Advanced mathematical modelling for time and frequency metrology

Purpose and goal

In this project we have deduced mathematical models for delay variations in links between time laboratories, as well as updated the existing models for clock stability. We have also deduced a method for estimating stability parameters from measurement data. The mathematical modeling is presented in detail in the report ´Clock models for Kalman filtering´ (SP Report 2016:48).

Expected results and effects

As a result of the mathematical modelling of clock stability and link delay variations, we now have software with more stringent handling of measurements in the generation of time scales. We have also methods for estimating stability property parameters of clocks. We are hence able to analyze the behavior of the present - and future - lab equipment, in order to utilize the combinations of clocks/links in best possible way.

Planned approach and implementation

Some changes in the priorities were made during the project, e.g. we emphasized the GNSS software development more than originally planned. This meant that the anticipated error detection algorithm was not finished during the project time. On the other hand, our knowledge regarding satellite orbit modeling has increased, which we will benefit from when new systems are launched. We have already applied this increased knowledge in the analysis of ´Two Way Time and Frequency Transfer´ data, where ´geostationary´ satellites are utilized.