On the use of Synchronous Ethernet over multiple paths for syntonization of distributed systems

This paper proposes the use of Synchronous Ethernet in networks with multiple paths for the synthesis of a precise frequency reference for distributed measurement systems. The paper presents novel approach based on a Kalman filter with outlier identification and removal followed by a linear quadratic regulator (LQR). The algorithm, to be implemented within a network element, is able to synthetize a single frequency reference from the combination of multiple frequency signals coming from different, redundant network paths. The effect is a shared and stable frequency reference available all across the distributed measurement system, ready, for instance, to be used by data acquisition boards. The performances of the proposed solution have been analyzed through simulations and compared with those of a previously proposed method based on iterative robust Weighted Least Squares (iWLS) estimation. Such simulations confirm that the proposed algorithm provides generally better results than selecting just a single input frequency reference at a time. In addition, it is robust to possible frequency or phase jumps due to faults or network problems.