US3883864A
Expired / Lapsed
US
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Analog-to-digital and digital-to-analog converter apparatus
Assignee: 148074 HOLDINGS CANADA Ltd
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Filing: 1974-02-22
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Granted: 1975-05-13
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Expires: 1994-02-22
Abstract
Abstract PCM encoder-decoder having a digital code generator which counts through a digital count during a comparison period. An analog voltage waveform generator sweeps in a non-linear manner from a maximum negative to a maximum positive voltage during the same period. The digital code generator and analog voltage waveform generator are synchronized so that during each instant of each comparison period they have corresponding values. At the start of each comparison period a sample of an audio voice signal to be encoded is trapped in a capacitor. During a comparison period the sample is compared with the output of the waveform generator. When equality is detected the count of the digital code generator at that instant is stored as a PCM digital signal for transmission with other PCM signals in accordance with known TDM techniques. A PCM digital signal which is received in accordance with known TDM techniques is stored in a register prior to the start of a comparison period. During a comparison period the stored digital signal is compared with the output of the digital code generator. When equality is detected, the voltage of the analog signal from the analog voltage waveform generator at that instant is trapped in a capacitor. At the end of the comparison period the trapped charge is released as a pulse to a low-pass filter. A series of pulses is converted to a continuous audio signal by the low-pass filter.
Inventors
- 👤 Robert M Thomas
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 19:19
CPC Classifications
H; H03; H03M; H03M1/00; H03M1/02; H03M1/12; H03M1/50; H03M1/56; H03M1/66; H03M1/74
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
357 words
Analog-to-digital and digital-to-analog converter apparatus comprising digital code generating means for producing a sequence of digital code signals during a comparison period of each operating cycle; analog voltage generating means for producing an analog voltage waveform during the comparison period of each operating cycle and being synchronized with said digital code generating means whereby for each digital code signal a corresponding analog voltage signal is produced at the same instant during the comparison period of each operating cycle; analog input signal storage means for storing an analog input signal prior to a comparison period; analog comparison means coupled to the analog input signal storage means and to the analog voltage generating means for comparing the stored analog input signal with said analog voltage waveform during a comparison period and for producing an output signal when the voltage of the analog voltage waveform is equal to the stored analog input signal; digital storage means coupled to the digital code generating means and to the analog comparison means for storing a digital signal equal to the digital code signal being produced by the digital code generating means in response to an output signal from the analog comparison means whereby a digital signal corresponding to the voltage of The stored analog input signal is stored in the digital storage means during the comparison period; digital input signal storage means for storing a digital input signal prior to a comparison period; digital signal comparison means coupled to the digital input signal storage means and to the digital code generating means for comparing the stored digital input signal with said sequence of digital code signals during a comparison period and for producing an output signal when the two digital signals are equal; and analog storage means coupled to the analog voltage generating means and to the digital signal comparison means for storing an analog signal equal to the analog signal being produced by the analog voltage generating means in response to an output signal from the digital signal comparison means whereby an analog signal corresponding to the stored digital input signal is stored in the analog storage means during the comparison period.
Claim 2
Dependent Claim
357 words
Analog-to-digital and digital-to-analog converter apparatus comprising digital code generating means for producing a sequence of digital code signals during a comparison period of each operating cycle; analog voltage generating means for producing an analog voltage waveform during the comparison period of each operating cycle and being synchronized with said digital code generating means whereby for each digital code signal a corresponding analog voltage signal is produced at the same instant during the comparison period of each operating cycle; analog input signal storage means for storing an analog input signal prior to a comparison period; analog comparison means coupled to the analog input signal storage means and to the analog voltage generating means for comparing the stored analog input signal with said analog voltage waveform during a comparison period and for producing an output signal when the voltage of the analog voltage waveform is equal to the stored analog input signal; digital storage means coupled to the digital code generating means and to the analog comparison means for storing a digital signal equal to the digital code signal being produced by the digital code generating means in response to an output signal from the analog comparison means whereby a digital signal corresponding to the voltage of The stored analog input signal is stored in the digital storage means during the comparison period; digital input signal storage means for storing a digital input signal prior to a comparison period; digital signal comparison means coupled to the digital input signal storage means and to the digital code generating means for comparing the stored digital input signal with said sequence of digital code signals during a comparison period and for producing an output signal when the two digital signals are equal; and analog storage means coupled to the analog voltage generating means and to the digital signal comparison means for storing an analog signal equal to the analog signal being produced by the analog voltage generating means in response to an output signal from the digital signal comparison means whereby an analog signal corresponding to the stored digital input signal is stored in the analog storage means during the comparison period.
