US3568061A
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US
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Bilateral digital transmission system with companding having same step size in each direction
Assignee: AT&T Inc
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Filing: 1968-04-29
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Granted: 1971-03-02
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Expires: 1988-04-29
Abstract
Abstract A digital transmission system is disclosed utilizing forward and backward acting companding for transmission from and to a central terminal to and from a plurality of remote terminals, respectively. A variable size step pulse source is used at each modulator to effectively achieve compression and another is used at each demodulator to effectively achieve complementary expansion. Apparatus is located at the central terminal which senses parameters of the message signals transmitted from and received by the central terminal, sums the sensed parameters and utilizes the sum to determine the amplitudes of the variable size step pulses produced for each modulator and demodulator.
Inventors
- 👤 Stephen J Brolin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 19:23
CPC Classifications
H; H04; H04B; H04B14/00; H04B14/02; H04B14/06; H04B14/062; H04B14/064
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
769 words
A delta modulation system with syllabic companding for transmission of one message signal from a central terminal to a remote terminal and for transmission of a second message signal from said remote terminal to said central terminal which includes at said central terminal: a delta modulator and a delta demodulator, with said delta modulator comprising; a first comparator having a single output and a pair of inputs; means to sample the output of said first comparator on a periodic repetitive basis; an output transmitter and a first step signal generator both connected to respond to the sampled output of said first comparator; said output transmitter producing a binary digit of one kind for transmission to said remote terminal whenever the sample is positive and a binary digit of another kind for transmission to said remote terminal whenever the sample is negative and said first step signal generator producing a step signal of one polarity whenever the sample is positive and a step signal of the opposite polarity whenever the sample is negative; a first integrator connected to receive the step signal produced by said first step signal generator; means to supply the message signal to be transmitted from said central terminal to said remote terminal and the output from said first integrator to the respective inputs of said first comparator; first means to controllably vary the magnitude of the step signal produced by said first step signal generator; said delta demodulator comprising a second step signal generator connected to respond to binary digits received from said remote terminal; said second step signal generator producing a step signal of one polarity whenever the received binary digit is of one kind and a step signal of the opposite polarity whenever the received binary digit is of the other kind; second means to controllably vary the magnitude of the step signal produced by said second step signal generator; a second integrator connected to receive the step signal produced by said second step signal generator; a low-pass filter connected to the output of said second integrator to recreate the message signal encoded at said remote terminal; means to sense the maximum slope of said message signal transmitted from said central to said remote terminal; means to sense the maximum slope of said recreated message signal; means to sum the sensed maximum slopes; means responsive to the summed signal to produce companding digits; said remote terminal comprising a delta modulator and a delta demodulator; said remote delta demodulator comprising a third step signal generator connected to respond to binary digits received from said output transmitter in said delta modulator in said central terminal; said third step signal generator producing a step signal of one polarity whenever the received binary digit is of one kind and a step signal of the opposite polarity whenever the received binary digit is of the other kind; third means to controllably vary the magnitude of the step signal produced by said third step signal generator; a third integrator connectEd to receive the step signal produced by said third step signal generator; a low-pass filter connected to the output of said third integrator to recreate the message signal encoded at said central terminal; said delta modulator at said remote terminal comprising a second comparator having a single output and a pair of inputs; means to sample the output of said second comparator on a periodic repetitive basis; an output transmitter and a fourth step generator both connected to respond to the sampled output of said second comparator; said last-named output transmitter producing a binary digit of one kind for transmission to said delta demodulator at said central terminal whenever the sample is positive and a binary digit of another kind for transmission to said delta demodulator at said central terminal whenever the sample is negative, and said fourth step generator producing a step signal of one polarity whenever the sample is positive and a step signal of the opposite polarity whenever the sample is negative; a fourth integrator connected ro receive the step signal produced by said third step signal generator; means to supply the message signal from a utilization device and the output of said fourth integrator to the respective inputs of said second comparator; said third controllably varying means connected to said fourth signal generator to controllably vary the magnitude of the step signal produced by said fourth step signal generator; and means responsive to said derived companding digits to control the magnitudes of the step signals at said delta modulators at said central and remote terminals and at said delta demodulators at said central and remote terminals.
