US3909723A
Expired / Lapsed
US
⏱️ 0.0 years remaining
FM/AM radio receiver tuning apparatus
Assignee: Motorola Solutions Inc
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Filing: 1974-08-05
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Granted: 1975-09-30
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Expires: 1994-08-05
Abstract
Abstract A phase locked loop including a voltage controlled oscillator utilized as the FM oscillator in the FM front end and the DC voltage from the phase locked loop also is utilized to tune the remaining front end circuits of the FM radio receiver. The output of the voltage controlled oscillator is mixed with the output of a fixed oscillator and divided so it is the same frequency as the output of the AM oscillator in the tuner. The AM oscillator and the divided frequency from the mixer are applied to two inputs of a phase comparator with the output being filtered and amplified to provide the DC for controlling the voltage controlled oscillator.
Inventors
- 👤 Peter St Clair Manson
- 👤 Basil P Hooten
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 12:26
CPC Classifications
H; H03; H03J; H03J3/00; H03J3/02; H03J3/16; H03J3/18; H03J3/185
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
187 words
FM/AM radio receiver tuning apparatus comprising: a. an AM oscillator and means for tuning said AM oscillator through a predetermined range; b. an FM radio receiver front end including an FM oscillator, an FM antenna circuit and RF circuits each including voltage sensitive means for electronically tuning said FM oscillator and remaining FM circuits to predetermined frequencies in response to predetermined voltages being applied thereto; c. a fixed oscillator; d. a mixer connected to said FM oscillator and said fixed oscillator for receiving signals therefrom and providing an output signal having a frequency which is a heterodyne or beat frequency of the frequencies of the two input signals; e. a phase comparator having two inputs and an output with one input connected to receive a signal from said AM oscillator; f. means connecting the output of said mixer to the second input of said comparator; and g. means connecting the output of said comparator to the voltage sensitive means of said FM oscillator, FM antenna circuit and RF circuits for providing a predetermined voltage thereto in response to said AM oscillator being tuned to a predetermined frequency.
Claim 2
Dependent Claim
187 words
FM/AM radio receiver tuning apparatus comprising: a. an AM oscillator and means for tuning said AM oscillator through a predetermined range; b. an FM radio receiver front end including an FM oscillator, an FM antenna circuit and RF circuits each including voltage sensitive means for electronically tuning said FM oscillator and remaining FM circuits to predetermined frequencies in response to predetermined voltages being applied thereto; c. a fixed oscillator; d. a mixer connected to said FM oscillator and said fixed oscillator for receiving signals therefrom and providing an output signal having a frequency which is a heterodyne or beat frequency of the frequencies of the two input signals; e. a phase comparator having two inputs and an output with one input connected to receive a signal from said AM oscillator; f. means connecting the output of said mixer to the second input of said comparator; and g. means connecting the output of said comparator to the voltage sensitive means of said FM oscillator, FM antenna circuit and RF circuits for providing a predetermined voltage thereto in response to said AM oscillator being tuned to a predetermined frequency.
Claim 3
Dependent Claim
30 words
FM/AM radio receiver tuning apparatus as claimed in claim 1 wherein the means connecting the output of the mixer to the second input of the comparator includes frequency divider circuitry.
Claim 4
Dependent Claim
43 words
FM/AM radio receiver tuning apparatus as claimed in claim 2 wherein the frequency of the FM receiver IF strip is 10.7 MHz, the fixed oscillator is tuned to 82.1 MHz and the frequency divider circuitry includes circuits which divide the frequency by twenty.
Claim 5
Dependent Claim
17 words
FM/AM radio receiver tuning apparatus as claimed in claim 1 wherein the voltage sensitive means include varactors.
Claim 6
Dependent Claim
30 words
FM/AM radio receiver tuning apparatus as claimed in claim 1 wherein the means connecting the output of the comparator to the voltage sensitive means includes a filter and DC amplifier.
Claim 7
Dependent Claim
23 words
FM/AM radio receiver tuning apparatus as claimed in claim 1 including in addition an automatic frequency control circuit connected to the fixed oscillator.
Claim 8
Dependent Claim
32 words
FM/AM radio receiver tuning apparatus as claimed in claim 1 wherein the phase comparator is a comparator which locks on the leading edge of input signals to prevent locking onto a harmonic.
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) | 1978-09-29 | 1979-03-31 | 1979-09-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-29 | 1983-03-31 | 1983-09-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-29 | 1987-03-31 | 1987-09-30 | $7700.00 | Window Closed / Lapsed |