A redundant subspace weighting procedure for clock ensemble

A redundant-subspace-weighting (RSW)-based approach is proposed to enhance the frequency stability on a time scale of a clock ensemble. In this method, multiple overlapping subspaces are constructed in the clock ensemble, and the weight of each clock in this ensemble is defined by using the spatial covariance matrix. The superimposition average of covariances in different subspaces reduces the correlations between clocks in the same laboratory to some extent. After optimizing the parameters of this weighting procedure, the frequency stabilities of virtual clock ensembles are significantly improved in most cases.