US3913016A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Circuit for curtailing effects of bit errors in pulse coded transmission
Assignee: AT&T Inc
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Filing: 1974-04-18
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Granted: 1975-10-14
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Expires: 1994-04-18
Abstract
Abstract A differentially pulse coded digital representation of a continuous analog signal is digitally accumulated, and each time polarity information indicates that the accumulated digital approximation changes sign the digital representation is complemented. The result of this action is that each bit of a predetermined type in the digital representation, and following the complementing point in a signal flow sense, has the same directional effect, on the digital accumulation, with respect to a predetermined signal reference level within the range of the continuous analog signal variation. Several embodiments are shown with different types of digital accumulation and different circuit locations for realizing the inversion of the digital representation.
Inventors
- 👤 James Charles Candy
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 20:03
CPC Classifications
H; H04; H04B; H04B14/00; H04B14/02; H04B14/06; H04B14/062; H04B14/064
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
69 words
In a communication system, a circuit for propagating difference pulse coded signals, means coupled to said circuit for digitally accumulating said pulse coded signals to produce a pulse coded digital approximation of an analog signal represented by said difference pulse coded signal, means for producing a signal indicating a change in polarity of said approximation, and means responsive to said indicating signal for complementing said difference pulse coded signals.
Claim 2
Dependent Claim
69 words
In a communication system, a circuit for propagating difference pulse coded signals, means coupled to said circuit for digitally accumulating said pulse coded signals to produce a pulse coded digital approximation of an analog signal represented by said difference pulse coded signal, means for producing a signal indicating a change in polarity of said approximation, and means responsive to said indicating signal for complementing said difference pulse coded signals.
Claim 3
Dependent Claim
35 words
The system in accordance with claim 1 which comprises, a difference modulation coder having said accumulating means connected in a feedback path thereof, and said complementing means are coupled in an output of said coder.
Claim 4
Dependent Claim
36 words
The system in accordance with claim 2 in which, said coder includes a feedback loop including said feedback path, and means are provided for coupling said complementing means in said coder output of said feedback loop.
Claim 5
Dependent Claim
55 words
The system in accordance with claim 2 in which said complementing means comprises, means for performing an EXCLUSIVE OR type of logic function on signals at first and second input connections thereof, means for coupling said difference pulse coded signals to said first input, and means for coupling said indicating signal to said second input.
Claim 6
Dependent Claim
42 words
The system in accordance with claim 2 in which, said coder includes a feedback loop comprising said feedback path, and means are provided for coupling said complementing means in said coder output in a forward signal path portion of said feedback loop.
Claim 7
Dependent Claim
39 words
The system in accordance with claim 2 in which, said feedback path includes a digital-to-analog converter responsive to an output of said accumulating means, and means are provided for coupling said polarity indicating signal for utilization in said converter.
Claim 8
Dependent Claim
44 words
The system in accordance with claim 1 in which, said pulse coded signals include a succession of multibit words each including a sign bit and magnitude bits, and said complementing means includes means for complementing said sign bit in response to said indicating signal.
Claim 9
Dependent Claim
52 words
The system in accordance with claim 1 which further comprises, means for detecting incipient overflow in said digital accumulating means, means responsive to said detecting means for forcing said difference pulse coded signals to a signal state for one code bit time for reversing the direction of accumulation in said accumulating means.
Claim 10
Dependent Claim
61 words
The system in accordance with claim 1 which comprises in addition, further means for digitally accumulating said pulse coded signals to produce a pulse coded digital approximation of said analog signal, and means for connecting said propagating circuit for transmitting said pulse coded signals from an input of the first mentioned accumulating means to an input of said further accumulating means.
Claim 11
Dependent Claim
35 words
The system in accordance with claim 9 in which there are provided, means for connecting said complementing means in said propagating circuit between inputs of sAid first mentioned accumulating means and said further accumulating means.
Claim 12
Dependent Claim
40 words
The system in accordance with claim 9 in which there are provided, means for connecting said complementing means to said propagating circuit for supplying said pulse coded signals to both said first mentioned accumulating means and said further accumulating means.
Claim 13
Dependent Claim
39 words
The system in accordance with claim 1 which comprises, a difference modulation coder having said accumulating means connected therein, and means for connecting said complementary means to supply said pulse coded signals to an input of said accumulating means.
