Vibrator performance monitor

Claim 2

In a seismic prospecting system utilizing at least one individual earth vibrator for generating seismic signals at a pattern of separated locations on the surface of the earth in accordance with a predetermined electrical driving signal, the method of monitoring individual vibrator operation comprising the steps of: a. producing a monitor electrical signal corresponding to each said seismic signal injected into the earth by said individual vibrator at each vibrator location; b. amplifying each said monitor electrical signal such that its amplitude approximately equals the amplitude of said predetermined electrical driving signal; c. comparing each said amplified monitor and said predetermined electrical driving signal such that a first malfunction signal is produced when said signals differ in a first predetermined amount indicative of faulty vibrator operation; and d. actuating a first indicator at said individual vibrator by said first malfunction signal, whereby the operator of said individual vibrator can be altered to the fact that his equipment is not operating correctly and should be adjusted.

Claim 3

A method as recited in claim 1 where said monitor signal producing step is accomplished by generating said monitor electrical signal with an elastic wave transducer placed at least near the base plate of said individual vibrator.

Claim 4

A vibrator monitoring method as recited in claim 1 where said comparing step is accomplished by use of a phase coMparator circuit such that said first malfunction signal is produced when the phase difference between said monitor and driving signals exceeds a predetermined value chosen to be indicative of faulty vibrator performance.

Claim 5

A vibrator monitoring method as recited in claim 1 where said comparing step is accomplished with an amplitude comparator circuit such that a change in amplitude ratio between said monitor and driving signals which as a function of frequency exceeds a predetermined value produces said first malfunction signal.

Claim 6

A method of vibrator monitoring as recited in claim 1 further comprising the steps of: a. filtering said monitor signal using a first band-pass filter to attenuate harmonics and noise generated by said individual vibrator during the injection process; and b. filtering said predetermined electrical drive signal with a second band-pass filter having essentially identical amplitude and phase response characteristics with said first band-pass filter for the purpose of introducing phase and amplitude distortions essentially equal to those introduced by said filtering step (a) above.

Claim 7

A vibrator monitoring method as recited in claim 1 further comprising the steps of: a. comparing said monitor and electrical driving signals such that a second malfunction signal is produced when said signals differ in a second predetermined manner indicative of more severe vibrator malfunction than said faulty operation indicated by said first malfunction signal; and b. actuating a second indicator within said individual vibrator vehicle by said second malfunction signal, whereby the operator of said individual vibrator can be altered that his equipment is seriously malfunctioning and should not be used further until repaired.

Claim 8

A method of vibrator operation monitoring as recited in claim 6 further comprising the step of automatically stopping said individual vibrator when said second malfunction comparison step produces said second malfunction signal indicating that said monitor and drive signals differ by said second predetermined amount.

Claim 9

In a seismic prospecting system having a plurality of individual earth vibrators for simultaneously injecting a sequence of seismic signals at separated locations on the earth''s surface in synchronism with a predetermined electrical drive signal, a remove seismic data amplifying and reproducible recording apparatus for amplifying and reproducibly recording the seismic data signals resulting from said seismic signal injection process, the method of monitoring said seismic signals injected into the earth by each of said individual vibrators during each cycle of said sequence comprising the steps of: a. at each of said individual vibrator locations producing a monitor electrical signal corresponding to said individual seismic signal injected into the earth by said individual vibrator; b. amplifying each of said monitor electrical signals such that its amplitude approximately equals the level of said predetermined electrical driving signal; c. filtering each said amplified electrical monitor signal to attenuate harmonics and other vibrator associated noise; d. transmitting said filtered monitor signals from each of said individual vibrators to a central control location; e. at said central control location producing a replica of said predetermined electrical drive signal; f. filtering said replica predetermined drive signal with a filter essentially identical to that used in step (c) above for the purpose of introducing essentially equal phase and amplitude response changes; g. first comparing each of said individual monitor signals with said replica predetermined electrical drive signal such that a third and fourth electrical malfunction signal is produced when any of said individual monitor signals correspondingly differ from said replica drive signal by a third and fourth predetermined amount, said third predetermined amount being chosen to indicate faulty Vibrator operation of a single vibrator of such degree as to require remedial vibrator repairs and said fourth predetermined amount being chosen to indicate serious seismic data quality degradation requiring shut down of said vibrator; h. electronically summing said individual monitor signals to produce a composite monitor signal corresponding to the total seismic signal simultaneously injected from all of said individual vibrators during any one injection cycle; i. comparing said composite monitor signal with said predetermined electrical drive signal to produce fifth and sixth electrical malfunction signals when said composite monitor and replica drive signals correspondingly differ by a fifth and sixth predetermined amount, said fifth predetermined amount being chosen to indicate moderate composite injected signal distortion such that the signal injection cycle sequence may be extended using the remaining good vibrators to improve seismic data quality; and said sixth predetermined amount being chosen to indicate severe composite injected signal distortion such that a repeated injection cycle sequence is required; and j. indicating by means of a plurality of audio-visual signals to an operator at said central control location when said fourth, fifth and sixth malfunction signals are present, thereby alerting him to faulty vibrator operation so that remedial action can be taken by directing a faulty vibrator to shut down when said fourth malfunction signal is actuated, extension of said injection cycle sequence with the remaining good vibrators when said fifth malfunction signal is present and repeating the entire injection cycle sequence when said sixth malfunction signal is present before the individual vibrators have been moved from their respective injection locations.

