Characterization of Time Error and Time Holdover Utilizing Estimation Calculations

An important approach to building a robust system for delivering accurate time couples a source of UTC such as GNSS with an autonomous frequency source such as an atomic oscillator. Analytic methods have been developed that optimize system time delivery when UTC time is not available. These same methods can be applied in two additional important ways. First, they can be used to select the best frequency sources in a population for system deployment. Second, they can be used for monitoring an active system to indicate how long that system can hold time within required bounds when operating autonomously. This paper will summarize these statistical analytic tools and show their use in selection and monitoring.