US3617641A
Expired / Lapsed
US
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Stereo multiplex demodulator
Assignee: Motorola Solutions Inc
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Filing: 1970-04-29
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Granted: 1971-11-02
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Expires: 1990-04-29
Abstract
Abstract A silicon, monolithic, integrated circuit, stereo multiplex demodulator includes a first-gated symmetrical demodulator for providing the desired left and right output signals. A secondgated synchronous demodulator similar to the first is supplied with the same composite input signals supplied to the first demodulator; but the signals supplied to the second demodulator are substantially attenuated, with the second demodulator are substantially attenuated, with the second demodulator providing output signals in phase opposition to the output signals supplied by the first demodulator. The outputs of the two demodulators are combined so that the crosstalk components are effectively eliminated, since the attenuation of the signal supplied to the second demodulator is chosen so that the output of the second demodulator is equal in magnitude to the crosstalk component in the output of the first demodulator.
Inventors
- 👤 James H Fiet
- 👤 Francis H Hilbert
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 22:04
CPC Classifications
H; H03; H03D; H03D1/00; H03D1/22; H03D1/2209; H03D1/2227
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
83 words
A crosstalk cAncellation circuit for use in conjunction with a stereophonic demodulator comprising in combination: a first stereophonic demodulator; means for supplying input signals to be demodulated to the first demodulator, said demodulator producing crosstalk components at its outputs, a second stereophonic demodulator having its outputs connected to the outputs of the first demodulator in phase opposition thereto; and means for attenuating the output signals supplied by the second demodulator, the amount of attenuation being proportional to the magnitude of said crosstalk components.
Claim 2
Dependent Claim
83 words
A crosstalk cAncellation circuit for use in conjunction with a stereophonic demodulator comprising in combination: a first stereophonic demodulator; means for supplying input signals to be demodulated to the first demodulator, said demodulator producing crosstalk components at its outputs, a second stereophonic demodulator having its outputs connected to the outputs of the first demodulator in phase opposition thereto; and means for attenuating the output signals supplied by the second demodulator, the amount of attenuation being proportional to the magnitude of said crosstalk components.
Claim 3
Dependent Claim
44 words
The combination according to claim 1 wherein said first and second demodulators are synchronous gated demodulators and further including means for supplying gating signals to said demodulators and wherein said demodulators each provide first and second outputs corresponding to right and left stereophonic outputs.
Claim 4
Dependent Claim
82 words
A crosstalk cancellation circuit for use in conjunction with a stereophonic demodulator comprising in combination: a first stereophonic demodulator; means for supplying input signals to be demodulated to the first demodulator, said demodulator producing crosstalk components at its outputs. a second stereophonic demodulator having its outputs connected to the outputs of the first demodulator in phase opposition thereto: and means for supplying attenuated input signals to the second demodulator, the amount of attenuation being proportional to the magnitude of said crosstalk components.
Claim 5
Dependent Claim
82 words
A crosstalk cancellation circuit for use in conjunction with a stereophonic demodulator comprising in combination: a first stereophonic demodulator; means for supplying input signals to be demodulated to the first demodulator, said demodulator producing crosstalk components at its outputs. a second stereophonic demodulator having its outputs connected to the outputs of the first demodulator in phase opposition thereto: and means for supplying attenuated input signals to the second demodulator, the amount of attenuation being proportional to the magnitude of said crosstalk components.
Claim 6
Dependent Claim
44 words
The combination according to claim 3 wherein said first and second demodulators are synchronous gated demodulators and further including means for supplying gating signals to said demodulators and wherein said demodulators each provide first and second outputs corresponding to right and left stereophonic outputs.
Claim 7
Dependent Claim
86 words
The combination according to claim 4 wherein the means for supplying input signals to the demodulators each includes an input transistor having at least base and emitter electrodes, and where input signals for the first demodulator are applied to the base of the input transistor for the demodulator and further wherein input signals for the input transistor for the second demodulator are supplied through an attenuating circuit from the emitter of the input transistor for the first demodulator to the input transistor for the second demodulator.
Claim 8
Dependent Claim
47 words
The combination according to claim 5 wherein the base of the input transistor for the second demodulator is connected to a predetermined reference potential and wherein the input signals for the input transistor for the second demodulator are applied through the attenuating circuit to the emitter thereof.
Claim 9
Dependent Claim
28 words
The combination according to claim 6 wherein the attenuating circuit includes a predetermined impedance connected between the emitters of the input transistors for the first and second demodulators.
Claim 10
Dependent Claim
41 words
The combination according to claim 6 wherein the emitters of the input transistors are connected together through a pair of resistors with an additional resistance being connected between the junction of said pair of resistors and a point of reference potential.
