US3675485A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for measuring variations in a quantity with respect to a known reference value
Assignee: CEOPHYSIQUE COMP GEN DE
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Filing: 1969-06-18
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Granted: 1972-07-11
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Expires: 1989-06-18
Abstract
Abstract A method is provided for measuring the deviations of a quantity from the standard value for the same quantity, in the presence of stray interferences of greater amplitude and higher frequency than the variations to be measured. The procedure for effecting the method consists essentially in measuring the instantaneous values of the aforesaid quantity; eliminating all instantaneous values falling outside of a limited region of amplitude variations of the aforesaid quantity, inside of which the standard value of the quantity is located; determining the average, in time, of the instantaneous values situated within said region; and determining the difference between the average and the standard value of the aforesaid quantity, which difference constitutes the deviation sought. Apparatus is also provided for the application of the method to vibrating-wire gravimetry.
Inventors
- 👤 Julien M Loeb
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 03:29
CPC Classifications
G; G01; G01V; G01V7/00; G01V7/005; G01H; G01H13/00
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
170 words
A method for use in the measurement of variations of a quantity with respect to a known reference value, in the presence of interference disturbances having greater amplitudes, and higher frequencies than those of the variations, said method comprising: supplying the output of a resonator, the natural resonant frequency of which is related to the quantity, through a feedback loop to form an oscillator assembly, subtracting the output of the oscillator assembly from a reference frequency, supplying the subtracted signal to the feedback loop of the assembly, said oscillator assembly thereby oscillating at the reference frequency only providing the difference between the said natural resonant frequency of the resonator and the reference frequency lies between prescribed limits, and measuring a phase difference between the outputs of the oscillator assembly and the reference frequency, said phase difference being representative of the difference between said natural resonant frequency and the reference frequency, and thereby of the variations of the quantity with respect to a known reference value, corresponding to the reference frequency.
Claim 2
Independent Claim
170 words
A method for use in the measurement of variations of a quantity with respect to a known reference value, in the presence of interference disturbances having greater amplitudes, and higher frequencies than those of the variations, said method comprising: supplying the output of a resonator, the natural resonant frequency of which is related to the quantity, through a feedback loop to form an oscillator assembly, subtracting the output of the oscillator assembly from a reference frequency, supplying the subtracted signal to the feedback loop of the assembly, said oscillator assembly thereby oscillating at the reference frequency only providing the difference between the said natural resonant frequency of the resonator and the reference frequency lies between prescribed limits, and measuring a phase difference between the outputs of the oscillator assembly and the reference frequency, said phase difference being representative of the difference between said natural resonant frequency and the reference frequency, and thereby of the variations of the quantity with respect to a known reference value, corresponding to the reference frequency.
Claim 3
Dependent Claim
35 words
A method as claimed in claim 1, further comprising integrating said phase difference with a predetermined time constant, to eliminate the influence of interference disturbances without altering the variations of the quantity to be measured.
Claim 4
Dependent Claim
63 words
A method as claimed in claim 1, further comprising clipping said phase difference to eliminate transient phenomena occurring when the difference between said natural resonant frequency and the reference frequency is equal to said prescribed limits, and integrating said phase difference with a predetermined time constant to eliminate the influence of interference disturbances without altering the variations of the quantity to be measured.
Claim 5
Independent Claim
227 words
An apparatus for the measurement of variations of a quantity with respect to a known reference value, in the presence of interference disturbances of greater amplitude and higher frequency than the variations, said apparatus comprising: a sensitive element having a natural resonance frequency characteristic of the quantity to be measured; an oscillator assembly comprising amplifying and feedback means having an output connected to the input of said sensitive element such that the natural oscillating frequency of the oscillator assembly will be equal to the resonance frequency of the sensitive element, a subtracting device having an output connected to the input of said amplifying and feedback meaNs; and a first input connected to the output of said sensitive element, a local oscillator of fixed and stable frequency having an output connected to the second input of said subtracting device; and a phasemeter connected between the outputs of to said subtracting device and of said local oscillator, the subtracting device combining the amplitudes of oscillation of the oscillator assembly and of the local oscillator such that the oscillator assembly is pulled into forced oscillation at the frequency of the local oscillator, the phasemeter furnishing indication of the phase difference between the oscillation amplitudes of the oscillator assembly and of the local oscillator, the value of said phase difference being characteristic when averaged of the variation value to be measured.
Claim 6
Independent Claim
227 words
An apparatus for the measurement of variations of a quantity with respect to a known reference value, in the presence of interference disturbances of greater amplitude and higher frequency than the variations, said apparatus comprising: a sensitive element having a natural resonance frequency characteristic of the quantity to be measured; an oscillator assembly comprising amplifying and feedback means having an output connected to the input of said sensitive element such that the natural oscillating frequency of the oscillator assembly will be equal to the resonance frequency of the sensitive element, a subtracting device having an output connected to the input of said amplifying and feedback meaNs; and a first input connected to the output of said sensitive element, a local oscillator of fixed and stable frequency having an output connected to the second input of said subtracting device; and a phasemeter connected between the outputs of to said subtracting device and of said local oscillator, the subtracting device combining the amplitudes of oscillation of the oscillator assembly and of the local oscillator such that the oscillator assembly is pulled into forced oscillation at the frequency of the local oscillator, the phasemeter furnishing indication of the phase difference between the oscillation amplitudes of the oscillator assembly and of the local oscillator, the value of said phase difference being characteristic when averaged of the variation value to be measured.
Claim 7
Dependent Claim
64 words
An apparatus as claimed in claim 4, in which said quantity is the vertical acceleration due to gravity, and said interference disturbances are spurious vertical accelerations of greater amplitude and higher frequency than the variations, the natural resonance frequency of the sensitive element corresponding to the value which is characteristic of the sum of vertical accelerations to which the sensitive element is being subjected.
Claim 8
Dependent Claim
26 words
An apparatus as claimed in claim 5, in which the sensitive element is a vibrating wire stretched taut by the action of gravity on a mass.
Claim 9
Dependent Claim
16 words
An apparatus as claimed in claim 4, in which the subtracting device is a differential amplifier.
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) | 1975-07-11 | 1976-01-10 | 1976-07-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-07-11 | 1980-01-10 | 1980-07-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-07-11 | 1984-01-10 | 1984-07-11 | $7700.00 | Window Closed / Lapsed |