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7583384 |
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...
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7515272 |
Digital feedback systems and methods for optical gyroscopes
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...
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7515271 |
Wavelength calibration in a fiber optic gyroscope
Methods and apparatus are provided for calibrating a fiber optic gyroscope (FOG) to compensate for wavelength fluctuations. The wavelength of the light propagating in the gyroscope is accurately...
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7505139 |
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...
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7336364 |
Minimal bias switching for fiber optic gyroscopes
A system and method is provided for reducing the sensitivity of the rotation rate measurement to the frequency dependence of the feedback modulator. Specifically, the system and method uses a...
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7333209 |
Fiber optic gyroscope asynchronous demodulation
A clock system for a fiber optic gyroscope is provided that includes a highly-tunable clock for the bias modulation and a separate asynchronous high-speed clock for the photodetector sampling. By...
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7324206 |
Method for determination/compensation of bias errors/random walk errors induced by the light source in fiber-optic Sagnac interferometers
A method for determination of/compensation for the bias/random walk errors induced by the light source in fiber-optic Sagnac interferometers employing a modulation method for stochastically...
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7295322 |
Optical power measurement of a closed loop fiber optic gyroscope
This disclosure describes fiber optic gyroscopes that have integrated power measurement capabilities, and related methods and apparatus. More particularly, it describes determining the optical...
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7283246 |
Method for regulating the operating frequency and multifunctional integrated circuit chip for a fiber-optic gyroscope
A method for regulating the operating frequency of a closed loop fiber optic gyroscope. The demodulated output signal of a detector, as actual signal, is applied to the input of a main controller...
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7268342 |
Determination of optical properties of a device under test in both directions in transmission and in reflection
A method and a measurement setup for determination of optical properties of a device under test in both directions in transmission and in reflection, includes a coding device distinguishably coding...
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7228024 |
Optical return loss detecting device
An optical return loss detecting device is provided for measuring the optical return loss (ORL) of a device under test (DUT). The detecting device comprises a light source, an optical isolator...
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7190463 |
Method for preventing bias-errors as a result of synchronous interference in fiber-optic gyroscopes
The method according to the invention for preventing bias errors as a result of synchronous interference in fiber-optic gyroscopes (FOGs) provides for an additional signal φ E , which is...
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7187448 |
Nonreciprocal phase shift fiber-optic gyrometer
The present invention relates to a fiber-optic gyrometer including a Sagnac interferometer using two light waves propagating in opposite directions in a interferometer loop including a...
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7167250 |
System and method for reducing fiber optic gyroscope color noise
A phase jump amplitude and timing controller is used in a fiber optic gyroscope for suppressing color noise. The phase jump amplitude and timing controller inserts a phase/voltage jump into the...
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6856751 |
Method and system for obtaining variable optical attenuation with very low polarization dependent loss over an ultra wide dynamic range
A method and system of operating a variable optical attenuator to provide a required total attenuation in a planar lightwave circuit. The method comprises providing a first Mach-Zehnder...
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6778720 |
Dual slope fiber optic array interrogator
An apparatus and method is presented presented to provide wide dynamic range measurements of the input phase to a time domain multiplex interferometer array using a dual slope modulation method for...
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6760111 |
Digital phase modulator
Apparatus and a method for compensating production or operationally-induced inaccuracies in the binary-weighted electrodes of a high-resolution digital phase modulator of, for example, a fiber...
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6744519 |
Methods and apparatus for fiber optic gyroscope dead band error suppression modulation
According to the preferred exemplary embodiments of the present invention, there is provided a phase jump amplitude and timing controller for suppressing the voltage-dependent errors responsible...
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6486960 |
Fiber optic sensor coil and tool for forming same
A tool for forming a sensor coil that may be employed, for example, in a fiber optic gyroscope with reduced Shupe effect-induced bias. The tool includes a takeup reel having a cylindrical mandrel...
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6473182 |
Automatic gain control of a closed loop fiber optic gyroscope using non-linear control laws
A closed loop gain circuit controls the gain of a variable gain amplifier and provides a stable AGC response irrespective of the actual gain level. The amplifier may be arranged to amplify...
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6469792 |
Method for processing the output of a fiber optic gyroscope to reduce the effects of vibration therefrom
A system and method for processing the output of a fiber-optic gyroscope. The inventive circuit ( 10 ) includes a photodetector ( 24 ) for detecting electromagnetic energy received from the...
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6376830 |
System and method for measuring the transfer function of a guided wave device
A method/system are provided for measuring the N×N scalar transfer function elements for an N-port guided wave device. Optical energy of a selected wavelength is generated at a source and directed...
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6373048 |
Method and device for stabilizing the scale factor of a fiber optic gyroscope
A method and apparatus for stabilizing the scale factor of a fiber optic gyroscope in which a superluminescence diode or broadband multimode laser comprises the light source. The emission bandwidth...
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6320664 |
Ruggedized structure for fiber optic gyroscope
A rectification error reducer for a fiber optic gyroscope, which is an intensity servo or compensator for reducing vibration effects in the optical signals caused by modulation at vibration...
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6317215 |
Pseudorandom bit sequence generation
The invention is a method and apparatus for generating a pseudorandom sequence of bits. The method comprises the steps of (1) selecting a "0" or a "1" as the next bit of the modified pseudorandom...
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6307631 |
Pseudorandom bit sequence generator
The invention is a method and apparatus for generating a primary pseudorandom bit sequence consisting of a plurality of contiguous P subsequences. Each P subsequence consists of a start sequence of...
