Method for signal demodulation using open-loop fiber optic gyroscope signal processing circuit

Abstract

The invention discloses an open-loop fiber optic gyroscope signal processing circuit using a single-chip high-precision impedance transformation system. The optical part and the photoelectric conversion part of the open-loop fiber optic gyroscope are composed of a wide-spectrum light source, a light source coupler, a polarizer, a ring coupler, a phase modulator, an optical fiber sensing ring, and a photodetector, which are consistent with the traditional structure; The signal processing circuit uses the single-chip high-precision impedance transformation system originally used for impedance measurement as the main circuit for gyro signal processing: use its internal direct digital frequency synthesizer DDS to obtain high-precision sinusoidal modulation waves to obtain low-distortion phase modulation ; Use its internal high-impedance amplifier to directly change the photocurrent signal of the photodetector into a voltage value; use its internal high-speed analog-to-digital conversion ADC-digital Fourier transform DTF module to obtain the angular velocity information of the gyroscope; use its internal The temperature sensor obtains a correction of the angular velocity of the gyroscope as a function of temperature.

Description

technical field [0001] The invention relates to a gyroscope, in particular to a method for signal demodulation using an open-loop fiber optic gyroscope signal processing circuit. Background technique [0002] The Sagnac effect signal of the interferometric fiber optic gyroscope is generally weak, and the optical power of the interfering optical signal reaching the detector is generally very small, and a typical value is 10uW. The useful signal amplitude of this order of magnitude optical signal after photoelectric conversion is basically on the order of 10uA, but the output noise of the detector is very large, so it is necessary to perform signal processing on the obtained electrical signal. A feasible solution is to apply a phase bias to the fiber optic gyroscope, so that the gyroscope works at a point with higher sensitivity. Interferometric fiber optic gyroscopes are divided into open-loop fiber optic gyroscopes and closed-loop fiber optic gyroscopes due to different mod...

AI Technical Summary

Problems solved by technology

However, there are many electronic units in the traditional open-loop fiber optic gyroscope signal processing circuit, which is difficult to debug, and the accuracy of the modulated sine wave is poor. The multiplier and integrator in the lock-in amplifier are divided into analog circuit and digital circuit. The zero bias of the former is greatly affected by temperature and humidity, and the latter is affected by the phase difference between the gyro signal and the reference signal, which is also a function of temperature. As a result, the result of the final gyro output is inaccurate, and it is not suitable for occasions with high precision requirements.

In addition, the temperature will greatly affect the stability and scale factors of the gyro, and an additional temperature sensor is required. The response of the temperature sensor is lagging, and the influence of temperature on the output of the gyro cannot be corrected in time.

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