Abstract: Signal authentication is the key technique to meet the security requirement of next-generation GNSS civil signals.Compared with navigation message authentication(NMA),the spreading code authentication(SCA)can achieve greater security.To avoid the influence on the non-authentication users,the spreading code authentication method based on chip-level amplitude modulation(CAM-SCA)was developed.The proposed CAM-SCA method introduced the authentication feature to the chip level of GNSS civil signal by amplitude modulation.To verify the effectiveness of the proposed method,the detection probability was analyzed with the help of theory and simulation,and compared with the Chimera method adopted by GPS L1C signal.The results show that the proposed CAM-SCA method has an improvement of 2.55-2.78dB in terms of detection performance.The research results can provide a reference for the design of the next generation high-security GNSS signal.

Key words: spreading code authentication(SCA), chip-level amplitude modulation(CAM), detection probability, global navigation satellite system(GNSS)