Distributed Time Scale in Sweden

Purpose and goal

The aim of the project was to calculate and distribute UTC(SP) from several locations in Sweden by combining clock data from time nodes located at SP in Borås and from a number of time nodes available in Sweden. This creates a more robust access to a more accurate UTC(SP) from several geographically separated sites in Sweden, including SP in Borås. Nothing prevents to (passively) also include commercial operators who need accurate time and frequency. These operators own their own reference clocks or maintain time scales using atomic clocks but often lack the traceability to UTC.

Expected results and effects

The project has resulted in a methodology for the calculation and distribution of the Swedish national time scale UTC(SP) from multiple geographically separated locations in Sweden. UTC(SP) becomes in this way a common time scale in Sweden. The method is based on the combination of so-called clock- and link data and consists of different software for the calculation and exchange of data developed during the project. Time transfer methods based on GNSS have primarily been used however also other types of time transfer methods, such as fiber optical methods, can be used.

Planned approach and implementation

All software has been developed and first tested at SP, after which it has been installed and tested on the different nodes that have been available and active. This has worked according to plan. However, all the software is not installed on all intended nodes for different reasons. Partly due to that the software development has taken more time than anticipated, and partly because that as an NMI we shall deliver time and frequency signals with high reliability in an operational mode. Thus, we have to test new software and new methods very careful before they are put into use.