Method of making geophones having matched sensitivities

Claim 1

A method of adjusting the impulse response sensitivity of a geophone having a coil mounted for movement relative to a permanent magnet, comprising: a. applying an electric impulse to the coil of the geophone to thereby displace the coil from a quiescent position; b. detecting the geophone''s response signal to said impulse, said response signal being generated by said coil; c. producing an error signal by comparing said response signal with a reference signal; and d. applying a magnetic field to the magnet of the geophone, said magnetic field having an amplitude and polarity in dependence upon said error signal.

Claim 2

A method of adjusting the impulse response sensitivity of a geophone having a coil mounted for movement relative to a permanent magnet, comprising: a. applying an electric impulse to the coil of the geophone to thereby displace the coil from a quiescent position; b. detecting the geophone''s response signal to said impulse, said response signal being generated by said coil; c. producing an error signal by comparing said response signal with a reference signal; and d. applying a magnetic field to the magnet of the geophone, said magnetic field having an amplitude and polarity in dependence upon said error signal.

Claim 4

A method of adjusting a geophone''s impulse response sensitivity so that it falls within a prescribed sensitivity deviation range, said geophone having a coil mounted for movement relative to a permanent magnet, said method comprising: a. maintaining said geophone in seismic isolation; b. magnetizing the magnet of said geophone with a saturatIng magnetic field; c. applying an electric impulse to the coil of said geophone; d. detecting the voltage generated by the coil of said geophone; e. applying a demagnetizing magnetic field to the magnet of said geophone; and f. repeating steps (be) through (e) as many times as necessary until the geophone''s impulse response sensitivity falls within said prescribed deviation range.

Claim 5

A method of adjusting a geophone''s impulse response sensitivity so that it falls within a prescribed sensitivity deviation range, said geophone having a coil mounted for movement relative to a permanent magnet, said method comprising: a. maintaining said geophone in seismic isolation; b. magnetizing the magnet of said geophone with a saturatIng magnetic field; c. applying an electric impulse to the coil of said geophone; d. detecting the voltage generated by the coil of said geophone; e. applying a demagnetizing magnetic field to the magnet of said geophone; and f. repeating steps (be) through (e) as many times as necessary until the geophone''s impulse response sensitivity falls within said prescribed deviation range.

Claim 6

A method of producing a geophone having a coil movable relative to a permanent magnet so that said geophone has a prescribed impulse response sensitivity, comprising: a. maintaining the geophone in seismic isolation; b. magnetizing the magnet of said geophone; c. applying an electric impulse to the coil of said geophone; d. detecting the peak voltage generated by the coil of said geophone; e. comparing the detected voltage with a reference voltage to thereby produce a deviation voltage; f. incrementally magnetizing the magnet of said geophone; and g. repeating steps (b) through (f) as many times as necessary until the geophone attains said prescribed impulse response sensitivity.

Claim 7

A method of producing a geophone having a coil movable relative to a permanent magnet so that said geophone has a prescribed impulse response sensitivity, comprising: a. maintaining the geophone in seismic isolation; b. magnetizing the magnet of said geophone; c. applying an electric impulse to the coil of said geophone; d. detecting the peak voltage generated by the coil of said geophone; e. comparing the detected voltage with a reference voltage to thereby produce a deviation voltage; f. incrementally magnetizing the magnet of said geophone; and g. repeating steps (b) through (f) as many times as necessary until the geophone attains said prescribed impulse response sensitivity.

Claim 8

A method of adjusting the impulse response sensitivity of an unknown geophone having a coil movable relative to a permanent magnet so that the geophone''s impulse response sensitivity matches the impulse response sensitivity of a standard geophone, comprising: a. maintaining said unknown and said standard geophones in seismic isolation; b. applying an electric impulse to the coil of each of said geophones; c. detecting the response signal generated by the coil of each geophone; d. comparing the detected response signals to thereby produce a resultant signal; e. applying a magnetic field to the magnet of the unknown geophone; and f. repeating steps (b) through (e) as many times as necessary to thereby change said resultant signal to a prescribed value.

Claim 9

A method of adjusting the impulse response sensitivity of an unknown geophone having a coil movable relative to a permanent magnet so that the geophone''s impulse response sensitivity matches the impulse response sensitivity of a standard geophone, comprising: a. maintaining said unknown and said standard geophones in seismic isolation; b. applying an electric impulse to the coil of each of said geophones; c. detecting the response signal generated by the coil of each geophone; d. comparing the detected response signals to thereby produce a resultant signal; e. applying a magnetic field to the magnet of the unknown geophone; and f. repeating steps (b) through (e) as many times as necessary to thereby change said resultant signal to a prescribed value.