Research On Digital Signal Processing For Single Source Dual Waves Sagnac Fiber Interferometer

Sagnac fiber optic interferometer is based on the Sagnac effect, for detecting the rotational angular velocity with respect to inertial space fiber optic sensor, was also called interferometric fiber optic gyroscope (IFOG). Currently the biggest problem of improving the accuracy of interferometric fiber optic gyro is how to ensure the stability of the scale factor stability of FOG when the outside temperature field is changing.This paper describes the various demodulation schemes for FOG, including the FPGA-based open-loop FOG detection and FPGA-based closed-loop detection scheme. Then we propose a new single source dual wavelength light source, utilizing a 980nm pump light source to stimulate erbium-doped fiber, and then getting two beams of wave with wide spectrum. The average wavelengths are 1539.81nm and 1558.09nmThen use the new light source instead of traditional light source SLD, to establish a single source dual wavelength fiber optic gyroscope structure. Meanwhile this paper also proposes two methods for compensation of FOG scale factor.The most important part of this paper is to realize demodulating for dual-wavelength fiber optic gyroscope signal. For different scale factor compensation scheme, different demodulation method is proposed. A new dual optical modulation circuit and FPGA-based signal processing scheme is designed, and a single source dual wavelength interferometric fiber optic gyro system is built.Finally, we successfully exploit τ/2 demodulation scheme, the interference signal of two beams of light simultaneously demodulate in a τ, and achieve feedback control. The zero bias for dual waves of 1539.81nm and 1558.09nm are-6.959 °/h and -6.890 °/h, zero drift are respectively,0.385 °/h and 0.378 °/h.