US4405835A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Receiver for AM stereo signals having a circuit for reducing distortion due to overmodulation
Assignee: US Philips Corp
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Filing: 1981-09-14
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Granted: 1983-09-20
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Expires: 2001-09-14
Abstract
Abstract A receiver for AM signals, in which the carrier is amplitude modulated with a first signal (L+R) and phase modulated with a second signal (L-R), includes a circuit for reducing distortion in the output signal due to amplitude overmodulation. This circuit includes an overmodulation detector for controlling a switch in a phase demodulation signal channel, which switch, coupled between a demodulator and an integrator in this signal channel, effectively short-circuits the input to the integrator causing the output thereof to remain constant for the duration of the overmodulation.
Inventors
- 👤 Winfried Jansen
- 👤 Wolfgang Nolde
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 22:52
CPC Classifications
H; H04; H04B; H04B1/00; H04B1/06; H04B1/10; H04H; H04H20/00; H04H20/44; H04H20/46; H04H20/47; H04H20/49
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
89 words
A receiver for receiving AM-signals the carrier being amplitude modulated with a first signal (L+R) and phase modulated with a second signal (L-R), said receiver comprising a signal channel having a phase demodulator as well as an electronic switch for blocking and releasing the signal channel, said electronic switch being controlled by an overmodulation detector, which is energized by an amplitude overmodulation of the carrier, characterized in that said phase demodulator comprises an FM-demodulator and a subsequent integrator, said electronic switch being connected between the FM-demodulator and the integrator.
Claim 2
Dependent Claim
89 words
A receiver for receiving AM-signals the carrier being amplitude modulated with a first signal (L+R) and phase modulated with a second signal (L-R), said receiver comprising a signal channel having a phase demodulator as well as an electronic switch for blocking and releasing the signal channel, said electronic switch being controlled by an overmodulation detector, which is energized by an amplitude overmodulation of the carrier, characterized in that said phase demodulator comprises an FM-demodulator and a subsequent integrator, said electronic switch being connected between the FM-demodulator and the integrator.
Claim 3
Dependent Claim
38 words
A receiver as claimed in claim 1, characterized in that said switch is connected for short-circuiting the integrator input at the occurrence of an amplitude-overmodulation of the carrier so that the output thereof remains constant during the overmodulation.
Claim 4
Dependent Claim
130 words
A receiver for receiving AM-signals the carrier being amplitude modulated with a first signal (L+R) and phase modulated with a second signal (L-R), said receiver comprising a signal channel having a phase demodulator as well as an electronic switch for blocking and releasing the signal channel, said electronic switch being controlled by an overmodulation detector, which is energized by an amplitude overmodulation of the carrier, characterized in that said phase-demodulator comprises a phase locked loop, said electronic switch being included within the phase locked loop between a phase comparator of the phase locked loop and an integrator, the integrator being connected to an output of the phase locked loop and, through a low pass loop filter, to a control input of a voltage controlled oscillator of the phase locked loop.
Claim 5
Dependent Claim
130 words
A receiver for receiving AM-signals the carrier being amplitude modulated with a first signal (L+R) and phase modulated with a second signal (L-R), said receiver comprising a signal channel having a phase demodulator as well as an electronic switch for blocking and releasing the signal channel, said electronic switch being controlled by an overmodulation detector, which is energized by an amplitude overmodulation of the carrier, characterized in that said phase-demodulator comprises a phase locked loop, said electronic switch being included within the phase locked loop between a phase comparator of the phase locked loop and an integrator, the integrator being connected to an output of the phase locked loop and, through a low pass loop filter, to a control input of a voltage controlled oscillator of the phase locked loop.
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) | 1986-09-19 | 1987-03-21 | 1987-09-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-09-19 | 1991-03-21 | 1991-09-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-09-19 | 1995-03-21 | 1995-09-20 | $7700.00 | Window Closed / Lapsed |