Claim 14
Dependent Claim
43 words
The system in accordance with claim 1 which comprises a difference modulation decoder having said accumulating means connected therein, and means for connecting said complementing means in said propagating circuit to supply said pulse coded signals to an input of said accumulating means.
Claim 15
Dependent Claim
24 words
The system in accordance with claim 1 in which, means are provided for connecting said complementing means in an input to said accumulating means.
Claim 16
Dependent Claim
34 words
The system in accordance with claim 1 in which, said accumulating means is a reversible binary counter having the direction of counting controlled by the binary signal state of said difference pulse coded signals.
Claim 17
Dependent Claim
32 words
The system in accordance with claim 15 in which, said producing means include means responsive to an output of the most significant bit position of said counter for controlling said complementing means.
Claim 18
Dependent Claim
62 words
The system in accordance with claim 15 in which, said producing means comprises means for deriving from said counter a signal indicating a binary all-ZERO condition in portions of said counter representing the magnitude of said digital approximation, and means responsive to both said all-ZERO indicating signal and a no-pulse condition in said difference pulse coded signals for actuating said complementing means.
Claim 19
Dependent Claim
75 words
The system in accordance with claim 15 in which there are provided, means for converting said digital approximation to a corresponding analog signal form, means for coupling outputs of said counter representing the magnitude of said digital approximation in bit parallel to said converting means, and means responsive to said polarity change indicating signal for switching polarity of said analog signal form in response to changes in the binary signal state of such indicating signal.
Claim 20
Dependent Claim
59 words
The system in accordance with claim 1 in which there are provided, a difference modulation coder having said digital accumulator in a feedback path thereof, a difference modulation decoder having a further accumulator and a further cooperating indicating signal producing means connected therein, and means for coupling an output of said coder to an input of said decoder accumulation.
Claim 21
Dependent Claim
76 words
The system in accordance with claim 19 in which said difference coded signal complementing means includes, means in the output of said coder for inverting said difference pulse coded signals in response to each polarity change of said digital approximation in said coder, and means in said input of said decoder for inverting said difference pulse coded signals in response to each polarity change of said digital approximation in said further accumulating means of said decoder.
Claim 22
Dependent Claim
116 words
The system in accordance with claim 19 in which, said difference code complementing means includes means in said coder feedback loop, but in the forward signal path portion thereof, for inverting said difference pulse coded signals in response to changes in the binary signal state of said coder indicating signal, means are provided in said coder, and responsive to each change in the binary signal state of the indicating signal thereof, for complementing said digital approximation output of said coder accumulating means, and said decoder further includes means responsive to each change in the binary signal state of the decoder indicaTing signal for complementing the digital approximation output of said further accumualting means in said decoder.
Claim 23
Dependent Claim
58 words
The system in accordance with claim 1 in which, there is provided a difference modulation coder having said digital accumulating means connected in a feedback path thereof, and said accumulating means is a reversible shift register biased to contain a shift companded pulse code and having the direction of shifting thereof controlled by said difference pulse coded signals.
Claim 24
Dependent Claim
123 words
The system in accordance with claim 22 in which said feedback path is connected around a predetermined portion of the forward signal path of said coder to form a feedback loop, said difference code signal complementing means are connected in said forward signal path portion, a difference modulation decoder is provided, means are provided for coupling said difference pulse code output of said coder to an input of said decoder, further digital accumulating means and cooperating further means for producing a polarity change indicating signal as set forth for said coder are included in said decoder, and means are provided in said decoder and responsive to the indicating signal from said further producing means for complementing an output of said further accumulating means.
Claim 25
Dependent Claim
69 words
In a communication system for difference pulse coded digital signals having successive digital signal times in which the digital signal state represents an amplitude step of at least one predetermined size in bipolar, variable, analog information, means for indicating a change in polarity of said analog information, and means, responsive to an output of said indicating means, for complementing subsequent ones of said digital signals after such polarity change.
Claim 26
Dependent Claim
69 words
In a communication system for difference pulse coded digital signals having successive digital signal times in which the digital signal state represents an amplitude step of at least one predetermined size in bipolar, variable, analog information, means for indicating a change in polarity of said analog information, and means, responsive to an output of said indicating means, for complementing subsequent ones of said digital signals after such polarity change.
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) | 1978-10-13 | 1979-04-14 | 1979-10-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-10-13 | 1983-04-14 | 1983-10-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-10-13 | 1987-04-14 | 1987-10-14 | $7700.00 | Window Closed / Lapsed |