Evaluation of GNSS-based Time Synchronisation for ToF Localisation with Software-Defined Radio

In distributed radio localisation systems based on time-of-flight measurements accuracy of time synchronisation between radio nodes places limits on the achievable performance. In this work, we evaluate feasibility of using pulse-per-second reference signals provided by off-the-shelf timing GNSS modules as a means for wireless synchronisation of distributed softwaredefines radio nodes. Our experimental results indicate that it is possible to achieve sub-nanosecond level synchronisation required for accurate time-of-flight estimation. This, however, requires post-processing and firmware modifications in order to remove the influence of instability of the timing reference signals.