US3745475A
Expired / Lapsed
US
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Measurement system
Assignee: National Aeronautics and Space Administration
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Filing: 1971-12-07
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Granted: 1973-07-10
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Expires: 1991-12-07
Abstract
Abstract A measurement system for providing an indication of a varying physical quantity represented by or converted to a variable frequency signal. Timing pulses are obtained marking the duration of a fixed number, or set, of cycles of the sampled signal and these timing pulses are employed to control the period of counting of cycles of a higher fixed and known frequency source. The counts of cycles thus obtained from the fixed frequency source provide a precise measurement of the average frequency of each set of cycles sampled, and thus successive discrete values of the quantity being measured. The frequency of the known frequency source is made such that each measurement is presented as a direct digital representation of the quantity measured.
Inventors
- 👤 J Turner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 11:40
CPC Classifications
G; G01; G01R; G01R23/00; G01R23/02; G01R23/10; G01R19/00; G01R19/25; G01R19/252; H; H03; H03M; H03M1/00; H03M1/12; H03M1/60
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
163 words
A measurement system for providing a series of discrete outputs indicative of the frequency of a source of variable frequency energy for discrete sampled periods comprising: a source of fixed frequency energy providing an output of a preselected frequency which is higher in frequency than the highest frequency of the source of variable frequency energy to be measured; timing means responsive to the output of said source of variable frequency energy for repetitively providing timing pulses marking the beginning and end of a selected like number of complete cycles of said source of variable frequency energy and denoting a sample period; and cycle counting means responsive to said timing pulses and said source of fixed frequency energy for sequentially counting cycles of said source of fixed frequency energy occurring between said timing pulses and for providing as said discrete outputs a series of discrete counts, each indicative of the average frequency of said source of variable frequency energy for a said sample period.
Claim 2
Dependent Claim
163 words
A measurement system for providing a series of discrete outputs indicative of the frequency of a source of variable frequency energy for discrete sampled periods comprising: a source of fixed frequency energy providing an output of a preselected frequency which is higher in frequency than the highest frequency of the source of variable frequency energy to be measured; timing means responsive to the output of said source of variable frequency energy for repetitively providing timing pulses marking the beginning and end of a selected like number of complete cycles of said source of variable frequency energy and denoting a sample period; and cycle counting means responsive to said timing pulses and said source of fixed frequency energy for sequentially counting cycles of said source of fixed frequency energy occurring between said timing pulses and for providing as said discrete outputs a series of discrete counts, each indicative of the average frequency of said source of variable frequency energy for a said sample period.
Claim 3
Dependent Claim
141 words
A measurement system for providing a series of discrete outputs, each being proportional to the magnitude of a physical quantity represented by an electrical signal varying directly in frequency with changes in said magnitude, comprising: a source of fixed frequency energy providing an output higher in frequency than the hIghest frequency of said signal; timing means responsive to said signal for providing timing pulses marking the beginning and end of sets of like numbers of complete cycles of said signal and defining sample periods for said discrete outputs; and cycle counting means responsive to said timing pulses and said source of fixed frequency energy for sequentially counting said cycles occurring between said timing pulses and for providing as said discrete outputs a series of discrete counts proportional to the average said magnitude of said physical quantity for a said sample period.
Claim 4
Dependent Claim
141 words
A measurement system for providing a series of discrete outputs, each being proportional to the magnitude of a physical quantity represented by an electrical signal varying directly in frequency with changes in said magnitude, comprising: a source of fixed frequency energy providing an output higher in frequency than the hIghest frequency of said signal; timing means responsive to said signal for providing timing pulses marking the beginning and end of sets of like numbers of complete cycles of said signal and defining sample periods for said discrete outputs; and cycle counting means responsive to said timing pulses and said source of fixed frequency energy for sequentially counting said cycles occurring between said timing pulses and for providing as said discrete outputs a series of discrete counts proportional to the average said magnitude of said physical quantity for a said sample period.
Claim 5
Dependent Claim
86 words
A measurement system as set forth in claim 2 wherein said cycle counting means includes a countdown counter, presettable after each said discrete output to a selected value and the frequency of said source of fixed frequency energy is selected to count down said countdown counts to a value corresponding to the lowest magnitude of said physical quantity, represented by a maximum said sample period, and to a maximum value corresponding to the maximum magnitude of said physical quantity, represented by a minimum said sample period.
Claim 6
Dependent Claim
46 words
A measurement system as set forth in claim 3 wherein the said minimum value of a said physical quantity is zero and said frequency of said source of fixed frequency energy is selected to fully count down said countdown counter in a maximum said sample period.
Claim 7
Dependent Claim
68 words
A measurement system as set forth in claim 4 wherein: said source of fixed frequency energy comprises means for selectively providing a plurality of different fixed frequency outputs enabling the selected scaling of counts indicated by said hertz counting means to correspond with the scale of magnitude of physical quantity versus frequency of said signal; and said countdown counter comprises means for selectively setting therein a preset count.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-07-09 | 1977-01-08 | 1977-07-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-07-09 | 1981-01-08 | 1981-07-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-07-09 | 1985-01-08 | 1985-07-10 | $7700.00 | Window Closed / Lapsed |