Earth vibrator tester

Claim 3

A method as recited in claim 1 further comprising the steps of: a. amplifying said filtered base plate signal using a first automatic gain control amplifier such that the amplitude of said filtered base plate signal remains substantially constant over the duration of said test signal; b. amplifying said filtered test signal with a second automatic gain control amplifier for the purpose of introducing phase shifts and amplitude changes in said filtered test signal which are essentially identical to those introduced in said base plate signal in step (a) above.

Claim 4

A method as recited in claim 2 further comprising the step of presetting said first and second automatic gain control amplifiers to a predetermined fixed gain for a period of time beginning at the inception of said test signal cycle and lasting until said test and base plate signals have effectively achieved control of said automatic gain control circuits.

Claim 5

A method as recited in claim 1 where said generating step is accomplished by varying the output frequEncy of a voltage controlled oscillator in correspondance with a voltage control signal having a manually selectable initial voltage, final voltage, duration, and voltage change as a function of time between said initial and final voltages.

Claim 6

A method as recited in claim 4 where said base plate and test signal filtering steps are accomplished using essentially identical voltage responsive filtering circuits controlled by said voltage control signal such that at any interval of time during the test signal duration the center pass-band frequency of said base plate signal filter and said test signal filter coincide with the frequency of the test signal generated by said voltage controlled oscillator.

Claim 7

A method as recited in claim 1 further comprising the step of tapering the amplitude of said predetermined frequency test signal such that said test signal amplitude increases from 0 to maximum value over a time interval of from 10 to 500 milliseconds after the inception of said test signal and decreases from maximum to 0 amplitude over a time interval of from 10 to 500 milliseconds prior to the termination of said test signal.

Claim 8

An individual earth vibrator testing method as recited in claim 1 where said displaying step is accomplished by reproducing said test and base plate signals on the face of an oscilloscope in a manner such that the time varying phase differences between said signals may be viewed by said earth vibrator operator in real time as said test signals are being injected into the earth.

Claim 9

An individual earth vibrator testing method as recited in claim 1 further comprising the step of plotting an oscillographic paper record having said base plate and test signals in close proximity such that phase differences between said test and base plate signals can be measured as a function of signal duration and frequency to permit said vibrator operator to determine the effect of equipment adjustments and repairs.

Claim 10

In seismic prospecting system having at least one mechanical earth vibrator for injecting a seismic signal into the earth, an electrical pilot signal generator at each earth vibrator location for producing a common predetermined electrical pilot signal, a first injected signal transducer rigidly attached to each mechanical earth vibrator for producing a first electrical signal corresponding to said seismic signal injected into the earth by said vibrator and a vibrator controller connected to said pilot signal generator, said mechanical vibrator and said first transducer for actuating said vibrator in substantial coincidence with said pilot signal, said vibrator controller containing a phase comparator circuit having a first input connected to said first transducer through a first filtering and integration network and a second input connected to said pilot signal generator through a second filtering and integration network and an output connected to a phase shifter for the purpose of maintaining a consistent phase relationship between said pilot and said first transducer signals by shifting the phase of said pilot signal before actuating said mechanical vibrator; an individual vibrator system testing apparatus comprising: a. a means for generating a predetermined variable frequency test signal switchably connected to said vibrator controller input such that said test signal may be directed to said vibrator controller in lieu of said pilot signal when desired by an operator of said individual vibrator; b. a second transducer located in close proximity to said mechanical earth vibrator for providing a second electrical signal corresponding to said injected seismic signal; c. a first filtering means switchably connected to said second transducer for attenuating harmonics and noise present on said second electrical signal; d. a second filtering means switchably connected to said test signal generating means, said second filtering means having essentially identical phase transfer characteristics as said first fiLtering means such that substantially the same phase shifts are introduced in said test signal as are introduced in said second electrical signal by said first filtering means; and e. display means switchably connected to the input and output of said first and second filtering means for providing a visual display to said individual vibrator operator of the phase relationship between said test and second electrical signals before and after filtering, thereby permitting said operator to monitor the performance of his individual vibrator.

