Coexisting Parallelogram Method to Handle Jump Point on Hough Transform-based Clock Skew Measurement

In this paper, we improve the robustness of the Hough transform-based clock skew measurement on the occurrence of a jump point. The current Hough transform-based skew method uses angle (θ), thickness (ω), and region (β), to create a parallelogram that covers the densest part of an offset-set. However, the assumption that all offsets are considered to line up roughly in only one direction restricts the ability of the current method when handling an offset-set in which its densest part is located separately, the jump point condition. By acquiring the parallelogram from coexisting angle-region tuples at the beginning and the ending parts of the offset-set, we completed the ability of the Hough transform-based method to handle the jump point. When handling the jump point problem, the proposed coexisting parallelogram method could reach 0.35 ppm accuracy compared with tens ppm by the current methods

A Regular Pattern of Timestamps Between Machines with Built-in System Time

This paper studied the effect of 15.6 ms time resolution where the collected timestamps are in a form of parallel dotted lines, instead of one straight line like in classical case. The dotted lines made the clock skew measurement of two devices to become incorrect as the measurement which normally follow the cluster of offsets but now follow the parallel dotted lines. Dotted lines pattern is required in order to understand how to correct the clock skew measurement on data containing dotted lines. To model the dotted lines pattern is through Dotted lines Grouping Method, a tools to find the characteristics of the dotted lines. The dotted lines grouping method was then tested data obtained from wired and wireless communication of two similar devices. The dotted line grouping method results equal maximum number of dot of 10 for both data, which indicated the robustness of the dotted lines grouping method