Self-test method for bandwidth of fiber optical gyroscope based on equivalent input

Since the turntable's input frequency is low in fiber optical gyroscope's (FOG) bandwidth test, the output signal in gyro demodulation is estimated according to its amplitude to obtain gyro's band-width, and this is by adding sine waves to the FOG's feedback step-waves, which works as equivalent input phase signal to instead of the outside input angular velocity. The requirements for sine wave's amplitude are analyzed. In view of the problem that the phase differences in modulating the sine signal change with frequencies, the phase differences are compensated. A bandwidth test scheme is put forward which uses the technique of direct digital synthesizers to generate the sine signal and uses the algorithm of extremism searching to test the signal's amplitude. And the bandwidth test is realized mainly by using FOG's own hardware. By establishing the model of digital close-loop FOG, a simulation based on Matlab Simulink is carried out. It demonstrates that the test method can realize the frequency-band measurement in the whole frequency-band of FOG without being limited by the test frequencies of outside input signal.