COMMISSIONER'S DECISION
Sec. 2; Sec. 28(3): Reducing Monochromatic Interference in Seismic Prospecting
Electrical transmission lines cause an interference signal in the area where
seismic prospecting is carried out. A system for reducing this interference
signal is considered patentable.
Final Action: Reversed, claims 13 to 19 are acceptable.
***************
Patent application 259,915 (Class 349-17), was filed on August 26, 1976
for an invention entitled METHOD OF REDUCING MONOCHROMATIC INTERFERENCE
IN CONTINUOUS WAVE SEISMIC PROSPECTING. The inventor is Allen B. Cunning-
ham, assignor to Exxon Production Research Company. The Examiner in
charge of the application took a Final Action or, November 5, 1979 refusing
to allow it to proceed to patent. In reviewing the rejection, the Patent
Appeal Board held a Hearing on November 10, 1982, at which the Applicant
was represented by Mr. H.C. Baker.
The subject matter of this application relates to the field of seismic
prospecting and to a means of reducing interference signals such as from
electrical transmission lines in the area where the test is located. Figure
1 shown here shows the components of the application.
(see formula I)
Antenna 13 detects the interference signal and directs it through clock gener-
ator 15 to the control signal generator 5. Generator 5 directs a control
signal to the vibrator 3 and to the recorder 19. Reflected seismic energy
from the subsurface reflecting interfaces is detected by geophone 21. By
selecting a signal pattern in the control generator such that the frequency
will have a time-phase relationship with the detected interference signal
the Applicant is able to eliminate the effects of the interference signal at
the geophone detecting location.
In the Final Action the Examiner rejected the application as being directed
to non patentable subject matter contrary to Section 2 and Section 28(3) of
the Patent Act. That action stated (in part):
Applicant argues that this is a new and patentable method. A
new seismic signal is produced, therefore the method may be
considered to be different; however, the method is not patentably
new. Each element of the disclosed apparatus operates in its
known and intended mode. The clock generator provides a timing
signal, the control signal generator (programmed in a conventional
manner) provides a desired control signal, the vibrator injects
the desired signal under control of the control signal, etc. Each
element operates according to its designed parameters. The
sole novelty is the information content of the injected signal
and perhaps the algorithm by which the control signal generator
operates. This algorithm and information content must be ignored
since the novelty of the algorithm is not a determining factor
and must be treated as though it were a familiar part of the prior
art. Considered in this light, the disclosed and claimed method
contains no patentable invention.
The method cannot be characterized as a new method for operating
an old apparatus. As stated above the apparatus is old and each
element operates according to its design parameters and for its
intended purpose. Applicant's method shows neither novelty of
operation nor novelty of purpose. There is no unexpected result,
but rather the result is completely within the capability of the
apparatus. The Office does allow method of use claims for this type
of apparatus, but only when accompanied by claims of the same scope
directed to novel and patentable apparatus, or for new uses for old
apparatus which yields unexpected results.
Applicant has discovered a mathematical relationship (an abstract
theorem or scientific principle), i.e. the necessary relationship
between the injected seismic signal and the monochromatic interference
signal to provide a cross correlation output signal free from inter-
ference frequencies. This abstract theorem or scientific principle has
not then been reduced to an invention, but has instead been embodied
in the form of prior art apparatus.
The only difference between the prior art method of operating
this apparatus and applicant's method is the algorithm by which
the control signal generator operates and thus the information
content or mathematical form of the resulting injected seismic
signal. The Patent Appeal Board (see CPOR 1 Aug. 1978 pages XIX
and XXIV) held that algorithms are merely sets of rules or processes
for solving problems in a finite number of steps, and in general
can be equated to an abstract theorem which is not patentable under
Section 28(3) of the Patent Act. The Board also stated that the
novelty of an algorithm lies solely in intellectual connotations
and is not patentable under Section 2 of the Patent Act.
The content of this application is directed to an abstract theorem
or scientific principle and since the method differs from the prior
art merely by the algorithm by which the control signal generator
operates and thus ultimately the information of the injected seismic
signal; the application is rejected as being directed to non
patentable subject matter contrary to Section 2 and Section 28(3)
of the Patent Act.
