## 5 Conclusions  
When GNSS signals are rejected, VLF radio navigation and timing can be used as a supplement and backup. Since the Alpha navigation system is the only navigation system based on VLF signals worldwide, it can provide a good signal source for VLF timing and navigation research. A multichannel orthogonal correlation method for Alpha navigation signal detection was proposed to solve the problems of noise and mutual interference in Alpha navigation signal detection. We verified the practicability of the proposed detection method and analyzed the detection performance of the method under different noise and mutual interference conditions. The results showed that the probability of successful signal detection reached more than 90% when the SNR was greater than \(-\)10 dB. The influence of mutual interference on the correlation peak of the expected signal was less than 1% when the SIR exceeded \(-\)28 dB. Hence, the proposed Alpha navigation signal detection method exhibited good performance. Finally, we designed experiments to verify the detection method using actual signals. The measured signal is the signal of the eastern secondary station, which is 6600 km from the receiving point. The quality of the signal is also very poor, and we cannot distinguish the signal through the spectrum diagram. However, after processing using the proposed method, the detection of the eastern secondary station could be easily realized. In addition to having good performance, the proposed detection method has a high application value and can be easily implemented on the hardware platform. It can fulfill the requirements of signal detection at the receiving end of navigation, timing, ionospheric research, etc. In the future, the performance of the detection method will be further improved through more advanced noise reduction processing. Conceptualization, W.Y. and S.L. ; methodology, W.Y. and X.M. ; validation, W.Y., S.L. and Y.S. ; formal analysis, Y.S. ; investigation, W.Y. and Y.S. ; resources, J.Y. ; data curation, W.Y. and J.Y. ; writing--original draft preparation, W.Y. ; writing--review and editing, W.Y. and Y.H. ; visualization, J.Y. and X.M. ; supervision, Y.H. and S.L. ; project administration, W.Y. All authors have read and agreed to the published version of the manuscript. This work was supported by the Chinese Academy of Sciences (CAS) \"Light of West China\" Program (Grant No. XAB2022 YN19) and the Open Fund Program of the Laboratory of Science and Technology on Marine Navigation and Control, China State Shipbuilding Corporation (Grant No. 2023010106). Not applicable. [PERSON] _Omega Navigation System_, 1 st ed. ; China Communication Press: Beijing, China, 1978; pp. 1-15. * [5] [PERSON]; [PERSON] Radio systems for long-range navigation. In _Aerospace Navigation Systems_, 1 st ed. ; Wiley Online Library: Chichester, UK, 2016; pp. 110-138. * [6] [PERSON]; [PERSON] Development status and trend of land-based radio navigation system. _GNSS World China_**2019**, _44_, 10-15. [CrossRef]
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