Spreading Code Authentication Technique Based on CSK Modulation

GNSS civil signal interface standard is open, malicious attackers can generate legitimate navigation signals according to the interface control document, GNSS open service signals face spoofing interference attacks. Anti-spoofing methods mainly include navigation signal detection, navigation information encryption authentication etc. Common signal authentication techniques include two types of navigation message authentication and spreading code authentication. This paper proposes a spreading code authentication method based on CSK modulation, which firstly performs CSK modulation on the authentication message chunks, and then modulates on the original satellite navigation signal by phase hopping modulation. This method improves the authentication information rate while ensuring the constant envelope signal, and gives the corresponding authentication information demodulation scheme. The analysis shows that the method can change the authentication message rate and the assigned power ratio by controlling the CSK (U, N) parameters and setting the phase hopping angle to meet the authentication requirements of different strength signals.