Patent US3871023A successfully refreshed from Google Patents.
US3871023A
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Limiting detector circuit and method of operating same
Assignee: Motorola Solutions Inc
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Filing: 1974-06-20
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Granted: 1975-03-11
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Expires: 1994-06-20
Abstract
Abstract An automatic hue control circuit for a color television receiver operates to improve the flesh tones reproduced by the receiver by causing signals lying near the +I axis to be shifted to the +I axis if they fall within a predetermined angle on either side of the +I axis. This is accomplished by splitting the chroma signal into its I and Q constituent parts and comparing the value of a predetermined fraction of the demodulated +I components with the absolute value of Q voltage components EQ to control the operation of a gating circuit to prevent or allow the passage of Q signal components to the conventional color demodulators in the receiver. To prevent operation of the automatic hue control circuit for highly saturated signals, the product detector or synchronous demodulator for demodulating the +I subcarrier signal components is supplied with reference or switching signals which have a maximum amplitude less than the maximum amplitude of the subcarrier signal components applied to it. This causes a limiting of the demodulated +I components established by the maximum amplitude of the switching signal thereby limiting the maximum value of the + I component which is compared with EQ .
Inventors
- 👤 Gerald L Caprio
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 05:17
CPC Classifications
H; H04; H04N; H04N9/00; H04N9/64; H04N9/643
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
73 words
A product detector having first and second inputs including in combination: means for supplying an amplituDe modulated input signal at a predetermined frequency to the first input of said product detector, the amplitude modulations of said input signal being subject to exceeding a predetermined amplitude; and means for supplying a reference signal at said predetermined frequency, and having an amplitude less than said predetermined amplitude, to the second input of said product detector.
Claim 2
Dependent Claim
73 words
A product detector having first and second inputs including in combination: means for supplying an amplituDe modulated input signal at a predetermined frequency to the first input of said product detector, the amplitude modulations of said input signal being subject to exceeding a predetermined amplitude; and means for supplying a reference signal at said predetermined frequency, and having an amplitude less than said predetermined amplitude, to the second input of said product detector.
Claim 3
Dependent Claim
73 words
A product detector having first and second inputs including in combination: means for supplying an amplituDe modulated input signal at a predetermined frequency to the first input of said product detector, the amplitude modulations of said input signal being subject to exceeding a predetermined amplitude; and means for supplying a reference signal at said predetermined frequency, and having an amplitude less than said predetermined amplitude, to the second input of said product detector.
Claim 4
Dependent Claim
73 words
A product detector having first and second inputs including in combination: means for supplying an amplituDe modulated input signal at a predetermined frequency to the first input of said product detector, the amplitude modulations of said input signal being subject to exceeding a predetermined amplitude; and means for supplying a reference signal at said predetermined frequency, and having an amplitude less than said predetermined amplitude, to the second input of said product detector.
Claim 5
Dependent Claim
173 words
A color television receiver which receives a composite signal comprising at least a subcarrier signal component modulated in phase and amplitude to represent hue and saturation of a color image and a burst component for phase locking the signal of an oscillator of the receiver, the maximum amplitude attainable by said subcarrier signal component being a first predetermined amplitude, said receiver including in combination: a reference oscillator supplied with at least said burst component for producing a reference switching signal at the frequency of said subcarrier signal and at a predetermined phase relative to the phase of said burst component; a synchronous product detector having a reference signal input and an information signal input; signal amplitude limiting means coupled between the output of said reference oscillator and the reference signal input of said product detector for applying reference switching signals to said product detector at a second predetermined amplitude less than said first predetermined amplitude; and means for applying said modulated subcarrier signal component to the information signal input of said product detector.
Claim 6
Dependent Claim
173 words
A color television receiver which receives a composite signal comprising at least a subcarrier signal component modulated in phase and amplitude to represent hue and saturation of a color image and a burst component for phase locking the signal of an oscillator of the receiver, the maximum amplitude attainable by said subcarrier signal component being a first predetermined amplitude, said receiver including in combination: a reference oscillator supplied with at least said burst component for producing a reference switching signal at the frequency of said subcarrier signal and at a predetermined phase relative to the phase of said burst component; a synchronous product detector having a reference signal input and an information signal input; signal amplitude limiting means coupled between the output of said reference oscillator and the reference signal input of said product detector for applying reference switching signals to said product detector at a second predetermined amplitude less than said first predetermined amplitude; and means for applying said modulated subcarrier signal component to the information signal input of said product detector.
Claim 7
Dependent Claim
14 words
The combination according to claim 2 wherein said product detector is a balanced demodulator.
Claim 8
Dependent Claim
16 words
The combination according to claim 2 wherein said amplitude limiting means comprises a variable resistance means.
References Cited (Backward Citations)
US3647941A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-03-10 | 1978-09-09 | 1979-03-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-03-10 | 1982-09-09 | 1983-03-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-03-10 | 1986-09-09 | 1987-03-11 | $7700.00 | Window Closed / Lapsed |