Time error analysis using real-time data is a complex and lengthy process that can take from weeks to months to perform. To help simplify and speed this process, SiTime has developed Time Error Simulator software to simulate how much wander is generated by the instabilities of the local oscillator. This software runs system simulations for both locked state and holdover state, providing an estimation of time and frequency errors, MTIE, and TDEV. It also provides the ability to recognize various causes of performance degradation including contributors such as temperature, drift and Allan deviation.
This tool simplifies and speeds time error estimation for the system and eliminates the need to perform long tests over many conditions and configurations. Only two basic tests (behavior over temperature and short-term frequency stability) and the drift specification of the local oscillator are needed to simulate time error for a range of scenarios. These scenarios include different system configurations (loop bandwidth, loop order), different conditions (temperature profile, locked state, holdover state) and different modes (PTP Only, PTP + SyncE).
This paper discusses the importance of the local oscillator in the overall synchronization performance of the system, provides how-to information on simulating time error, and covers a variety of models used for time error simulation for PTP and PTP + SyncE applications.