Claim 10

In a seismic prospecting system having a plurality of individual earth vibrators for simultaneously injecting a sequence of seismic signals at separated locations on the earth''s surface in synchronism with a predetermined electrical drive signal, a remove seismic data amplifying and reproducible recording apparatus for amplifying and reproducibly recording the seismic data signals resulting from said seismic signal injection process, the method of monitoring said seismic signals injected into the earth by each of said individual vibrators during each cycle of said sequence comprising the steps of: a. at each of said individual vibrator locations producing a monitor electrical signal corresponding to said individual seismic signal injected into the earth by said individual vibrator; b. amplifying each of said monitor electrical signals such that its amplitude approximately equals the level of said predetermined electrical driving signal; c. filtering each said amplified electrical monitor signal to attenuate harmonics and other vibrator associated noise; d. transmitting said filtered monitor signals from each of said individual vibrators to a central control location; e. at said central control location producing a replica of said predetermined electrical drive signal; f. filtering said replica predetermined drive signal with a filter essentially identical to that used in step (c) above for the purpose of introducing essentially equal phase and amplitude response changes; g. first comparing each of said individual monitor signals with said replica predetermined electrical drive signal such that a third and fourth electrical malfunction signal is produced when any of said individual monitor signals correspondingly differ from said replica drive signal by a third and fourth predetermined amount, said third predetermined amount being chosen to indicate faulty Vibrator operation of a single vibrator of such degree as to require remedial vibrator repairs and said fourth predetermined amount being chosen to indicate serious seismic data quality degradation requiring shut down of said vibrator; h. electronically summing said individual monitor signals to produce a composite monitor signal corresponding to the total seismic signal simultaneously injected from all of said individual vibrators during any one injection cycle; i. comparing said composite monitor signal with said predetermined electrical drive signal to produce fifth and sixth electrical malfunction signals when said composite monitor and replica drive signals correspondingly differ by a fifth and sixth predetermined amount, said fifth predetermined amount being chosen to indicate moderate composite injected signal distortion such that the signal injection cycle sequence may be extended using the remaining good vibrators to improve seismic data quality; and said sixth predetermined amount being chosen to indicate severe composite injected signal distortion such that a repeated injection cycle sequence is required; and j. indicating by means of a plurality of audio-visual signals to an operator at said central control location when said fourth, fifth and sixth malfunction signals are present, thereby alerting him to faulty vibrator operation so that remedial action can be taken by directing a faulty vibrator to shut down when said fourth malfunction signal is actuated, extension of said injection cycle sequence with the remaining good vibrators when said fifth malfunction signal is present and repeating the entire injection cycle sequence when said sixth malfunction signal is present before the individual vibrators have been moved from their respective injection locations.

Claim 11

The method as recited in claim 8 further comprising the steps of: a. encoding said third, fourth, fifth and sixth malfunction signals produced by said individual vibrator and said composite signal comparing steps in a form such that the encoded signal frequencies fall within the bandwidth of said remote seismic data amplifying and reproducible recording apparatus; b. transmitting said encoded malfunction signal from said central control location to said remote seismic data amplifying and recording apparatus location; c. decoding said encoded malfunction signal to reproduce said third, fourth, fifth and sixth malfunction signals in their original form at said remote amplifying and recording apparatus location; d. indicating to a recorder operator by means of audio visual signals when said fourth, fifth and sixth malfunction signals are present such that said recorder operator can delete seismic data signals recorded during a faulty vibrator injection cycle.

