Method for improving the performance of fiber-optic gyros by calculating the bias from using a broadband source

Abstract

The invention is a method for improving the performance of a fiber-optic gyro comprising counter-propagating light beams from a broadband source in an optical fiber configured as a coil. The fiber-optic gyro is of the type where the phases of the light beams are step-modulated at one or both ends of the optical fiber at time intervals equal to the light propagation time .tau. through the optical fiber, the step being in the range from 0 to 2.pi.-.delta. radians where .delta. is an infinitesimal. The step is the sum of an estimate of the Sagnac phase residual .phi..sub.SE with reversed sign and the quantity (2.pi.k+j.phi..sub.M) where the index k can take on the values -1, 0, and 1, and the index j can take on the values -1 and 1. The phase angle .phi..sub.M is a positive constant less than .pi. radians. The method comprises the steps of determining the interferometer output light intensity, determining the Sagnac fringe number n, calculating the error P.sub.nkj in the interferometer output light intensity attributable to the use of a broadband light-beam source for particular values of an index pair (k,j), determining estimates A.sub.kj of the probabilities of the index pairs (k,j) by counting the occurrences of each index pair (k,j) over a period of time, and determining the bias .epsilon. in the output of a fiber-optic gyro. The bias .epsilon. can be made independent of the Sagnac fringe number by proper design of the statistical properties of the phase modulating function.

Dependencies are inferred from the claim text.