GNSS Anti-sapoofing Method Based on Signal Transmission Time Density Clustering

Satellite fault or errors in ephemeris calculation may affect satellite position, signal transmission time and other parameters, resulting in receiver positioning failure or incorrect positioning results. To cope with these abnormal situations, in addition to using RAIM method, GNSS receivers usually filter the signals according to the transmission times before performing the positioning calculation, so as to exclude these signals with notably abnormal transmission time. However, when there is spoofing interference, this way may cause all the authentic signals to be excluded, and only the spoofing signals are used for positioning calculation. When the spoofing signals satisfy the consistency, RAIM method cannot detect anomaly, which affects the safe application of satellite navigation system. Aiming at this problem, this article proposes an anti-spoofing method based on signal transmission time density clustering, and analyses the selection of the density clustering threshold. This method can not only deal with abnormal situations such as satellite fault or errors in ephemeris calculation, but also detect spoofing interference which deviates from the authentic signal transmission time to a certain extent, thus improving the anti-spoofing capability of GNSS receivers.