Claim 12

The method as recited in claim 9 further comprising the step of reproducibly recording said encoded malfunction signal on an auxiliary seismic data channel in said amplifying and reproducible recording apparatus for the purpose of subsequent decoding at a remote data processing center to recover said third, fourth, fifth and sixth malfunction signals thereby permitting subsequent data editing where vibrator failures have occurred.

Claim 13

The method as recited in claim 9 further comprising the step of reproducibly recording said third, fourth, fifth and sixth decoded malfunction signals on separate individual recording channels for the purpose of subsequent identification and analysis of faulty vibrator performance.

Claim 14

The method as recited in claim 9 further comprising the step of automatically stopping the summation of received seismic signals in said amplifying and reproducibly recording apparatus when said sixth malfunction signal is present.

Claim 15

An improved seismic prospecting method where a plurality of earth vibrators simultaneously inject a sequence of essentially identical seismic signals into the earth at a first series of separated vibrator locations on the earth''s surface, a plurality of seismOmeters located at a second series of separated seismometer locations produce electrical seismometer signals corresponding to said seismic signal at each seismometer location after reflection and refraction by said surface acoustical interfaces, at a remote multichannel recording apparatus location separately amplifying each seismometer signal, summing the corresponding seismometer signals produced during each cycle of the injection sequence and reproducibly recording the separate final sum signals when each injection sequence is complete, wherein the improvement comprises: a. at each separated vibrator location producing a predetermined vibrator drive signal for the purpose of controlling said vibrator, said drive signal being essentially synchronized with all other drive signals produced by other vibrator locations; b. at each separated vibrator location producing a monitor electrical signal corresponding to the seismic signal actually injected into the earth by said earth vibrator; c. at said remote recording apparatus location producing a replica of said predetermined vibrator drive signals essentially in synchronism with said predetermined drive signals produced at each of said earth vibrator locations; d. amplifying said monitor signal at each separated vibrator location until its amplitude essentially equals that of said predetermined drive signal; e. filtering said monitor signal to attenuate harmonics and other vibrator noises; f. transmitting each of said filtered monitor signals separately from each of said plurality of earth vibrator locations to a central control location; g. multiplexing said plurality of earth vibrator monitor signals at said central location to form a single multiplexed monitor signal; h. retransmitting said single multiplexed monitor signal from said central control location to said remote multichannel recording apparatus location; i. at said remote recording apparatus location demultiplexing said multiplexed monitor signal to produce separate monitor electrical signals corresponding to each of said original plurality of seismic vibrator signals; j. filtering said replica of said predetermined vibrator drive signals produced at said remote recording apparatus in step (c) above where said filter is essentially identical to said filters used in step (e) above to eliminate harmonics and other noises on the individual vibrator monitor signals, said filtering being for the purpose of introducing essentially identical phase and amplitude distortions on the monitor and driving signals; k. comparing said filtered replica drive signal with each of said demultiplexed electrical monitor signals to produce a seventh malfunction signal when any of said monitor signals differ from said predetermined replica drive signal by a seventh predetermined amount chosen to indicate faulty vibrator operation which may impair seismic data quality; l. comparing said filter replica drive signal with each of said demultiplexed electrical monitor signals to produce an eighth malfunction signal when any of said monitor signals differ from said predetermined replica drive signal by an eighth predetermined amount chosen to indicate a more severe vibrator malfunction than in step (k) above such that a severe degradation in the seismic data quality wll occur; m. indicating to said recorder operator by means of a seventh audio-visual indicator when said seventh malfunction signal is produced in comparison step (k) above; and n. indicating to said recorder operator by means of an eighth audiovisual indicator when said eighth malfunction signal is produced by said comparison step (l) above.

