US4574383A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Decoder of adaptive differential pulse code modulation
Assignee: NTT Inc
•
Filing: 1983-12-05
•
Granted: 1986-03-04
•
Expires: 2003-12-05
Abstract
Abstract A transcoder which transcodes adaptive differential pulse code modulation (ADPCM) signals to pulse code modulation (PCM) signals without cumulative transcoding noises even if mutual transcoding between ADPCM signals and non-linear PCM signals is repeatedly conducted. Two PCM signals are generated having values of one step higher and one step lower than a third PCM signal having a nominal code value. The three signals are fed to a selector, which sequentially selects one of the three. The output of the selector is then decoded and fed to one input of a subtractor, and a prediction signal is fed to the other input of the subtractor. The output of the subtractor is coded into an ADPCM signal in a step size of the input ADPCM signal. The logical value of that coded ADPCM signal is compared with the logical value of the input ADPCM signal by a comparator. A gate allows the PCM signal output from the selector to pass only when the comparator has an equal output.
Inventors
- 👤 Kazunari Irie
- 👤 Masahiro Taka
- 👤 Hideyo Murakami
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 09:07
CPC Classifications
H; H03; H03M; H03M7/00; H03M7/30; H03M7/3002; H03M7/3044; H03M7/3046; G; G06; G06T; G06T9/00; G06T9/004; H03M3/00; H03M3/04; H03M3/042
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
274 words
A decoder for adaptive differential pulse code modulation (ADPCM) input signals developed with a predetermined prediction logic, comprising: means for decoding an input ADPCM signal, means for adding a prediction signal to the output signal from said decoding means, prediction means fed with an output signal from said adding means for generating said prediction signal at a logic equal to said predetermined prediction logic and supplying said prediction signal to an input of said adding means for adding therein as aforesaid, coding means for coding the output signal from said adding means as a PCM signal having a nominal code value, and, transcoding means operative on three signals namely said ADPCM signal, said prediction signal and said nominal valued PCM signal for developing a desired PCM signal, including: means for generating a PCM signal having a value one step higher than said nominal code value and a PCM signal having a value one step lower than said nominal value, means for selecting one of the said nominal higher and lower valued PCM signals, second decoding means for decoding the selected PCM signal from said selecting means, substraction means for subtracting the output signal of said decoding means and the output prediction signal from said prediction means, second means for coding said subtraction into an ADPCM signal having a logical value, by a step size of said input ADPCM signal, means for comparing the logical value of the output ADPCM signal from said second coding means with that of said input ADPCM signal, and gate means for gating out the output PCM signal from said selecting means when the comparing means has an equal output.
Claim 2
Dependent Claim
274 words
A decoder for adaptive differential pulse code modulation (ADPCM) input signals developed with a predetermined prediction logic, comprising: means for decoding an input ADPCM signal, means for adding a prediction signal to the output signal from said decoding means, prediction means fed with an output signal from said adding means for generating said prediction signal at a logic equal to said predetermined prediction logic and supplying said prediction signal to an input of said adding means for adding therein as aforesaid, coding means for coding the output signal from said adding means as a PCM signal having a nominal code value, and, transcoding means operative on three signals namely said ADPCM signal, said prediction signal and said nominal valued PCM signal for developing a desired PCM signal, including: means for generating a PCM signal having a value one step higher than said nominal code value and a PCM signal having a value one step lower than said nominal value, means for selecting one of the said nominal higher and lower valued PCM signals, second decoding means for decoding the selected PCM signal from said selecting means, substraction means for subtracting the output signal of said decoding means and the output prediction signal from said prediction means, second means for coding said subtraction into an ADPCM signal having a logical value, by a step size of said input ADPCM signal, means for comparing the logical value of the output ADPCM signal from said second coding means with that of said input ADPCM signal, and gate means for gating out the output PCM signal from said selecting means when the comparing means has an equal output.
Claim 3
Dependent Claim
36 words
The decoder for adaptive differential pulse code modulation signals as claimed in claim 1 wherein said selecting means selects all said three signals, and said comparing means compares all of them to discriminate an equal one.
Claim 4
Dependent Claim
43 words
The decoder for adaptive differential pulse code modulation signals as claimed in claim 1 wherein said selecting means selects the nominal valued PCM signal and omits selection for the other two of said three signals when said comparing means has an equal output.
Claim 5
Dependent Claim
91 words
The decoder for adaptive differential pulse code modulation signals as claimed in claim 3 wherein said selecting means selects the nominal valued PCM signal first, said comparing means detects whether the level output of said coded ADPCM signal is larger or smaller and when an equal output is not obtained detects the level of said input ADPCM signal, and said selecting means selects either the data of said one step higher or the data of said one step lower depending on the result of the dimensional detection of said selecting means.
Claim 6
Dependent Claim
21 words
The decoder for adaptive differential pulse code modulation signals as claimed in claim 1 wherein said prediction means conducts adaptive prediction.
Claim 7
Dependent Claim
37 words
The decoder for adaptive differential pulse code modulation signals as claimed in claim 1 wherein the input ADPCM signal is coded by a non-linear quantization step and makes the step adaptively vary corresponding to an input 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) | 1989-03-03 | 1989-09-02 | 1990-03-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-03-03 | 1993-09-02 | 1994-03-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-03-03 | 1997-09-02 | 1998-03-04 | $7700.00 | Window Closed / Lapsed |