US4642800A
Expired / Lapsed
US
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Noise subtraction filter
Assignee: Baker Hughes Oilfield Operations LLC
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Filing: 1985-08-26
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Granted: 1987-02-10
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Expires: 2005-08-26
Abstract
Abstract A filter for use in filtering noise from cyclical signals having a data component and a noise component in which a predetermined number of the cyclical signals are averaged to produce an average signature signal. The average signature signal is updated each cycle to produce a current updated average signature signal, and the current cyclical signals and the current updated average signals are subtracted from one another to remove the noise component and produce a residual signal which contains the data component. The time frames of the current cyclical signals and the current updated average signals are adjusted to be equal so as to enable point by point subtraction. As an additional feature, the updating of the average pump signature combines a portion of the last average pump signature with a portion of the last residual signal.
Inventors
- 👤 Takato Umeda
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 21:29
CPC Classifications
E; E21; E21B; E21B47/00; E21B47/12; E21B47/14; E21B47/18; G; G01; G01V; G01V1/00; G01V1/28; G01V1/36; G01V1/364; G01V2210/00; G01V2210/30; G01V2210/32; G01V2210/324
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
106 words
A method of filtering noise from signals having a data component and a cyclical noise component having a substantially unidirectional polarity comprising averaging a predetermined number of the cyclical signals to produce an average signature signal in synchronism with the cyclical noise component, updating the average signature signal each cycle to produce a current average signature signal, and subtracting the current cyclical signals and the current average signature signals from one another to produce a residual signal which contains the data component, with the average signature signal being updated by adding a fraction of the residual signal to a fraction of the current average signature signal.
Claim 2
Independent Claim
106 words
A method of filtering noise from signals having a data component and a cyclical noise component having a substantially unidirectional polarity comprising averaging a predetermined number of the cyclical signals to produce an average signature signal in synchronism with the cyclical noise component, updating the average signature signal each cycle to produce a current average signature signal, and subtracting the current cyclical signals and the current average signature signals from one another to produce a residual signal which contains the data component, with the average signature signal being updated by adding a fraction of the residual signal to a fraction of the current average signature signal.
Claim 3
Independent Claim
142 words
A method of noise subtraction for use in processing data that is telemetered by pressure pulses that are transmitted through well drilling fluid that is circulated by pumping in repetitive cycles, comprising producing composite signals that are representative of the pressure changes in the fluid having a data component that is representative of the telemetered data and having a cyclical noise component of substantially unidirectional polariaty that is produced by the pumping of the fluid, producing an average signature signal in synchronism with the cyclical noise component that is representative of the average of said composite signals over a selected number of current pumping cycles, and subtracting the current composite signals and the current average signature signal from one another to cause the cyclical noise components that are produced by pumping to cancel leaving a residual signal that contains the data component.
Claim 4
Independent Claim
142 words
A method of noise subtraction for use in processing data that is telemetered by pressure pulses that are transmitted through well drilling fluid that is circulated by pumping in repetitive cycles, comprising producing composite signals that are representative of the pressure changes in the fluid having a data component that is representative of the telemetered data and having a cyclical noise component of substantially unidirectional polariaty that is produced by the pumping of the fluid, producing an average signature signal in synchronism with the cyclical noise component that is representative of the average of said composite signals over a selected number of current pumping cycles, and subtracting the current composite signals and the current average signature signal from one another to cause the cyclical noise components that are produced by pumping to cancel leaving a residual signal that contains the data component.
Claim 5
Dependent Claim
35 words
The method of claim 2 wherein the time frame of the signals is adjusted so that the composite signals and the average signature signals have the same time frame with respect to the pumping cycles.
Claim 6
Dependent Claim
29 words
The method of claim 2 wherein the average signature signal is produced by adding a portion of the current pump signature to a portion of the current residual signal.
Claim 7
Dependent Claim
27 words
The method of claim 2 wherein the average signature signal is produced by adding 14/15 of the current pump signature to 1/15 of the current residual signal.
Claim 8
Dependent Claim
97 words
A noise subtraction filter comprising means for producing a repetitive signal having a data component and a noise component having a substantially unidirectional polarity, means synchronized with said noise component for continuously averaging a predetermined number of the current repetitive signals to produce an average signature signal, means for updating the average signature signal periodically to produce a current average signature signal, and means for subtracting the current repetitive signals and the current average signature signal, whereby the noise component in the current repetitive signal is substantially cancelled leaving a residual signal which contains the data component.