Claim 16

An improved seismic prospecting method where a plurality of earth vibrators simultaneously inject a sequence of essentially identical seismic signals into the earth at a first series of separated vibrator locations on the earth''s surface, a plurality of seismOmeters located at a second series of separated seismometer locations produce electrical seismometer signals corresponding to said seismic signal at each seismometer location after reflection and refraction by said surface acoustical interfaces, at a remote multichannel recording apparatus location separately amplifying each seismometer signal, summing the corresponding seismometer signals produced during each cycle of the injection sequence and reproducibly recording the separate final sum signals when each injection sequence is complete, wherein the improvement comprises: a. at each separated vibrator location producing a predetermined vibrator drive signal for the purpose of controlling said vibrator, said drive signal being essentially synchronized with all other drive signals produced by other vibrator locations; b. at each separated vibrator location producing a monitor electrical signal corresponding to the seismic signal actually injected into the earth by said earth vibrator; c. at said remote recording apparatus location producing a replica of said predetermined vibrator drive signals essentially in synchronism with said predetermined drive signals produced at each of said earth vibrator locations; d. amplifying said monitor signal at each separated vibrator location until its amplitude essentially equals that of said predetermined drive signal; e. filtering said monitor signal to attenuate harmonics and other vibrator noises; f. transmitting each of said filtered monitor signals separately from each of said plurality of earth vibrator locations to a central control location; g. multiplexing said plurality of earth vibrator monitor signals at said central location to form a single multiplexed monitor signal; h. retransmitting said single multiplexed monitor signal from said central control location to said remote multichannel recording apparatus location; i. at said remote recording apparatus location demultiplexing said multiplexed monitor signal to produce separate monitor electrical signals corresponding to each of said original plurality of seismic vibrator signals; j. filtering said replica of said predetermined vibrator drive signals produced at said remote recording apparatus in step (c) above where said filter is essentially identical to said filters used in step (e) above to eliminate harmonics and other noises on the individual vibrator monitor signals, said filtering being for the purpose of introducing essentially identical phase and amplitude distortions on the monitor and driving signals; k. comparing said filtered replica drive signal with each of said demultiplexed electrical monitor signals to produce a seventh malfunction signal when any of said monitor signals differ from said predetermined replica drive signal by a seventh predetermined amount chosen to indicate faulty vibrator operation which may impair seismic data quality; l. comparing said filter replica drive signal with each of said demultiplexed electrical monitor signals to produce an eighth malfunction signal when any of said monitor signals differ from said predetermined replica drive signal by an eighth predetermined amount chosen to indicate a more severe vibrator malfunction than in step (k) above such that a severe degradation in the seismic data quality wll occur; m. indicating to said recorder operator by means of a seventh audio-visual indicator when said seventh malfunction signal is produced in comparison step (k) above; and n. indicating to said recorder operator by means of an eighth audiovisual indicator when said eighth malfunction signal is produced by said comparison step (l) above.

Claim 17

A method as recited in claim 13 further comprising the step of reproducibly recording said demultiplexed electrical monitor signals and said replica predetermined drive signal on auxiliary channels of said reproducible recording apparatus for subsequent analysis in conjunction with said reproducibly recorded seismic data sigNals.

Claim 18

In a seismic prospecting system of the type having a plurality of earth vibrators which simultaneously inject vibratory seismic signals into the earth, a means within each of said earth vibrators for producing a predetermined electrical driving signal, a vibrator control means within each individual earth vibrator for actuating said individual vibrator in response to said predetermined electrical driving signal such that such injected vibratory seismic signal approximately coincides with said predetermined electrical signal, an individual vibrator performance monitoring apparatus comprising: a. means for producing a monitor electrical signal corresponding to said vibratory signal injected into the earth by each of said plurality of vibrators at its respective operating location; b. means for amplifying said monitor electrical signal such that its level essentially equals that of said predetermined electrical driving signal produced within each of said plurality of vibrators; c. means for filtering said amplified monitor electrical signal to remove harmonics and noise; d. means for filtering said predetermined electrical driving signal in an essentially identical manner as accomplished by said monitor signal filtering means in step (c) above, for the purpose of introducing equal phase shifts and amplitude variations in said monitor and driving signals; e. means for comparing said filtered predetermined electrical driving signal and said filtered electrical monitor signal so as to produce first and second malfunction signals when said driving and monitoring signals differ respectively by a first predetermined amount and a second predetermined amount, said first predetermined amount being chosen to indicate faulty vibrator operation of a degree which requires remedial action by said vibrator operator but not complete shutdown and said second predetermined amount being established to indicate severe vibrator malfunction which would degrade seismic data produced by its continued operation; and f. means within each of said plurality of vibrators for producing both visual and oral indications of said first and second malfunction signals to alert an operator of said individual earth vibrator that his equipment is malfunctioning.