Claim 11
Dependent Claim
153 words
A continuous wave receiver of the type for receiving composite stereophonic multiplex radio signals including an integrated demultiplexing circuit comprising in combination: first and second input transistors formed as part of said integrated circuit, the first input transistor being supplied with said composite signals; first and second synchronous demodulators, each having a pair of outputs and each including a pair of switching transistors supplied with signals from the first and second input transistors, respectively, and formed as part of said integrated circuits the first demodulator producing crosstalk components at its outputs; means for providing the second input transistor with signals from the output of the first input transistor, said provided signals being attenuated with respect to the signalS supplied to the first demodulator; and means for combining the output of the two demodulators out of phase so that the output from the second demodulator is subtracted from the output of the first demodulator.
Claim 12
Dependent Claim
153 words
A continuous wave receiver of the type for receiving composite stereophonic multiplex radio signals including an integrated demultiplexing circuit comprising in combination: first and second input transistors formed as part of said integrated circuit, the first input transistor being supplied with said composite signals; first and second synchronous demodulators, each having a pair of outputs and each including a pair of switching transistors supplied with signals from the first and second input transistors, respectively, and formed as part of said integrated circuits the first demodulator producing crosstalk components at its outputs; means for providing the second input transistor with signals from the output of the first input transistor, said provided signals being attenuated with respect to the signalS supplied to the first demodulator; and means for combining the output of the two demodulators out of phase so that the output from the second demodulator is subtracted from the output of the first demodulator.
Claim 13
Dependent Claim
46 words
The combination according to claim 9 wherein the attenuation of the signals supplied to the second demodulator is adjusted so that the outputs of the second demodulator are equal in magnitude to the magnitude of the crosstalk components present in the outputs of the first demodulator.
Claim 14
Dependent Claim
32 words
The combination according to claim 10 wherein the attenuation of the signals provided to the second demodulator is obtained by a predetermined impedance inserted into the input circuit for the second demodulator.
Claim 15
Dependent Claim
81 words
The combination according to claim 11 wherein the first and second input transistors have at least base and emitter electrodes and wherein the composite signals are supplied to the base of the first input transistor and wherein the signals from the output of the first input transistor provided to the second input transistor are applied through an impedance to the emitter of the second input transistor, with the base of the second input transistor being connected to a predetermined reference potential.
Claim 16
Dependent Claim
165 words
The combination according to claim 12 wherein each pair of switching transistors in the first and second demodulators includes first and second transistors having base, emitter, and collector electrodes, and wherein the collector electrodes of the first transistors of each pair are connected together to a common output terminal, the collector electrodes of the second transistors of each pair are connected together to a common output terminal, and the emitters of the first and second transistors in each of said pairs are connected together to the collector electrode of the input transistor for the respective demodulator pair, and further including means for alternately switching the first and second transistors of each of the demodulators between a state of conduction and nonconduction, with the first transistor of the first demodulator being rendered conductive simultaneously with the second transistor of the second demodulator and the second transistor of the first demodulator being rendered conductive simultaneously with the first transistor of the second demodulator by said switching means.
Claim 17
Dependent Claim
92 words
In a stereophonic receiver, a stereophonic demodulator circuit comprising in combination: a first stereophonic demodulator; means for supplying input signals to be demodulated to the input of the first demodulator, said demodulator producing demodulated stereophonic signals at first and second outputs; a second stereophonic demodulator having first and second outputs connected to the outputs of the first demodulator in phase opposition thereto; and means for providing the same DC operating signal levels to both of the demodulators so that a constant DC operating point is provided at the outputs of the demodulators.
Claim 18
Dependent Claim
92 words
In a stereophonic receiver, a stereophonic demodulator circuit comprising in combination: a first stereophonic demodulator; means for supplying input signals to be demodulated to the input of the first demodulator, said demodulator producing demodulated stereophonic signals at first and second outputs; a second stereophonic demodulator having first and second outputs connected to the outputs of the first demodulator in phase opposition thereto; and means for providing the same DC operating signal levels to both of the demodulators so that a constant DC operating point is provided at the outputs of the demodulators.
Claim 19
Dependent Claim
87 words
The combination according to claim 14 wherein the first and second demodulators are synchronous gated demodulators, and further including means for supplying gating signals to the demodulators wherein the demodulators each provide first and second outputs with the first output of the first demodulator being connected to the second output of the second demodulator and with the second output of the first demodulator being connected to the first output of the second demodulator, so that the gating signal components are cancelled from the outputs of the demodulators.
Claim 20
Dependent Claim
46 words
The combination according to claim 15 wherein the first and second synchronous demodulators each include a pair of switching transistors supplied with the gating signals and with input signals to be demodulated being supplied in parallel to the pair of switching transistors in the first demodulator.
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) | 1974-11-01 | 1975-05-03 | 1975-11-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-11-01 | 1979-05-03 | 1979-11-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-11-01 | 1983-05-03 | 1983-11-02 | $7700.00 | Window Closed / Lapsed |