Prototype Implementation of a Time Synchronization Framework based on BDS Multi-Frequency Joint Processing

The Global Navigation Satellite System (GNSS) provides an effective and reliable approach for achieving precise time synchronization with global coverage. Consequently, GNSS has been widely applied in fields such as telecommunications, financial transactions, power grid management, and data centers. Users can synchronize their local clocks to the GNSS clock system by correcting clock bias and clock drift, which are determined through the processing of GNSS signal measurements. Traditionally, this has been accomplished using single-frequency GNSS signals; however, this conventional approach is being increasingly supplanted by multi-frequency techniques, which enhance the accuracy, reliability, and robustness of time synchronization by utilizing multiple frequencies transmitted by GNSS satellites. In this paper, we aim to assess the performance of a time synchronization framework based on multi-frequency joint processing with a specific focus on the BeiDou System (BDS). The BDS is chosen due to its advantages over other GNSS systems, including its regional emphasis and well-developed frequency combinations. The framework details several methods for estimating and correcting errors to improve time synchronization accuracy. To evaluate its performance, we developed a prototype based on an FPGA/ARM platform and conducted six experiments using two independent platforms, each lasting over two hours. The experimental results demonstrate that the Root Mean Square Error (RMSE) of the 1 Pulse-Per-Second (1PPS) signal is within 10 nanoseconds, and the peak-to-peak value of the 1PPS signal is within 50 nanoseconds on average. Overall, the presented framework provides a reference for studies on time synchronization using multi-frequency joint processing, and the experimental results obtained from the self-developed prototype establish a baseline for future comparisons with advanced techniques.