In re Walter

618 F.2d 758, 205 U.S.P.Q. (BNA) 397, 1980 CCPA LEXIS 265
CourtCourt of Customs and Patent Appeals
DecidedMarch 27, 1980
DocketAppeal No. 79-599
StatusPublished
Cited by24 cases

This text of 618 F.2d 758 (In re Walter) is published on Counsel Stack Legal Research, covering Court of Customs and Patent Appeals primary law. Counsel Stack provides free access to over 12 million legal documents including statutes, case law, regulations, and constitutions.

Bluebook
In re Walter, 618 F.2d 758, 205 U.S.P.Q. (BNA) 397, 1980 CCPA LEXIS 265 (ccpa 1980).

Opinion

RICH, Judge.

This appeal is from the decision of the Patent and Trademark Office (PTO) Board of Appeals (board), affirming the examiner’s final rejection of claims 7-14 and 16-18 in application serial No. 303,693, filéd November 6, 1972, entitled “Seismic Prospecting System.” The sole ground of rejection of the claims is that they are directed to nonstatutory subject matter under 35 U.S.C. § 101. We affirm.

The Invention

Appellant’s invention is used in seismic prospecting and surveying. In this field, seismic source waves are generated and transmitted downwardly into the earth. There they are deflected by subsurface formations and anomalies. The deflected waves return to the earth’s surface and are detected by transducers, known as geophones, which are distributed on the surface over the area of exploration. The geophones convert the returning mechanical vibrations into electrical signals, which are then recorded on a record medium, such as magnetic tape or chart recorder, for analysis. By studying the records of the deflected waves, analysts are able to make determinations concerning the nature of the subsurface structure of the earth.

Several types of seismic source waves have been used in seismic prospecting and surveying. One type, known as impulse waves, are sharp pulses lasting 0.05 second or less and are generated by a powerful force of short duration, such as an explosion. Another type of seismic source wave, with which appellant’s invention is used, are “chirp” signals. A chirp signal is a frequency-modulated continuous wave in which the frequency of vibration is varied as a function of time, usually a linear function, over a substantial period of as much as several seconds. Chirp signals are often referred to as “sweep” signals, since the frequency is swept from one value to another. Chirp signals are generated by mechanical apparatus which vibrates against the surface of the earth.

[761]*761As a chirp signal travels down into the earth, it is deflected by subsurface features which lie at varying depths and at different distances from the numerous geophones which are set out on the surface. At any given instant, therefore, a single geophone receives portions of the returning chirp signal which have been deflected from different depths and locations. This composite signal is a jumble of different frequency components. Before the results of the survey can be evaluated, the jumbled signal must be broken down into its components and its individual deflected portions identified.

Appellant has invented a method, and apparatus for performing the method, of cross-correlating the returning jumbled signal with the original chirp signal which was transmitted into the earth. As a result, the returning signal is effectively unscrambled; each of the trains of waves received at each geophone station is converted to a form equivalent to the type of signal which would have been produced had an impulse-type signal been used in place of the chirp signal. Appellant’s claims identify these end products as “partial product signals.”

Appellant’s method is performed on the record signal made from each geophone. The record signal is sampled and converted to a digital format. It is then divided into segments. Several mathematical operations are performed, including computing Fourier transforms and cross-correlation utilizing the Cooley-Tukey algorithm as modified by Bergland.1 Appellant’s claim 7 is illustrative of his invention:

7. In a method of seismic surveying in which a train of seismic source waves is transmitted downwardly into the earth and is there deflected by subsurface formations and in which corresponding trains of seismic waves deflected by such formation are received at geophone stations in a spread at the surface of the earth and wherein;
each train of received seismic waves is converted into a corresponding series of digital sample signals; and
a series of reference signals corresponding to sample of said transmitted seismic waves is developed;
the improved method of correlating said series of sample signals for each geophone station with respect to said series of reference signals that comprises
a) converting said, series of sample signals into an augmented series of sample signals divided into N + 1 segments of equal length thereby forming a series of sequential segments S¡ of said augmented series, including an empty end segment, where i = 1 . . . , N + 1;
b) forming a Fourier transform FTS; of each respective series of signals composed of pairs of successive segments S¡ and S¡ +1 of said augmented series, each said Fourier transform being represented by a first series of transform signals,
c) forming a combined segment of each segment Cj of said reference signals and an empty segment of equal length, where j = 1, . . . L, each said combined segment comprising a series of signals of double length, where L <C N.
d) forming a corresponding Fourier transform FTCj of each said combined segment, each said latter Fourier transform being represented by a second series of transform signals,
e) forming the non-zero conjugate complex vector products of pairs of the respective Fourier transforms and adding them together in accordance with the following expression:

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Bluebook (online)
618 F.2d 758, 205 U.S.P.Q. (BNA) 397, 1980 CCPA LEXIS 265, Counsel Stack Legal Research, https://law.counselstack.com/opinion/in-re-walter-ccpa-1980.