Claim 11

In seismic prospecting system having at least one mechanical earth vibrator for injecting a seismic signal into the earth, an electrical pilot signal generator at each earth vibrator location for producing a common predetermined electrical pilot signal, a first injected signal transducer rigidly attached to each mechanical earth vibrator for producing a first electrical signal corresponding to said seismic signal injected into the earth by said vibrator and a vibrator controller connected to said pilot signal generator, said mechanical vibrator and said first transducer for actuating said vibrator in substantial coincidence with said pilot signal, said vibrator controller containing a phase comparator circuit having a first input connected to said first transducer through a first filtering and integration network and a second input connected to said pilot signal generator through a second filtering and integration network and an output connected to a phase shifter for the purpose of maintaining a consistent phase relationship between said pilot and said first transducer signals by shifting the phase of said pilot signal before actuating said mechanical vibrator; an individual vibrator system testing apparatus comprising: a. a means for generating a predetermined variable frequency test signal switchably connected to said vibrator controller input such that said test signal may be directed to said vibrator controller in lieu of said pilot signal when desired by an operator of said individual vibrator; b. a second transducer located in close proximity to said mechanical earth vibrator for providing a second electrical signal corresponding to said injected seismic signal; c. a first filtering means switchably connected to said second transducer for attenuating harmonics and noise present on said second electrical signal; d. a second filtering means switchably connected to said test signal generating means, said second filtering means having essentially identical phase transfer characteristics as said first fiLtering means such that substantially the same phase shifts are introduced in said test signal as are introduced in said second electrical signal by said first filtering means; and e. display means switchably connected to the input and output of said first and second filtering means for providing a visual display to said individual vibrator operator of the phase relationship between said test and second electrical signals before and after filtering, thereby permitting said operator to monitor the performance of his individual vibrator.

Claim 12

An individual earth vibrator test apparatus as recited in claim 9 further comprising: a. a first switch means connected between said first filter means, said second transducer and said first phase comparator input for the purpose of permitting said vibrator operator to observe on said display said first transducer signal after integration and filtering accomplished within said vibrator controller prior to input to said phase comparator in lieu of second transducer signal when said first switch means is activated; and b. a second switch means connected between said second filtering means, said test signal generating means and said second phase comparator input for the purpose of permitting said vibrator operator to observe on said display said test signal input to said phase comparator after integration and filtering accomplished within said vibrator controller in lieu of said test signal directly from said test signal generating means.

Claim 13

An individual earth vibrator testing apparatus as recited in claim 9 where said variable frequency test signal generation means comprises: a. means for producing a variable voltage control signal having a manually selectable initial voltage, duration, final voltage, and voltage change as a function of time over said duration between said initial and final voltages; and b. a voltage controlled oscillator means connected to said means for producing said variable frequency test signal such that the frequency of said test signal corresponds to the voltage of said control signal.

Claim 14

An individual earth vibrator testing apparatus as recited in claim 11 where said first filtering means comprises a voltage controlled filter connected to said variable voltage control signal producing means such that the center frequency of the pass band of said filter corresponds to said voltage controlled signal in essentially the same manner as said voltage controlled oscillator means thereby passing with substantially no attenuation the instantaneous frequency of said second transducer signal corresponding to the same instantaneous frequency of said test signal, the band width of said pass band being chosen such that harmonics of any test signal frequency are attenuated.

Claim 15

An individual earth vibrator testing apparatus as recited in claim 11 where said second filtering means comprises a voltage controlled filter connected to said variable voltage control signal producing means such that the phase shift produced by said second filtering means is essentially identical to the phase shift produced by said first filtering means at each voltage controlled frequency thereby phase shifting said test signals substantially the same amount at each frequency as the phase shift introduced in said second transducer signal by said first filtering means.

Claim 16

An individual earth vibrator testing apparatus as recited in claim 9 where said displaying means comprises: a. an oscilloscope connected to said test and transducer signal filtering means having a two-channel electronic switch and internal time base generator for displaying said test and transducer wave forms side-by-side mounted so said vibrator operator can observe phase differences between said test and transducer signals as a function of time; and b. an oscillographic display means connected to said test and transducer signal filter means for intermittently producing a paper record with said test and transducer signals plotted in such a foRm that phase variations can be detected by said vibrator operator as a function of test frequency signal and duration.

Claim 17

An individual vibrator testing apparatus as recited in claim 14 further comprising: a. a first automatic gain control means connected between said first filtering means and said display means for the purpose of maintaining substantially constant amplitude on said second transducer signal; and b. a second automatic gain control means connected between said second filtering means and said display means for the purpose of introducing essentially identical phase shifts in said variable frequency test signal as introduced by said first automatic gain control means in said second transducer signal in step (a) above.

Claim 18

An individual vibrator testing apparatus as recited in claim 15 further comprising a time sequence controller connected to said variable frequency generating means, said oscillographic display means and said first and second automatic gain control means for providing a predetermined time sequence of switching functions following an initiation pulse produced by said vibrator operator, said time sequence controller providing a switch closure to initiate said variable frequency test signal generation, a switch closure of a predetermined duration chosen to produce an oscillographic record of duration long enough to encompass said variable frequency test signal duration, switch closures of sufficient duration to apply a preset signal to said first and second AGC amplifiers for the purpose of maintaining a fixed output display signal level during the period before said test and second transducer signals can effectively control gain of said amplifiers.