US3772479A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Gain modified multi-channel audio system
Assignee: Motorola Solutions Inc
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Filing: 1971-10-19
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Granted: 1973-11-13
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Expires: 1991-10-19
Abstract
Abstract A stereo-effect enhancement system for increasing the apparent spatial separation in a multi-channel audio system includes variable gain amplifiers and comparator circuits which compare the amplitudes of the audio input signals and adjust the gain of the variable gain amplifiers in accordance with the ratio of the amplitudes of the audio input signals. Spatially expanded two channel stereo, pseudo three channel stereo, pseudo four channel stereo or automatic stereo balance control may be achieved by variously combining the audio signals from the enhancement system with the unmodified audio input signals.
Inventors
- 👤 F Hilbert
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 17:24
CPC Classifications
H; H04; H04S; H04S1/00; H04S1/002
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
485 words
A system for deriving a plurality of output signals from first and second stereophonically related signals from first and second signal sources, such system including in combinatiOn: first and second variable gain amplifiers each having an input, an output and a control terminal, the input terminal of said first amplifier being connected to said first source and receiving said first stereophonically related signal, and the input terminal of said second amplifier being connected to said second source and receiving said second stereophonically related signal, each of said amplifiers having a gain that varies in accordance with a control signal applied to said control terminal; amplitude sensing means for sensing the amplitudes of the first and second stereophonically related signals and providing control signals only to said amplifiers for simultaneously increasing the gain of one of said amplifiers and decreasing the gain of the other of said amplifiers in accordance with the ratio of the amplitudes of said first and second stereophonically related signals in a manner such that the gain of said first amplifier is greater than the gain of said second amplifier when one of said stereophonically related signals is larger, and such that the gain of said second amplifier is greater when the other of said stereophonically related signals is larger, said amplitude sensing means being connected to said first and second signal sources and receiving said first and second stereophonically related signals therefrom, and only to said first and second amplifiers and controlling the gain thereof; means for combining said stereophonically related signals; and a third variable gain amplifier connected to said combining means and receiving said combined stereophonically related signals therefrom and providing output signals in response thereto, said third variable gain amplifier having gain which varies in accordance with a control signal applied thereto, summing means connected to each of said signal sources for receiving and adding said stereophonically related signals and providing sum signals proportional to the degree of correlation between said stereophonically related signals, difference means connected to each of said signal sources for receiving and subtracting said stereophonically related signals and providing difference signals proportional to the lack of correlation between said stereophonically related signals, and second amplitude sensing means connected to said summing means and said difference means for receiving said sum and difference signals, said second amplitude sensing means being further connected to said first, second and third variable gain amplifiers for providing control signals thereto in response to the difference between said sum signals and said difference signals, said second amplitude sensing means and said first, second and third amplifiers being interconnected in a predetermined manner thereby to increase the gain of said third amplifier relative to said first and second amplifiers when said sum signal exceeds said difference signal, and to increase the gain of said first and second amplifiers relative to said third amplifier when said difference signal exceeds said sum signal.
Claim 2
Independent Claim
485 words
A system for deriving a plurality of output signals from first and second stereophonically related signals from first and second signal sources, such system including in combinatiOn: first and second variable gain amplifiers each having an input, an output and a control terminal, the input terminal of said first amplifier being connected to said first source and receiving said first stereophonically related signal, and the input terminal of said second amplifier being connected to said second source and receiving said second stereophonically related signal, each of said amplifiers having a gain that varies in accordance with a control signal applied to said control terminal; amplitude sensing means for sensing the amplitudes of the first and second stereophonically related signals and providing control signals only to said amplifiers for simultaneously increasing the gain of one of said amplifiers and decreasing the gain of the other of said amplifiers in accordance with the ratio of the amplitudes of said first and second stereophonically related signals in a manner such that the gain of said first amplifier is greater than the gain of said second amplifier when one of said stereophonically related signals is larger, and such that the gain of said second amplifier is greater when the other of said stereophonically related signals is larger, said amplitude sensing means being connected to said first and second signal sources and receiving said first and second stereophonically related signals therefrom, and only to said first and second amplifiers and controlling the gain thereof; means for combining said stereophonically related signals; and a third variable gain amplifier connected to said combining means and receiving said combined stereophonically related signals therefrom and providing output signals in response thereto, said third variable gain amplifier having gain which varies in accordance with a control signal applied thereto, summing means connected to each of said signal sources for receiving and adding said stereophonically related signals and providing sum signals proportional to the degree of correlation between said stereophonically related signals, difference means connected to each of said signal sources for receiving and subtracting said stereophonically related signals and providing difference signals proportional to the lack of correlation between said stereophonically related signals, and second amplitude sensing means connected to said summing means and said difference means for receiving said sum and difference signals, said second amplitude sensing means being further connected to said first, second and third variable gain amplifiers for providing control signals thereto in response to the difference between said sum signals and said difference signals, said second amplitude sensing means and said first, second and third amplifiers being interconnected in a predetermined manner thereby to increase the gain of said third amplifier relative to said first and second amplifiers when said sum signal exceeds said difference signal, and to increase the gain of said first and second amplifiers relative to said third amplifier when said difference signal exceeds said sum signal.
