Experimental Evaluation of the Jitter Generated in Timing Transfer

Modern telecommunications networks maintain synchronization and distribute accurate timing information using approaches with strict requirements on clock quality and jitter and wander at interfaces. In the future, packet networks may be used for timing distribution and synchronization e.g. using IEEE 1588v2 specifying the Precision Time Protocol (PTP). Without amelioration, there may be effects on data buffers within telecommunications networks which have been designed with particular assumptions of clock quality. Applications such as digital audio and video also have synchronization requirements and limits on jitter and wander tolerance. Attention is needed on the impact of clock quality due to clock synchronization on the synchronization and jitter and wander limits for data services over networks. A well-understood approach to the transfer of timing for a data service over a packet network is the Synchronous Residual Time Stamp (SRTS) method. We previously presented a novel approach to modelling and visualising jitter spectra in SRTS timing transfer due to jitter in the reference clocks. In this paper, we present experimental results, which validate the appropriateness of our approximations. Experimental results also show the existence of some spectral components not predicted from the modelling. In the paper we discuss the origins of these spectral components.