US3569821A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Programmable digital to analogue converter system
Assignee: BAC AND BRITISH AEROSPACE
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Filing: 1969-01-30
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Granted: 1971-03-09
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Expires: 1989-01-30
Abstract
Abstract Automatic test equipment requires highly accurate test signals. The maintenance of a substantially constant input, accurately defined within precise limits, insures such a test signal. A digital comparator wherein the measured values of the responses to the test signals are compared with predetermined values available from a programmed tape is also employed to maintain the signal constant.
Inventors
- 👤 Ronnie Pepper
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 22:14
CPC Classifications
H; H03; H03M; H03M1/00; H03M1/10; H03M1/1071
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
332 words
Apparatus for setting up a test signal in automatic test equipment for application to selected points of the equipment being tested, comprising: a. a constant voltage source; b. a voltage divider energized from said source and having a plurality of sections, the voltage increments across adjacent ones of the said sections being in the ratio of the radix of the numerical system in which the value of the required test signal is to be expressed such that each section represents a different denomination of the said numerical value; c. a plurality of tapping points positioned along said divider; d. means for selecting at least one of said tapping points to control the output voltage from said divider; e. an analogue to digital voltage converter connected to receive the output from said divider and convert it to digital form; f. a digital comparator having a first input connected to receive the digital representation of the output from said divider and second and third inputs connected to receive predetermined upper and lower limit values respectively of the test signal; g. means responsive to an output from said comparator signifying that said digital representation lies below the lower limit value to energize said selector means to select a tapping point providing a higher output voltage; h. means responsive to an output from said comparator signifying that said digital representation lies above the upper limit value to energize said selector means to select a tapping point providing a lower output voltage; and i. means responsive to a direct transition of the output from said comparator from a signal signifying that said digital representation lies below the lower limit to a signal signifying that said digital representation lies above the upper limit to energize said selector means to select a tapping point in an adjacent section of said divider representing the next most significant denomination, whereby the output from said voltage divider is continually ramped up or down until said digital representation lies within said limit values.
Claim 2
Dependent Claim
332 words
Apparatus for setting up a test signal in automatic test equipment for application to selected points of the equipment being tested, comprising: a. a constant voltage source; b. a voltage divider energized from said source and having a plurality of sections, the voltage increments across adjacent ones of the said sections being in the ratio of the radix of the numerical system in which the value of the required test signal is to be expressed such that each section represents a different denomination of the said numerical value; c. a plurality of tapping points positioned along said divider; d. means for selecting at least one of said tapping points to control the output voltage from said divider; e. an analogue to digital voltage converter connected to receive the output from said divider and convert it to digital form; f. a digital comparator having a first input connected to receive the digital representation of the output from said divider and second and third inputs connected to receive predetermined upper and lower limit values respectively of the test signal; g. means responsive to an output from said comparator signifying that said digital representation lies below the lower limit value to energize said selector means to select a tapping point providing a higher output voltage; h. means responsive to an output from said comparator signifying that said digital representation lies above the upper limit value to energize said selector means to select a tapping point providing a lower output voltage; and i. means responsive to a direct transition of the output from said comparator from a signal signifying that said digital representation lies below the lower limit to a signal signifying that said digital representation lies above the upper limit to energize said selector means to select a tapping point in an adjacent section of said divider representing the next most significant denomination, whereby the output from said voltage divider is continually ramped up or down until said digital representation lies within said limit values.
Claim 3
Dependent Claim
29 words
Apparatus according to claim 1 in which each section of said voltage divider includes a plurality of tappings to enable different numerical values to be selected within each denomination.
Claim 4
Dependent Claim
156 words
Apparatus according to claim 2 for use with decimal notation in which said voltage divider comprises a resistor chain, each resistor corresponding to one decade and the tapping points in each decade being connected to relay contacts for short circuiting the portion of the resistor between a respective tapping and one end of the resistor, and in which the said selector means comprises a plurality of bistable circuits for selectively energizing the relays associated with said relay contacts in response to triggering pulses from said comparator, the bistables forming a binary counter for each decade and said triggering pulses comprising ''''add'''' or ''''substract'''' signals corresponding to the digital representation lying below the lower tolerance limit or above the upper tolerance limit respectively, and each binary counter being connected to a binary decimal converter such that said relay contacts are successively closed along each resistor in turn in accordance with tHe binary count for the corresponding decade.
References Cited (Backward Citations)
US3187323A
Cited
US3270275A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-03-08 | 1974-09-07 | 1975-03-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-03-08 | 1978-09-07 | 1979-03-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-03-08 | 1982-09-07 | 1983-03-09 | $7700.00 | Window Closed / Lapsed |