Claim 3
Independent Claim
492 words
A system for deriving a plurality of output signals from first and second stereophonically related signals from first and second signal sources, such system including in combination: first and second variable gain amplifiers each having an input, an output and a control terminal, the input terminal of said first amplifier being connected to said first source and receiving said first stereophonically related signal, and the input terminal of said second amplifier being connected to said second source and receiving said second stereophonically related signal, each of said amplifiers having a gain that varies in accordance with a control signal applied to said control terminal; amplitude sensing means for sensing the amplitudes of the first and second stereophonically related signals and providing control signals only to said amplifiers for simultaneously increasing the gain of one of said amplifiers and decreasing the gain of The other of said amplifiers in accordance with the ratio of the amplitudes of said first and second stereophonically related signals in a manner such that the gain of said first amplifier is greater than the gain of said second amplifier when one of said stereophonically related signals is larger, and such that the gain of said second amplifier is greater when the other of said stereophonically related signals is larger, said amplitude sensing means being connected to said first and second signal sources and receiving said first and second stereophonically related signals therefrom, and only to said first and second amplifiers and controlling the gain thereof; and third and fourth variable gain amplifiers each connected to one of said signal sources to receive one of said stereophonically related signals therefrom and to provide output signals in response thereto, said third and fourth variable gain amplifiers having gain which varies in accordance with a control signal applied thereto, summing means connected to each of said signal sources for receiving and adding said stereophonically related signals and providing sum signals proportional to the degree of correlation between said stereophonically related signals, difference means connected to each of said signal sources for receiving and subtracting said stereophonically related signals and providing difference signals proportional to the lack of correlation between said stereophonically related signals, and second amplitude sensing means connected to said summing means and said difference means for receiving said sum and difference signals, said second amplitude sensing means being further connected to said first, second, third and fourth variable gain amplifiers and providing control signals thereto in response to the difference between said sum signals and said difference signals, said second amplitude sensing means and said first, second, third and fourth amplifiers being interconnected in a predetermined manner thereby to increase the gains of said third and fourth amplifiers relative to said first and second amplifiers when said sum signal exceeds said difference signal, and to increase the gains of said first and second amplifiers relative to said third and fourth amplifiers when said difference signal exceeds said sum signal.
Claim 4
Independent Claim
492 words
A system for deriving a plurality of output signals from first and second stereophonically related signals from first and second signal sources, such system including in combination: first and second variable gain amplifiers each having an input, an output and a control terminal, the input terminal of said first amplifier being connected to said first source and receiving said first stereophonically related signal, and the input terminal of said second amplifier being connected to said second source and receiving said second stereophonically related signal, each of said amplifiers having a gain that varies in accordance with a control signal applied to said control terminal; amplitude sensing means for sensing the amplitudes of the first and second stereophonically related signals and providing control signals only to said amplifiers for simultaneously increasing the gain of one of said amplifiers and decreasing the gain of The other of said amplifiers in accordance with the ratio of the amplitudes of said first and second stereophonically related signals in a manner such that the gain of said first amplifier is greater than the gain of said second amplifier when one of said stereophonically related signals is larger, and such that the gain of said second amplifier is greater when the other of said stereophonically related signals is larger, said amplitude sensing means being connected to said first and second signal sources and receiving said first and second stereophonically related signals therefrom, and only to said first and second amplifiers and controlling the gain thereof; and third and fourth variable gain amplifiers each connected to one of said signal sources to receive one of said stereophonically related signals therefrom and to provide output signals in response thereto, said third and fourth variable gain amplifiers having gain which varies in accordance with a control signal applied thereto, summing means connected to each of said signal sources for receiving and adding said stereophonically related signals and providing sum signals proportional to the degree of correlation between said stereophonically related signals, difference means connected to each of said signal sources for receiving and subtracting said stereophonically related signals and providing difference signals proportional to the lack of correlation between said stereophonically related signals, and second amplitude sensing means connected to said summing means and said difference means for receiving said sum and difference signals, said second amplitude sensing means being further connected to said first, second, third and fourth variable gain amplifiers and providing control signals thereto in response to the difference between said sum signals and said difference signals, said second amplitude sensing means and said first, second, third and fourth amplifiers being interconnected in a predetermined manner thereby to increase the gains of said third and fourth amplifiers relative to said first and second amplifiers when said sum signal exceeds said difference signal, and to increase the gains of said first and second amplifiers relative to said third and fourth amplifiers when said difference signal exceeds said sum signal.
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) | 1976-11-12 | 1977-05-14 | 1977-11-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-11-12 | 1981-05-14 | 1981-11-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-11-12 | 1985-05-14 | 1985-11-13 | $7700.00 | Window Closed / Lapsed |