Method and apparatus for controlling damping and in situ determination of frequency response for high bandwidth force-balance single-coil geophone
OwnerThomas R. VanZandt, Stephen J. Manioninventors
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Abstract
Force-balance feedback geophone apparatus and methods for characterization of the geophone apparatus. Control inputs (65) provide for switching (61, 63) of a force-balance feedback geophone between operational states, thereby allowing for in situ determination of geophone characteristics. Feedback circuit modification provides for increased bandwidth and a series RC circuit in the reference resistance provides for increased damping without significantly affecting low frequency performance.
Claims15
A force balance feedback geophone comprising:
- a geophone housing having a coil mounted by a spring therein, the coil being in a magnetic field and having a first terminal and a second terminal;
- an amplifier with a feedback circuit forming a feedback path, the amplifier having an input coupled to the first terminal;
- a feedback switch in the feedback path responsive to a control input, the feedback switch having a first state opening the feedback path and a second state closing the feedback path;
- and
- a bias switch coupled to the first terminal or the second terminal, the bias switch being responsive to the control input and having a first state coupling the first terminal or the second terminal to a bias input and a second state not coupling the first terminal or the second terminal to the bias input.
A method of characterizing a force balance feedback geophone comprising:
- disconnecting a feedback element of the force balance feedback geophone from a coil of the force balance feedback geophone;
- displacing the coil of the force balance feedback geophone;
- connecting the feedback element of the force balance feedback geophone to the coil of the force balance feedback geophone;
- and
- measuring an output of the force balance feedback geophone.
A force balance feedback geophone comprising:
- a single coil velocity geophone having first and second terminals;
- an amplifier with a first input coupled to the first terminal, a second input coupled to a reference resistance, and a first feedback path to the first terminal and a second feedback path to the second terminal;
- and
- the second feedback path providing RC feedback compensation.
A force balance feedback geophone comprising:
- a single coil velocity geophone having first and second terminals;
- an amplifier with a first input coupled to the first terminal, a second input coupled to a reference resistance, and a first feedback path to the first terminal and a second feedback path to the second terminal, the second feedback path including a resistance in parallel with a capacitance.
A force balance feedback geophone comprising:
- a single coil velocity geophone having first and second terminals;
- an amplifier with a first input coupled to the first terminal, a second input coupled to a reference resistance, and a first feedback path to the first terminal and a second feedback path to the second terminal;
- and
- a capacitance in parallel with the reference resistance.
Dependencies are inferred from the claim text.