# Adaptive Satellite Navigation Anti-Interference Algorithm Based on Inverse Cosine Function
## 5 Conclusions  
This paper proposes an LMS time-domain algorithm based on the inverse cosine function, aiming to address the vulnerability of satellite navigation receivers to narrowband interference. The algorithm exhibits fast convergence, enhanced stability, and a lower steady-state error compared to existing algorithms, thereby improving the receiver's immunity to interference. In satellite navigation signal narrowband interference suppression experiments, the algorithm in this paper significantly outperformed existing algorithms in suppressing the added narrowband interference signals. Upon capturing the navigation signal, the algorithm proposed in this paper significantly enhances the prominence of the signal's peak while effectively reducing interference peaks. As a result, the risk of incorrect navigation signal capture due to excessive interference is mitigated, leading to improved capture accuracy. The research conducted in this paper establishes a crucial theoretical foundation for mitigating narrowband interference within navigation receiver systems. Moreover, its applicability extends to other domains, such as speech processing and equipment noise reduction, catering to scenarios that require the attenuation or elimination of noise.  
Figure 9: Satellite capture results: (**a**) ICVS-LMS algorithm capture results; (**b**) LVS-LMS algorithm capture results; (**c**) VVS-LMS algorithm capture results; (**d**) NDVS-LMS algorithm capture results.  
**Author Contributions:** Conceptualization, P.Q. and Z.Y.; methodology, P.Q.; software, P.Q.; validation, P.Q., Z.Y., and E.W.; formal analysis, P.Q. and Z.Y.; investigation, P.Q.; resources, P.Q., Z.Y., and E.W.; data curation, P.Q.; writing--original draft preparation, Z.Y.; writing--review and editing, P.Q., Z.Y., E.W., S.X., and T.L.; visualization, P.Q.; supervision, P.Q.; project administration, P.Q.; funding acquisition, P.Q. and E.W. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research was funded by the National Natural Science Foundation of China under Grant 62173237; in part by the SongShan Laboratory Foundation under Grant YYJC062022017; in part by the Open Fund of State Key Laboratory of Satellite Navigation System and Equipment Technology under Grant CEPNT2022B04; in part by the Open Fund of State Key Laboratory of Satellite Navigation System and Equipment Technology under Grant CEPNT2022A01; in part by the Open Fund of Key Laboratory of Civil Aviation Flights Wide Area Surveillance and Safety Control Technology, Civil Aviation University of China, under Grant 202105; in part by the Liaoning Provincial Department of Education Project under Grant IJKZ0175; in part by the Applied Basic Research Programs of Liaoning Province under Grant 2022020502 JH2/1013; in part by the Open Fund of Key Laboratory of Flight Techniques and Flight Safety CAAC under Grant FZ021 KFI5 and Grant FZ2021 ZZ06; and in part by the Special Funds Program of Shenyang Science and Technology under Grant 22-32-3-34.  
**Data Availability Statement:** Not applicable.  
**Acknowledgments:** The authors sincerely appreciate all financial and technical support.  
**Conflicts of Interest:** The authors declare no conflict of interest.