US4223282A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of reducing interference components in a frequency modulated signal and device for carrying out said method
Assignee: US Philips Corp
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Filing: 1978-07-10
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Granted: 1980-09-16
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Expires: 1998-07-10
Abstract
Abstract A method of reducing interference components in a frequency-modulated carrier signal in which the modulating signal contains a composite color television signal with a chrominance signal modulated on a chrominance subcarrier wave. In addition to the frequency modulation, the carrier signal is pulse-width modulated by the first-order lower side-band component of the frequency-modulated signal produced by the modulated chrominance subcarrier signal.
Inventors
- 👤 Eeltje de Boer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 06:09
CPC Classifications
H; H04; H04N; H04N9/00; H04N9/79; H03; H03C; H03C3/00; H03C3/02; H04N9/7908; H04N9/7912
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
53 words
A method of reducing interference components in a frequency-modulated signal, comprising a carrier signal being frequency-modulated by at least one modulating signal of a fixed frequency, wherein the carrier signal is pulse-width modulated by the first-order lower side-band component which is contained in the frequency-modulated signal as a result of the modulating signal.
Claim 2
Independent Claim
53 words
A method of reducing interference components in a frequency-modulated signal, comprising a carrier signal being frequency-modulated by at least one modulating signal of a fixed frequency, wherein the carrier signal is pulse-width modulated by the first-order lower side-band component which is contained in the frequency-modulated signal as a result of the modulating signal.
Claim 3
Dependent Claim
52 words
A method as claimed in claim 1, wherein the modulation index for the pulse-width modulation is selected so that the second-order lower side-band component produced during this pulse-width modulation is of, at least substantially, the same magnitude as the second-order lower side-band component of the frequency-modulated signal, caused by the modulating signal.
Claim 4
Dependent Claim
36 words
A method as claimed in claim 1 or 2, wherein the pulse-width modulation is obtained, starting from, at least in approximation, a single side-band frequency-modulated signal with finitely steep edges and by symmetrically limiting that signal.
Claim 5
Dependent Claim
23 words
A method as claimed in claim 3, wherein the carrier signal contained in the frequency-modulated signal is selectively attenuated prior to the limiting.
Claim 6
Dependent Claim
25 words
A method as claimed in claim 3, wherein the first-order lower side-band component contained in the frequency-modulated signal is selectively amplified prior to the limiting.
Claim 7
Dependent Claim
40 words
A method as claimed in claim 5, wherein the selective amplification of the first-order lower side-band component is obtained by extracting said component from the frequency-modulated signal, amplifying it by a predetermined factor, and adding it to the frequency-modulated signal.
Claim 8
Dependent Claim
64 words
A method as claimed in claim 1 or 2, wherein a symmetrical frequency-modulated signal is used, and which further comprises extracting the first-order lower side-band component from said signal, amplifying said first-order lower side-band component by a predetermined factor, after which pulse-width modulation is obtained by adding said amplified first-order lower side-band component to the frequency modulated signal and symmetrically limiting the sum signal.
Claim 9
Independent Claim
55 words
A device for reducing interference components in a frequency-modulated signal, said signal having a carrier signal which is frequency-modulated by at least one modulating signal at a fixed frequency, wherein the device comprises a modulation device for the pulse-width modulation of the carrier signal by the first order lower side-band component in said frequency-modulated signal.
Claim 10
Independent Claim
55 words
A device for reducing interference components in a frequency-modulated signal, said signal having a carrier signal which is frequency-modulated by at least one modulating signal at a fixed frequency, wherein the device comprises a modulation device for the pulse-width modulation of the carrier signal by the first order lower side-band component in said frequency-modulated signal.
Claim 11
Dependent Claim
21 words
A device as claimed in claim 8, wherein the modulation device comprises a limiting circuit for symmetrically limiting the frequency-modulated signal.
Claim 12
Dependent Claim
32 words
A device as claimed in claim 9, wherein the device further comprises a low-pass filter for the suppression of upper side-band components of the frequency-modulated signal, which filter precedes the limiting circuit.
Claim 13
Dependent Claim
30 words
A device as claimed in claim 9 or 10, wherein the modulation device further comprises an attenuation circuit for selectively attenuating the carrier signal, which circuit precedes the limiting circuit.
Claim 14
Dependent Claim
37 words
A device as claimed in claim 11, wherein the attenuation circuit comprises a low-pass filter having a cut-off frequency which is situated between the frequency of the first-order lower side-band component and that of the carrier signal.
Claim 15
Dependent Claim
35 words
A device as claimed in claim 9 or 10, wherein the modulation device further comprises a selective amplifier device for selectively amplifying the first-order lower side-band component, which selective amplifier device precedes the limiting circuit.
Claim 16
Dependent Claim
61 words
A device as claimed in claim 13, wherein the modulation device further comprises an adding device, first means for applying the frequency-modulated signal to said adding device, a band-pass filter for extracting the first-order lower side-band component from the frequency-modulated signal, and second means for applying said extracted first-order lower side-band component, amplified by a predetermined factor, to the adding device.
References Cited (Backward Citations)
US3132339A
Cited
US3893163A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-09-16 | 1984-03-17 | 1984-09-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-09-16 | 1988-03-17 | 1988-09-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-09-16 | 1992-03-17 | 1992-09-16 | $7700.00 | Window Closed / Lapsed |