Claim 9
Dependent Claim
97 words
A noise subtraction filter comprising means for producing a repetitive signal having a data component and a noise component having a substantially unidirectional polarity, means synchronized with said noise component for continuously averaging a predetermined number of the current repetitive signals to produce an average signature signal, means for updating the average signature signal periodically to produce a current average signature signal, and means for subtracting the current repetitive signals and the current average signature signal, whereby the noise component in the current repetitive signal is substantially cancelled leaving a residual signal which contains the data component.
Claim 10
Dependent Claim
153 words
A noise subtraction filter for use in processing data that is telemetered through well drilling fluid that is circulated by pump means that operates in repetitive cycles, comprising means adapted to be coupled to the well drilling fluid for producing composite signals representative of pressure changes in the fluid having a data component that is representative of the data that is telemetered through the well drilling fluid and having a cyclical noise component of substantially unidirectional polarity that results from the changes in pressure that are produced by the pump means, means synchronized with the pump cycles for averaging a predetermined number of said composite signals during a predetermined number of pump cycles to produce an average signature signal, and means for subtracting the current composite signals and the current average signature signal from one another to cause the cyclical noise components to cancel leaving a residual signal which contains the data component.
Claim 11
Dependent Claim
153 words
A noise subtraction filter for use in processing data that is telemetered through well drilling fluid that is circulated by pump means that operates in repetitive cycles, comprising means adapted to be coupled to the well drilling fluid for producing composite signals representative of pressure changes in the fluid having a data component that is representative of the data that is telemetered through the well drilling fluid and having a cyclical noise component of substantially unidirectional polarity that results from the changes in pressure that are produced by the pump means, means synchronized with the pump cycles for averaging a predetermined number of said composite signals during a predetermined number of pump cycles to produce an average signature signal, and means for subtracting the current composite signals and the current average signature signal from one another to cause the cyclical noise components to cancel leaving a residual signal which contains the data component.
Claim 12
Dependent Claim
183 words
A noise subtraction filter for use in processing data that is telemetered through well drilling fluid that is circulated by pump means that operates in repetitive cycles in which the pressure in the well drilling fluid is increased in periodic cycles to cause cyclical noise, comprising means coupled to the well drilling fluid for producing composite signals representative of pressure changes in the fluid having a data component that is representative of the data that is telemetered through the well drilling fluid and having said cyclical noise that results from the changes in pressure that are produced by the pump means, means synchronized with the repetitive cycles of said pump means for producing an average pump signature signal that is representative of the average of said composite signals during a predetermined number of pump cycles, and means for subtracting the current composite signals and the current average signature signal from one another to cause the cyclical noise components that are produced by the pump means to cancel leaving a residual signal at the output of the subtracting means that contains the data component.
Claim 13
Dependent Claim
183 words
A noise subtraction filter for use in processing data that is telemetered through well drilling fluid that is circulated by pump means that operates in repetitive cycles in which the pressure in the well drilling fluid is increased in periodic cycles to cause cyclical noise, comprising means coupled to the well drilling fluid for producing composite signals representative of pressure changes in the fluid having a data component that is representative of the data that is telemetered through the well drilling fluid and having said cyclical noise that results from the changes in pressure that are produced by the pump means, means synchronized with the repetitive cycles of said pump means for producing an average pump signature signal that is representative of the average of said composite signals during a predetermined number of pump cycles, and means for subtracting the current composite signals and the current average signature signal from one another to cause the cyclical noise components that are produced by the pump means to cancel leaving a residual signal at the output of the subtracting means that contains the data component.
Claim 14
Dependent Claim
46 words
The apparatus of claim 8 wherein the means for substracting the current composite signals and the current average signature signals includes means for compressing or expanding the time frame of one of the signals to cause both of the signals to have the same time frame.
Claim 15
Dependent Claim
30 words
The apparatus of claim 8 wherein the average pump signature signal is produced by adding a portion of the current pump signature to a portion of the current residual signal.
Claim 16
Dependent Claim
28 words
The apparatus of claim 8 wherein the average pump signature signal is produced by adding 14/15 of the current pump signature to 1/15 of the current residual signal.
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) | 1990-02-09 | 1990-08-11 | 1991-02-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-02-09 | 1994-08-11 | 1995-02-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-02-09 | 1998-08-11 | 1999-02-10 | $7700.00 | Window Closed / Lapsed |