US3790714A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Fm stereophonic receiver
Assignee: Sony Corp
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Filing: 1971-07-12
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Granted: 1974-02-05
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Expires: 1991-07-12
Abstract
Abstract A receiver for stereophonic program signals which employs a narrow-band intermediate-frequency signal extracting circuit and a noise signal detecting circuit for producing a gate signal. The receiver further includes a change-over switch which is controlled by the gate signal to select the monaural or stereophonic mode of operation so that the receiver may achieve monaural reproduction when noise in the received signal exceeds a predetermined level.
Inventors
- 👤 M Ohsawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 04:28
CPC Classifications
H; H04; H04B; H04B1/00; H04B1/06; H04B1/16; H04B1/1646; H04B1/1661
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
255 words
In an FM stereophonic receiver having an intermediatefrequency amplifier, an FM discriminator and a monaural-tostereophonic switching means, said receiver comprising: A. Means for extracting from the output of said intermediatefrequency amplifier an intErmediate-frequency signal having a narrower frequency band than that of said intermediatefrequency amplifier; B. Means for producing a first gate signal only if the extracted narrow band intermediate-frequency signal exceeds a predetermined amplitude; C. Noise signal detecting means for detecting a noise signal in the output from said FM discriminator and providing an output signal above a predetermined level when the detected noise signal rises above a first noise level and, thereafter, until said detected noise signal falls below a second relatively lower noise level, said noise signal detecting means including a band pass filter connected with said output of the FM discriminator, and a rectifier circuit having a rectifying transistor connected to the output side of said band pass filter, a transistor amplifier connected to the output of said rectifying transistor, an integrating circuit connected to the output of said transistor amplifier and a feedback circuit for feeding the output of said integrating circuit back to the rectifying transistor; D. Means for producing a second gate signal if said output signal from said noise signal detecting means is above said predetermined level; and E. Means for controlling said monaural-to-stereophonic switching means by said first and second gate signals so as to effect stereophonic operation of the receiver only when said first gate signal exists in the absence of said second gate signal.
Claim 2
Dependent Claim
255 words
In an FM stereophonic receiver having an intermediatefrequency amplifier, an FM discriminator and a monaural-tostereophonic switching means, said receiver comprising: A. Means for extracting from the output of said intermediatefrequency amplifier an intErmediate-frequency signal having a narrower frequency band than that of said intermediatefrequency amplifier; B. Means for producing a first gate signal only if the extracted narrow band intermediate-frequency signal exceeds a predetermined amplitude; C. Noise signal detecting means for detecting a noise signal in the output from said FM discriminator and providing an output signal above a predetermined level when the detected noise signal rises above a first noise level and, thereafter, until said detected noise signal falls below a second relatively lower noise level, said noise signal detecting means including a band pass filter connected with said output of the FM discriminator, and a rectifier circuit having a rectifying transistor connected to the output side of said band pass filter, a transistor amplifier connected to the output of said rectifying transistor, an integrating circuit connected to the output of said transistor amplifier and a feedback circuit for feeding the output of said integrating circuit back to the rectifying transistor; D. Means for producing a second gate signal if said output signal from said noise signal detecting means is above said predetermined level; and E. Means for controlling said monaural-to-stereophonic switching means by said first and second gate signals so as to effect stereophonic operation of the receiver only when said first gate signal exists in the absence of said second gate signal.
Claim 3
Dependent Claim
66 words
An FM stereophonic receiver as claimed in claim 1, wherein said feedback circuit comprises: A. A switching transistor; B. A series circuit comprising a first resistor connected in series with said switching transistor between the emitter of said rectifying transistor and ground, said switching transistor being controlled by the output of the integrating circuit; and C. A second resistor connected in parallel with said series circuit.
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) | 1977-02-04 | 1977-08-06 | 1978-02-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-02-04 | 1981-08-06 | 1982-02-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-02-04 | 1985-08-06 | 1986-02-05 | $7700.00 | Window Closed / Lapsed |