US3889229A
Expired / Lapsed
US
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System for eliminating monochromatic signals from data records
Assignee: ExxonMobil Upstream Research Co
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Filing: 1973-12-03
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Granted: 1975-06-10
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Expires: 1993-12-03
Abstract
Abstract Apparatus is described for eliminating monochromatic interfering frequency components of seismic signals detected during the course of seismic exploration comprising an electrical circuit for producing a monochromatic nulling signal that has the same frequency as the interfering signal. The monochromatic nulling signal is produced by generating a truncated triangular wave having the same period as the interfering signal and filtering the truncated triangular wave to remove all components thereof except those having the period of the interfering signal. Circuit means are provided for controlling the amount of truncation of the truncated triangular wave, and for controlling the time phase thereof. The filtered signal is combined with the geophone signal in such a manner that the filtered signal at least partially cancels out the interfering component of the seismic signal. Circuit means are provided for detecting the phase of the residual signal resulting from incomplete cancellation of the interfering signal to provide an indication of the amplitude of the nulling signal. Means are also provided for detecting the time phase of the nulling signal. The truncation of the truncated triangular wave, and the time phase of the truncated triangular wave are controlled so as to result in more complete cancellation.
Inventors
- 👤 Richard J Kostelnicek
- 👤 Curtis B Herbert
- 👤 Thomas H Crawford
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 16:30
CPC Classifications
H; H03; H03L; H03L7/00; G; G01; G01V; G01V1/00; G01V1/28; G01V1/36; G01V1/364; G01V2210/00; G01V2210/20; G01V2210/21
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
143 words
Signal processing apparatus for eliminating a substantially monochromatic signal from an electrical signal that may include a data signal and said substantially monochromatic signal, said apparatus comprising: first means for producing a substantially sinusoidal nulling signal having the same frequency as the substantially monochromatic signal; second means for subtracting said nulling signal from said electrical signal thereby producing a residual signal; circuit means for filtering the residual signal to eliminate signals having frequencies otHer than the frequency of the said substantially monochromatic signal thereby producing a filtered residual signal; and third means responsive to the phase difference between the nulling signal and the substantially monochromatic signal to reduce the phase difference between the nulling signal and the substantially monochromatic signal and responsive to the phase of said filtered residual signal relative to a reference signal to reduce the amplitude of said residual signal.
Claim 2
Dependent Claim
143 words
Signal processing apparatus for eliminating a substantially monochromatic signal from an electrical signal that may include a data signal and said substantially monochromatic signal, said apparatus comprising: first means for producing a substantially sinusoidal nulling signal having the same frequency as the substantially monochromatic signal; second means for subtracting said nulling signal from said electrical signal thereby producing a residual signal; circuit means for filtering the residual signal to eliminate signals having frequencies otHer than the frequency of the said substantially monochromatic signal thereby producing a filtered residual signal; and third means responsive to the phase difference between the nulling signal and the substantially monochromatic signal to reduce the phase difference between the nulling signal and the substantially monochromatic signal and responsive to the phase of said filtered residual signal relative to a reference signal to reduce the amplitude of said residual signal.
Claim 3
Dependent Claim
71 words
The apparatus of claim 1 wherein said third means includes: second circuit means for producing a sum signal equal to the sum of the substantially monochromatic signal and the nulling signal; and means responsive to said sum signal and said filtered residual signal for producing a first control signal for varying the phase of said nulling signal to reduce the phase difference between the nulling signal and the substantially monochromatic signal.
Claim 4
Dependent Claim
64 words
The apparatus of claim 2 wherein said first means includes means for producing said reference signal, said reference signal having a phase related to said nulling signal, and said third means includes a fourth means for detecting whether the filtered residual signal is leading or lagging said reference signal and for producing a second control signal for reducing the amplitude of said residual signal.
Claim 5
Dependent Claim
134 words
The apparatus of claim 3 wherein said first means includes: fifth means for producing a pulse train having a pulse repetition rate that is a multiple of the frequency of said substantially monochromatic signal; sixth means for increasing or decreasing the pulse repetition rate of said pulse train in response to said first control signal; seventh means for counting the pulses in the pulse train; eighth means for producing a stepped triangular wave of which the amplitude at any step is a function of the pulse count; ninth means for truncating the stepped triangular wave in response to said second control signal thereby varying the amplitude of the nulling signal; and tenth means for eliminating those components of the stepped triangular wave having a frequency greater than the frequency of the substantially monochromatic signal.
Claim 6
Dependent Claim
109 words
The apparatus of claim 3 wherein the third means comprises: means for producing a first signal equal to the sum of the electrical signal and the nulling signal; means for filtering from said first signal all frequency components not of substantially the frequency of said substantially monochromatic signal; means for producing a second signal indicative of the sum of the filtered first signal and the filtered residual signal; means for producing a third signal indicative of the difference of the filtered first signal and the filtered residual signal; and means for producing said first control signal as a function of the phase relationship between said second and third signals.
