Closed-loop RFOG based on square wave quadrature demodulation

Abstract

Aiming at the closed-loop RFOG, based on the bipolar serrodyne and sine phase modulations, the demodulation curve’s characteristic under the square wave signal’s phase fluctuation is studied. And it is found that when the square wave signal’s phase fluctuates, the demodulation curve’s slope would fluctuate and deviate from its maximum, which would have negative effects upon the closed-loop RFOG. Because of that, the square wave quadrature demodulation (SWQD) scheme is proposed and studied in the closed-loop RFOG. And the phase working point of the SWQD is optimized to reduce the non-ideal working point induced demodulation curve fluctuation. According to the gyro output signal test results over 6 h, when the SWQD scheme is used, the bias stability, based on the Allan deviation analysis, would be about 42.1% of that without the SWQD scheme.