Authors: Xueli Guo; Lei Wang*; You Li
E-mail:[email protected]
ABSTRACT
Almanac is an elegant design to help Global Navigation Satellite Systems (GNSS) signal acquisition, which has been adopted by all global satellite navigation systems. For the future low earth orbit (LEO) navigation constellation, the almanac will be more critical due to larger constellation and signal Doppler variation, while the LEO orbit prediction is more challenging due to complex perturbation forces, especially atmospheric drag. This study introduces a novel 9-parameter almanac model for LEO constellation, leveraging the empirical mode decomposition (EMD) method. Our innovative approach uniquely balance almanac accuracy and simplicity by considering the atmosphere drag effects, addressing a critical gap in existing models. The proposed almanac model is validated with four in-orbit LEO satellites at various altitudes. For the LEO with a 600 km orbit or lower, our model achieves a 50% improvement in 23-day orbit prediction accuracy compared to the classical GPS almanac model. This significant enhancement extends to visibility prediction and signal acquisition performance. Our design limits the maximum elevation angle error to less than 1.5 degrees, efficiently excluding invisible satellites during LEO navigation signal acquisition. Furthermore, for visible satellite, the proposed LEO almanac reduces the signal frequency searching range by about 20 times during acquisition, with Doppler prediction errors better than 0.5 kHz/0.3 kHz for 95% of cases. These advancements represent a substantial leap in LEO navigation technology, offering improved efficiency and accuracy for future satellite systems.
Related Papers
- 郭学立, 王磊*. 低轨卫星导航增强系统精密星历设计方法研究[J]. 大地测量与地球动力学, 2021, 41(8): 800-805.
- Guo, X., Wang, L*., Fu, W., Suo, Y., Chen, R. & Sun, H. An optimal design of the broadcast ephemeris for LEO navigation augmentation systems. Geo-spatial Information Science 25, 34-46, doi:10.1080/10095020.2021.2017760 (2022).
- Optimal Design of the Long-Term LEO Almanac by Considering the Atmosphere Drag Effects
If you use LEO-Almanac for your academic research, please cite at least one of our related papers.
Due to the huge work of LEO, all the codes are being sorted out. If you are in urgent need, please contact Xueli Guo.