Phase modulation signal generating device for fiber-optic gyroscope
A phase modulation signal generating device for a fiber-optic gyroscope includes a sine wave generating part and a superimposing part. The sine wave generating part generates a fundamental sine wave of an odd-order frequency (v=(2n+1)v e , where n=0, 1, 2, . . . ) of the eigenfrequency (v e ) of the fiber-optic coil and a higher-order sine wave of an odd-order harmonic frequency ((2m+1) v, where m=1, 2, 3, . . . ) of the odd-order frequency (v). The superimposing part superimposes the fundamental sine wave and higher-order sine wave generated by the sine wave generating part at a ratio using a modulation index optimized according to a noise target to be minimized and outputs the resultant signal as a phase modulation signal.
1 . A phase modulation signal generating device for a fiber-optic gyroscope that generates a phase modulation signal to a multi-function integrated optical circuit having a phase modulator that modulates light to enter a fiber-optic coil of an interference type fiber-optic gyroscope, the phase modulation signal generating device for a fiber-optic gyroscope comprising:
a sine wave generator that generates a fundamental sine wave of an odd-order frequency (v=(2n+1)v c , where n=0, 1, 2, . . . ) of the eigenfrequency (v c ) of the fiber-optic coil and a higher-order sine wave of an odd-order harmonic frequency ((2m+1) v, where m=1, 2, 3, . . . ) of the odd-order frequency (v); and
a superimposer that superimposes the fundamental sine wave and higher-order sine wave generated by the sine wave generator at a ratio using a modulation index optimized according to relative intensity noise or shot noise, or mixing noise thereof to be minimized and outputs the resultant signal to the phase modulator as a phase modulation signal.
2 . The phase modulation signal generating device for a fiber-optic gyroscope according to claim 1 , wherein
the odd-order harmonic frequency of the higher-order sine wave generated by the sine wave generator is 3 v.
3 . The phase modulation signal generating device for a fiber-optic gyroscope according to claim 1 , wherein
the odd-order harmonic frequency of the higher-order sine wave generated by the sine wave generator is 3 v and 5 v.
4 . The phase modulation signal generating device for a fiber-optic gyroscope according to claim 1 , wherein
the fundamental sine wave generated by the sine wave generator is used as a reference signal for demodulation.
5 . The phase modulation signal generating device for a fiber-optic gyroscope according to claim 1 , wherein
a superimposed signal output from the superimposer is used as a reference signal for demodulation.
6 . The phase modulation signal generating device for a fiber-optic gyroscope according to claim 1 , wherein
a noise target to be minimized in the superimposer is relative intensity noise.
7 . The phase modulation signal generating device for a fiber-optic gyroscope according to claim 2 , wherein
a noise target to be minimized in the superimposer is relative intensity noise.
8 . The phase modulation signal generating device for a fiber-optic gyroscope according to claim 3 , wherein
a noise target to be minimized in the superimposer is relative intensity noise.
9 . The phase modulation signal generating device for a fiber-optic gyroscope according to claim 4 , wherein
a noise target to be minimized in the superimposer is relative intensity noise.
10 . The phase modulation signal generating device for a fiber-optic gyroscope according to claim 5 , wherein
a noise target to be minimized in the superimposer is relative intensity noise.