Research Progress of Inter-satellite Precision Measurement and Time-Frequency Synchronization Technology Based on USO

Ultra-stable oscillator (USO) is a kind of OCXO with excellent short-term frequency stability performance. It has been gradually applied in the aerospace field such as high-precision measurement and time-frequency synchronization with very good results and exhibited huge application potential in China in recent years. Firstly, the paper outlines the characteristics of USO and the development status at home and abroad. The background of the first use of USO in China and the progress of localization is introduced. Secondly, for high-precision inter-satellite time synchronization requirements, we have achieved inter-satellite time synchronization performance with accuracy better than 0.1 ns using USO and low-orbit GPS receiver. Relevant performance evaluation method and actual measurement results are introduced. Finally, an inter-satellite ranging system combining USO and GPS precision orbit determination with actual measurement performance better than 5 um accuracy is achieved. The overall plan, evaluation mechanism, progress and results are given as well. The article gives the potential application direction of USO in the future, which has certain reference and reference significance for future gravity field detection, gravitational wave detection and load research in other scientific fields in China.