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6268922 |
Method and apparatus for determining fringe number in a fiber-optic gyro
The invention is a method and apparatus for determining the fringe number for a fiber-optic gyro. The fiber-optic gyro comprises a light source feeding an interferometer which in turn feeds a...
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6256101 |
Open loop fiber optic gyroscope for measuring ultra-high rates of rotation
A fiber optic gyroscope for measuring a rotation rate of an object. The gyroscope includes a light source for generating a light beam and a bidirectional coupler for receiving and forwarding the...
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6215809 |
Stabilization of laser sources with closely-coupled optical reflectors using an internal dither circuit
Apparatus for providing a laser source optically coupled to an optical waveguide, such as an optical fiber, having a reflective grating positioned from the output facet of the laser source a...
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6181428 |
Closed loop fiber optic gyro with shupe effect compensation
A method and a device for compensating Shupe effect drift errors in a fiber gyro that result from time-dependent temperature changes. A closed loop fiber optic gyro includes a VCO control loop and...
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6130755 |
Fiber-optic gyro utilizing pseudorandom-bit-sequence light modulation
The invention is a method and apparatus for determining the rotation of a medium through which a light beam propagates by modulating the light beam with a pseudorandom sequence of bits. The method...
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5999304 |
Fiber optic gyroscope with deadband error reduction
A deadband error reducer for a fiber optic gyroscope, which is an offset modulation signal that averages the deadband producing error over the range of the feedback modulation signal provided to...
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5999260 |
Method and apparatus for initialization of a fiber optic gyroscope
A method and apparatus are provided for initializing a closed-loop fiber optic gyroscope system of the type that includes a fiber optic gyroscope for generating an interferometric measurement of...
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5953123 |
Fixed interval background auto-alignment for closed loop interferometric fiber optic gyroscopes
This invention relates to an improved method and mechanism by which to align closed loop interferometric fiber optic gyroscopes. Such method and means includes aligning the gyroscope periodically...
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5953122 |
Method and apparatus for increasing the stability of a fiber optic gyroscope by controlling the phase and amplitude of the source modulating current
A small modulation current is applied to the light source of a Sagnac-type fiber optic gyroscope to increase accuracy and/or stability of scale factor (open loop configuration) and to reduce bias...
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5949545 |
Fiber optic gyroscope with variable output period
The linearity of a fiber optic gyroscope can be improved by dithering the gyroscope's feedback signal. An output signal can be taken over any time interval by sampling the feedback signal before...
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5946097 |
Vibration rectification error reducer for fiber optic gyroscope
An apparatus for eliminating or reducing vibration-induced errors due to vibration rectification by applying a variable weighting function at the demodulator or analog-to-digital converter by...
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5926275 |
Vibration error reduction servo for a fiber optic gyroscope
A rectification error reducer for a fiber optic gyroscope, which is an intensity servo or compensator for reducing vibration effects in the optical signals caused by modulation at vibration...
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5923424 |
Fiber optic gyroscope vibration error compensator
A rectification error reducer for a fiber optic gyroscope, which is an intensity servo or compensator for reducing vibration effects in the optical signals caused by modulation at vibration...
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5914781 |
Method for stabilizing the phase modulator transfer function in closed loop interferometric fiber optic gyroscopes
This invention relates to an improved method and mechanism for eliminating acceleration-dependent errors and loop interaction effects in gain-stabilized, closed-loop, interferometric fiber optic...
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5898496 |
Optical signal noise reduction for fiber optic gyroscopses
The RIN (random intensity noise) component of the random walk error of a fiber optic gyroscope can be reduced by utilizing an unpolarized light signal during processing. By depolarizing the light...
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5883716 |
Rate control loop for fiber optic gyroscope
A closed-loop system for regulating a fiber optic gyroscope is configured so that the residual error of a so-called deadbeat system assumes a higher order function of frequency. The closed-loop...
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5781296 |
Closed loop type fiber optic gyroscope for measuring absolute rotation by delta serrodyne wave phase modulation
A fiber optic gyro can overcome the defects encountered with conventional fiber optic gyros of phase-modulation method, closed-loop system with serrodyne modulation and digital modulation. A...
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5767968 |
Coherent pickup error cancellation device
A device for eliminating coherent pickup error in a fiber optic gyroscope. The polarity of the drive signal to the phase modulator of the gyroscope is switched periodically. The scale factor...
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5684591 |
Fiber optic gyroscope with reduced non-linearity at low angular rates
The linearity of a fiber optic gyroscope can be improved by dithering the gyroscope's feedback signal. Any undesirable effects introduced by the dithering signal are removed by processing the...
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5684589 |
Loop controller for fiber optic gyro with distributed data processing
A loop controller for a fiber optic gyroscope employs distributed data processing to compress numerous additional useful functions into each loop transit time. The architecture of the loop...
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5627644 |
Kerr effect compensation by optical power balancing in interferometric fiber optic gyroscopes
An interferometric fiber optic gyroscope having an intensity servo electronics feedback loop that monitors the intensity of the counterpropagating beams relative to each other, and provides a...
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5602642 |
Magnetically insensitive fiber optic rotation sensor
A fiber optic gyroscope having at least one forty-five degree splice connected to a polarization maintaining sensing coil. The splice is an alignment of forty-five or so degrees between a major...
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5563705 |
Optical power balancing in interferometric fiber optic gyroscopes
An interferometric fiber optic gyroscope having a wavelength-sensitive splitter which has a splitting ratio that changes according to light wavelength. A feedback circuit indicates any difference...
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5513003 |
Fiber optic gyro digital control with rate extension
A digitally operated fiber optics gyro system in which the 2π/SF rate limit has been removed by storing the number of 2π reset that have occurred and combining this with the signal sensed by the...
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