Abstract: Lower noise and complexity techniques are disclosed for compensating for time varying phase changes in fiber optics in a resonant fiber optic gyroscope (RFOG). Orthogonal components derived from an electrical beat note signal and a difference between clockwise and counterclockwise resonant frequencies of an optical resonator coil of the RFOG are determined. The orthogonal products are converted to a phase which is differentiated with respect to time to obtain a beat note correction signal.

Abstract: Lower noise and complexity techniques are disclosed for compensating for time varying phase changes in fiber optics in a resonant fiber optic gyroscope (RFOG). Orthogonal components derived from an electrical beat note signal and a difference between clockwise and counterclockwise resonant frequencies of an optical resonator coil of the RFOG are determined. The orthogonal products are converted to a phase which is differentiated with respect to time to obtain a beat note correction signal.

Abstract: Systems and methods are provided to reduce at least one differential harmonics of a resonance tracking modulation in a resonant fiber optic gyroscope (RFOG). The fundamental frequency of the resonance tracking modulation of each of the clockwise and counter clockwise optical signals is substantially identical; however, the amplitude and phase of the Nth harmonic of a clockwise (CW) resonance tracking modulation and the Nth harmonic of a clockwise (CCW) resonance tracking modulation may differ due to non-linearities in the RFOG. Embodiments of the invention diminish, e.g., reduce to zero such vectoral difference. Differential harmonics may be generated at one or more harmonics.

Abstract: Systems and methods are provided to reduce at least one differential harmonics of a resonance tracking modulation in a resonant fiber optic gyroscope (RFOG). The fundamental frequency of the resonance tracking modulation of each of the clockwise and counter clockwise optical signals is substantially identical; however, the amplitude and phase of the Nth harmonic of a clockwise (CW) resonance tracking modulation and the Nth harmonic of a clockwise (CCW) resonance tracking modulation may differ due to non-linearities in the RFOG. Embodiments of the invention diminish, e.g., reduce to zero such vectoral difference. Differential harmonics may be generated at one or more harmonics.

Abstract: In one embodiment, a phase lock loop circuit includes a control circuit, wherein the control circuit is configured to input an estimation having a second frequency and a second phase. The second frequency is selected from a range of frequencies including a first frequency from an acquired signal. A numerically controlled oscillator is coupled to the control circuit, wherein the control circuit is configured to control an output response of the numerically controlled oscillator. The numerically controlled oscillator is configured to receive the estimation from the control circuit and generate an output signal in response to the estimation. A phase detector is coupled to the control circuit and the numerically controlled oscillator, wherein the phase detector is configured to compare the first signal and the output signal and produce a comparison output, the comparison output indicative of a phase difference between the first signal and the estimation.

Abstract: In one embodiment, a phase lock loop circuit includes a control circuit, wherein the control circuit is configured to input an estimation having a second frequency and a second phase. The second frequency is selected from a range of frequencies including a first frequency from an acquired signal. A numerically controlled oscillator is coupled to the control circuit, wherein the control circuit is configured to control an output response of the numerically controlled oscillator. The numerically controlled oscillator is configured to receive the estimation from the control circuit and generate an output signal in response to the estimation. A phase detector is coupled to the control circuit and the numerically controlled oscillator, wherein the phase detector is configured to compare the first signal and the output signal and produce a comparison output, the comparison output indicative of a phase difference between the first signal and the estimation.

Abstract: A RFOG, comprising: a master laser emitting a reference optical signal; first and second slave lasers emitting first and second optical signals; an optical resonator ring cavity coupled to the lasers, the first and second optical signals propagating in first and second directions through the optical resonator ring cavity; one or more signal generators to inject first and second modulation signals at first and second frequencies on both optical signals; first and second photodetectors that generate first and second signals; first and second demodulators to demodulate the first and second signals using first and second reference signals and the first and second frequencies; a differencing function to output the difference between resonance frequencies of the first and second signals; at least a third demodulator to detect reference phase errors; and at least one phase servo to adjust the phase of at least one of the first and second reference signals.

Abstract: A RFOG, comprising: a master laser emitting a reference optical signal; first and second slave lasers emitting first and second optical signals; an optical resonator ring cavity coupled to the lasers, the first and second optical signals propagating in first and second directions through the optical resonator ring cavity; one or more signal generators to inject first and second modulation signals at first and second frequencies on both optical signals; first and second photodetectors that generate first and second signals; first and second demodulators to demodulate the first and second signals using first and second reference signals and the first and second frequencies; a differencing function to output the difference between resonance frequencies of the first and second signals; at least a third demodulator to detect reference phase errors; and at least one phase servo to adjust the phase of at least one of the first and second reference signals.

Abstract: A system comprising a fiber optic gyroscope and a mixed signal application specific integrated circuit (ASIC) connected to the gyroscope is provided. The mixed signal ASIC comprises a digital logic unit, a relative intensity noise (RIN) analog-to-digital converter (ADC) coupled to the digital logic unit and configurable to receive a signal from a RIN detector, and a rate ADC coupled to the digital logic unit and configurable to receive a signal from a rate detector. The mixed signal ASIC also includes a light source digital-to-analog converter (DAC) coupled to the digital logic unit, and a thermo-electric cooler DAC coupled to the digital logic unit, both of which are configurable to send control signals to a light source of the gyroscope. The mixed signal ASIC further includes an integrated optical chip DAC, an eigen-frequency servo DAC, and a heater servo DAC, all of which are coupled to the digital logic unit.

Abstract: A system comprising a fiber optic gyroscope and a mixed signal application specific integrated circuit (ASIC) connected to the gyroscope is provided. The mixed signal ASIC comprises a digital logic unit, a relative intensity noise (RIN) analog-to-digital converter (ADC) coupled to the digital logic unit and configurable to receive a signal from a RIN detector, and a rate ADC coupled to the digital logic unit and configurable to receive a signal from a rate detector. The mixed signal ASIC also includes a light source digital-to-analog converter (DAC) coupled to the digital logic unit, and a thermo-electric cooler DAC coupled to the digital logic unit, both of which are configurable to send control signals to a light source of the gyroscope. The mixed signal ASIC further includes an integrated optical chip DAC, an eigen-frequency servo DAC, and a heater servo DAC, all of which are coupled to the digital logic unit.