Patent US3662266A successfully refreshed from Google Patents.
US3662266A
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Nonlinearly sampled differential quantizer for variable length encoding
Assignee: AT&T Inc
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Filing: 1970-05-18
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Granted: 1972-05-09
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Expires: 1990-05-18
Abstract
Abstract A differential quantizer for predictive PCM transmission systems in which difference signals are quantized at the Nyquist rate when they are below a predetermined level but are quantized at twice the Nyquist rate when they exceed that level. The difference signals are encoded for transmission but an extra bit follows each code word representing a level above the predetermined threshold to indicate to the receiver whether that sample is to be inserted by the receiver at a Nyquist interval or one-half a Nyquist interval from the preceding sample. Where the difference signal to be encoded is large due to a substantial change in the input signal, several such samples taken at twice the Nyquist rate serve to rapidly reduce the difference signal and provide a better approximation of the input signal to the receiver.
Inventors
- 👤 John Ormond Limb
- 👤 Frank William Mounts
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 17:09
CPC Classifications
H; H04; H04B; H04B1/00; H04B1/66; H03; H03M; H03M3/00; H03M3/04; H03M3/042; H04J; H04J3/00; H04J3/16; H04J3/1682; H04J3/1688
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
261 words
A transmission system comprising, in combination, a source of an analog information signal, a subtractor circuit for obtaining a difference signal by subtracting from said analog information signal generated feedback signals, means for sampling said difference signal at predetermined intervals when said difference signal is less than the absolute value of a predetermine level, means for sampling said difference signal at said predetermined intervals and midway between said predetermined intervals when said difference signal is equal to or greater than the absolute value of a predetermined level, means for quantizing said samples of said difference signal, a digital-to-analog converter connected to receive said quantized samples. an integrator circuit connected between the output of said converter and said subtractor circuit to provide said generated feedback signals, means for encoding and transmitting said quantized samples said encoding and transmitting means including a store capable of storing a predetermined quantity of information said encoding and transmitting means operating to encode and transmit all quantized samples when the quantity of information stored in said store is less than said predetermined quantity and to encode only samples taken at said predetermined intervals when the quantity of information stored in said store is equal to or greater than said predetermined quantity and also including apparatus to transmit information to indicate whether an encoded sample representing a level equal to or greater than said predetermined level was obtained by said sampling means at one said predetermined interval or at an interval occurring midway between, and receiver apparatus connected to receive said transmitted signals to reconstruct said information signal.
Claim 2
Dependent Claim
261 words
A transmission system comprising, in combination, a source of an analog information signal, a subtractor circuit for obtaining a difference signal by subtracting from said analog information signal generated feedback signals, means for sampling said difference signal at predetermined intervals when said difference signal is less than the absolute value of a predetermine level, means for sampling said difference signal at said predetermined intervals and midway between said predetermined intervals when said difference signal is equal to or greater than the absolute value of a predetermined level, means for quantizing said samples of said difference signal, a digital-to-analog converter connected to receive said quantized samples. an integrator circuit connected between the output of said converter and said subtractor circuit to provide said generated feedback signals, means for encoding and transmitting said quantized samples said encoding and transmitting means including a store capable of storing a predetermined quantity of information said encoding and transmitting means operating to encode and transmit all quantized samples when the quantity of information stored in said store is less than said predetermined quantity and to encode only samples taken at said predetermined intervals when the quantity of information stored in said store is equal to or greater than said predetermined quantity and also including apparatus to transmit information to indicate whether an encoded sample representing a level equal to or greater than said predetermined level was obtained by said sampling means at one said predetermined interval or at an interval occurring midway between, and receiver apparatus connected to receive said transmitted signals to reconstruct said information signal.
Claim 3
Dependent Claim
112 words
Apparatus in accordance with claim 1 wherein said encoding and transmitting means comprises, a code generator connected to receive the output of said quantizing means and a parallel-to-serial converter connected between said store and said code generator, and said means to transmit information to indicate whether an encoded sample was obtained at one of said predetermined intervals or an interval occurring midway between comprises an AND gate enabled at intervals midway between said predetermined intervals and connected to receive an output from said quantization means indicative of the occurrence of a level equal to or greater than said predetermined level and having an output connected to the input of said sErial-to-parallel converter.
Claim 4
Dependent Claim
131 words
Apparatus in accordance with claim 1 wherein said receiver apparatus comprises in combination, a buffer store connected to receive said transmitted signals, a serial-to-parallel converter connected to the output of said buffer store, a detector connected to the output of said converter to detect the reception of digital signals representing a level equal to or greater in absolute value than said predetermined level and generate an output upon such detection, means responsive to said level detector output to cause said buffer to write out an extra bit when said level detector generates an output, storage means connected to the output of said converter, and means to govern the interval at which signals are generated at the output of said storage means in accordance with the information contained in said extra bit.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-05-09 | 1975-11-08 | 1976-05-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-05-09 | 1979-11-08 | 1980-05-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-05-09 | 1983-11-08 | 1984-05-09 | $7700.00 | Window Closed / Lapsed |