Abstract: Systems and methods for environmentally insensitive high-performance fiber-optic gyroscopes are provided. In one embodiment, a loop closure electronics apparatus for a fiber optic gyroscope having an optical phase modulator characterized by a transfer function that includes an error component of at least second order is provided. The apparatus comprises: a first digital circuit that generates a digital bias modulation signal; a second digital circuit that generates a digital feedback signal; at least one digital-to-analog converter that produces an electrical signal that drives the phase modulator from the digital bias modulation signal and the digital feedback signal; and a compensator that includes an analog filter of at least second order and a digital filter of at least second order, wherein the analog filter and the digital filter pre-filter the electrical signal to compensate for the error component.

Abstract: Systems and methods for environmentally insensitive high-performance fiber-optic gyroscopes are provided. In one embodiment, a loop closure electronics apparatus for a fiber optic gyroscope having an optical phase modulator characterized by a transfer function that includes an error component of at least second order is provided. The apparatus comprises: a first digital circuit that generates a digital bias modulation signal; a second digital circuit that generates a digital feedback signal; at least one digital-to-analog converter that produces an electrical signal that drives the phase modulator from the digital bias modulation signal and the digital feedback signal; and a compensator that includes an analog filter of at least second order and a digital filter of at least second order, wherein the analog filter and the digital filter pre-filter the electrical signal to compensate for the error component.

Abstract: A synchronous fiber optic gyroscope includes a light source, an optical coupler in optical communication with the light source, an optical modulator in optical communication with the coupler, and a fiber optic coil in optical communication with the modulator. A detector is configured to receive an optical signal from the coupler and convert the optical signal to an electrical signal. A loop closure signal processor has a first input configured to receive the electrical signal from the detector. A phase lock loop has an output operatively connected to a second input of the processor. A direct digital synthesizer is operatively coupled to an input of the phase lock loop, with the synthesizer configured to generate a low-frequency signal that is transmitted to the phase lock loop. The phase lock loop converts the low-frequency signal to a high-frequency signal that is transmitted to the second input of the processor, and the phase lock loop provides signal modulation that is synchronous with signal demodulation.

Abstract: A synchronous fiber optic gyroscope includes a light source, an optical coupler in optical communication with the light source, an optical modulator in optical communication with the coupler, and a fiber optic coil in optical communication with the modulator. A detector is configured to receive an optical signal from the coupler and convert the optical signal to an electrical signal. A loop closure signal processor has a first input configured to receive the electrical signal from the detector. A phase lock loop has an output operatively connected to a second input of the processor. A direct digital synthesizer is operatively coupled to an input of the phase lock loop, with the synthesizer configured to generate a low-frequency signal that is transmitted to the phase lock loop. The phase lock loop converts the low-frequency signal to a high-frequency signal that is transmitted to the second input of the processor, and the phase lock loop provides signal modulation that is synchronous with signal demodulation.

Abstract: A digital feedback system for an optical gyroscope include a fiber optic sensing coil, an optical phase modulator, a photo detector and a processor. The sensing coil induces a phase differential between light waves traveling though the coil. The optical phase modulator causes a second phase differential between the light waves. The photo detector receive the light waves and outputs an intensity signal representing a phase difference between the light waves. The processor determines a rate of rotation of the fiber optic sensing coil based on the phase difference. for the system operates by generating a closed loop feedback signal, demodulating the signal to determine the phase difference, determining a rate of rotation, periodically incrementing a feedback ramp signal once every ? second period based on the rate of rotation, and resetting the feedback ramp signal when the ramp is incremented a predetermined number of times since a previous reset.

Abstract: A digital feedback system and for an optical gyroscope include a fiber optic sensing coil, an optical phase modulator, a photo detector and a processor. The sensing coil induces a phase differential between light waves traveling though the coil. The optical phase modulator causes a second phase differential between the light waves. The photo detector receive the light waves and outputs an intensity signal representing a phase difference between the light waves. The processor determines a rate of rotation of the fiber optic sensing coil based on the phase difference. for the system operates by generating a closed loop feedback signal, demodulating the signal to determine the phase difference, determining a rate of rotation, periodically incrementing a feedback ramp signal once every ? second period based on the rate of rotation, and resetting the feedback ramp signal when the ramp is incremented a predetermined number of times since a previous reset.

Abstract: A least-mean-squares based algorithm is used to adaptively update dither stripper gains, in a dither stripper of a ring laser gyro. The algorithm is used in conjunction with a dither estimator of the dither stripper. The dither stripper substantially reduces effects of dithering a ring laser gyro, during operation of the ring laser gyro.

Abstract: A system for detecting the eigen frequency of a sensing coil in a fiber optic gyro (FOG) that includes a fiber coupler connected to the light source, an integrated optics chip (IOC) capable of modulating light received from the light source via the fiber coupler, a sensing coil in communication with the IOC, a first modulation generator for imparting a first modulation signal to the light, and a photodetector for receiving light returning from the sensing coil that is representative of a rotation rate of the sensing coil. Along with the foregoing there is provided a second modulation generator for imparting a second, preferably sinusoidal, modulation signal to the light, a high-frequency demodulator in communication with a signal produced, at least indirectly, by the photodector, and a low-frequency demodulator in communication with the high-frequency demodulator.

Abstract: A system for detecting the eigen frequency of a sensing coil in a fiber optic gyro (FOG) that includes a fiber coupler connected to the light source, an integrated optics chip (IOC) capable of modulating light received from the light source via the fiber coupler, a sensing coil in communication with the IOC, a first modulation generator for imparting a first modulation signal to the light, and a photodetector for receiving light returning from the sensing coil that is representative of a rotation rate of the sensing coil. Along with the foregoing there is provided a second modulation generator for imparting a second, preferably sinusoidal, modulation signal to the light, a high-frequency demodulator in communication with a signal produced, at least indirectly, by the photodector, and a low-frequency demodulator in communication with the high-frequency demodulator.