US4170716A
Expired / Lapsed
US
⏱️ 0.0 years remaining
AM stereo receiver with correction limiting
Assignee: Motorola Solutions Inc
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Filing: 1977-10-14
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Granted: 1979-10-09
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Expires: 1997-10-14
Abstract
Abstract An AM receiver receiving a compatible stereo signal and utilizing a cosine correction signal for restoring the original stereo information limits the amount of correction at very large modulation angles to prevent excessive noise from being introduced by the increased gain.
Inventors
- 👤 Francis H. Hilbert
- 👤 Norman W. Parker
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 19:56
CPC Classifications
H; H04; H04H; H04H20/00; H04H20/44; H04H20/46; H04H20/47; H04H20/49
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
119 words
In an AM stereo receiver for receiving signals of the form (1+L+R) cos (ω c t+φ) where φ is arc tan {(L-R)/(1+L+R)}, L and R represent first and second program information signals, and ω c t is a carrier frequency, and requiring a cos φ correction signal to restore the stereo information, a corrector control arrangement comprising in combination; input means for receiving the broadcast signal and deriving therefrom an intermediate frequency signal; means for detecting stereo information in the intermediate frequency signal; means coupled to the input means for deriving a correction signal which is a function of the cosine of the angle of modulation; control means coupled to limit the range of values of the correction signal.
Claim 2
Dependent Claim
119 words
In an AM stereo receiver for receiving signals of the form (1+L+R) cos (ω c t+φ) where φ is arc tan {(L-R)/(1+L+R)}, L and R represent first and second program information signals, and ω c t is a carrier frequency, and requiring a cos φ correction signal to restore the stereo information, a corrector control arrangement comprising in combination; input means for receiving the broadcast signal and deriving therefrom an intermediate frequency signal; means for detecting stereo information in the intermediate frequency signal; means coupled to the input means for deriving a correction signal which is a function of the cosine of the angle of modulation; control means coupled to limit the range of values of the correction signal.
Claim 3
Dependent Claim
24 words
An AM stereo receiver in accordance with claim 1 and wherein the allowed range of values corresponds to values of the modulation angle 0°≦φ≦80°.
Claim 4
Dependent Claim
51 words
An AM stereo receiver in accordance with claim 1 and wherein the control means includes reference means for establishing a reference signal and means for maintaining the value of the second correction signal at the level of the reference signal when the first correction signal is less than said reference signal.
Claim 5
Dependent Claim
27 words
An AM stereo receiver in accordance with claim 1 and further including means for dividing at least a portion of the stereo information by the correction signal.
Claim 6
Dependent Claim
34 words
An AM stereo receiver in accordance with claim 4 and wherein the portion of the stereo information is proportional to (L-R) cos φ and the output of the divider means is proportional to (L-R).
Claim 7
Dependent Claim
22 words
An AM stereo receiver in accordance with claim 1 wherein the correction signal is proportional to cosine of the angle of modulation.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-10-08 | 1983-04-09 | 1983-10-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-10-08 | 1987-04-09 | 1987-10-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-10-08 | 1991-04-09 | 1991-10-09 | $7700.00 | Window Closed / Lapsed |