Eigenfrequency tracking measurement method of Sagnac optical fiber ring of optical fiber gyroscope

Abstract

The invention relates to an eigenfrequency tracking measurement method of a Sagnac optical fiber ring of an optical fiber gyroscope, and belongs to the technical field of fiber-optic gyroscopes. The eigenfrequency tracking measurement method comprises the following steps: after going through a coupler and a Y waveguide phase modulator, dividing light into two beams of linearly polarized light, respectively propagating the two beams of linearly polarized light clockwise and anticlockwise along an optical fiber sensing ring, performing sawtooth wave phase modulation and square wave bias phase modulation at the phase modulator and then returning to a Y waveguide position for interference; after processing, demodulating an error signal from an FPGA (field programmable gate array); and adjusting the frequency of a sawtooth wave modulation signal and the frequency of a square wave bias modulation signal according to the intensity of the error signal, wherein the frequency of the sawtooth wave signal is equal to the even number times of the eigenfrequency, and the error signal is zero, and at the moment, the square wave bias modulation frequency is accurately located on the eigenfrequency, the frequency of the sawtooth wave modulation signal is just the even number times of the eigenfrequency, and the square wave bias modulation frequency is equal to the eigenfrequency. According to the method, the purposes of tracking measurement for the eigenfrequency of the optical fiber gyroscope and adjustment of the square wave bias frequency onto the eigenfrequency are realized.

Description

technical field [0001] The invention belongs to the technical field of fiber optic gyroscopes, and in particular relates to a method for tracking and measuring the eigenfrequency of Sagnac fiber optic rings of fiber optic gyroscopes. Background technique [0002] Fiber optic gyro is an angular rate sensor based on the Sagnac effect. It has the advantages of small size, light weight, large dynamic range, and high sensitivity. It is used in military fields such as aviation, aerospace, navigation, and weapons, and civilian fields such as oil exploration. With the successful application of medium and low-precision fiber optic gyroscopes in recent years and the improvement of the performance of optical devices, the development of high-precision fiber optic gyroscopes for inertial navigation systems has become a development trend. [0003] Digital closed-loop fiber optic gyroscope is the main solution of medium and high-precision fiber optic gyroscope, and digital closed-loop fibe...

AI Technical Summary

Problems solved by technology

However, this solution not only needs to change the optical path structure, but also needs to add an additional phase modulator in the optical path, and needs to change the circuit structure, adding components such as comparators makes the circuit very complicated and increases the cost of the device

[0008] The bias modulation frequency of the fiber optic gyroscope needs to be accurately modulated to the eigenfrequency. The deviation of the bias modulation frequency from the eigenfrequency will have an adverse effect on the performance of the fiber optic gyroscope, which will affect the zero bias of the gyroscope and cause the accuracy of the gyroscope to decrease.

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