Claim 7
Dependent Claim
151 words
The apparatus of claim 4 wherein: said seventh means includes a first binary counter means for producing an output count, which if applied to a digital-to-analog converter would produce a stepped saw-tooth wave signal; said eighth means include means for complementing the output count of said first binary counter on alternate counting cycles thereby producing an output count, which if applied to a digital-to-analog converter would produce a stepped triangular wave; said ninth means includes UP-DOWN counter means for producing a reference count and for increasing and decreasing said reference count responsive to said second control signal, and means including latch circuit means connected to said seventh means for truncating the output count from said seventh means when the count is less than said reference count or greater than the complement of said reference count; and a digital-to-analog converter means for converting said truncated count to a truncated triangular wave signal.
Claim 8
Dependent Claim
119 words
The apparatus of claim 6 wherein said means including latch circuit means coMprises: comparator circuit means for producing first output pulses when the output count from said eighth means is equal to the count produced by said UP-DOWN counter means and for producing second output pulses when the output count from said eighth means is equal to Y (2n - 1) - X where X is the output count from said UP-DOWN counter means ''''Y'''' is the output count from said eighth means; and latch circuit means for truncating the increasing count of said eighth means responsive to said first output pulses and for truncating the decreasing count of said first circuit means responsive to said second output pulses.
Claim 9
Dependent Claim
170 words
Signal processing apparatus for eliminating a substantially monochromatic signal from an electrical signal that may include said substantially monochromatic signal and a data signal, said apparatus comprising: first means for producing a substantially sinusoidal nulling signal having the same frequency as the substantially monochromatic signal; second means for producing a residual signal by subtracting the nulling signal from said electrical signal, said residual signal being the output signal of said apparatus; third means for filtering the residual signal to eliminate signals having frequencies other than the frequency of the substantially monochromatic signal, thereby producing a filtered residual signal; fourth means for detecting the phase difference between the nulling signal and substantially monochromatic signal and for generating a first control signal for reducing said phase difference; and fifth means for producing a second control signal responsive to the phase of said filtered residual signal relative to a reference signal for varying the amplitude of said nulling signal to reduce the amplitude difference between the nulling signal and the substantially monochromatic signal.
Claim 10
Dependent Claim
170 words
Signal processing apparatus for eliminating a substantially monochromatic signal from an electrical signal that may include said substantially monochromatic signal and a data signal, said apparatus comprising: first means for producing a substantially sinusoidal nulling signal having the same frequency as the substantially monochromatic signal; second means for producing a residual signal by subtracting the nulling signal from said electrical signal, said residual signal being the output signal of said apparatus; third means for filtering the residual signal to eliminate signals having frequencies other than the frequency of the substantially monochromatic signal, thereby producing a filtered residual signal; fourth means for detecting the phase difference between the nulling signal and substantially monochromatic signal and for generating a first control signal for reducing said phase difference; and fifth means for producing a second control signal responsive to the phase of said filtered residual signal relative to a reference signal for varying the amplitude of said nulling signal to reduce the amplitude difference between the nulling signal and the substantially monochromatic signal.
Claim 11
Dependent Claim
39 words
The apparatus of claim 8 wherein said fifth means comprises sixth means for detecting whether said filtered residual signal is of a substantially given phase or of the opposite phase, and producing said second control signal in accordance therewith.
Claim 12
Dependent Claim
58 words
The apparatus of claim 8 wherein said first means includes means for producing said reference signal, said reference signal having a phase related to said nulling signal, and said fifth means comprises circuit means for detecting whether the filtered residual signal is leading or lagging said reference signal and for producing said second control signal in accordance therewith.
Claim 13
Dependent Claim
130 words
The apparatus of claim 8 wherein said first means includes: first circuit means for producing a pulse train having a pulse repetition rate that is a multiple of the frequency of said substantially monochromatic signal; second circuit means for increasing or decreasing the pulse repetition rate of said pulse train, and for counting the pulses in said pulse train; third circuit means for producing a truncated triangular wave from the output of said second circuit means; fourth circuit means for eliminating all components of the truncated triangular wave other than the component having a frequency equal to the frequency of the substantially monochromatic signal; and fifth means responsive to said second control signal for varying the truncation of said truncated triangular wave to vary the amplitude of the nulling signal.
Claim 14
Dependent Claim
120 words
The apparatus of claim 8 wherein the fourth means comprises: circuit means for producing a first sum signal equal to the sum of the electrical signal and the nulling signal; circuit means for filtering from said first sum signal all components not of substantially the frequency of said substantially monochromatic signal; circuit means for producing a second sum signal indicative of the sum of said filtered first sum signal and said filtered residual signal; circuit means for producing a difference signal indicative of the difference of said filtered sum signal and said filtered residual siGnal; and circuit means for producing said first control signal as a function of the phase relationship between said second sum signal and said difference signal.
Claim 15
Dependent Claim
142 words
The apparatus of claim 1 wherein said first means comprises: means for detecting electromagnetic energy; phase-locked loop means for producing an output signal having a frequency which is a multiple of the frequency of the detected electromagnetic energy; counter means for producing a linearly increasing digital signal responsive to the output signal of said phase-locked loop means; means for producing a second digital signal from the output of said counter means equal to the output of said counter means on alternate counting cycles, and equal to the complement of the output of said counter means on the other alternate cycles; digital-to-analog converter means for converting the second digital signal to a signal whose amplitude is proportional to the count of said second digital signal; and filter means for producing a substantially monochromatic signal from the output signal of said digital-to-analog converter means.
