Class / Patent application number | Description | Number of patent applications / Date published |
356464000 | Having null feedback loop | 10 |
20080218765 | Signal Processing For A Sagnac Interferometer - Disclosed is a method and apparatus for modulating the phase difference between a pair of optical waves that exit a Sagnac interferometer, and, more particularly, one that is commonly employed as a fiber gyro, and includes a detector responsive to phase difference between the pair of waves that exit the interferometer, and a phase modulator that forms part of two control loops that are instrumental in deriving an accurate measurement of rotation rate. As disclosed herein, phase modulation applied equally to the pair of waves as they counter-propagate through the phase modulator induces modulation of the phase-difference between the two waves as they exit the interferometer. This phase difference modulation includes (i) a bias phase-difference modulation component having a selected frequency, amplitude, and waveform, (ii) a rotation-rate feedback phase-difference component that is equal in magnitude to, and opposite in sign of, the Sagnac phase difference, so that the sum thereof is controlled to be substantially zero, and (iii) a calibration feedback phase-difference modulation component that is characterized by a predetermined phase difference magnitude having substantially alternating positive and negative sign values. | 09-11-2008 |
20090059237 | DIGITAL FEEDBACK SYSTEMS AND METHODS FOR OPTICAL GYROSCOPES - 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 τ 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. | 03-05-2009 |
20090128826 | HIGH RESOLUTION IOC DRIVE AND METHOD FOR DRIVING FIBER OPTIC GYROSCOPES - Methods and system are provided for driving light through a sensing coil of an optical gyro. The system includes a photodetection circuit having an input for receiving an optical output from the sensing coil and having an output, and a signal processing circuit having an input coupled to the output of the photodetection circuit and having an output for supplying an output signal to modulate the sensing coil. The photodetection system produces a digital signal from the optical output. The signal processing circuit produces a feedback signal from the digital signal and adds a random number to the feedback signal to produce the output signal. | 05-21-2009 |
20090161112 | METHOD AND POWER-ASSISTED OPTIC-FIBER MEASURING DEVICE AND GYRO - The invention relates to a method and an optical-fibre measuring device including a light source with a light power P, a Sagnac ring interferometer in which propagate two counter-propagating waves, a detector receiving a light flux from the interferometer and converting it into an electrical signal representing the total phase difference δφ | 06-25-2009 |
20100141953 | Automatic gain Control for fiber optic gyroscope deterministic control loops - An automatic gain control system for a fiber optic gyroscope control loop includes an adjustable gain applied to the gyro output signal. A pilot signal is injected into the fiber optic gyroscope control loop. A compensation loop receives signals output from the control loop and also receives pilot signals. The compensation loop processes the pilot signal to produce a compensation signal that is combined with signals output from the control loop to provide a compensated fiber optic gyroscope output signal. An automatic gain control loop is connected between the compensation loop and the adjustable gain applied to the fiber optic gyroscope output signal. The automatic gain control loop includes a gain error demodulator that multiplies the compensated fiber optic gyroscope output signal and the compensation signal together to produce a gain error signal used to control the adjustable gain in order to stabilize the gain of the gyro control loop. | 06-10-2010 |
20100253948 | SYSTEMS AND METHODS FOR RESONATOR FIBER OPTIC GYROSCOPE INTENSITY MODULATION CONTROL - Systems and methods for improved resonator fiber optic gyroscope intensity modulation control are provided. In one embodiment, a resonant fiber optic gyroscope (RFOG) having a residual intensity modulation (RIM) controller comprises: an intensity modulator optically coupled to receive a light beam from a laser source modulated at a resonance detection modulation frequency; an optical tap device optically coupled to the intensity modulator; and a feedback servo coupled to the optical tap device and the intensity modulator, the demodulating feedback servo generating a sinusoidal feedback signal to the intensity modulator. The feedback servo adjusts an amplitude and phase of the sinusoidal feedback signal provided to intensity modulator based on a residual intensity modulation detected by the demodulating feedback servo. | 10-07-2010 |
20100284018 | SYSTEMS AND METHODS FOR EFFECTIVE RELATIVE INTENSITY NOISE (RIN) SUBTRACTION IN DEPOLARIZED GYROS - Effective relative intensity noise (RIN) subtraction systems and methods for improving ARW performance of a depolarized gyros. This invention taps the RIN detector light in the sensing loop, after the light transmits through the depolarizer and the coil but before it combines with the counter propagating lightwave. The tapped RIN lightwaves are polarized with pass-axis orientated in the same direction as that of the IOC, so that the RIN detector receives lightwaves with spectrum substantially identical to that of the rate detector, leading to more effective RIN subtraction. | 11-11-2010 |
20110181887 | SYNCHRONOUS RADIATION HARDENED FIBER OPTIC GYROSCOPE - 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. | 07-28-2011 |
20130044328 | SYSTEMS AND METHODS FOR ENVIRONMENTALLY INSENSITIVE HIGH-PERFORMANCE FIBER-OPTIC GYROSCOPES - 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. | 02-21-2013 |
20150116723 | FIBRE-OPTIC MEASUREMENT DEVICE, RATE GYRO, AND INERTIAL STABILISATION AND NAVIGATION UNIT - A fibre-optic measurement device ( | 04-30-2015 |