Claim 2
Dependent Claim
769 words
A delta modulation system with syllabic companding for transmission of one message signal from a central terminal to a remote terminal and for transmission of a second message signal from said remote terminal to said central terminal which includes at said central terminal: a delta modulator and a delta demodulator, with said delta modulator comprising; a first comparator having a single output and a pair of inputs; means to sample the output of said first comparator on a periodic repetitive basis; an output transmitter and a first step signal generator both connected to respond to the sampled output of said first comparator; said output transmitter producing a binary digit of one kind for transmission to said remote terminal whenever the sample is positive and a binary digit of another kind for transmission to said remote terminal whenever the sample is negative and said first step signal generator producing a step signal of one polarity whenever the sample is positive and a step signal of the opposite polarity whenever the sample is negative; a first integrator connected to receive the step signal produced by said first step signal generator; means to supply the message signal to be transmitted from said central terminal to said remote terminal and the output from said first integrator to the respective inputs of said first comparator; first means to controllably vary the magnitude of the step signal produced by said first step signal generator; said delta demodulator comprising a second step signal generator connected to respond to binary digits received from said remote terminal; said second step signal generator producing a step signal of one polarity whenever the received binary digit is of one kind and a step signal of the opposite polarity whenever the received binary digit is of the other kind; second means to controllably vary the magnitude of the step signal produced by said second step signal generator; a second integrator connected to receive the step signal produced by said second step signal generator; a low-pass filter connected to the output of said second integrator to recreate the message signal encoded at said remote terminal; means to sense the maximum slope of said message signal transmitted from said central to said remote terminal; means to sense the maximum slope of said recreated message signal; means to sum the sensed maximum slopes; means responsive to the summed signal to produce companding digits; said remote terminal comprising a delta modulator and a delta demodulator; said remote delta demodulator comprising a third step signal generator connected to respond to binary digits received from said output transmitter in said delta modulator in said central terminal; said third step signal generator producing a step signal of one polarity whenever the received binary digit is of one kind and a step signal of the opposite polarity whenever the received binary digit is of the other kind; third means to controllably vary the magnitude of the step signal produced by said third step signal generator; a third integrator connectEd to receive the step signal produced by said third step signal generator; a low-pass filter connected to the output of said third integrator to recreate the message signal encoded at said central terminal; said delta modulator at said remote terminal comprising a second comparator having a single output and a pair of inputs; means to sample the output of said second comparator on a periodic repetitive basis; an output transmitter and a fourth step generator both connected to respond to the sampled output of said second comparator; said last-named output transmitter producing a binary digit of one kind for transmission to said delta demodulator at said central terminal whenever the sample is positive and a binary digit of another kind for transmission to said delta demodulator at said central terminal whenever the sample is negative, and said fourth step generator producing a step signal of one polarity whenever the sample is positive and a step signal of the opposite polarity whenever the sample is negative; a fourth integrator connected ro receive the step signal produced by said third step signal generator; means to supply the message signal from a utilization device and the output of said fourth integrator to the respective inputs of said second comparator; said third controllably varying means connected to said fourth signal generator to controllably vary the magnitude of the step signal produced by said fourth step signal generator; and means responsive to said derived companding digits to control the magnitudes of the step signals at said delta modulators at said central and remote terminals and at said delta demodulators at said central and remote terminals.
Claim 3
Dependent Claim
27 words
Apparatus as set forth in claim 1 wherein said first, second, third and fourth step signal means comprises means to produce a plurality of discrete step sizes.
Claim 4
Dependent Claim
26 words
Apparatus as set forth in claim 2 wherein said derived companding digits are applied to said first, second, third and fourth step signal means in succession.
Claim 5
Dependent Claim
192 words
A digital transmission system with companding comprising: a first terminal comprising a first transmitter and a first receiver; a second terminal comprising a second transmitter and a second receiver; said first transmitter comprising a first modulator and first means to apply a controllably variable magnitude step pulse to said first modulator; said first receiver comprising a first demodulator and second means to apply a controllably variable magnitude step pulse to said first demodulator; said second transmitter comprising a second modulator and third means to apply a controllably variable magnitude step pulse to said second modulator; said second receiver comprising a second demodulator and fourth means to apply a controllably variable magnitude step pulse to said second demodulator; and a single parameter sensing means located at said first terminal and responsive to a parameter of the message signal transmitted and a parameter of the reconstructed message signal received at said first terminal for generating companding control signals for controlling the outputs of said first and second variable magnitude step pulse means and for the transmission to said second terminal for controlling the output of said third and fourth variable magnitude step pulse means.
Claim 6
Dependent Claim
192 words
A digital transmission system with companding comprising: a first terminal comprising a first transmitter and a first receiver; a second terminal comprising a second transmitter and a second receiver; said first transmitter comprising a first modulator and first means to apply a controllably variable magnitude step pulse to said first modulator; said first receiver comprising a first demodulator and second means to apply a controllably variable magnitude step pulse to said first demodulator; said second transmitter comprising a second modulator and third means to apply a controllably variable magnitude step pulse to said second modulator; said second receiver comprising a second demodulator and fourth means to apply a controllably variable magnitude step pulse to said second demodulator; and a single parameter sensing means located at said first terminal and responsive to a parameter of the message signal transmitted and a parameter of the reconstructed message signal received at said first terminal for generating companding control signals for controlling the outputs of said first and second variable magnitude step pulse means and for the transmission to said second terminal for controlling the output of said third and fourth variable magnitude step pulse means.
