A cost-efficient regional synchronization system

GNSS timing is currently used worldwide in critical real-time systems that require precise synchronization or time-stamping at geographically dispersed sites, such as wireless telecom stations, electrical power grids, and financial services. For applications where multiple equipment needs to be deployed, it is desirable to use low-cost, single-frequency receivers. Increasing demands in cost-saving and accuracy will make the availability of precise single-frequency solutions more and more interesting. In the space operations domain, an application example of GNSS-based synchronization is passive ranging for geostationary satellites. This paper analyzes the application of low-cost GNSS receivers to multi-site synchronization for geostationary satellite orbit determination based of Time Difference of Arrival (TDOA) measurements. The receiver timing signals are measured at the Physikalisch-Technische Bundesanstalt (PTB) in Braunschweig, Germany. By comparing the receiver output timepulse with the reference UTC(PTB) timescale clock using a Time Interval Counter (TIC), one can fully characterize the behavior of the GNSS-derived time solution, and also calibrate the average receiver chain delay. It is expected that the largest contribution to the GNSS timepulse error will be the ionosphere.