapsed
US
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Method and circuitry for controlling the intermediate frequency of an FM receiver to lessen phase distortion
Assignee: Trio KK
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Filing: 1981-02-17
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Granted: 1983-02-08
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Expires: 2001-02-17
Abstract
Abstract Circuitry for controlling the intermediate frequency of an FM receiver comprising modulating means for frequency modulating the intermediate frequency signal with a modulating signal of predetermined frequency; detecting means for detecting the absolute amount of distortion incurred by the modulating signal of predetermined frequency at the intermediate frequency amplification stage of the FM receiver; and control means for changing the intermediate frequency by incremental amounts to control the intermediate frequency so that the distortion at the intermediate frequency amplification stage is minimized in accordance with the increase or decrease in the distortion detected by the detecting means.
Inventors
- 👤 Ryoichi Kaneda
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 10:07
CPC Classifications
H; H03; H03J; H03J7/00; H03J7/02; H04; H04B; H04B1/00; H04B1/06; H04B1/10; H04B1/14
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
260 words
Circuitry for controlling the intermediate frequency signal occurring at an intermediate frequency amplification stage of an FM receiver having FM signals applied thereto comprising modulating means for frequency modulating the intermediate frequency signal with a modulating signal of predetermined frequency where said modulating means includes a voltage controlled oscillator, the output of which is mixed with the FM signals applied to the receiver and a sine wave generator, the output of which FM modulates the voltage controlled oscillator; detecting means for detecting the absolute amount of distortion incurred by said modulating signal of predetermined frequency at the intermediate frequency amplification stage of the FM receiver; and control means for changing the intermediate frequency by incremental amounts to control the intermediate frequency so that the distortion at the intermediate frequency amplification stage is minimized in accordance with any increase or decrease in the distortion detected by said detecting means where said control means includes means for generating a DC signal which is added to the output of the sine wave generator where the DC signal determines the central frequency of the voltage controlled oscillator; means for establishing an initial value of said DC voltage and the value of an incremental voltage; means for successively adding or subtracting said incremental voltage from the initial DC voltage to obtain an incremented DC voltage; comparison means for comparing the incremented DC voltage before and after each increment thereof; and means responsive to the comparison means for continuing the incrementing of the DC voltage until the distortion at the intermediate frequency amplification stage is minimized.
Claim 2
Dependent Claim
260 words
Circuitry for controlling the intermediate frequency signal occurring at an intermediate frequency amplification stage of an FM receiver having FM signals applied thereto comprising modulating means for frequency modulating the intermediate frequency signal with a modulating signal of predetermined frequency where said modulating means includes a voltage controlled oscillator, the output of which is mixed with the FM signals applied to the receiver and a sine wave generator, the output of which FM modulates the voltage controlled oscillator; detecting means for detecting the absolute amount of distortion incurred by said modulating signal of predetermined frequency at the intermediate frequency amplification stage of the FM receiver; and control means for changing the intermediate frequency by incremental amounts to control the intermediate frequency so that the distortion at the intermediate frequency amplification stage is minimized in accordance with any increase or decrease in the distortion detected by said detecting means where said control means includes means for generating a DC signal which is added to the output of the sine wave generator where the DC signal determines the central frequency of the voltage controlled oscillator; means for establishing an initial value of said DC voltage and the value of an incremental voltage; means for successively adding or subtracting said incremental voltage from the initial DC voltage to obtain an incremented DC voltage; comparison means for comparing the incremented DC voltage before and after each increment thereof; and means responsive to the comparison means for continuing the incrementing of the DC voltage until the distortion at the intermediate frequency amplification stage is minimized.
Claim 3
Dependent Claim
16 words
Circuitry as in claim 1 where said modulating signal of predetermined frequency is a sine wave.
Claim 4
Dependent Claim
57 words
Circuitry as in claim 1 or 2 where said FM receiver includes a demodulator for demodulating the intermediate frequency signal and a low pass filter responsive to the demodulator for passing broadcast signals where said predetermined frequency of the modulating signal is greater than those of the broadcast signals and is removed by the low pass filter.
Claim 5
Dependent Claim
35 words
Circuitry as in claim 3 where said detecting means includes a high pass filter responsive to the demodulator for passing a signal having a frequency more than twice said predetermined frequency of the modulating signal.
Claim 6
Dependent Claim
249 words
Method of controlling the intermediate frequency signal occurring at an intermediate frequency amplification stage of an FM receiver having FM signals applied thereto comprising the steps of frequency modulating the intermediate frequency signal with a modulating signal of predetermined frequency where said modulating step is effected by a voltage controlled oscillator and where said method includes the steps of (a) mixing the output of the voltage controlled oscillator with the FM signals applied to the receiver and (b) generating a sine wave which FM modulates the voltage controlled oscillator; detecting the absolute amount of distortion incurred by said modulating signal of predetermined frequency at the intermediate frequency amplification stage of the FM receiver; and controlling the frequency of the intermediate frequency signal by changing the frequency thereof by incremental amounts so that the distortion at the intermediate frequency amplification stage is minimized in accordance with any detected increase or decrease in the distortion where said controlling step includes generating a DC signal which is added to the output of the sine wave generator where the DC signal determines the central frequency of the voltage controlled oscillator; establishing an initial value of said DC voltage and the value of an incremental voltage; successively adding or subtracting said incremental voltage from the initial DC voltage to obtain an incremented DC voltage; comparing the incremented DC voltage before and after each increment thereof; and continuing the incrementing of the DC voltage until the distortion at the intermediate frequency amplification stage is minimized.
Claim 7
Dependent Claim
249 words
Method of controlling the intermediate frequency signal occurring at an intermediate frequency amplification stage of an FM receiver having FM signals applied thereto comprising the steps of frequency modulating the intermediate frequency signal with a modulating signal of predetermined frequency where said modulating step is effected by a voltage controlled oscillator and where said method includes the steps of (a) mixing the output of the voltage controlled oscillator with the FM signals applied to the receiver and (b) generating a sine wave which FM modulates the voltage controlled oscillator; detecting the absolute amount of distortion incurred by said modulating signal of predetermined frequency at the intermediate frequency amplification stage of the FM receiver; and controlling the frequency of the intermediate frequency signal by changing the frequency thereof by incremental amounts so that the distortion at the intermediate frequency amplification stage is minimized in accordance with any detected increase or decrease in the distortion where said controlling step includes generating a DC signal which is added to the output of the sine wave generator where the DC signal determines the central frequency of the voltage controlled oscillator; establishing an initial value of said DC voltage and the value of an incremental voltage; successively adding or subtracting said incremental voltage from the initial DC voltage to obtain an incremented DC voltage; comparing the incremented DC voltage before and after each increment thereof; and continuing the incrementing of the DC voltage until the distortion at the intermediate frequency amplification stage is minimized.
Claim 8
Dependent Claim
17 words
A method as in claim 5 where said modulating signal of predetermined frequency is a sine wave.
Claim 9
Dependent Claim
48 words
A method as in claim 5 or 6 including the steps of demodulating the intermediate frequency signal and passing broadcast signals included in the demodulated signals, said predetermined frequency of the modulating signal being greater than those of the broadcast signals and being removed from the broadcast signals.
Claim 10
Dependent Claim
27 words
A method as in claim 7 where said detecting step includes passing a signal having a frequency more than twice said predetermined frequency of the modulating signal.
References Cited (Backward Citations)
US4237556A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-02-07 | 1986-08-09 | 1987-02-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-02-07 | 1990-08-09 | 1991-02-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-02-07 | 1994-08-09 | 1995-02-08 | $7700.00 | Window Closed / Lapsed |