Claim 7
Dependent Claim
38 words
Apparatus as set forth in claim 4 wherein said single parameter sensing means is responsive to the sum of a parameter of the message signal transmitted and a parameter of the message signal received at said first terminal.
Claim 8
Dependent Claim
109 words
Apparatus as set forth in claim 4 wherein said single parameter sensing means comprises: means to sense a parameter of the message signal transmitted from said first transmitter to said second receiver; means to sense a parameter of the message signal transmitted from said second transmitter to said first receiver; means to sum the sensed parameters; an n digit pulse code encOder connected to encode the sum of the sensed parameters in terms of n binary digits; and means to transmit n binary digits to said second receiver, second transmitter and first receiver to control the magnitude of said fourth, third and second variable magnitude step pulse means, respectively.
Claim 9
Dependent Claim
25 words
Apparatus as set forth in claim 4 wherein said first and second modulators comprise delta modulators and said first and second demodulators comprise delta demodulators.
Claim 10
Dependent Claim
248 words
A digital system with companding employed for transmission comprising: a central terminal having a plurality of modulator-demodulator pairs; a plurality of remote terminals, each terminal having a plurality of modulator-demodulator pairs, the total number of remote modulator-demodulator pairs being greater than the number of central modulator-demodulator pairs; a plurality of transmission channels, each coupled to a different one of said plurality of central modulator-demodulator pairs, and each coupled selectively to a different remote modulator-demodulator pair; first and second means in each modulator and demodulator, respectively, in said central modulator-demodulator pairs to provide a controllably variable size step for each modulator and demodulator of said central modulator-demodulator pairs; third and fourth means in each modulator and demodulator, respectively, in said remote modulator-demodulator pairs to provide a controllably variable size step for each modulator and demodulator of said remote modulator-demodulator pairs; and a plurality of single parameter-sensing means, one of which is located at each of said plurality of central modulator-demodulator pairs with each one coupled to a different transmission channel and responsive to a parameter of the message signal transmitted and to a parameter of the reconstructed message signal received at each respective central modulator-demodulator pair for generating companding control signals for controlling the first and second controllably variable size step means in each modulator and demodulator, respectively, in each said central modulator-demodulator pair and for transmission to said third and fourth controllably variable size step means in each modulator and demodulator, respectively, in each said remote modulator-demodulator pair.
Claim 11
Dependent Claim
248 words
A digital system with companding employed for transmission comprising: a central terminal having a plurality of modulator-demodulator pairs; a plurality of remote terminals, each terminal having a plurality of modulator-demodulator pairs, the total number of remote modulator-demodulator pairs being greater than the number of central modulator-demodulator pairs; a plurality of transmission channels, each coupled to a different one of said plurality of central modulator-demodulator pairs, and each coupled selectively to a different remote modulator-demodulator pair; first and second means in each modulator and demodulator, respectively, in said central modulator-demodulator pairs to provide a controllably variable size step for each modulator and demodulator of said central modulator-demodulator pairs; third and fourth means in each modulator and demodulator, respectively, in said remote modulator-demodulator pairs to provide a controllably variable size step for each modulator and demodulator of said remote modulator-demodulator pairs; and a plurality of single parameter-sensing means, one of which is located at each of said plurality of central modulator-demodulator pairs with each one coupled to a different transmission channel and responsive to a parameter of the message signal transmitted and to a parameter of the reconstructed message signal received at each respective central modulator-demodulator pair for generating companding control signals for controlling the first and second controllably variable size step means in each modulator and demodulator, respectively, in each said central modulator-demodulator pair and for transmission to said third and fourth controllably variable size step means in each modulator and demodulator, respectively, in each said remote modulator-demodulator pair.
Claim 12
Dependent Claim
46 words
Apparatus as set forth in claim 8 wherein said plurality of parameter sensing single means located at said central modulator-demodulator pairs is responsive to the sum of a parameter of the message signal transmitted and a parameter of the message signal received at said central terminal.
Claim 13
Dependent Claim
94 words
Apparatus as set forth in claim 8 wherein each of said plurality of single parameter sensing means comprises: means to sense a parameter of the message signal transmitted from said central modulator to said remote demodulator; means to sum the sensed parameters; an n digit pulse code encoder connected to encode the sum of the sensed parameters in terms of n binary digits; and means to transmit said n binary digits to said remote demodulator, remote modulator and central demodulator to control the magnitude of said fourth, third and second variable size step means.
Claim 14
Dependent Claim
25 words
Apparatus as set forth in claim 8 wherein said central and remote modulators comprise delta modulators and said central and remote demodulators comprise delta demodulators.
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) | 1974-03-01 | 1974-08-31 | 1975-03-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-03-01 | 1978-08-31 | 1979-03-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-03-01 | 1982-08-31 | 1983-03-02 | $7700.00 | Window Closed / Lapsed |