Claim 19

In a seismic prospecting system of the type having a plurality of earth vibrators which simultaneously inject vibratory seismic signals into the earth, a means within each of said earth vibrators for producing a predetermined electrical driving signal, a vibrator control means within each individual earth vibrator for actuating said individual vibrator in response to said predetermined electrical driving signal such that such injected vibratory seismic signal approximately coincides with said predetermined electrical signal, an individual vibrator performance monitoring apparatus comprising: a. means for producing a monitor electrical signal corresponding to said vibratory signal injected into the earth by each of said plurality of vibrators at its respective operating location; b. means for amplifying said monitor electrical signal such that its level essentially equals that of said predetermined electrical driving signal produced within each of said plurality of vibrators; c. means for filtering said amplified monitor electrical signal to remove harmonics and noise; d. means for filtering said predetermined electrical driving signal in an essentially identical manner as accomplished by said monitor signal filtering means in step (c) above, for the purpose of introducing equal phase shifts and amplitude variations in said monitor and driving signals; e. means for comparing said filtered predetermined electrical driving signal and said filtered electrical monitor signal so as to produce first and second malfunction signals when said driving and monitoring signals differ respectively by a first predetermined amount and a second predetermined amount, said first predetermined amount being chosen to indicate faulty vibrator operation of a degree which requires remedial action by said vibrator operator but not complete shutdown and said second predetermined amount being established to indicate severe vibrator malfunction which would degrade seismic data produced by its continued operation; and f. means within each of said plurality of vibrators for producing both visual and oral indications of said first and second malfunction signals to alert an operator of said individual earth vibrator that his equipment is malfunctioning.

Claim 20

A vibrator performance monitoring apparatus as recited in claim 15 where said comparing means comprises: a. means for measuring the phase shift between said monitor and driving signals; b. means for producing a low level phase malfunction signal when said phase shift measured by said phase measuring means exceess a first predetermined phase difference; c. means for producing a high level phase malfunction signal when said phase shift measured by said phase measuring means exceeds a second predetermined phase difference beyond said first predetermined phase difference; d. means for measuring an amplitude difference between said monitor and driving signals; e. means for producing a low-level amplitude malfunction signal when said amplitude difference measured by said amplitude measuring means exceeds a first predetermined amplitude difference threshold; f. means for producing a high-level amplitude malfunction signal when said amplitude difference measured by said amplitude measuring means exceeds a second predetermined amplitude difference threshold beyond said first predetermined amplitude threshold; g. a first four position, low-level switching means connected between a first malfunction signal output terminal, said low-level phase malfunction signal producing means and said low level amplitude malfunction signal producing means where said first malfunction signal is produced at said first output terminal by said low-level phase malfunction signal alone in the first position, by said low-level amplitude malfunction signal alone in the second position, by either said low-level phase or low-level amplitude malfunction signals in the third position, and by both the low-level phase anD low-level amplitude malfunction signals in the fourth position; and h. a second four position, high-level switching means connected between a second malfunction signal output terminal, said high-level phase malfunction signal producing means, and said high-level amplitude malfunction signal producing means, where said second malfunction signal is produced at said second output terminal by said high-level phase malfunction signal alone in the first switch position by said high-level amplitude malfunction signal alone in the second switch position by either said high-level phase malfunction signal or high-level amplitude malfunction signal in the third position and by both high-level phase and high-level amplitude malfunction signals in the fourth switch position.

Claim 21

A vibrator performance monitoring apparatus as recited in claim 15 further comprising: a. transmission means located within each of said plurality of earth vibrators switchably connected to said monitor electrical signal filtering means for the purpose of transmitting said individual earth vibrator monitor signals to a central control location for comparison with other signals from other individual vibrators; b. reception means connected to said transmission means located at a central control location for separately reproducing said monitor signals from each of said plurality of earth vibrators; c. means for producing a first replica of said predetermined electrical driving signal at said central control location; d. means for filtering said replica driving signal in essentially an identical manner as accomplished by said monitor and driving signal filtering means performed at each of said plurality of earth vibrator locations for the purpose of introducing phase shift and amplitude variations essentially equal to those introduced by said filtering means located at each earth vibrator location; e. summing means connected to said reception means for compositing monitor signals received at said central control location from each of said plurality of earth vibrators, thereby producing a summed monitor signal representative of the composite seismic signal injected into the earth by all of said plurality of earth vibrators operating simultaneously; f. a plurality of control location comparing means each for comparing said filtered replica predetermined electrical driving signal with each of said monitor signals received at said central control location by said reception means and with said summed monitor signal produced by said summing means, producing a third and fourth malfunction signal when said replica driving signal and corresponding individual monitor signals differ respectively by a third and fourth predetermined amount, said third predetermined amount being chosen to indicate faulty vibrator operation of a degree which requires remedial action but not so severe as to require repeating the seismic signal injection procedure and said fourth predetermined amount being chosen to indicate severe vibrator malfunction of a degree which requires repetition of the seismic injection procedure after vibrator repairs have been effected; and g. a plurality of audio-visual indicating means each connected on one of said comparing means for the purpose of providing a visual and audible indication of said third and fourth malfunction signals to personnel at said central control location so that remedial action to repair faulty vibrators can be taken and seismic signal injection cycles repeated where required.

