US3735393A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Self companding pulse code modulation systems
Assignee: AT&T Inc
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Filing: 1971-11-22
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Granted: 1973-05-22
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Expires: 1991-11-22
Abstract
Abstract A self companding analog digital system produces a desired compression expansion curve by switching the gain ratio of an operational amplifier in accordance with a binary code.
Inventors
- 👤 R Carbrey
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 14:01
CPC Classifications
H; H03; H03M; H03M1/00; H03M1/12; H03M1/34; H03M1/38
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
142 words
In a system that utilizes both analog type signals and coded digital type signals at different points therein, means for converting a signal of one type to a corresponding signal of the other type comprising an amplifier for producing at its output quantized versions of the analog signal under control of the coded digital signals, said amplifier having an input and feedback circuit, means for applying a reference voltage from a source to the input of said amplifer, and means for varying the gain of said amplifier in accordance with a nonlinear quantizing function comprising means for varying the ratio of the feedback to the input voltages of said amplifier in response to the coded digital signals, said last mentioned means comprising means for simultaneously varying both the impedance in the feedback circuit and impedance in the input circuit of said amplifier.
Claim 2
Dependent Claim
142 words
In a system that utilizes both analog type signals and coded digital type signals at different points therein, means for converting a signal of one type to a corresponding signal of the other type comprising an amplifier for producing at its output quantized versions of the analog signal under control of the coded digital signals, said amplifier having an input and feedback circuit, means for applying a reference voltage from a source to the input of said amplifer, and means for varying the gain of said amplifier in accordance with a nonlinear quantizing function comprising means for varying the ratio of the feedback to the input voltages of said amplifier in response to the coded digital signals, said last mentioned means comprising means for simultaneously varying both the impedance in the feedback circuit and impedance in the input circuit of said amplifier.
Claim 3
Dependent Claim
34 words
A converting means as claimed in claim 1 and further including means for reversing the polarity of the input voltage in response to the state of the first digit of a digital signal word.
Claim 4
Dependent Claim
39 words
A converting means as claimed in claim 1 wherein said means for varying the ratio of the feedback to the input voltage comprises a resistance network having a plurality of resistors weighted in accordance with the particular quantizing function.
Claim 5
Dependent Claim
83 words
An analog to digital signal converter comprising means for sampling the analog signal to be converted, an amplifier, a reference voltage source, means for comparing the output of said amplifier and said sampling means and producing an output indicative of the difference between the signal sample and the amplifier output, means responsive to the output of the comparator for varying the ratio of amplifier feedback voltage to input voltage from said reference source, said last mentioned means comprising a switched voltage divider network.
Claim 6
Dependent Claim
83 words
An analog to digital signal converter comprising means for sampling the analog signal to be converted, an amplifier, a reference voltage source, means for comparing the output of said amplifier and said sampling means and producing an output indicative of the difference between the signal sample and the amplifier output, means responsive to the output of the comparator for varying the ratio of amplifier feedback voltage to input voltage from said reference source, said last mentioned means comprising a switched voltage divider network.
Claim 7
Dependent Claim
25 words
A signal converter as claimed in claim 4 wherein said voltage divider network comprises a plurality of resistors weighted in accordance with a quantizing function.
Claim 8
Dependent Claim
35 words
A signal converter as claimed in claim 4 and further including means for switching the polarity of the reference voltage source in accordance with the polarity of the signal sample relative to the amplifier output.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-05-21 | 1976-11-20 | 1977-05-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-05-21 | 1980-11-20 | 1981-05-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-05-21 | 1984-11-20 | 1985-05-22 | $7700.00 | Window Closed / Lapsed |