Study and Characterization of a Two-Way Satellite Time and Frequency Transfer Link using Software-Defined Radio solutions to both code and carrier-phase signals

This paper presents a complete study and characterization of a two-way satellite time and frequency transfer link between two remote earth stations equipped with analog modems and software-defined radio receivers driven by atomic clocks. Techniques based on code-phase and carrier-phase measurements were developed to compute time and frequency deviations between these clocks. A comparison of different methods using conventional bandwidth, broadband, carrier-phase information and software-defined radio solution is given. In addition, the paper is completed by a description of calibration aspects, more specifically on the software-defined radio link, an essential step in calculating the differences between remote time scales with very high accuracy, reaching a level of uncertainty of the order of 0.5 nanosecond.