Claim 3
Dependent Claim
51 words
Analog-to-digital and digital-to-analog converter apparatus in accordance with claim 1 wherein said digital code generating means produces a sequence of digital code signals each of which varies from the preceding signal by an equal digital amount; and said analog voltage generating means produces an analog voltage waveform of continuously increasing voltage.
Claim 4
Dependent Claim
79 words
Analog-to-digital and digital-to-analog converter apparatus in accordance with claim 2 wherein said digital code generating means includes clock pulse generating means for producing periodic clock pulses, and counting means coupled to the clock pulse generating means for counting clock pulses during the comparison period of each operating cycle and for producing a sequence of digital code signals representing the number of pulses counted; and said analog voltage generating means produces a non-linear analog voltage waveform of continuously increasing voltage.
Claim 5
Dependent Claim
220 words
Analog-to-digital and digital-to-analog converter apparatus in accordance with claim 1 including a control means; an analog input signal receiving means for receiving analog input signals; an analog input signal gating means connected between the analog input signal receiving means and the analog input signal storage means and being coupled to the control means; said control means being operable to cause the analog input signal gating means to load an analog input signal present at the analog signal receiving means into the analog input signal storage means prior to a comparison period; and wherein said analog storage means includes a storage element; and analog storage gating means connected between the analog voltage generating means and the storage element, said analog storage gating means being coupled to the digital signal comparison means and to the control means; said control means being operable to cause the analog storage gating means to provide a conductive path therethrough during a comparison period; said analog storage gating means being operable to be switched from providing a conductive path therethrough to provide an open circuit in response to an output signal from said digital signal comparison means whereby a voltage equal to the voltage of the analog voltage waveform at the instant the digital signal comparison means produces the output signal is stored in the storage element.
Claim 6
Dependent Claim
136 words
Analog-to-digital and digital-to-analog converter apparatus in accordance with claim 4 wherein said analog storage gating means includes a gating element connected between the analog voltage generating means and the storage element; and gate control means coupled to the gating element, said digital signal comparison means, and said control means; said gate control means having a first operating state during which said gating element provides a conductive path therethrough and a second operating state during which said gating element provides an open circuit; said control means being operAble to cause the gate control means to operate in said first operating state during a comparison period; and said gate control means being operable to be switched from said first operating state to said second operating state in response to an output signal from said digital signal comparison means.
Claim 7
Dependent Claim
51 words
Analog-to-digital and digital-to-analog converter apparatus in accordance with claim 5 wherein said digital code generating means produces a sequence of digital code signals each of which varies from the preceding signal by an equal digital amount; and said analog voltage generating means produces an analog voltage waveform of continuously increasing voltage.
Claim 8
Dependent Claim
79 words
Analog-to-digital and digital-to-analog converter apparatus in accordance with claim 6 wherein said digital code generating means includes clock pulse generating means for producing periodic clock pulses, and counting means coupled to the clock pulse generating means for counting clock pulses during the comparison period of each operating cycle and for producing a sequence of digital code signals representing the number of pulses counted; and said analog voltage generating means produces a non-linear analog voltage waveform of continuously increasing voltage.
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) | 1978-05-12 | 1978-11-11 | 1979-05-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-05-12 | 1982-11-11 | 1983-05-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-05-12 | 1986-11-11 | 1987-05-13 | $7700.00 | Window Closed / Lapsed |