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Patent US3711652A successfully refreshed from Google Patents.
US3711652A
Expired / Lapsed
US
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Monolithic stereo decoder with balanced decoder operation
Assignee: RCA Licensing Corp
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Filing: 1971-03-10
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Granted: 1973-01-16
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Expires: 1991-03-10
Abstract
Abstract A monolithic integrated circuit decoder for deriving stereophonically related audio frequency signals from a composite signal includes an input circuit for generating DC voltagebalanced signals including the composite signal for balanced, linear operation of the decoder. The decoder further includes a phase-locked loop having a temperature compensated current controlled oscillator and a frequency dividing dual rank flipflop of simplified structure producing a staircase waveform on alternate half-cycles. The decoder also includes an audio mute circuit for muting the output of the decoder between stations.
Inventors
- 👤 J Metro
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 20:46
CPC Classifications
H; H03; H03D; H03D1/00; H03D1/22; H03D1/2209; H03D1/2236
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
259 words
In a decoder for deriving first and second stereophonically related audio frequency signals from a composite signal including frequency components in the form of the sidebands of a difference combination of said first and second audio frequency signals amplitude modulated on a suppressed carrier wave of given frequency, a sum combination of said first and second audio frequency signals lying in a frequency band lower in frequency than said sidebands and separated therefrom by a frequency gap, and a pilot signal at a frequency equal to one half that of said suppressed carrier wave and which lies in said frequency gap, said decoder comprising means for reconstituting said suppressed carrier, means for detecting the presence of a suitable stereo signal, and means for deriving said first and second stereophonically related audio frequency signals from said composite signal in response to an indication from said detecting means that a suitable signal is present and under the control of said reconstituted suppressed carrier, an input circuit for said decoder for receiving said composite signal and establishing a DC voltage for combining therewith, said input circuit having first and second output channels responsive to the combined signal and means for removing the composite signal from said second channel such that a DC voltage-balanced composite signal including said composite signal at said DC voltage level on said first channel and said DC voltage on said second channel, is applied to said reconstituting means, the detecting means and the deriving means by said first and second channels for balanced linear operation of said decoder.
Claim 2
Dependent Claim
259 words
In a decoder for deriving first and second stereophonically related audio frequency signals from a composite signal including frequency components in the form of the sidebands of a difference combination of said first and second audio frequency signals amplitude modulated on a suppressed carrier wave of given frequency, a sum combination of said first and second audio frequency signals lying in a frequency band lower in frequency than said sidebands and separated therefrom by a frequency gap, and a pilot signal at a frequency equal to one half that of said suppressed carrier wave and which lies in said frequency gap, said decoder comprising means for reconstituting said suppressed carrier, means for detecting the presence of a suitable stereo signal, and means for deriving said first and second stereophonically related audio frequency signals from said composite signal in response to an indication from said detecting means that a suitable signal is present and under the control of said reconstituted suppressed carrier, an input circuit for said decoder for receiving said composite signal and establishing a DC voltage for combining therewith, said input circuit having first and second output channels responsive to the combined signal and means for removing the composite signal from said second channel such that a DC voltage-balanced composite signal including said composite signal at said DC voltage level on said first channel and said DC voltage on said second channel, is applied to said reconstituting means, the detecting means and the deriving means by said first and second channels for balanced linear operation of said decoder.
Claim 3
Dependent Claim
46 words
A decoder as recited in claim 1 wherein said reconstituting means, said detecting means and said deriving means each include a differential amplifier and said first and second channels are coupled to apply said DC voltage-balanced composite signal to the two inputs of each differential amplifier.
Claim 4
Dependent Claim
29 words
A decoder as recited in claim 1 wherein said input circuit includes feedback amplifier means for establishing said DC voltage and providing a high input impedance for said decoder.
Claim 5
Dependent Claim
107 words
A decoder as recited in claim 1 further including an audio mute circuit for muting the output of said decoder in the absence of a suitable signal received by said decoder, said audio mute circuit coupled to said input circuit to provide a third channel having a DC voltage substantially equal to the DC voltage on said first and second channels, and containing switch means responsive to said received signal to apply said DC voltage-balanced composite signal to said deriving means in the presence of a suitable received signal and to apply the two channels of DC voltage thereto in the absence of a suitable received signal.
References Cited (Backward Citations)
US3158690A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-01-16 | 1976-07-17 | 1977-01-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-01-16 | 1980-07-17 | 1981-01-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-01-16 | 1984-07-17 | 1985-01-16 | $7700.00 | Window Closed / Lapsed |