Design Of Signal Processing System For Three-Laser Resonant Fiber Optic Gyro

As an inertial sensor that uses the Sagnac effect to detect the rotational angular velocity,the fiber optic gyroscope is widely used in aerospace,military defense,civil navigation and other fields.Fiber optic gyroscopes mainly include three types: resonant fiber optic gyro(RFOG),interferometric fiber optic gyroscope,and Brillouin fiber optic gyroscope.Among them,Brillouin fiber optic gyroscope is still in the initial stage of research,and interferometric fiber optic gyroscope has been widely used in various fields.application.In principle,the resonant fiber-optic gyro can achieve the same high detection accuracy as the interferometric fiber-optic gyro by using a fiber-optic ring resonator with a length of less than ten meters.It is attracting more and more research interest from domestic and foreign institutions.One of the most promising and most eye-catching fiber optic gyroscopes.Because the Sagnac effect is very weak,the signal detection technology of the resonant fiber optic gyroscope plays a decisive role in the detection accuracy that can be achieved.However,the current resonant fiber optic gyro signal processing technology can not effectively suppress the backscattering noise and Kerr noise in the RFOG system.In this paper,based on the three-laser dual-loop closed-loop composite beat frequency technology,a three-laser resonant fiber optic gyroscope can be designed to suppress the backscattering noise in principle.At the same time,the three-laser RFOG system designed in this paper contains two cavity input optical powers.The ripple suppression loop can effectively suppress Kerr noise in the system.This article mainly includes the following aspects:(1)Based on the basic principle of resonant fiber optic gyroscope and three-laser dual-loop closed-loop matching beat frequency technology,a three-laser resonant fiber optic gyroscope system including optical power fluctuation suppression loop is designed,and the backscattering noise is suppressed for the RFOG system.The advantages of Kerr noise were analyzed.(2)Design and analysis of the RFOG signal processing system designed in this paper,including the resonant frequency servo loop,optical phase-locked loop loop and optical power fluctuation suppression loop in the three-laser RFOG system.Firstly,the design of the servo controller in the resonant frequency servo loop is completed by loop simulation,and then the parameters of the homodyne optical phase-locked loop and the heterodyne optical phase-locked loop in the RFOG system are based on the optical phase-locked loop technology.Design and modeling simulation,finally through the relationship between the even harmonic demodulation output and the optical power input into the cavity and the characteristics of the optical and optical frequency shifter to adjust the optical power,establish the second harmonic demodulation output suppression into the cavity The scheme of optical power fluctuation is simulated and analyze d by the optical power fluctuation suppression loop.(3)The implementation of the three-laser RFOG signal processing system is elaborated,including the overall scheme design,the hardware circuit implementation and the implementation of each software module in the FPGA.The software modules in the FPGA mainly include the modulation module,the demodulation module,and the resonant frequency servo control.Module,optical phase-locked loop module and optical power fluctuation suppression module.(4)The three-laser RFOG system was tested,mainly including module function test and system overall test.Among them,the module function test mainly includes modulation signal test.Resonance phenomenon,pre-filtering effect test,resonant frequency servo loop test and optical power fluctuation suppression loop test.The overall system test includes Backscattered noise test and Kerr noise test.