Method and apparatus for improving performance of a force balance accelerometer based on a single-coil velocity geophone

摘要

The invention concerns methods and apparatus for improving the performance of a force-balance accelerometer based upon a conventional, single-coil, velocity geophone. Specifically, the operating temperature range is increased through the use of both a temperature-compensating reference impedance, and a new electronic circuit architecture. Two specific types of temperature-compensating reference impedances are disclosed. One is a pure DC-resistance, with the temperature coefficient of the DC resistance matching that of a single coil of a conventional geophone. A second reference impedance adds a series reactance which closely matches the ratio of total impedance to DC-resistance, and the temperature coefficient of this ratio, with that of the geophone coil. ;A method is also described which provides for decreased magnitude of a reference impedance required in an accelerometer. This allows for a significant reduction in the physical size of the reference impedance. The reduction in size reduces the physical size of the impedance and the sensitivity of the accelerometer to external time-varying magnetic fields.