China has achieved a breakthrough in satellite-ground time synchronization, demonstrating picosecond-level accuracy using a novel carrier-phase-based method. Researchers from the National Time Service Center of the Chinese Academy of Sciences, utilizing the China Space Station (CSS)-ground system, published their findings in *Satellite Navigation*, showcasing a significant advancement over traditional pseudocode-based techniques. This method combines pseudocode with carrier phase observations, creating a robust synchronization framework. Laboratory tests confirmed picosecond-level precision, and satellite-to-ground testing showed stability improvements by nearly an order of magnitude compared to conventional methods, according to Allan Deviation analysis.
The technique compensates for motion delays, relativistic time dilation, and atmospheric perturbations through a triple-frequency mode that corrects for ionospheric and tropospheric distortions. Precise orbit determination and real-time atmospheric data further enhance accuracy, while minimizing hardware biases and short-term fluctuations. Dr. Shuaihe Gao, the lead researcher, emphasized the method's potential for space exploration and fundamental physics research.
This advancement has implications for global navigation satellite systems (GNSS), promising improved positioning accuracy for transportation, logistics, and telecommunications. It also benefits deep space exploration by enabling precise timekeeping for navigation and interstellar communication. Furthermore, it supports high-precision experiments in fundamental physics and could refine global clock networks, improving scientific measurements and time signal dissemination.