...
In response to the Final Action the Applicant stated (in part):
...
The applicant has developed an ingenious method for reducing the
effects of the monochromatic interference signal on the signal
resulting from the cross-correlation by perceiving that the problems
encountered with filters can be neatly sidestepped by transmitting
into the earth a seismic signal having a substantially null
component within its power spectrum substantially at the frequency
of the interference signal. This method then produces a correlation
signal for which any energy at interference frequency in the received
signal becomes multiplied by Zero (absent frequency in the transmitted
signal band) and therefore does not affect such correlation signal.
Applicant's invention is significant because it permits a seismic
signal to be transmitted into the earth having a power spectrum
with significant power over a frequency range which includes the
interference signal frequency without requiring filtering of the
received data to remove the interference. Thus a severe problem
in seismic exploration is cleverly solved by a novel and unobvious
method.
A wide variety of possibilities for the transmitted signal can be
envisaged, for instance one method would be to transmit a repeating
swept sine wave signal whose spectrum includes the interference fre-
quency but in which such frequency and its closely adjacent
frequencies are absent from the transmitted signal by appropriate
construction and cancellation in the transmitter.
In a preferred embodiment of applicant's invention, a signal pattern
corresponding to a properly structured binary coded sine wave is
transmitted, the pattern being nonrepetitive for at least as long
as the longest travel time of the seismic wave from the transmitting
location to the detecting location. A signal pattern that is
particularly useful is the binary coded sine wave of maximal
length, in which any sequence of "n" bits does not repeat during
any sequence of 2n-1 bit intervals.
It is not contended that the use of a binary coded sine wave in
seismic exploration is novel per se; however, it has not previous-
ly been suggested that such a signal could be structured to solve
the seismic data distortion problem caused by an interference
signal, such as 60 Hz power line interference.
...
The consideration before the Board is whether or not the application is
directed to patentable subject matter under Sections 2 and 28(3) of the Pat-
ent Act and also whether the subject matter is obvious.
Section 2 defines "invention" while Section 28(3) specifies that no patent
shall issue for "any mere scientific principle or abstract theorem". Before
we consider these sections of the Act let us review the application in order
to determine what is described therein.
From the disclosure we find that the Applicant describes a "system for re-
ducing the effects of a monochromatic interference signal on seismic data
records." In other words signals of the 60 c.p.s. type in electrical power
distribution lines in the area of the seismic test interfere with the reflected
signal at the geophone. According to the application prior art means for
removal of this interference signal involved various filtering techniques which
"included filters incorporated into field systems and computer programs that
remove interference signal during data processing". This required use of
additional hardware in the seismic field equipment or additional computes
programming during data processing. As stated on page 3 at line 10 of this
application the monochromatic interference signal effects are reduced by selecting
a signal pattern "such that the frequency of the interference signal is closer
to the frequency of the null component than to either of the two components
in said power spectrum adjacent said null component." Advantages of this system
are described at the bottom of page 3 where it outlines how it avoids the
distortion in seismic data at frequencies near the interference frequency caused
by most previously used systems and how it reduces the amount of hardware needed
by the prior art systems.
A description of the preferred embodiment begins at page 4 where "apparatus
useful to practicing this invention is illustrated in Figure 1." As described
on page 5, a control signal generator generates the electrical input control
signal for the vibrator positioned on the earth's surface. This control signal
"will have a bit period related to the period of the monochromatic interference
signal present in the area where seismic exploration is to be conducted. The
interference signal may be detected by antenna 13 which is shown coupled to
the control signal generator through clock generator 15".
After listening to Mr. Baker's presentation at the Hearing the Examiner's
director indicated that he considers claims 13 to 19 acceptable because they
are directed to a combination not found in the art. But he maintained the
view that the remaining claims are unacceptable because they define the
operation of prior art apparatus with merely a change in the information content
of the transmitted signal, so essentially they are directed to a method of
data processing which, in its broadest sense, is reduced to an algorithm,
thereby failing to comply with Sec. 2 and 28(3) of the Patent Act.
