US3918042A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Delta modulator having increased dynamic range
Assignee: Motorola Solutions Inc
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Filing: 1974-04-29
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Granted: 1975-11-04
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Expires: 1994-04-29
Abstract
Abstract Delta modulator wherein a digital output signal is produced from an analog modulating signal, with the digital signal being filtered and compared with the modulating signal to produce an error signal for controlling the modulator, and wherein the filtered digital signal is fed back to the comparator through a nonlinear circuit which decreases the amplitude of small amplitude signals being fed back. The nonlinear circuit may have a first linear response portion for translating signals below the normal threshold of the modulator, and a second linear response portion for signals above the normal threshold, with the gain of the second portion being substantially greater than that of the first portion. Since the signal fed back is smaller than it would otherwise be for weak signal conditions, less input signal is required to establish adequate error voltage to operate the delta modulator, thus extending the dynamic range to signal levels too weak to operate a known delta modulator. The nonlinear circuit may include first and second parallel paths, with a transistor stage in one path having means rendered operative at a given signal level to limit the output, so that at low signal levels the signal is translated without substantial attenuation and at high signal levels the signal is attenuated. The signal in the path including the transistor stage acts to cancel a portion of the signal in the other path to control the signal fed back from the filter to the comparator, to increase the signal fed back at high level digital outputs.
Inventors
- 👤 Richard E Werner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 22:43
CPC Classifications
H; H03; H03M; H03M3/00; H03M3/02
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
185 words
A delta modulator for developing a digital signal in response to a modulating signal, including in combination: comparator means having input means and an output, said comparator means producing a signal at said output representing the difference between signals applied at said input means, means applying a modulating signal to said input means of said comparator means, digital signal generation means coupled to said output of said comparator means and responsive to the signal therefrom for producing a digital signal, and feedback means coupled between said digital signal generation means and said input means of said comparator means and including filter means and nonlinear translating means, said filter means being connected to the output of said digital signal generation means and producing a signal varying with the average amplitude of said digital signal, said nonlinear translating means being connected to receive the signal from said filter means and producing a modified feedback signal having reduced amplitude in response to a signal from said filter means which is below a predetermined value and said translating means being connected to said input means of said comparator means.
Claim 2
Dependent Claim
185 words
A delta modulator for developing a digital signal in response to a modulating signal, including in combination: comparator means having input means and an output, said comparator means producing a signal at said output representing the difference between signals applied at said input means, means applying a modulating signal to said input means of said comparator means, digital signal generation means coupled to said output of said comparator means and responsive to the signal therefrom for producing a digital signal, and feedback means coupled between said digital signal generation means and said input means of said comparator means and including filter means and nonlinear translating means, said filter means being connected to the output of said digital signal generation means and producing a signal varying with the average amplitude of said digital signal, said nonlinear translating means being connected to receive the signal from said filter means and producing a modified feedback signal having reduced amplitude in response to a signal from said filter means which is below a predetermined value and said translating means being connected to said input means of said comparator means.
Claim 3
Dependent Claim
91 words
A delta modulator according to claim 1 wherein said comparator means has first and second inputs, one of which inverts the signal applied thereto, with said modulating signal being applied to said first input and said modified feedback signal being applied to said second input, said comparator producing an output of one polarity in response to a modulating signal which is more positive than the modified feedback signal and producing an output of the opposite polarity in response to a modulating signal which is more negative than the modified feedback signal.
Claim 4
Dependent Claim
72 words
A delta modulator according to claim 2 wherein said digital signal generation means includes means responsive to clock pulses for producing output signals of first and second levels, said signal generation means producing an output of said first level in response to a signal from said comparator means of one polarity and producing an output signal of said second level in response to a signal from said comparator means of opposite polarity.
Claim 5
Dependent Claim
49 words
A delta modulator according to claim 1 wherein said nonlinear translating means includes means forming first and second signal paths connected in parallel, with said first signal path including means for inverting the signal therein to cancel at least a portion of the signal in said second signal path.
Claim 6
Dependent Claim
85 words
A delta modulator in accordance with claim 4 wherein said nonlinear translating means includes means in said first path which inverts the signal, and limiting means for limiting the amplitude of the signal in said first path to a predetermined value, whereby at low signal levels the signal in said first path substantially cancels the signal in said second path and at high signal levels the signal in said first path is limited and cancels only a portion of the signal in said second path.
Claim 7
Dependent Claim
22 words
A delta modulator in accordance with claim 5 wherein said means in said first path which inverts the signal includes a transistor.
Claim 8
Dependent Claim
256 words
A communication system for translating an analog input signal to a digital signal, for transmission of the digital signal, and for translating the digital signal into an analog output signal, including in combination, a delta modulator including comparator means having input means for receiving the analog input signal and an output, digital signal generation means coupled to said output of said comparator means and responsive to the signal therefrom for producing a digital signal, and feedback means coupled between said digital signal generation means and said input means and including filter means and nonlinear translating means, said filter means being connected to the output of said digital signal generation means and producing a signal varying with the average amplitude of said digital signal, said nonlinear translating means being connected to receive the signal from said filter means and producing a modified feedback signal which has a reduced amplitude in response to a signal from said filter means which is below a predetermined value and said translating means being connected to said input means of said comparator means, transmission means for translating said digital signal, and a delta demodulator coupled to said transmission means and including signal restoring means for restoring the digital signal produced by said digital modulator, filter means for producing a signal varying with the average amplitude of said digital signal, and nonlinear translating means coupled to said filter means and producing an output analog signal having reduced amplitude in response to a signal from said filter means which is below a predetermined value.
Claim 9
Dependent Claim
256 words
A communication system for translating an analog input signal to a digital signal, for transmission of the digital signal, and for translating the digital signal into an analog output signal, including in combination, a delta modulator including comparator means having input means for receiving the analog input signal and an output, digital signal generation means coupled to said output of said comparator means and responsive to the signal therefrom for producing a digital signal, and feedback means coupled between said digital signal generation means and said input means and including filter means and nonlinear translating means, said filter means being connected to the output of said digital signal generation means and producing a signal varying with the average amplitude of said digital signal, said nonlinear translating means being connected to receive the signal from said filter means and producing a modified feedback signal which has a reduced amplitude in response to a signal from said filter means which is below a predetermined value and said translating means being connected to said input means of said comparator means, transmission means for translating said digital signal, and a delta demodulator coupled to said transmission means and including signal restoring means for restoring the digital signal produced by said digital modulator, filter means for producing a signal varying with the average amplitude of said digital signal, and nonlinear translating means coupled to said filter means and producing an output analog signal having reduced amplitude in response to a signal from said filter means which is below a predetermined value.
Claim 10
Dependent Claim
60 words
A communication system according to claim 7 wherein said nonlinear translating means of said delta modulator and said nonlinear translating means of said delta demodulator each includes means forming first and second signal paths connected in parallel, with said first signal path including means for inverting the signal therein to cancel a portion of the signal in said second path.
Claim 11
Dependent Claim
87 words
A communication system in accordance with claim 8 wherein said nonlinear translating means includes a transistor in said first sIgnal path which inverts the signal, and limiting means for limiting the amplitude of the signal in said first path to a predetermined value, whereby at low signal levels the signal in said first path substantially cancel the signal in said second path, and at high signal levels the signal in said first path is limited and cancels only a portion of the signal in said second path.
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) | 1978-11-03 | 1979-05-05 | 1979-11-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-11-03 | 1983-05-05 | 1983-11-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-11-03 | 1987-05-05 | 1987-11-04 | $7700.00 | Window Closed / Lapsed |