Relative Intensity Noise Reduction Strategy Of High Precision Fiber Optic Gyroscope Light Source

High-precision fiber optic gyroscope(FOG)commonly used erbium-doped fiber optic light source,which has the advantages of large output power,wide spectrum,and good center wavelength stability.The intensity noise of fiber optic gyroscope with erbium-doped fiber light source is the main factor that influences the random walk coefficient of fiber optic gyro.In order to further improve the performance of fiber optic gyroscope,it is necessary to suppress the relative intensity noise of fiber optic gyroscope.Based on the principle of fiber optic gyroscope,the paper discusses the source of the relative intensity noise and its influence on the back end signal.In the control strategy of the relative intensity noise,the solutions of the front end and the back end of the fiber optic gyroscope are studied respectively.The solutions focus on the front-end,adopting the digital subtraction method and the external light intensity modulation method.In the back-end solutions,the paper applying filtering technique by modeling.The main work of this paper is as follows:The principle of fiber optic gyroscope is theoretically analyzed.The fiber optic gyro light source is introduced,and the relative intensity noise caused by fiber optic gyro light source is analyzed in detail.The effects of wavelength stability,spectral width and optical power,etc.on the signal intensity were studied.By analyzing the noise mechanism and its characteristics,this paper answers the representation of relative intensity noise,which can be used to describe the overall noise level.It can be characterized by random walk coefficient or signal to noise ratio.For the relative intensity noise,in the front-end solution,this paper analyzes a variety of solutions.This paper also analyzes the digital circuit subtraction method,and carries on the simulation analysis,discusses its technical difficult problem.In this paper,the system structure of the light intensity external modulation method is designed,and the feedback control circuit design of the light intensity external modulation method is given.The parameters are determined according to the system requirements so as to effectively suppress the relative intensity noise.And the simulation analysis is accomplished.The experimental results show that both schemes can reduce the influence of relative intensity noise.In the process of dealing with the back-end noise,this paper uses the filtering technique.Firstly,according to the characteristics of the output data of the fiber optic gyro,the model is established and then filtered.The steps as follows:In the process of dealing with the back-end noise,this paper proposes and establishes the cue model according to the basis of the characteristics of the output data of the fiber optic gyro.After filtering,the relative intensity noise is evaluated by the random walk coefficient.(1)First of all,the basic content of time series analysis method is discussed in detail,based on this,it expands and creates a clue model.The cue model is a dynamic model,which can update the model parameters by using new information.This paper also discusses the essence of time series analysis modeling and thread modeling,and deeply explores their connotation.(2)Secondly,on the basis of the established model,the model is converted into state equation,this change in order to improve the model,and add a constant term,the updated model is acceptable,it won't make the calculation of surge.According to the output data of fog,online real-time refresh parameters.(3)Finally,according to the state equation of the system,the data is processed by Kalman filter.Considering the influence of relative intensity noise on gyro random walk coefficient,Allan variance analysis method is used to identify the random walk coefficient of fiber optic gyroscope.By comparing the random walk coefficient before and after filtering,this method is proved to be effective of the intensity of noise reduction.