Claim 16
Dependent Claim
87 words
The apparatus of claim 13 wherein the means for reducing the amplitude of the residual signal comprises: circuit means for producing a first output signal when the output of said counter is between a variable number and its complement and for producing a second output signal when the output of said counter is greater than said variable number or less than its complement; and second counter means for generating said variable number under control of said second control signal to reduce the amplitude of said residual signal.
Claim 17
Independent Claim
155 words
A method of eliminating an unwanted sinusoidal signal of electromagnetic wave origin from an electrical signal that is a composite of a seismic detector signal and the unwanted signal comprising: detecting the electromagnetic waves and producing a first electrical signal corresponding thereto; producing a substantially sinusoidal nulling signal having a frequency equal to that of the unwanted signal; subtracting the nulling signal from the electrical signal that is a composite of a seismic detector signal and the unwanted signal thereby producing a residual signal; filtering the residual signal to remove signals having frequencies other than the frequency of the unwanted signal; varying the phase of said nulling signal to reduce the phase difference between said nulling signal and the unwanted signal; comparing the phase of the filtered residual signal to a reference signal; and varying the amplitude of said nulling signal in accordance with said phase comparison to reduce the amplitude of said residual signal.
Claim 18
Independent Claim
155 words
A method of eliminating an unwanted sinusoidal signal of electromagnetic wave origin from an electrical signal that is a composite of a seismic detector signal and the unwanted signal comprising: detecting the electromagnetic waves and producing a first electrical signal corresponding thereto; producing a substantially sinusoidal nulling signal having a frequency equal to that of the unwanted signal; subtracting the nulling signal from the electrical signal that is a composite of a seismic detector signal and the unwanted signal thereby producing a residual signal; filtering the residual signal to remove signals having frequencies other than the frequency of the unwanted signal; varying the phase of said nulling signal to reduce the phase difference between said nulling signal and the unwanted signal; comparing the phase of the filtered residual signal to a reference signal; and varying the amplitude of said nulling signal in accordance with said phase comparison to reduce the amplitude of said residual signal.
Claim 19
Independent Claim
124 words
A method of eliminating a substantially sinusoidal unwanted signal of electromagnetic wave origin from an electric geophysical signal that is a composite of a seismic detector output signal and the unwanted signal comprising: detecting the electromagnetic waves and producing first electrical signal corresponding thereto; producing a binary count having a repetition rate equal to the frequency of the unwanted signal; producing a substantially sinusoidal nulling signal having a frequency equal to the repetition rate of the binary count; subtracting the nulling signal from said electric geophysical signal; varying the frequency of said binary count to reduce the phase difference between said nulling signal and the unwanted signal; and varying the counting range of said binary count to reduce the amplitude of said residual signal.
Claim 20
Independent Claim
124 words
A method of eliminating a substantially sinusoidal unwanted signal of electromagnetic wave origin from an electric geophysical signal that is a composite of a seismic detector output signal and the unwanted signal comprising: detecting the electromagnetic waves and producing first electrical signal corresponding thereto; producing a binary count having a repetition rate equal to the frequency of the unwanted signal; producing a substantially sinusoidal nulling signal having a frequency equal to the repetition rate of the binary count; subtracting the nulling signal from said electric geophysical signal; varying the frequency of said binary count to reduce the phase difference between said nulling signal and the unwanted signal; and varying the counting range of said binary count to reduce the amplitude of said residual signal.
Claim 21
Dependent Claim
156 words
The method of claim 16 wherein the frequency of the binary count is varied to reduce the phase difference between said nulling signal and said unwanted signal by the following steps: producing a sum signal that is the sum of said electric geophysical signal and said nulling signal; removing from said sum signal the component thereof produced by said seismic detector output signal to produce a fiLtered sum signal; filtering the residual signal resulting from the subtraction of the nulling signal from said electric geophysical signal; producing a second sum signal equal to the sum of said filtered sum signal and said residual signal; producing a difference signal equal to the difference between said filtered sum signal and said residual signal; detecting the phase difference between said second sum signal and said difference signal; and varying the frequency of said binary count to reduce said phase difference between said second sum signal and said difference signal.
Claim 22
Dependent Claim
51 words
The method of claim 16 wherein the phase of the residual signal is compared with a reference signal having a phase related to said nulling signal, and the amplitude of the nulling signal is increased or decreased in accordance with the phase of the residual signal relative to the reference signal.
Claim 23
Dependent Claim
17 words
The method of claim 16 wherein the binary count is a pulse train of substantially rectangular waveform.
Claim 24
Dependent Claim
35 words
The method of claim 18 wherein the nulling signal is increased in amplitude if the residual is of a given phase relative to the reference signal, and decreased if it is of the opposite phase.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-06-09 | 1978-12-09 | 1979-06-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-06-09 | 1982-12-09 | 1983-06-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-06-09 | 1986-12-09 | 1987-06-10 | $7700.00 | Window Closed / Lapsed |