US3825831A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Differential pulse code modulation apparatus
Assignee: NEC Corp
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Filing: 1971-10-26
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Granted: 1974-07-23
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Expires: 1991-10-26
Abstract
Abstract A differential pulse code modulator includes a delta modulator for converting an analog input signal to a delta modulated signal, a digital filter for removing quantizing noise components, and a direct feedback pulse code modulation encoder. The feedback encoder includes a subtractor for determining the difference between a decoded digital signal and the output of the digital filter, a digital integrator for integrating the output of the subtractor, a digital coder for converting the output of the integrator to a differential pulse code modulation signal and a digital decoder for converting the differential signal to the decoded digital signal supplied to the subtractor. Clock pulses are supplied to the delta modulator, the digital filter, and the direct feedback pulse code modulation encoder.
Inventors
- 👤 T Ishiguro
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 15:00
CPC Classifications
H; H03; H03M; H03M3/00; H03M3/04; H03M3/02
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
216 words
A non-linear differential pulse code modulation signal processing apparatus comprising: delta modulator means for converting an analog input signal to a delta modulated signal having a clock frequency determined by clock pulses supplied thereto; digital filter circuit means for receiving the delta modulated signal, removing quantizing noise components that fall outside a predetermined transmission band from the delta modulated signal, and for converting the delta modulated signal into a differential pulse code modulation signal; a direct feedback pulse code modulation encoder that operates at a sampling frequency equal to the clock frequency divided by a positive integer for converting the differential pulse code modulation signal into a non-linear differential pulse code modulation signal, including subtractor means for determining the difference between a decoded digital signal and the differential pulse code modulation signal from the digital filter means, a digital integrator means for integrating the output of the subtractor means, a digital encoder means for converting the output of the integrator means to a non-linear differential pulse code modulation signal, and a digital decoder means for converting the non-linear differential pulse code modulation signal to the decoded digital signal supplied to the subtractor means; and means for supplying clock pulses to the delta modulator means, the digital filter means, and the direct feedback pulse code modulation encoder.
Claim 2
Dependent Claim
216 words
A non-linear differential pulse code modulation signal processing apparatus comprising: delta modulator means for converting an analog input signal to a delta modulated signal having a clock frequency determined by clock pulses supplied thereto; digital filter circuit means for receiving the delta modulated signal, removing quantizing noise components that fall outside a predetermined transmission band from the delta modulated signal, and for converting the delta modulated signal into a differential pulse code modulation signal; a direct feedback pulse code modulation encoder that operates at a sampling frequency equal to the clock frequency divided by a positive integer for converting the differential pulse code modulation signal into a non-linear differential pulse code modulation signal, including subtractor means for determining the difference between a decoded digital signal and the differential pulse code modulation signal from the digital filter means, a digital integrator means for integrating the output of the subtractor means, a digital encoder means for converting the output of the integrator means to a non-linear differential pulse code modulation signal, and a digital decoder means for converting the non-linear differential pulse code modulation signal to the decoded digital signal supplied to the subtractor means; and means for supplying clock pulses to the delta modulator means, the digital filter means, and the direct feedback pulse code modulation encoder.
Claim 3
Dependent Claim
38 words
The apparatus set further in claim 1, wherein the digital filter has a transfer function that takes the value zero at frequencies equal to an integral multiple of the sampling frequency of the direct feedback pulse-code modulation encoder.
References Cited (Backward Citations)
US3526855A
Cited
US3610901A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-07-22 | 1978-01-21 | 1978-07-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-07-22 | 1982-01-21 | 1982-07-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-07-22 | 1986-01-21 | 1986-07-23 | $7700.00 | Window Closed / Lapsed |