伽利略偏心轨道卫星星载原子钟在轨性能评估分析OA

In this study,1 216 consecutive days of ESA precise clock products(January 2022 to April 2025)were analyzed by combining clock-fit parameters,frequency-stability metrics,and spectral analysis to assess the long-term behavior of the onboard clocks.Results show that E14 experienced three phase jumps and two frequency jumps during this period,more frequently than nominal circular-orbit satellites.Following the frequency jump in April 2024,its frequency drift and fitting ac-curacy deteriorated markedly:residual peaks exceeded 10 ns,and an anomalous periodicity of about 0.63 h emerged with increasing amplitude and no evident secondary component.The frequency stabili-ty simultaneously worsened,showing oscillatory behavior near 100 s.After another frequency jump in March 2025,both residuals and stability improved,with stability reaching 2.50× 10-13,6.52×10-14,and 9.70 × 10-14 at 100 s,1 000 s,and 10 000 s,respectively.No dominant periodic term was ob-served afterward,but the drift exhibited a systematic bias,and a"dip"feature appeared near 4 000 s.In contrast,the co-orbital E18 satellite maintained stable performance throughout the same period,with fitting residuals confined within±0.2 ns,no significant high-frequency periodic components,and frequency stability comparable to that of nominal MEO satellites,showing no anomalous behav-ior.