Bandwidth measurement of digital closed-loop fiber optic gyroscope based on Faraday effect

Bandwidth of fiber optic gyroscope (FOG) was a parameter that can not be fully measured at present. Measurement range of the traditional method (based on the dynamic test turn table) was several hundred Hertz, could only measure low frequency section of the FOG. To solve this problem, proposed the measurement principle based on the magneto-optic Faraday effect of the FOG. The finite element transmission model of the fiber coil was established. Derived the Faraday effect output model of the FOG under the high birefringence optic fiber and packaged fiber coil were used. The Faraday effect output of FOG is proportional to the magnetic field intensity. Based on the detection principle of the FOG, the equivalence of this method and the traditional method was analyzed. High frequency magnetic field could be easily obtained by using high frequency current, the measurement range can cover the bandwidth of the FOG. Established bandwidth measurement system, frequency is more than 50 kHz and distortion is less than 0.1%. The measurement results were presented. Magnitude-frequency and phase-frequency figure shows that the bandwidth of FOG with 1500 m length fiber coil is about 2.1 kHz. This method can solve the low frequency output disadvantage of the dynamic test turn table and test the whole bandwidth frequency response of the FOG.