Abstract: A control system for a mechanical oscillator having a sinusoidal drive signal with a frequency that is a fractional multiple of a frequency of a signal of the mechanical oscillator. The drive signal may be in phase and in registration with the signal from the mechanical oscillator. A sense signal may be picked off from the oscillator and be demodulated to obtain a parameter sensed by the oscillator. The drive signal to the oscillator may be selected or blanked out while receiving and demodulating the sense signal.

Abstract: A proximity sensor for determining the gap between a sensor and a metal target which is insensitive to noise, changes in temperature of the sensor and different lengths of wire by measuring the AC conductance, DC conductance and susceptance of the sensor and using the measured values with a predetermined data base to derive the desired gap distance.

Abstract: A proximity sensor for determining the gap between a sensor and a metal target which is insensitive to noise, changes in temperature of the sensor and different lengths of wire by measuring the AC conductance, DC conductance and susceptance of the sensor and using the measured values with a predetermined data base to derive the desired gap distance.

Abstract: A system to analyze the impedance of interference-tolerant proximity sensors. A lock-in amplifier (LIA) is implemented as a resonance-tracking oscillator. The control loop of the amplifier monitors the response of sensor in relation to the output of a local oscillator to adjust the oscillator's frequency to resonance. The nature of the sensor acts as a pre-filter of noise for a synchronous demodulator, which demodulates the sensor's response with the local oscillator's driving signal. The output of the system is a filtered version of this demodulated signal. This system is effective in sensing objects in the presence of electromagnetic noise that is many times stronger than the signal produced by the local oscillator.

Abstract: An error reducer for reducing rotation rate backscattering errors in a rotation sensor by adjusting amplitudes of bias phase modulators introduced phase changes or amplitudes of a backscatter phase modulator introduced phase change and bias phase modulator introduced phase changes.