Claim 22

A vibrator performance monitoring apparatus as recited in claim 17 further comprising: a. a signal encoder connected to each of said plurality of comparing means for encoding said third and fourth malfunction signals from each comparing means into a single encoded signal having a band width commensorate with a bandwith recording capability of a seismic recording apparatus; b. transmission means switchably connected to said encoding means for transmitting said Encoded signal to a remote recording apparatus location; c. reception means connected to said transmission means for reproducing signals from said transmission means at a remote recording apparatus location; d. decoding means connected to said remote recorder reception means for decoding said encoded signal thereby reproducing said third and fourth malfunction signals from each of said comparing means at said remote recorder; e. a plurality of audio-visual indicator means located at said remote recorder location connected to said decoding means to visually and audibly alert said recorder equipment operator when said third and fourth malfunction signals are present, thereby permitting him to delete a seismic data recording taken during a faulty vibrator injection cycle and to repeat an injection cycle where necessary; f. an automatic switch means connected between said decoding means and a seismic data signal summing means such that when a fourth malfunction signal is produced by said composite signal comparison means seismic data summed during a faulty vibrator injection cycle will be automatically deleted from previous seismic data summed before said faulty vibrator injection cycle; and g. an encoded signal recording means connected between said reception means and said seismic recording apparatus for amplifying and reproducibly recording said encoded signal in conjunction with seismic data signals produced by said plurality of earth vibrators.

Claim 23

A vibrator performance monitor apparatus as recited in claim 17 further comprising: a. signal multiplexing means connected to said reception means and to said replica driving signal producing means at said central location for the purpose of multiplexing said individual vibrator monitor signals and said replica driving signal, said signal multiplexing means being connected to said transmission means through a switch which when in the multiplex position will cause said transmission means to transmit said multiplex signal in lieu of said encoded signal; b. a demultiplexing means located at said recording apparatus switchably connected to said receiver means such that said multiplex signal received from said central control location is demultiplexed thereby reproducing the original monitor signals from each of said plurality of vibrators and said central control location replica driving signal; c. a recorder signal generator located at said recording apparatus for producing a second replica of said predetermined electrical vibrator driving signal; d. means for filtering said second replica driving signal in an essentially identical manner as accomplished by said driving signal filtering means at said central control location and at each individual vibrator location for the purpose of introducing equivalent phase shifts and amplitude variations at said recording apparatus location; e. comparing means switchably connected to said second replica driving signal filtering means and to said demultiplexing means for producing a fifth and sixth malfunction signal when said second replica driving signal respectively differs from a switch selected monitor signal output from said demultiplexer means by a fifth and sixth predetermined amount, said fifth predetermined amount being chosen to indicate faulty vibrator performance of a degree requiring shutdown of that particular vibrator and further injection cycles on the part of the remaining good vibrators and said sixth predetermined amount being chosen to indicate such severe vibrator malfunctions that the entire injection procedure by all vibrators must be terminated until repairs have been effected; and f. audio-visual indicating means connected to said replica signal comparing means for indicating the presence of said fifth and sixth malfunction signals to said recording equipment operator to permit him to make appropriate adjustments in the field operating procedure to correct for vibrator malfunctions.

Claim 24

A vibrator monitoring apparatUs as recited in claim 19 further comprising switching means at each individual vibrator for connecting said individual vibrator transmission means to said individual vibrator predetermined electrical driving signal producing means, thereby permitting said recording equipment operator to check synchronization between each of said driving signal producing means located in each individual vibrator, said central control location, and said recording equipment location.