Design and Simulation of a linear adaptive system to remove the CWI in Loran navigation system receivers

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Abstract

The use of Loran system is a strong defense for navigation due to its immunity against jamming and ability to penetrate indoor locations. This system can be used as a navigation aid system especially in times of crisis and GPS disconnection. Continuous Wave Interference (CWI) is one of the most important noise sources that make errors in signal phase tracking. Consequently, undesirable errors are constructed in time of arrival (TOA) measurement and ultimately navigation precision is reduced dramatically. In this paper, a new method is proposed in order to eliminate the CWI in Loran navigation system using linear adaptive algorithm. The specific innovation of this study is analyzing of Loran signal and obtaining the required delay to adopt the appropriate inputs in the adaptive filter. The used adaptive filter is the most relevant one in practical applications. The greatest advantage of the proposed method is that it dose not require knowledge of interference frequencies and frequency distribution. The proposed system is automatically obtained and eliminates interference frequency at the input. The simulation results show that the proposed algorithm provides a tremendous improvement in the SIR input. After applying the proposed algorithm, ratio of output to input of SIR, depending on the amount of SIR at the entrance of 36 to 80 dB is improved. Each iteration of the algorithm requires multiplication operator is 3N+1 (N number of adaptive filter weights), and without any restrictions implemented hardware and computational time.

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