摘要 |
In a fiber optic gyroscope (10) having a pair of light waves counter-propagating in a fiber optic loop (44), a phase modulator (28) driven with a variable frequency and amplitude modulation signal on a line (32) so as to null any rotation induced optical phase shift; and using the difference between the drive frequency and the loop eigenfrequency as a measure of rotation rate, is provided with a calibration circuit (34) which determines the actual loop eigenfrequency while in rotation. A modulation signal is applied having an amplitude that causes the closed loop output frequency to equal the loop eigenfrequency independent of rotation rate. The amplitude is fine tuned by applying a phase dither and adjusting the amplitude until effects of the dither are minimized.
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