title: Quadrature demodulation with synchronous difference for interferometric fiber-optic gyroscopes.
abstract: We propose a novel method of quadrature demodulation with synchronous difference for suppressing noise in interferometric fiber-optic gyroscopes (IFOGs). For an IFOG with sine wave phase modulation, an in-phase result and a quadrature result are obtained simultaneously by coherent detection. Eigenfrequency modulation is used and a phase shift of 45° is set between the modulation signal and the reference signal, so that two results have the same expectation of amplitude but with opposite signs. A synchronous difference procedure is carried out for output, in which signals are added up and common noise between two results is eliminated. Theoretical analysis and experimental results show that both short term noise and long term instability of the IFOG are reduced by this method. In experimental comparison with the traditional demodulation method on the same IFOG with a 1982 m fiber coil, this method reduces the bias drift from 0.040°/h to 0.004°/h.
authors.affiliation: State Key Laboratory of Advanced Optical Communication Systems & Networks, Department of Electronics, Peking University, Beijing 100871, China. znwang@pku.edu.cn
authors.forename: Zinan
authors.initials: Z
authors.lastname: Wang
authors.forename: Yi
authors.initials: Y
authors.lastname: Yang
authors.forename: Yongxiao
authors.initials: Y
authors.lastname: Li
authors.forename: Xiaoqi
authors.initials: X
authors.lastname: Yu
authors.forename: Zhenrong
authors.initials: Z
authors.lastname: Zhang
authors.forename: Zhengbin
authors.initials: Z
authors.lastname: Li