In the Final Action it is stated that the "content of this application is dir-
ected to an abstract theorem or scientific principle" and the application was rejected
as being directed to non patentable subject matter contrary to Section 2 and
Section 28(3) of the Patent Act. After reviewing the specification we find
that it does describe a system for reducing the effect on seismic data records
of a monochromatic interference signal present in the area in which the seismic
prospecting is conducted. Also, since it is now acknowledged that certain claims
are directed to a combination not found in the art, we cannot support a re-
jection of the application under Sec. 2 and Sec. 28(3) of the Patent Act and
recommend withdrawal of the rejection.
As some discussion with respect to the claims took place at the Hearing we
make the following comments with respect to claims 13 and 1. Claim 13 reads:
In a system for seismic prospecting wherein a vibrator is utilized
to transmit a continuous wave of seismic energy in response to an
electrical input control signal into the earth from a first loca-
tion and reflections of the signal from the subsurface are there-
after detected at a second location and cross-correlated with the
transmitted signal, the method of reducing the effects on the
signal resulting from the cross-correlation of a monochromatic
interference signal present in the area in which seismic prospect-
ing is conducted comprising:
generating said input control signal in the form of
a binary coded sine wave having a substantially null
component in the power spectrum thereof;
detecting said interference signal present in the area
in which seismic prospecting is conducted;
generating a clock signal at the frequency of said in-
terference signal;
controlling the frequency of said binary coded sine wave
with said clock signal so that said null component is
substantially at the frequency of said interference signal.
This claim specifies the combination by which a monochromatic interference
signal is removed from seismic data records by transmitting into the earth
a seismic signal having a null component in its power spectrum.
In the absence of cited art we have no objection to this claim since it
meets the requirements of Sec. 36(2) of the Patent Act.
Turning now to claim 1 which is shown below:
In a continuous wave method of seismic prospecting wherein
a seismic signal is transmitted into the earth from a first
location and reflections of the signal from the subsurface
are thereafter detected at a second location and cross-
correlated with the transmitted signal, the method of re-
ducing the effect of a monochromatic interference signal
on the signal resulting from the cross-correlation which
comprises:
transmitting a seismic signal having a power spectrum
containing a substantially null component therein at
a frequency nearer to the interference signal frequency
than either of the frequencies of the components in
said power spectrum adjacent said substantially null
component are to said interference signal frequency.
Means of overcoming the interfering signals originating in power lines in
the seismic test area is discussed by a number of patents referred to in the
disclosure. These patents utilize filtering techniques in which "nulling
signal frequency, phase and amplitude characteristics are adjusted to match
the interference signal manually" or by feedback loops. On page 5 the dis-
closure of this application indicates that the interference signal is
obtained by antenna 13 and on page 7 line 16 it states that one of the
advances in the seismic prospecting art disclosed herein is in the use
of a transmitting signal having a null in the power spectrum thereof sub-
stantially at the frequency of the interference signal.
It is necessary to detect the interference signal present in the area
where seismic prospecting is conducted and subsequent processing of this
signal is required to achieve the objectives described in the application.
As the method recited in claim 1 does not incorporate any detecting means
we find it not sufficiently distinct and explicit as required by Sec. 36(2)
of the Patent Act.
Claims 13 to 19 define the arrangement of components for conducting seismic
wave prospecting shown in figures 1 and 2 of the application. Since these
claims are now considered acceptable and no art has been cited, we find no
basis for the rejection on the grounds of obviousness.
In summary, we recommend the rejection of the application as obvious and
as directed to non patentable subject matter contrary to Section 2 and Section
28(3) be withdrawn, and that the application be returned for continued prosecution.
A. McDonough S.D. Kot M.G. Brown
Chairman Member Member
Patent Appeal Board
I have reviewed the prosecution of this application and concur with the
reasoning and findings of the Board. Accordingly, I withdraw the Final Action
and I am returning the application to the Examiner for further prosecution.
J.H.A. Gari‚py
Commissioner of Patents
Dated at Hull, Quebec
this 1st. day of June, 1983