Zero-crossing demodulation for open loop fiber optic gyroscopes

This paper describes a new low-cost signal processing scheme for open-loop fiber optic gyroscopes using zero-crossing demodulation. This digital demodulation method detects the Sagnac phase difference, proportional to the rotation rate of the system, as the difference of time intervals determined by zero crossing points. Based on the theoretical points of view, the proposed technique provides advantages in relation to those using synchronous clock on an integration period and asynchronous clock on several integration periods, making possible a considerable improvement on resolution and noise minimization in the measure system. The demodulation scheme using this technique allowed us to conclude that it is possible to measure variations of phase as low as 40 μrad using circuits with low-cost electronic components.